A Mariner’s Guide to

Marine Weather Services

Great Lakes

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Weather Service

NOAA PA 98053
Small Craft

Advisory:

Gale Warning:

Storm Warning:

Special Marine

Warning:

NWS issues Small Craft Advisories for

hazardous lake conditions that may affect

small craft operations.

Forecast winds of 34 to 47 knots.

Forecast winds of 48 knots or greater.

Potentially hazardous over-water events

of short duration (up to 2 hours).

These advisories and warnings are headlined in marine forecasts.

(Details are included elsewhere in this brochure.) Small Craft

Advisories are usually issued 2 to 6 hours before the onset of

adverse conditions and warnings may be issued up to 24 hours in

advance.

Introduction

Few people are affected more by weather than the mariner. An

unexpected change in winds, waves, or visibility can reduce the

efficiency of marine operations and threaten the safety of a vessel and

its crew. The National Weather Service (NWS), a part of the National

Oceanic and Atmospheric Administration (NOAA), provides marine

weather warnings and forecasts to serve all mariners who use the Great

Lakes for livelihood or recreation. This pamphlet describes marine

weather services available from the NWS and other agencies.

Warning and Forecast Services

The warning and forecast program is the core of the NWS’s responsibility

to mariners. Warnings and forecasts help the mariner plan and make

decisions protecting life and property. NWS also provides information

through weather statements or outlooks that supplement basic warnings

and forecasts. The following are the basic marine warning products the

NWS offers.
Great Lakes Regional Products

Great Lakes Storm Summary...Issued every 3 hours to describe conditions

when winds of 50 knots or greater are reported on some part of the Great Lakes

and are expected to prevail for 12 hours or more.

Great Lakes Freeze-up Outlook...Issued in the late fall until the routine Great

Lakes Ice Outlook product begins.

Great Lakes Ice Outlook...Routinely issued during the winter and early spring

months with ice watches and warnings as needed

Great Lakes Break-up Outlook...Issued once or twice a year in the spring.

St. Lawrence Freeze-up Date Outlook...Expected freeze-up date on the St.

Lawrence River at Massena, NY.

Great Lakes Marine Products

Open Lakes Forecasts

Issued by NWS offices in Chicago (Lake Michigan), Detroit (Lake Huron and

Lake St. Clair), Cleveland (Lake Erie), Buffalo (Lake Ontario) and Marquette

(Lake Superior).

Effective/Issuance Times

Issued four times daily at 4 a.m./p.m. and 10 a.m./p.m. local time and valid for up to 48

hours, with an outlook to 5 days.

Content and Format

GLFLS

LSZ260-142000-

LAKE SUPERIOR FORECAST

NATIONAL WEATHER SERVICE MARQUETTE MI

1000 AM EDT FRI MAY 14 1999

LAKE SUPERIOR FORECAST BEYOND FIVE NAUTICAL MILES FROM SHORE

.SYNOPSIS...A DEEP LOW PRESSURE SYSTEM OVER MINNESOTA WILL MOVE NORTH

INTO CANADA TONIGHT. THIS SYSTEM WILL PRODUCE GALE FORCE WINDS THIS

AFTERNOON.

...GALE WARNING IN EFFECT...

.THIS AFTERNOON...SOUTHWEST WINDS TO 40 KNOTS. WAVES 10 TO 12 FEET.

.TONIGHT...SOUTH WINDS TO 30 KNOTS. WAVES SUBSIDING TO 4 TO 6 FEET.

.SATURDAY...SOUTH WINDS 10 TO 20 KNOTS BECOMING SOUTHWEST. AFTERNOON

THUNDERSTORMS LIKELY. WAVES 1 TO 3 FEET.

.OUTLOOK FOR SATURDAY NIGHT THROUGH TUESDAY...WINDS BELOW 20 KNOTS.

$$

LSZ261-142000-

MAFOR 1415/

SUPERIOR...GALE WARNING IN EFFECT...13550 11440 13430 11420 WAVES 10 TO 12

FEET THIS AFTERNOON SUBSIDING TO 4 TO 6 FEET TONIGHT AND TO 1 TO 3 FEET

SATURDAY MORNING. 221012
Great Lakes Nearshore Forecasts

Issued from spring through fall by NWS offices at Duluth, MN; Marquette, MI;

Green Bay, WI; Milwaukee, WI; Chicago, IL; Grand Rapids, MI; Gaylord, MI;

Detroit, MI; Cleveland, OH; and Buffalo, NY.

Effective/Issuance Times

Issued four times daily at 4 a.m./p.m. and 10 a.m./p.m. local time from spring through fall

and valid for up to 36 hours.

Content and Format

NEARSHORE MARINE FORECAST

NATIONAL WEATHER SERVICE MARQUETTE MI

1000 AM EDT FRI MAY 14 1999

FOR WATERS WITHIN FIVE NAUTICAL MILES OF SHORE

LSZ241-142215-

LAKE SUPERIOR...SAXON HARBOR TO ONTONAGON MI1100 AM EDT FRI MAY 14 1999

...GALE WARNING IN EFFECT...

.THIS AFTERNOON...SOUTHWEST WINDS TO 40 KNOTS. MOSTLY CLOUDY. WAVES

10 TO 12 FEET.

.TONIGHT...SOUTH WINDS TO 30 KNOTS. PARTLY CLOUDY. WAVES SUBSIDING TO 4

TO 6 FEET.

.SATURDAY...SOUTH WINDS 10 TO 20 KNOTS BECOMING SOUTHWEST. AFTERNOON

THUNDERSTORMS LIKELY. WAVES 1 TO 3 FEET.

$$

Lakeshore Warnings

Lakeshore warnings are issued for lakeshore flooding or significant shoreline

erosion that is occurring or expected within the next 12 hours and poses a threat

to life or property.

Lakeshore Statements

Lakeshore statements are used to advise mariners and other people who live

along the shore of flooding or erosion potential. They are also used to update

warning issuances.
NOAA Weather

Radio (NWR)

The NWR network provides voice broadcasts of coastal and marine

forecasts on a continuous cycle. This network covers most of the

Great Lakes shorelines. When severe weather threatens, an alarm

tone is sent to automatically turn on compatible NWR receivers in the

transmitter’s coverage area.

Many NWS forecast offices offer recorded marine and local forecasts

by telephone. These numbers are usually listed in the telephone directory

under “United States Government, Commerce Department, National

Weather Service.”

USCG broadcasts warnings and forecasts on VHF channel 22A

following an initial call on VHF Channel 16. The USCG VHF network

provides near-continuous coverage of the Great Lakes.

NAVTEX is a broadcast of products in text form. The Canadian

government operates the NAVTEX service for the Great Lakes and

provides weather and in-season ice information.

♦ NOAA Home Page: http://www.noaa.gov

♦ NWS Home Page, links to local NWS office Web sites:

http://www.nws.noaa.gov

♦ NOS Home Page: http://www.nos.noaa.gov

♦ Marine Weather Dissemination Home Page: ww

http://www.nws.noaa.gov/om/marine/home.htm

♦ USCG Home Page: http://www.uscg.mil

♦ USCG Navigation Center: http:/www.navcen.uscg.mil

(Excellent descriptions of marine communications)

Obtain the latest lake weather observations through a telephone service,

Dial-A-Buoy. The service provides wind and wave measurements

taken within the last hour at Great Lakes stations. To access, dial

228/688-1948 on a touch tone or cellular phone. Enter the five-digit

station identifier when prompted. The menu tree has a selection for

the caller to receive a map of buoy station identifiers via return call

fax. Station identifiers can be obtained at: http://seaboard.ndbc.

noaa.gov.

DIAL-A-BUOY

Web Sites

of Interest

NAVTEX

USCG VHF

VOICE

NOAA

Telephone

Recordings

Dissemination Of Marine

Weather Products

Marine weather products are widely disseminated via U.S. Coast Guard (USCG)

broadcasts, NOAA Weather Radio and the Internet. Schedules for marine broadcasts

are listed in NIMA Publication 117 and NWS Marine Weather Service Charts, available

at your local National Ocean Service chart agent. To find dissemination details on

marine products go to the Marine Weather Dissemination Information Home Page.

Special Marine Warnings

The NWS issues Special Marine Warnings for potentially hazardous over-water

events, usually of short duration (up to 2 hours), not adequately covered by

other marine warnings and forecasts. These events include thunderstorms,

waterspouts, squalls, wind shifts, and other short-lived conditions.

If a tornado or severe thunderstorm is expected to move over the lakes, NWS

issues a Special Marine Warning. If a severe thunderstorm or waterspout is

expected to move ashore, NWS issues a separate warning for the shoreside areas.

Content and Format

BULLETIN - IMMEDIATE BROADCAST REQUESTED

SPECIAL MARINE WARNING

NATIONAL WEATHER SERVICE BUFFALO NY

226 AM EDT THU OCT 1 1998

THE NATIONAL WEATHER SERVICE IN BUFFALO NY HAS ISSUED A

* SPECIAL MARINE WARNING FOR . . .

LAKE ERIE FROM RIPLEY TO BUFFALO

BUFFALO HARBOR AND UPPER NIAGARA RIVER

* EFFECTIVE UNTIL 335 AM EDT

* AT 235 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR

INDICATED STRONG THUNDERSTORMS FROM NIAGARA FALLS TO

CENTRAL LAKE ERIE...MOVING EAST AT 40 KNOTS

* THESE THUNDERSTORMS WILL REACH BUFFALO HARBOR BY 330AM

* ALL MARINE INTERESTS SHOULD REMAIN ALERT AND SMALL BOATS

TAKE SHELTER IMMEDIATELY.

Marine Weather Statements

Marine Weather Statements are used to follow up the Special Marine Warnings

or to provide information on non-severe conditions such as fog.
Marine Weather Service Charts

MSC charts are available for 15 segments of the continental United States, Alaska,

Hawaii, Puerto Rico and the Virgin Islands, and Guam and the Northern Mariana

Islands, and the Great Lakes. These charts are regularly updated. MSC 11/12

covers the Great Lakes.

MSC charts contain maps of the area including locations of NWR transmitters,

USCG stations, and marine observation sites; helpful information such as locations,

times, and frequencies of marine broadcasts; and NWS telephone numberss. MSC

charts can be purchased from:

National Ocean Service

Distribution Division (N/ACC3)

Riverside, MD 20737-1199

Telephone: 301-436-8301

MSC charts can also be found on-line at http://www.nws.noaa.gov/om/marine/

pub.htm.

For boating safety weather rules, see Safe Boating Weather Tips (NOAA PA 94058)

at http://www.nws.noaa.gov/om/nwspub.htm.