Service Assessment

La Plata, Maryland, Tornado Outbreak

April 28, 2002

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Weather Service

Silver Spring, Maryland
Cover Photos:

Top left: April 28, 2002, La Plata supercell. (Courtesy of William Rison)

Top right: The La Plata tornado moving southeast across Chesapeake Bay as a waterspout. 

Photograph taken from Long Beach, Maryland, April 28, 2002. (Courtesy of

Ted L. Dutcher)

Bottom left: La Plata, Maryland, tornado tracking map. (National Oceanic and Atmospheric

Administration [NOAA])

Bottom right: CVS drugstore in La Plata, Maryland. (Courtesy of Dawn Glencer)
Service Assessment

La Plata, Maryland, Tornado Outbreak of 

April 28, 2002

September 2002

U.S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr.

National Weather Service

John J. Kelly, Jr., Assistant Administrator
ii

Preface

A violent tornado, rated F4 on the Fujita Tornado Intensity Scale (see appendix A),

moved across southern Maryland and devastated the town of La Plata. Tornadoes along the

Atlantic coast are not common, and tornadoes of this magnitude are extremely rare. Only six

F4 tornadoes have occurred farther north and east of the La Plata storm: Worchester,

Massachusetts - 1953; New York/Massachusetts - 1973; Windsor Locks, Connecticut - 1979;

five counties in New York - 1989; New Haven, Connecticut - 1989; North Egremont,

Massachusetts - 1995. None were as close to the coast. The tornado traveled across the

Chesapeake Bay almost to the Atlantic.

Due to the magnitude and rarity of this event in this part of the country, a service

assessment team was formed to examine the warning and forecast services provided by the

National Weather Service (NWS) to emergency managers, government agencies, and the public

in southern Maryland. Service assessments provide a valuable contribution to our ongoing

efforts to improve the quality and timeliness of our products and services for the protection of

life and property. Findings and recommendations from this assessment will improve techniques,

products, and services.

John J. Kelly, Jr.

Assistant Administrator

 for Weather Services

September 2002
iii

Table of Contents

Page

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

Service Assessment Team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

Acronyms ....................................................................v

Service Assessment Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Facts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Findings and Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Best Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Appendix A Fujita Tornado Intensity Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Appendix B Maryland Tornado Fatalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Appendix C Maryland Tornado Outbreak of April 28, 2002, 

WFO Baltimore/Washington Chronological Product Highlights . . . . . . . . . . . C-1
iv

Service Assessment Team

The service assessment team was activated on May 1, 2002. Team members visited the

La Plata, Maryland, damage area, Charles and Calvert County emergency management, local

radio and TV stations, and the Weather Forecast Office (WFO) Baltimore/Washington. In

addition, telephone interviews were conducted with the Storm Prediction Center (SPC) and

WFO Wakefield, Virginia. The team comprised the following individuals.

John Ogren Team Leader, Meteorologist in Charge (MIC), WFO Indianapolis, Indiana

Richard Kane Warning Coordination Meteorologist (WCM), WFO Pittsburgh,

Pennsylvania

Steve Brueske Science and Operations Officer (SOO), WFO Charleston, South Carolina

Michael Vescio SOO, WFO Ft. Worth, Texas

John Leslie Public Affairs Specialist, NWS Headquarters, Silver Spring, Maryland

Wayne Presnell NWS Headquarters, Office of Climate, Water, and Weather Services

(OCWWS), Silver Spring, Maryland

Tim Marshall Consultant, Haag Engineering, Carrollton, Texas

Other valuable contributors include:

William Lerner NWS Headquarters, OCWWS, Silver Spring, Maryland

Linda Kremkau NWS Headquarters, OCWWS, Silver Spring, Maryland

Special thanks to:

Frank Lucia Federal Communications Commission, Retired
v

Acronyms

AWIPS Advanced Weather Interactive Processing System

BPAT Building Performance Assessment Team

CWA County Warning Area

EAS Emergency Alert System

EDT Eastern Daylight Time

FCC Federal Communications Commission

FEMA Federal Emergency Management Agency

HMT Hydrometeorological Technician

MIC Meteorologist in Charge

NAWAS National Warning System

NCF Network Control Facility 

NOAA National Oceanic and Atmospheric Administration

NWR NOAA Weather Radio

NWS National Weather Service

OCWWS Office of Climate, Water, and Weather Services

QRT Quick Response Team

SAME Specific Area Message Encoding

SOO Science and Operations Officer

SPC Storm Prediction Center

TVS Tornado Vortex Signature

WCM Warning Coordination Meteorologist

WDM Warning Decision Making

WERC Wind Engineering Research Council

WES Weather Event Simulator

WFO Weather Forecast Office

WSR-88D Weather Surveillance Radar-1988 Doppler
1

Service Assessment Report

Introduction

On Sunday evening, April 28, 2002, a violent F4 tornado carved a 64-mile path across

southeast Maryland. The La Plata, Maryland, tornado was part of a large severe weather

outbreak that began in the mid-Mississippi Valley early on that day and spread across portions of

the Ohio Valley and Mid-Atlantic States. In Maryland, 3 deaths and 122 injuries were a direct

result of the storm (see appendix B). Property damage exceeded $100 million. This is not the

deadliest tornado to strike La Plata. In 1926, a tornado killed 14 children at a school.

An NWS service assessment team was formed to review the products and services

provided by the Storm Prediction Center (SPC) and the Weather Forecast Offices (WFOs)

Baltimore/Washington and Wakefield, Virginia. Emergency managers, people in the media, and

local residents were interviewed to obtain feedback on NWS performance. The assessment team

learned NWS customers and partners were satisfied with the information received before and

during the La Plata tornado. Critical warnings reached the public despite the failure of one part

of the dissemination system (see “Dissemination” section). NWS policy of using multiple

dissemination methods worked during this event and remains a vital component of the NWS

mission of protecting life and property.

One purpose of service assessments is to identify issues and recommend improvements. 

In this case, the La Plata service assessment team identified three such issues: Emergency Alert

System (EAS), WFO Baltimore/Washington warning decision process, and tornado intensity

rating. These are discussed in detail in this report.

Overview

The weather system spawning the La Plata tornado contained the large-scale features

typical of significant severe weather episodes (see figures 1a and 1b). A strong upper-level

trough moved rapidly from the Ohio Valley to the Mid-Atlantic coast during the day. Jet stream

winds greater than 90 mph were associated with the upper system and contributed to an

atmosphere conducive to the development of supercell thunderstorms and tornadoes. Supercell

thunderstorms are the most violent type of severe thunderstorm and produce large hail,

damaging winds, and the majority of the tornadoes that occur across the United States. Supercell

thunderstorms developed during the late morning over Ohio and Kentucky along a strong cold

front and in association with the upper system. These storms raced eastward and crossed the 
2

Figure 1a. Composite map from 7 a.m. EDT, Sunday, April 28,

2002, depicting the surface fronts, surface dew points (dashed

lines) and upper level jet stream wind (solid lines). (NOAA)

Figure 1b. Composite map from 7 p.m. EDT, Sunday, April 28,

2002, depicting the surface fronts, surface dew points (dashed

lines) and upper level jet stream wind (solid lines). (NOAA)
1

 All times listed in this service assessment are EDT.

3

Appalachian Mountains between 3 and 4 p.m. Eastern Daylight Time (EDT).1

 Many of the

storms weakened as they crossed the high peaks of the Blue Ridge Mountains. However, the

storm that struck La Plata remained a strong supercell as it moved from West Virginia through

northern Virginia into southern Maryland.

In the La Plata area, a warm front was located just south of the town early Sunday

morning (see figure 1a). Cool air reinforced by clouds and precipitation led to a stable air mass

early in the day. However, the warm front moved north of the area by midday (see figure 1b),

resulting in rapid air mass destabilization and provided ideal conditions for severe weather as the

supercell moved into the area.

The La Plata tornado first touched down at 6:56 p.m., south of the town of Marbury in

western Charles County, Maryland (see photo 1, aerial view of the tornado track; and figure 2,

map of the entire tornado track and an inset of the tornado path through La Plata). Although

initial damage was minimal, the tornado intensified as it approached the town of La Plata, and

F3 damage occurred in two subdivisions west of town. Damage and eye witness accounts

indicate a second weaker tornado formed a quarter of a mile south of the first tornado. Both

tornadoes crossed the heart of La Plata between 7:02 p.m. and 7:07 p.m., causing widespread F2-

F3 damage. Destruction in a one-square-block area on the east side of La Plata was most severe

and rated F4 (see photo 2 of downtown La Plata F4 damage). The secondary tornado dissipated

while the main tornado continued moving east through the rest of Charles County. Although

much of the area east of La Plata was rural, 100 homes, 49 businesses, and numerous barns were

destroyed. Acres of dense forest were leveled. At 7:30 p.m., the tornado crossed into Calvert

County where it killed an elderly couple and destroyed an additional 10 homes and damaged

another 125. It moved out onto the Chesapeake Bay just north of the Calvert Cliffs Nuclear

Power Plant. A secondary vortex, a waterspout, formed for a few miles on the Bay. The

primary tornado continued across Dorchester County again intensifying to F3 before dissipating

as it approached Salisbury, Maryland.

WFO Baltimore/Washington has warning and forecast responsibility for a small part of

the West Virginia Panhandle, extreme northern Virginia, and most of Maryland, including

Charles and Calvert Counties. On the day of the tornado, the office issued all its routine

products, a 13-county flood watch, a flash flood warning, 14 tornado warnings, 13 severe

thunderstorm warnings, 4 special marine warnings, plus many special and severe weather

statements. The Science and Operations Officer (SOO) stated that April 28 was “the busiest day

he had worked in the last 8 years.”

The forecast office issued its first tornado warning for Shenandoah County, Virginia, at

4:37 p.m. for the thunderstorm that eventually spawned the La Plata tornado. The storm

produced a tornado south of Mount Jackson at 4:55 p.m. Subsequent tornado warnings were
4

Photo 1. Aerial view of tornado path looking east toward La Plata, Maryland. Dots indicate

the center of damage path. The tornado traveled through the Quailwood Subdivision in the

foreground destroying several homes along Morgans Ridge Road. (Courtesy of Tim Marshall,

Haag Engineering)
5

Figure 2. Map of the tornado track and an inset of the tornado track through LaPlata, MD. (NOAA)
6

Photo 2. Aerial view showing F4 damage to two homes in downtown La Plata, Maryland. 

These homes were downwind of a lumber yard and impacted by its debris. (Courtesy of Tim

Marshall, Haag Engineering)
7

issued along the storm’s path across northern Virginia through 6:45 p.m., but no additional

tornadoes occurred. A severe thunderstorm warning was issued for northern Charles and Calvert

Counties at 6:45 p.m. The call-to-action statement mentioned the possibility of tornadoes: 

“SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO

ADVANCE WARNING....” At 7:02 p.m., 6 minutes after the tornado touched down, the tornado

warning was issued for Charles and Calvert Counties.

Warning and Forecast Services

WFO Baltimore/Washington

Before the Event

The Baltimore/Washington WFO preplanning was excellent. Awareness of the potential for

severe weather prior to the onset of this event was extremely high. Planning began Saturday

afternoon, April 27, the day before the tornado. People scheduled on the Sunday, April 28, evening

shift were prepared to come in early should severe weather develop. The Network Control Facility

(NCF) was notified at 8:30 a.m., Sunday morning, April 28, to put the Baltimore/Washington WFO

in a critical weather watch for the Advanced Weather Interactive Processing System (AWIPS). The

NCF serves as the AWIPS control center and identifies, diagnoses, and corrects system faults and

outages; monitors site equipment operations; and alerts users at each site when malfunctions or

degradations occur. During critical weather situations, the WFO may ask the NCF to keep a closer

eye on AWIPS operations. Two additional forecasters arrived at the WFO by 2 p.m. and an

additional Hydrometeorological Technician (HMT) arrived by 4 p.m. A short meeting was held at

3 p.m., Sunday, April 28, to determine staff responsibilities.

Several outlook and forecast products were issued for the severe weather threat over Virginia

and Maryland. The first mention of possible severe weather was in the Baltimore/

Washington WFO’s Hazardous Weather Outlook issued at 5:25 a.m., Saturday, April 27. It stated,

“SOME OF THESE STORMS MAY BE ON THE STRONG SIDE...WITH GUSTY WINDS THE

PRIMARY THREAT.” At 3:20 a.m., Sunday, April 28, another Hazardous Weather Outlook was

headlined, “POSSIBLE SEVERE THUNDERSTORMS TODAY.” The Outlook focused on

damaging winds during the afternoon. The 10:30 a.m., Sunday, April 28, Hazardous Weather

Outlook was the first to mention a tornado threat and gave the specific times: between 3 p.m. and 8

p.m. SPC issued a tornado watch at 3:30 p.m.
8

During the Event

The Baltimore/Washington WFO was staffed with eight people, including the Meteorologist

in Charge (MIC), Warning Coordination Meteorologist (WCM), SOO, three lead forecasters, and

two HMTs.

The WFO began issuing warnings when the La Plata supercell first entered its county

warning area (CWA). Warning forecasters issued the first tornado warning for Shenandoah County,

Virginia, at 4:37 p.m., and a tornado touched down south of Mount Jackson at 4:55 p.m. This F2

tornado destroyed 3 homes, 19 barns, and damaged 27 other residences. While the WFO received

confirmation of the Shenandoah tornado, this confirmation was not passed to the warning forecasters

during the event. Based on radar, the warning forecasters issued additional tornado warnings

between 5 and 6:45 p.m. as the storm crossed Virginia. SKYWARN spotters and county warning

points reported a funnel cloud, wind damage, and large hail associated with the storm, but no

additional tornadoes. Without a confirmed tornado report, and believing the supercell’s tornadic

potential was decreasing, the warning forecasters issued a severe thunderstorm warning for Charles

and Calvert Counties at 6:45 p.m. The call-to-action statement in the severe thunderstorm warning

did state, “SEVERE THUNDERSTORMS CAN PRODUCE TORNADOES WITH LITTLE OR NO

ADVANCE WARNING....” 

Another forecaster working the severe weather episode called the Charles County 

9-1-1 Operations Center between 6:10 and 6:20 p.m. to discuss the approaching storm. This

forecaster stated, “There is a tornadic thunderstorm headed your way.” Charles County personnel

informed the forecaster they were watching the storm on radar and knew they were in a tornado

watch.

The thunderstorm crossed the Potomac River into Maryland where the La Plata tornado first

touched down near Marbury at 6:56 p.m. At 7:02 p.m., 6 minutes after the tornado touched down, a

tornado warning was issued for Charles and Calvert Counties. As the tornado warning was being

issued, another forecaster called Charles County personnel in La Plata to warn them that radar

indicated a tornado, but it took three attempts to get through because damage calls from Ripley and

other locations west of La Plata were already clogging the telephone lines. The first fatality

occurred 8 minutes later at 7:10 p.m. in La Plata. At 7:30 p.m., two more people died as the tornado

entered Calvert County. See appendix C for WFO Baltimore/Washington chronological product

highlights.

After the Event/Damage Assessment

Tornadoes are rated using the Fujita Tornado Intensity Scale or F-scale, which is named after

Dr. T. Theodore Fujita, former professor of Meteorology, University of Chicago. The 

F-scale is a subjective visual interpretation used by the NWS to rate the worst building damage

anywhere along the path from 0 to 5, with 5 being the most destructive (see appendix A). 

Empirically-derived wind speed ranges are also associated with the F-scale. An accurate F-scale

rating is important for historical, statistical, and climatological reasons and allows the public to get a

sense of the storm’s destructive force.
9

WFOs assign an F-scale rating for tornadoes occurring in their CWAs except when a service

assessment is undertaken. In those cases, the WFO rating is preliminary and the assessment team in

coordination with the WFO assigns a final F-scale. WFO Baltimore/

Washington surveyed the damage in La Plata, Monday, April 29. The WFO first rated the tornado

an F4, but later raised the assessment to F5, based on building damage just east of downtown La

Plata. This information was disseminated to the public and media through Public Information

Statements and a news story prepared by the NWS Public Affairs Office without a “preliminary”

indicator. Subsequent updates to the news story did contain the word “preliminary.” Current policy

states “preliminary” should be used whenever a service assessment is possible. (Weather Service

Operations Manual Chapter J-02, Significant Hydrometeorological Events, Post-storm Data

Acquisition, and Service Assessments, section 6: “If unsure whether a service assessment...is

needed, the local office shall indicate that F-scale determinations are preliminary and subject to

revision after further analysis.”) The assessment team concluded the Baltimore/Washington WFO

was unsure if a service assessment would be undertaken. Also, the assessment team questioned

whether “preliminary” is a strong enough word to allow for any subsequent change to the rating. 

(Finding 1)

As mentioned above, Baltimore/Washington WFO personnel rated the worst damage F5. 

This preliminary F5 rating to a brick building in downtown La Plata (see photo 3) was lowered to F4

after the assessment team determined some of the damage was due to flying debris from a lumber

company upwind. Damage to homes rated F5 by the WFO were lowered to F4 when the assessment

team’s structural engineer, Tim Marshall, performed a detailed analysis of the construction. He

determined these homes were not adequately anchored causing them to fail at a lesser wind force

(see photos 4 and 5). In some cases, destroyed homes still had mailboxes and storage sheds left

intact (see photo 6). WFO personnel who are trained in damage assessment receive it only once. In

addition, violent F4 and F5 tornadoes are extremely rare, and there are few opportunities to view

storm damage of this magnitude. (Finding 2)

The assessment team learned building damage surveys were being done by the Federal

Emergency Management Agency’s (FEMA) Building Performance Assessment Team (BPAT) and

Wind Engineering Research Council (WERC) at the same time the NWS was conducting their

damage survey. (Finding 3)

After the tornado event on Sunday, April 28, Jim Travers, MIC, and Barbara Watson, WCM,

WFO Baltimore/Washington, spent approximately 12 hours conducting interviews with national and

local media. Most media reports were positive or neutral. A Public Affairs officer was present at

the WFO Baltimore/Washington all day, Monday, April 29, and most of the next day. NOAA

praised NWS Public Affairs staff for preparing news stories and updates.
10

Photo 3. Aerial view of a lumber yard and downed water tower in downtown La

Plata, Maryland. (Courtesy of Tim Marshall, Haag Engineering)

Photo 4. Aerial view of residential damage in the Quailwood Subdivision looking

east. Several poorly attached homes slid off their foundations and rated F1. (Courtesy

of Tim Marshall, Haag Engineering)
11

Photo 5. Aerial view looking east of residential damage at end of Hawkins Gate

Road, located just east of La Plata, Maryland. Split-level homes slid off their

foundations into a ravine. The home had been anchor-bolted to its foundation but

failed where the wall studs were straight nailed to the bottom plate. (Courtesy of

Tim Marshall, Haag Engineering)

Photo 6. Poorly anchored home on Morgans Ridge Road was swept clean off its

foundation while mailboxes remained undamaged. This example illustrates the

difficulties in assigning an F-scale rating. (Courtesy of Tim Marshall, Haag

Engineering)
12

WFO Performance

WFO Baltimore/Washington fulfilled its mission by issuing timely warnings, forecasts, and

statements, and maintaining frequent contact with partners. Customers and partners were satisfied

with the services provided. The team did note some areas where services could be improved.

The assessment team focused on why the warning forecasters decided to issue a severe

thunderstorm warning rather than a tornado warning for Charles County and La Plata when tornado

warnings had been issued for this storm in Virginia. Based on their responses, the assessment team

identified four factors: warning forecasters did not receive a confirmed report of a tornado; radar

indications of a weakening supercell; lack of a continuous weather watch on the supercell; and

concern over false alarms. The combination of these four factors led to the decision to issue a severe

thunderstorm warning. (Finding 4)

Warning forecasters did not receive a confirmed report of a tornado. As mentioned earlier,

WFO staff received confirmation of a tornado in Shenandoah County, but this confirmation was not

communicated to the warning forecasters. WFO Baltimore/Washington policy states when a person

receives a severe weather report, this information is to be passed immediately to the warning team.

The NWS offers a 4-day Warning Decision Making (WDM) Workshop. One of the subjects

is “Strategies for Optimizing Severe Weather Performance.” A key topic covered is the importance

of effective communication within the office: “Do everything you can to ensure critical information

is relayed to those who need it as quickly as possible and that open communication is encouraged.”

Radar indications of a weakening supercell. Based on radar indications, the warning

forecasters thought the storm was weakening and losing its potential to produce a tornado. 

Assessment team members reviewed the archived data from the Weather Surveillance Radar-1988

Doppler (WSR-88D) and found the significant hook echo, or pendant, evident on the lowest radar

scans from 6:10 to 6:20 p.m. on the southwest side of the storm, had dissipated by the 6:30 to 6:40

p.m. scans. Hook echos at low levels are frequently indicative of rotating storms and often indicate

tornadoes, but are only one of the several signatures available to identify severe storms. In addition,

at 6:20 p.m., the WSR-88D’s algorithms did not indicate a mesocyclone (a deep, symmetrical,

rotating vortex) or a Tornado Vortex Signature (TVS) previously identified in the storm. Cycles of

weakening and regeneration are common in long-lived supercell thunderstorms.

Despite the loss of the hook echo signature, at 6:35 p.m. the radar’s Tornado Vortex

Detection algorithm indicated a TVS that extended from the lowest level observed by the radar

(1,800 feet above ground at the particular storm’s location) to over 10,000 feet. The detection of

this signature automatically triggered an alarm on the AWIPS that the warning forecasters noticed. 

In addition, the radar’s mesocyclone detection algorithm identified a mesocyclone within the storm

that extended from 9,200 feet to 20,500 feet within the storm. From 6:35 p.m. (21 minutes before

tornado touchdown) until the storm reached the Patuxent River over an hour later, the WSR-88D’s

algorithms continuously identified both the mesocyclone and TVS. This final TVS was the first

signature associated with a tornado since the Shenandoah storm.
13

The WDM Workshop provides guidelines on optimizing procedures for efficient analysis of

severe weather. The guidelines recommend “Be very slow to downgrade from a Tornado Warning

to a Severe Thunderstorm Warning.” Eastern Region’s Severe Weather Best Practices Web site

states, “It is a good rule of thumb to continue tornado warnings for a few volume scans following

the dissipation of the radar-observed vortex signature.”

Lack of a continuous weather watch on the supercell. Two forecasters combined their efforts

to issue warnings for the entire CWA. When the La Plata tornado first touched down, the warning

forecasters were issuing a severe thunderstorm warning for Anne Arundel, Howard, and

Montgomery Counties in Maryland at 6:58 p.m. This practice prevented a full weather watch by the

warning team on more than one part of the CWA at any given time.

The May 3, 1999, Oklahoma/Southern Kansas Tornado Outbreak Service Assessment

recommends as a best practice “Sectorization of Warning Operations.” The Performance Strategies

section of the WDM Workshop recommends use of a team-centered approach of sectorized

operations using multiple workstations.

Concern over false alarms. In recent years, the NWS has emphasized improving products

and services. The warning forecasters believed the emphasis was on verification scores and that

perception led to false alarm concerns. In this case, several tornado warnings issued for Virginia

had not verified. 

Eastern Region’s Severe Weather Best Practices Web site states, “When supercells are

possible and/or indicated by radar, it is important to err on the side of safety and issue a tornado

warning,” and “Since supercells are relatively rare, we are not increasing the FAR [False Alarm

Rate] much if a given supercell...doesn’t produce a tornado.” In November 2000, the Director,

Eastern Region, discussed the importance of performance rather than focusing on statistical

measures of performance, including false alarm rates, with the WFO Baltimore/

Washington staff.
14

WFO Wakefield, Virginia

The WFO in Wakefield, Virginia, provided good warning and forecast services for the

La Plata tornado as it moved through Dorchester and Wicomico Counties. WFO Wakefield’s CWA

was located on the southeastern fringe of the severe weather area that occurred on Sunday, April 28. 

SPC outlooks indicated Wakefield’s CWA had a slight risk of severe weather and WFO Wakefield’s

public products blended well with these outlooks.

The La Plata tornado crossed the Chesapeake Bay, moved across Dorchester County with

maximum F3 intensity, and dissipated in Wicomico County. Tornado warnings were issued for both

counties. Lead time was 11 minutes for Dorchester County, and 7 minutes for Wicomico County. 

There were no fatalities or injuries, all systems performed adequately, and staffing was sufficient for

the event.

Storm Prediction Center

The SPC, part of the National Centers for Environmental Prediction, provided good outlook

and watch services for the April 28 severe weather outbreak.

The SPC put much of the Mid-Atlantic region in a slight risk of severe weather in the Day 2

Outlook issued at 3 a.m., Saturday, April 27. The Outlook stated the primary risk was for damaging

winds. However, the Outlook stated, “THE TORNADO/HAIL THREAT IS CONDITIONAL

BASED ON THE DEGREE OF DESTABILIZATION. IF CONFIDENCE INCREASES...AN

INCREASE TO MODERATE RISK MAY BE NECESSARY.”

The Day 1 Outlook, issued at 2 a.m., Sunday, April 28, forecast a moderate risk of severe

weather for the central Appalachians and the Mid-Atlantic States. The Outlook stated the primary

threat was for widespread damaging winds. An update was issued at 9 a.m., stating, “ISOLATED

TO SCATTERED SEVERE STORMS...POSSIBLY SUPERCELLS...CANNOT BE RULED OUT

FROM THE D.C. AREA ACROSS VA. DURING THE EVENING.” SPC issued a tornado watch

at 3:05 p.m., valid from 3:30 p.m. until 9 p.m., for Washington, DC; Maryland; and western and

central Virginia.

Partner and Customer Coordination and Response

The effectiveness of the weather warning system is dependent on close coordination,

cooperation, and a clear consistent message among the various agencies responsible for public

safety. This includes the NWS, the media, and state and local governments. Customers said they

were satisfied with the warning, forecast, and other services provided before, during, and after the

event.
15

Emergency Management

There is excellent communication between WFO Baltimore/Washington and state and local

emergency management. When asked, Charles County Emergency Management Director, Don

McGuire, stated, “We have a very good working relationship with the Baltimore/

Washington NWS office. We routinely call the office for weather updates.” This sentiment was

echoed by Calvert County Emergency Management Director, Don Hall. A review of the past

2 years of emergency management contacts show numerous meetings where issues were discussed.

Mr. McGuire said he was very pleased with the speed at which the WFO Baltimore/

Washington conducted the preliminary investigation the day immediately after the storm. By midweek, the potential for more severe weather threatened recovery and cleanup operations. The NWS

provided frequent and timely weather briefings to the Emergency Operations Center throughout the

afternoon of Thursday, May 2. The Charles County emergency management director was very

grateful for the additional weather support by the NWS.

Media

Overall, the Washington, DC, area television weathercasters complimented the WFO

Baltimore/Washington on the quality of service. None of the TV weathercasters mentioned

problems receiving the warnings and forecasts from the Baltimore/Washington WFO. For example,

Tony Pann, weekend meteorologist at the CBS affiliate WUSA-TV (Channel 9), said the services

and products from WFO Baltimore/Washington during the April 28 tornado event were

“outstanding, excellent, timely, and the duration of the warnings was very good.” Topper Shutt,

chief meteorologist at the station said, “[WFO] Sterling could have been a little ahead of the game

with the Charles County tornado warning, but I am very happy with their services during this

event.”

Doug Hill, the chief meteorologist at the ABC affiliate WJLA-TV (Channel 7), said,

“Jim Travers runs a great shop.” However, he added the NWS should look into installing

a separate telephone line only for local TV weathercasters to access a forecaster. The

Baltimore/Washington WFO, as do many forecast offices, has a media line. During major events

like this, these phone lines are in heavy use and often busy. Based on the collective expertise and

experience of the assessment team, it concluded additional phone lines will not improve this

situation.

Two local radio stations noted they did not receive EAS activation notification. Dave

Garner, WTOP radio, Washington, DC, said, “...not receiving the alert [EAS codes] from Sterling

was unusual. Usually we receive more than we need, an overload.” WTOP radio monitors the

Manassas, Virginia, NOAA Weather Radio (NWR) transmitter and is the state EAS relay point for

the Washington, DC, metropolitan area. Mike Friedman, WJFK radio, echoed Mr. Garner’s

comments noting flood products from the WFO were received during the morning, but no watches

or warnings were received during the afternoon. More detail on this subject is contained in the

“Dissemination” section.
16

Radio station WSMD in Mechanicsville, Maryland, serves the southern Maryland listening

area. The station was off the air during the time the tornado warning was issued due to a power

failure. When power was restored, the station received the warning from a TV station and

rebroadcast it. Station spokeswoman, Heather Kincaid, said she was pleased with WFO

Baltimore/Washington’s services during the event.

News articles generally discussed the tornado watch and warnings being issued well in

advance and being widely received. An April 29, 2002, Washington Post article stated, “despite

tornado alerts that the NWS began issuing, many people said they had known nothing about the

impending danger.” An April 29, 2002, New York Times article quoted Charles County

spokeswoman, Nina W. Voehl, “the National Weather Service issued a tornado warning (watch)

[sic] four hours before La Plata was hit. But residents said they became aware of one only when

they saw the tornado and heard it.” This was confirmed in interviews where most people said they

were not paying close attention to the media on a Sunday afternoon.

Public

La Plata area residents interviewed by the assessment team knew severe weather was

possible that afternoon. Most heard watches over The Weather Channel and local TV or radio

stations. When warnings where issued, some mentioned local TV stations’ crawlers only contained

information pertaining to the type of warning and county affected. One Calvert County resident

whose home was just missed by the tornado said, “I saw the tornado warning on Channel 9, then I

didn’t see a thing outside because I ran to my basement!”

Even though a tornado watch was issued well in advance and a severe thunderstorm warning

was in effect 11 minutes before the tornado touched down, people not tuned to a media source did

not believe there was a threat. Most of these people took action based on seeing the tornado or

being told by neighbors. Many La Plata residents did follow the correct safety procedures by taking

shelter from the tornado.

Dissemination

Weather warnings are disseminated by various voice and text methods. The NWS broadcasts

over NWR, National Warning System (NAWAS), telephone, and amateur radio networks. Text

dissemination methods include NOAA Weather Wire Service, Family of Services, Internet, and

Emergency Management Weather Information Network.
17

Emergency Alert System

There was a problem with the EAS activation process. EAS is a Federal Communications

Commission (FCC) program for TV and radio stations to relay emergency alerts, including tornado

watches and warnings, to the public. EAS receivers are certified by the FCC. NWS activates EAS

with text messages through government and private vendors’ dissemination systems and audio

messages through NWR. TV stations broadcasting in the La Plata listening area had no problem

receiving severe weather warning information during this event. Radio stations use NWR which

activates EAS when warnings containing digital Specific Area Message Encoding (SAME) are

broadcast. Problems with EAS activation were limited to radio stations.

Radio station WTOP in Washington, DC, is the Local Primary 1 (LP1) EAS station. It 

distributes information to, and is monitored by, 25 radio stations throughout the Washington, DC,

region. Radio station WJFK in Manassas, Virginia, is the Local Primary 2 (LP2) EAS station and

serves as a backup to WTOP. Other stations voluntarily monitor NWR as an additional backup to

WTOP/WJFK. Team members interviewed the chief engineer at WTOP. He stated the radio station

did not receive the NWR SAME alerts for tornado watches and warnings issued on Sunday,

April 28, and the EAS was not activated for the La Plata tornado. The WTOP engineer also said,

“We received flash flood watches earlier in the day but did not receive any watches or warnings

during the afternoon.” Fifty-three percent of radio stations broadcasting into the La Plata listening

area experienced similar problems.

Frank Lucia (a retired FCC employee and EAS expert) and team members contacted 16 radio

stations whose broadcast areas include La Plata. Of the 16, 7 radio stations received all watches and

warnings broadcast via NWR on April 28. The 9 stations that did not, all use 

FCC-certified equipment manufactured by the same company. Eight of these radio stations received

watch and warning information from alternate sources and rebroadcast it to the public.

A test was conducted using the identical NWR SAME location codes as were used on April

28. The 9 receivers failed again. In discussions with the company, Mr. Lucia learned when more

than 28 NWR SAME location codes are transmitted to a receiver manufactured in 1996/1997, and

the station’s NWR is plugged into Channel 3 or higher, the system fails. The only WFOs in the

NWS that transmit more than 28 NWR SAME location codes on a single transmitter are WFOs

Baltimore/Washington and Blacksburg, Virginia. The receiver manufacturer and the radio stations

are working to rectify the problem. (Finding 5)
18

NOAA Weather Radio

NWR is the NWS’s direct method of disseminating weather warnings to the public. Several

NWS employees received warnings through NWR. However, there is limited knowledge of NWR

among La Plata area residents.

• There was no NWR receiver in the Charles County Sheriff’s office which is the 

9-1-1 Operations Center and contact point for the NWS.

• One law enforcement officer mentioned when he sees a warning on TV, he usually

tunes to the main radio station in the area, WSMD. However, the station lost power

and was off the air. This same officer was asked if he owned an NWR receiver. He

did not know about NWR but when it was described to him, he said, “No, but I’m

going to get one now!”

• Of the 40 residents interviewed, only one Charles County resident knew about NWR

but heard the warning from a TV station.

WFO Baltimore/Washington has conducted numerous NWR outreach activities. In June

2002, Maryland Gov. Parris N. Glendening distributed NWR receivers to all schools in Maryland. 

This project began well before the La Plata tornado.

NAWAS

NAWAS is a FEMA communications “hotline” used by NWS and state and local

emergency management to communicate critical weather information. Maryland’s county

emergency management community relies heavily on the NAWAS circuit for the exchange of

severe weather information between individual counties and the NWS. Maryland is one of the

few states with an NAWAS drop in each of its counties. However, Charles and Calvert Counties are

unable to monitor the exchange of severe weather information between Virginia and the NWS.

The Charles County emergency management director stated he needs more advance notice

and would like a “heads up” when severe weather is over Virginia and before warnings are issued

for southern Maryland. The assessment team found the WFO communicated directly with Charles

County several times before and during the event. This included notification of the tornado watch

and the severe thunderstorm and tornado warnings, as well as a “heads-up” call indicating the

potential for tornadic storms about 40 minutes before tornado touchdown. (Finding 6)
19

Facts

Introduction

FACT: On Sunday evening, April 28, 2002, a violent F4 tornado carved a 64-mile path

across southeast Maryland.

FACT: The assessment team learned NWS customers and partners were satisfied with the

information received before and during the La Plata tornado. 

Overview

FACT: Destruction in a one-square-block area on the east side of La Plata was most severe

and rated F4.

Warning and Forecast Services

WFO Baltimore/Washington

Before the Event

FACT: The Baltimore/Washington WFO preplanning was excellent.

During the Event

FACT: Without a confirmed tornado report, and believing the supercell’s tornadic potential

was decreasing, the warning forecasters issued a severe thunderstorm warning for

Charles and Calvert Counties at 6:45 pm.

FACT: At 7:02 p.m., 6 minutes after the tornado touched down, the tornado warning was

issued for Charles and Calvert Counties.

After the Event/Damage Assessment

FACT: Baltimore/Washington WFO personnel rated the worst damage F5. 
20

WFO Performance

FACT: The assessment team focused on why the warning forecasters decided to issue a

severe thunderstorm warning rather than a tornado warning for Charles County and

La Plata and identified four factors: warning forecasters did not receive a confirmed

report of a tornado; radar indications of a weakening supercell; lack of a continuous

weather watch on the supercell; and concern over false alarms.

Partner and Customer Coordination and Response

Emergency Management

FACT: Charles County Emergency Management Director, Don McGuire, stated, “We have a

very good working relationship with the Baltimore/Washington NWS office. We

routinely call the office for weather updates.” 

Media

FACT: Topper Shutt, chief meteorologist at the station said, “[WFO] Sterling could have

been a little ahead of the game with the Charles County tornado warning, but I am

very happy with their services during this event.”

Dissemination

Emergency Alert System

FACT: There was a problem with the EAS activation process. Fifty-three percent of the

radio stations broadcasting into the La Plata listening area experienced problems.
21

Findings and Recommendations

Warning and Forecast Services

WFO Baltimore/Washington

After the Event/Damage Assessment

Finding 1: The WFO first rated the tornado an F4, but later raised the assessment to

F5. This information was disseminated to the public and media without a

“preliminary” indicator. Current policy states “preliminary” should be

used whenever a service assessment is possible. 

 

Recommendation 1a: The Office of Climate, Water, and Weather Services (OCWWS) should

create a national Quick Response Team (QRT) to determine the final

rating for all tornadoes suspected to be F4 or F5.

Recommendation 1b: OCWWS should modify appropriate directives and require WFOs to use

“potentially greater than F3" whenever tornado damage of F4 or F5

intensity is suspected and until the QRT makes its final determination.

Finding 2: WFO personnel who are trained in damage assessment receive it only

once. In addition, violent F4 and F5 tornadoes are extremely rare, and

there are few opportunities to view storm damage of this magnitude. 

Recommendation 2: OCWWS should provide WFOs with a standardized damage assessment

guide.

Finding 3: The assessment team learned building damage surveys were being done

by the Federal Emergency Management Agency’s (FEMA) Building

Performance Assessment Team (BPAT) and Wind Engineering Research

Council (WERC) at the same time the NWS was conducting their damage

survey.

Recommendation 3: OCWWS should work to establish Memoranda of Understanding with

FEMA and WERC to create a notification process when assessment teams

are deployed.
22

WFO Performance

Finding 4: Warning forecasters decided to issue a severe thunderstorm warning rather

than a tornado warning for Charles County and La Plata because: warning

forecasters did not receive a confirmed report of a tornado; radar

indications of a weakening supercell; lack of a continuous weather watch

on the supercell; and concern over false alarms.

Recommendation 4a: OCWWS, in cooperation with Regional Scientific Services Divisions,

should summarize practices for severe weather operations contained in the

WDM Workshop and in service assessment/regional best practices, and

provide material to all WFOs. Internal office communication, radar

analysis, sectoring of warning operations, and performance principles

should be included.

Recommendation 4b: Regions should ensure WFOs review the severe weather operations

summary material through station drills and a demonstration of

proficiency prior to each severe weather season.

Dissemination

Emergency Alert System

Finding 5: The 9 radio stations that did not receive NWR SAME messages all have

FCC-certified EAS equipment manufactured by the same company. The

receiver manufacturer and the radio stations are working to rectify the

problem. 

Recommendation: 5: OCWWS should monitor actions by the receiver company.

NAWAS

Finding 6: The Charles County emergency management director stated he needs

more advance notice and would like a “heads up” when severe weather is

over Virginia and before warnings are issued for southern Maryland.

Recommendation 6: WFO Baltimore/Washington and the Charles County emergency

management director should make mutually acceptable modifications to

the communication process to ensure “heads up” when severe weather is

over Virginia.
23

Best Practices

1. Preplanning

Awareness of the potential for severe weather prior to the onset of this event was extremely

high. Planning began Saturday afternoon, April 27, the day before the tornado. People

scheduled on the Sunday, April 28, evening shift were prepared to come in early should

severe weather develop. The NCF was notified at 8:30 a.m., Sunday morning, April 28, to

put the Baltimore/Washington WFO in a critical weather watch for AWIPS. Two additional

forecasters arrived by 2 p.m. and an additional HMT by 4 p.m. A short meeting was held at

3 p.m., Sunday, April 28, to determine staff responsibilities. The WFO

Baltimore/Washington was well staffed with eight people for this event, including the MIC,

WCM, SOO, three lead forecasters, and two HMTs. 

2. Public Affairs Assistance

After the tornado event on Sunday, April 28, Jim Travers, MIC, WFO Baltimore/

Washington, called the NWS Public Affairs director to request support Monday morning,

April 29, to handle the anticipated barrage of media calls. A Public Affairs officer was

present at WFO Baltimore/Washington all day, Monday, April 29, and most of the next day. 

NOAA praised NWS Public Affairs staff for preparing news stories and updates after the

event. As a result, the national media received the latest information directly from the

official source.

3. Additional Weather Support

The Charles County emergency management director stated he was very pleased with the

speed at which the Baltimore/Washington WFO conducted the preliminary investigation the

day immediately after the storm. By mid-week, the potential for severe weather threatened

recovery and cleanup operations. The NWS provided frequent and timely weather briefings

to the Emergency Operations Center throughout the afternoon of Thursday, May 2. The

Charles County emergency management director was very grateful for the additional weather

support by the NWS.
2

 From J. Atmos. Sci., August 1981, p. 1517-1519.

A-1

Appendix A

Fujita Tornado Intensity Scale2

The Fujita Tornado Intensity Scale is a scale of wind damage intensity which wind speeds are

inferred from an analysis of wind damage.

Category Definition and Effect

F0 Gale tornado (40-72 mph): Light damage. Some damage to chimneys; break

branches off trees; push over shallow-rooted trees; damage sign boards.

F1 Moderate tornado (73-112 mph): Moderate damage. The lower limit is the

beginning of hurricane wind speed; peel surface off roofs; mobile home pushed

off foundations or overturned; moving autos pushed off the roads.

F2 Significant tornado (113-157 mph): Considerable damage. Roofs torn off

frame houses; mobile homes demolished; boxcars pushed over; large trees

snapped or uprooted; light-object missiles generated.

F3 Severe tornado (158-206 mph): Severe damage. Roofs and some walls torn off

well-constructed houses; trains overturned; most trees in forest uprooted; heavy

cars lifted off ground and thrown.

F4 Devastating tornado (207-260 mph): Devastating damage. Well-constructed

houses leveled; structure with weak foundation blown off some distance; cars

thrown and large missiles generated.

F5 Incredible tornado (261-318 mph): Incredible damage. Strong frame houses

lifted off foundations and carried considerable distance to disintegrate;

automobile-sized missiles fly through the air in excess of 100 yards; trees

debarked; steel-reinforced structures badly damaged; incredible phenomena will

occur.
B-1

Appendix B

Maryland Tornado Fatalities

Charles County, Maryland

Date Cause Age Gender Circumstances

04/28/02 Tornado 51 Male Permanent Home

Calvert County, Maryland

Date Cause Age Gender Circumstances

04/28/02 Tornado 68 Male Permanent Home

04/28/02 Tornado 65 Female Permanent Home
C-1

Note: Format of following paragraphs will be as follows:

Valid time (EDT) Product issued or Severe Report Area/Counties Affected

Remarks

Appendix C

Maryland Tornado Outbreak of April 28, 2002

WFO Baltimore/Washington

Chronological Product Highlights

Valid Time Product Issued/ Area/Counties

(EDT) Severe Report Affected

FRIDAY

1445 4/26/02 AFD Entire LWX CWA

Thunderstorms possible during daylight hours Sunday.

SATURDAY

0242 4/27/02 AFD WFO LWX CWA

Late day thunderstorms and rain showers reasonable Sunday.

0333 SWODY2 All of Maryland and Northern and

Western Virginia

Slight risk of severe weather on Day 2 (28 0800 EDT to 29 0800 EDT).

0525 OPU (Hazardous Weather Outlook) WFO LWX CWA

Scattered thunderstorms possible late in the day Sunday. Some of these may be on the strong

side...with gusty winds the primary threat.

1025 AFD Entire LWX CWA

Late day thunderstorms and rain showers reasonable Sunday.
C-2

1030 OPU (Hazardous Weather Outlook) WFO LWX CWA

Scattered thunderstorms possible late in the day Sunday. Some of these may be on the strong

side...with gusty winds the primary threat.

1255 SWODY2 All of Maryland and Northern and

Western Virginia

Slight risk of severe weather on Day 2 (28th 0800 EDT to 29th 0800 EDT).

1500 AFD WFO LWX CWA

Looks good tomorrow (Sunday) for some strong to severe storms during mid afternoon to early

evening. Main threat, damaging winds.

1530 ZFP WFO LWX CWA

“Some thunderstorms may contain strong gusty winds.”

2053 ZFP WFO LWX CWA

“Some thunderstorms may contain strong gusty winds.”

2135 AFD WFO LWX CWA

“Mid-Atlantic is outlooked slight risk of severe...thunderstorms with strong winds look to be main

threat.”

SUNDAY

0156 SWODY1 All of Maryland and most of Northern

and Western Virginia

Moderate risk of severe weather on Day 1 (28th 0800 EDT to 29th 0800 EDT).

0248 4/28/02 AFD WFO LWX CWA

“Best chance for thunderstorms here will be this afternoon. Strong winds will be the primary

threat.”

0320 OPU (Hazardous Weather Outlook) WFO LWX CWA

Headline “...POSSIBLE SEVERE THUNDERSTORMS TODAY....” Primary threat will be strong

and potentially damaging winds. The peak time of the threat will be this afternoon.

0406 ZFP

Forecast mentions scattered showers and thunderstorms, with some thunderstorms containing

strong gusty winds.

0412 SPS (Severe Weather Outlook) WFO LWX CWA

Headline “...POSSIBLE SEVERE THUNDERSTORMS TODAY....” Primary threat strong and

potentially damaging winds. The peak time of threat will be this afternoon.
C-3

0605 OPU (Hazardous Weather Outlook...updated) WFO LWX CWA

Headline “...POSSIBLE SEVERE THUNDERSTORMS TODAY....” Primary threat strong and

potentially damaging winds. The peak time of the threat will be this afternoon. SKYWARN

activation may be necessary today.

0827 SWODY1 All of Maryland and portions of Northern

Virginia

Moderate risk area for severe weather. “...Widespread damaging winds...a couple of

tornadoes...and hail are likely...from late morning through this evening....”

0830

SOO Called NCF and asks that NCF place LWX in “Critical weather watch” for the entire day. 

0945 NOW Portions of West Virginia, Western

Virginia, and Maryland

“Expect wind gusts to 35 MPH early in the afternoon.”

0950 AFD WFO LWX CWA

“Much concern about afternoon weather...biggest threat is for damaging winds...best chance for

thunderstorms will be this afternoon...strong winds the primary threat.”

1030 OPU (Hazardous Weather Outlook...updated) WFO LWX CWA

Headlined, “...Heavy rainfall through noontime...” and “...POSSIBLE SEVERE

THUNDERSTORMS THIS AFTERNOON....” Also states, “Primary threat strong and potentially

damaging winds...peak time of threat will be 3 p.m. until 8 p.m.” And additionally “isolated

tornadoes and large hail are possible.”

1100 FFA Portions of Western Virginia, West

Virginia, and Western Maryland

Flooding is possible but not imminent.

1115 ZFP Portions of Western Virginia, West

Virginia, and Western Maryland

Zone forecast updated to headline flood watch for additional portions of county warning area.

1130 SPS (Severe Weather Outlook...Updated) WFO LWX CWA

Headlined “...POSSIBLE SEVERE THUNDERSTORMS THIS AFTERNOON....”

Also states “peak time of threat will be 3 p.m. until 8 p.m.” and “isolated tornadoes and large hail

are possible this afternoon.”

1301 SWODY1 Most of Maryland and Virginia

Slight risk area for severe weather with a moderate risk area just to the west of the region. 
C-4

1315 Conference call

Conference call between SPC, LWX and surrounding offices to coordinate tornado watch #168.

LWX counties not included in Tornado watch as was coordinated with LWX SOO and SPC

forecaster.

1321 SPCSEL8

Tornado watch #168 issued for most of West Virginia and Western Maryland panhandle. Valid until

1700 EDT.

1442 NOW Portions of West Virginia and Maryland

“Thunderstorms with wind gusts in excess of 35 mph, heavy rain, and small hail.”

1500 AFD WFO LWX CWA

“Main focus this afternoon and early evening is potential for severe weather.” Also states, “Severe

weather parameters indicating potential for tornado threat this afternoon.”

1500 

Conference call between SPC, LWX and surrounding offices to coordinate tornado watch #172. 

Tornado watch includes parts of northern Virginia and most of Maryland.

1505 SPCSEL2

Tornado watch #172 issued for most of western Virginia and most of Maryland. Valid until 2100

EDT. “Tornadoes...hail to 2 inches in diameter...thunderstorm wind gusts to 70 mph...and

dangerous lightning are possible in these areas.”

1529 SLS Portions of Virginia and Maryland

Redefining Statement for Tornado Watch Number 172.

1535 NOW Portions of West Virginia

Headlined “...Tornado Watch in Effect until 9 PM....”

Also states “Thunderstorms with heavy rain, small hail, and wind gusts to 40 mph.”

1545 ZFP WFO LWX CWA

States “some storms may contain damaging winds and large hail.”

1603 SWODY1 Western half of Maryland and most of

northern and western Virginia

Moderate risk area for severe weather.

1603 SVR Grant and Hardy Counties in eastern

West Virginia

“Radar indicated a severe thunderstorm with a history of producing nickel-sized hail.” Also,

“Severe thunderstorms can produce tornadoes with little or no advance warning.”

1616 SVS Grant and Hardy Counties
C-5

Headlined “...Severe thunderstorm warning continues....” Also includes “Remember...severe

thunderstorms can and occasionally do produce tornadoes with little or no warning.”

1637 TOR Shenandoah and Northern Rockingham

Counties in Virginia

First tornado warning of the event issued. “RADAR indicated a tornado.”

1647 SVS Northern Rockingham and Shenandoah

Counties

Headlined “...Tornado warning continues....”

1658 SVR Page, Rappahannock, and Shenandoah

Counties in Northwest Virginia

“Radar indicated a severe thunderstorm. Severe thunderstorms can and occasionally do produce

tornadoes.”

1715 NOWLWX Portions of Virginia and Maryland

Headlined “...Tornado Watch in Effect until 9 PM....” Also, “Thunderstorms with wind gusts to 45

mph and small hail.”

1717 SVR Grant, Hardy Counties in eastern West

Virginia

“Radar indicated a severe thunderstorm.” Also, “ Severe thunderstorms can and occasionally do

produce tornadoes.”

1723 SVS Shenandoah, Page, and Rappahannock

Counties

Headlined “...Severe thunderstorm warning continues....” Also “Severe thunderstorms can

produce tornadoes with little or no advance warning.”

1737 SVS Grant and Hardy Counties

Headlined “...Severe thunderstorm warning continues....” Also “Severe thunderstorms can

produce tornadoes with little or no advance warning.”

1743 LSR

Reports of wind damage and 0.75 inch hail.

1748 TOR Northern Culpeper, Fauquier, and

eastern Rappahannock Counties in

Virginia

“RADAR indicated a tornado.”
C-6

1748 LSR

Reports of tornado damage in Shenandoah County, Virginia, at 1645.

1755 

Conference call between SPC, LWX, and surrounding offices to coordinate tornado watch #177. 

Tornado watch includes eastern portions of Virginia and portions of southern Maryland.

1757 SPCSEL7 Eastern Virginia and portions of

Southern Maryland

Tornado watch #177. Valid from until 2200 EDT. States “Tornadoes...hail to 2 inches in

diameter...thunderstorm wind gusts to 70 mph...and dangerous lightning are possible in these

areas.”

1802 SMW Tidal Potomac from Key Bridge to Indian

Head Maryland

“Mariners can expect wind gusts over 35 kt...large hail...locally high waves...dangerous

lightning...and heavy downpours.”

1806 MWS Tidal Potomac from Key Bridge to Indian

Head Maryland

Headlined “...Special Marine Warning...” and “...Tornado Watch in effect until 9 PM for entire

tidal Potomac and Maryland portion of Chesapeake Bay....”

1810 SPS

Headlined “...Severe thunderstorm warning for Hardy County expired...” and “...Tornado watch

remains in effect until 900 pm....”

1810 SLS Portions of Maryland

Note: See 1830L issuance for additional VA locations. 

Redefining Statement for Tornado Watch Number 177

1810-1820

Forecaster called Charles County, MD, 911 center and briefs them that a severe thunderstorm in

Virginia is headed their way.

1812 TOR City of Manassas, southern Fairfax,

eastern Fauquier, and Prince William

Counties in Virginia

“RADAR indicated a tornado.”

1825 SVS Fauquier County

Headlines state “...Tornado warning for Fauquier County has been cancelled...” and “...A tornado

warning continues for Manassas...Southern Fairfax County and Prince William County in Northern

Virginia until 645 pm....”
C-7

1830 SLS Portions of Virginia and Maryland

Redefining Statement for Tornado Watch Number 177.

1845 SVR Extreme southern Anne Arundel, Prince

George’s, Calvert and northern Charles

Counties in Maryland and southern

Fairfax and eastern Prince William

Counties in Virginia

“Radar indicated a severe thunderstorm.” Also,“Severe thunderstorms can produce tornadoes with

little or no advance warning.”

1853 LSR

Reports of additional wind damage and 1.75 inch hail.

1858 SVR Northern Anne Arundel, Howard, and

eastern Montgomery Counties in

Maryland

“Radar indicated a severe thunderstorm.” Also, “Severe thunderstorms can produce tornadoes

with little or no advance warning.”

1858 LSR

Reports of additional 1.75 inch hail.

1900-1903

Forecaster calls Charles County, MD, 911 center and warns them of a tornado. The forecaster

received immediate feedback from 911 operator of a tornado in La Plata at the time.

1902 TOR Southern Prince George’s, Calvert,

Charles, extreme northern St. Mary’s

Counties in Maryland

“RADAR indicated a tornado.”

1905 SMW Chesapeake Bay

“Tornado reported in La Plata.” Also states “Storms will move into Chesapeake Bay between 7:30

and 8 pm.”

1911 SVS Prince William, Fairfax, Anne Arundel,

Charles, Prince George’s, Calvert,

St. Mary’s Counties

Headlines, “...Severe thunderstorm warning cancelled for...” and “...Tornado warning continues

for...” as well as “...A tornado watch continues....” Also stated later in the product is “At 702

pm...emergency officials reported a tornado on the ground over La Plata in Charles County moving

east. This is a dangerous storm. Seek shelter immediately!”
C-8

1912 LSR

Additional reports of tornado and 1.75 inch hail in La Plata at 1903.

1924 SVS Prince George’s, Calvert, Charles,

St. Mary’s Counties

Headlined “...TORNADO WARNING CONTINUES UNTIL...” and “...A TORNADO WATCH

CONTINUES....” Also stated later in the product is “At 715 pm...emergency officials reported a

tornado on the ground at Route 6...the tornado has caused extensive damage in La Plata. This is an

extremely dangerous storm! Seek shelter immediately if you are in the path of this storm.”

1925 LSR

Additional tornado information. 1 dead, several structures demolished in La Plata at 1910.

1933 SVS Anne Arundel, Howard, Montgomery

Counties

Headlined “...Severe thunderstorm warning has been cancelled....”

1944 TOR Calvert County, Maryland

“RADAR indicated a tornado.”

1954 SVS Calvert County

“...Tornado warning has been cancelled....”

2042 LSR

Reports of funnel cloud sighted near Key Bridge. Tornado reported at Bowens in Calvert County at

1940. House collapse, numerous houses damaged.

2115 NOW Portions of Maryland

“Heavy rain, small hail, and wind gusts in excess of 35 mph.”

2155 LSR

“Tornado reported at Benedict in Calvert County at 1940. 1 dead.”