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**The ArkLaMiss Observer**

Fifth Edition, Spring 2005

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**Back-2-Back**

***The Outbreaks of November 23rd and 24th***

***And***

***December 7th***

The unusually quiet fall weather came to an abrupt end in 2004 as a pair
of vigorous systems roared through the Ark-La-Miss. The first system,
the more significant of the two, was well telegraphed. Unprecedented
model consistency and accuracy was observed in advance of this system.
For 5 days prior to the historic event, the computer models did not
waiver on the strength, track or timing of the system. Each day, the
model output suggested a possibility for a historic event occurring on
the night of the 23rd.

![](media/image5.png){width="2.1104166666666666in"
height="1.91875in"}Recall that for significant severe convective
activity to occur, a deep layer of moisture is needed along with surface
based instability, a lifting mechanism, and wind shear are needed. All
four of these criteria were easily met, and exceeded. For tornadic
events, such as this, other atmospheric parameters should be in place as
well. Strongly veering winds within the first few thousand feet of the
atmosphere help generate strong low-level helicity, which aids in the
formation of tornadic supercells (when moisture, instability and lift
are present.) Low cloud base heights, usually 3,000 feet or less, are
also beneficial. The low cloud bases decrease the distance that is
required for a funnel cloud to reach the surface. Both of these
additional parameters were in place for the event.

This first event produced an astounding 17 tornadoes across the Jackson
forecast area. The width of several tornadoes exceeded 300 yards, and
tornado tracks greater than 15 miles were observed. Perhaps the most
remarkable thing about this event, given the high numbers of tornadoes
experienced, was that no densely populated areas were hit. On the
diagram, note how close some of the tornadoes came to impacting the
Jackson metro area. Another tornado seemingly stopped on the outskirts
of Meridian.

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The second tornado outbreak was a little less obvious to discern ahead
of time. The model output consistency was not nearly as good as it was
for the previous system. There were also timing issues. The different
computer models kept slowing the system\'s approach as the event neared.
The degree of instability was also in question. While significant
moisture was in place, along with lift and wind shear, the expected
instability appeared to be marginal. Other ingredients like low-level
veering winds and low cloud base heights were expected to be in place as
well. Again the main question was, \"Will there be enough instability?\"
About 24 hours before the event, the models began trending upward in
their depiction of surface-based instability.

The event produced a total of 8 tornadoes with one weak tornado, an F-0,
causing minor damage to some homes near Brandon. Another tornado, an F-2
in Lowndes County, picked up a large camper, flipped it, and tossed it.
This same tornado crushed a mobile home. A 300 to 400 yard wide tornado
moved through western Hinds County and produced structural damage to
houses and barns.

In summary, at total of 25 tornadoes occurred in the Jackson forecast
area. There were

2 F-3s, 6 F2s, 8 F1s, and 9 F0s. There was one fatality. It is very
possible that some of these tornadoes would have been stronger than this
had they tracked over more populated areas. Thankfully, they didn\'t.

**The New Warning Philosophy\
The Polygon Method**

This spring, NWS Jackson will serve as a test site for the new polygon
method for forecasting severe thunderstorms. The polygon method is
different than the current method in several ways. This article will
look at some of the differences between the new method for issuing
warnings and the existing method in an effort to show how the new
approach will improve service to you, our customer.

Using the current methodology, not the polygon method, severe
thunderstorm and tornado warnings are issued on a county by county
basis. At any given time, there may only be one severe thunderstorm or
tornado warning out for each county. Also if one warning is issued for a
storm that is expected to move through three counties, then that one
warning will actually count as three separate warnings (one warning for
each county affected.)

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**Using the current methodology, the entire area of both counties in the
image above would be warned. Using the new methodology, only the area
within the polygon would be warned.**

There are three major disadvantages to this current method. First, the
entire area of all three counties is under the effect of the warning.
This means that areas that may not be in the path of the storm will be
covered under the warning, thus creating a false alarm to those not
affected. Another disadvantage is that the current process does not
effectively draw attention to multiple severe thunderstorms that are
moving through one county. For example, there may be a warning out for
northern Madison County for a tornadic storm. Now, a second severe
thunderstorm may be getting ready to enter southern Madison County.
Under the current system, a Severe Weather Statement (SVS) is issued to
alert the public to the anticipated track of the second severe storm
through southern Madison County, not a new warning. A third disadvantage
applies to the storm verification process. Since the one warning that
was issued actually counts as three warnings, then that warning has to
be verified in each of the three counties individually.

Using the polygon method, these issues are addressed. First, the areas
within the polygon box are the only areas that are under the effect of
the warning. Therefore, other areas in the affected county(ies) are
**not** under the affect of that warning. Secondly, it will be now
possible to have out multiple warnings for a single county. For example,
it will be possible to have 2 severe thunderstorm warnings in effect for
Rankin County simultaneously. The only drawback to this is that it could
create some confusion. However, by tailoring the warning text to say
something like, "A severe thunderstorm warning is in effect for
***southern*** Rankin County...," any confusion that might develop would
be minimized. Finally, the warning verification would be easier.
Consider a warning polygon warning box that covers a storm that is
expected to move across three counties. Using the new methodology, it is
not necessary to verify that warning in each of the 3 county areas that
lie within that polygon. Only one point within the polygon box needs to
be verified.

As stated before, the new polygon warning methodology should show an
increase in the service rendered by providing more accurate warnings
with a lower false alarm rate.

**Training for Severe Weather**

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**Being a meteorologist in the Ark-La-Miss is nothing short of exciting.
During the Spring and Fall seasons, severe weather affects the area on a
regular basis. Strong atmospheric winds, resulting from strikingly
different colliding airmasses aid in the formation of intense storms
which often produce damaging winds, hail and sometimes tornadoes. It is
during these periods of time that warning forecasters draw upon their
comprehensive training and experience to accomplish the mission of the
National Weather Service which is to "protect lives and property." What
does this training involve, and how is it acquired?**

**Perhaps the most affective training method used is the Weather Event
Simulator, (WES). In recent years, the National Weather Service has
developed and maintained an extensive database of historical weather
events from across the country. For these events radar data, satellite
data, storm reports, computer model data and other forms of data have
been saved. The data is saved into an archive folder and is given a
date, which is usually the date of the event. Each year, the Science and
Operations Officer (SOO) at each forecast office across the country
choose two to four events for each operational staff member to work
through. Since the WES uses the same operating system, AWIPs, that is
used in the normal operational environment, warning forecasters are able
to look at radar (and other) data to assess storm development and
severity just like they would for a "real" event. During a WES
simulation, if a storm is deemed severe, then a simulated warning is
issued for that county. Since the WES simulates real life situations so
closely, it has proven to be a tremendously affective training tool to
maintain, and sharpen a warning forecaster's operational skills.**

**In addition to the WES, other training methods are used to develop
forecaster knowledge and skills. Usually each month, the SOO will choose
computer model data from a past event to use as a training exercise. The
purpose of each exercise is to enhance severe weather forecasting
techniques. During such exercises, forecasters are given enough model
and upper air data to construct a forecast. Given the data, the
forecasters are asked several questions like: Are severe thunderstorms
expected, and if so how widespread will the coverage be? Where will the
activity be focused? What modes of severe thunderstorm activity are
expected (hail, winds, or tornadoes?) Do you expect any other
significant weather from this event, like flooding? Unlike the WES,
which trains the forecaster to deal with ongoing severe weather, these
training exercises teach the meteorologists on how to be better
forecasters of severe weather.**

**The training doesn't stop here though. In house seminars, teletraining
sessions, and online training sessions further develop the skill set by
sharing experiences from lessons learned across the country. Case
studies are performed on significant events to gain additional
knowledge. Map discussions are given daily to share knowledge with staff
members. These discussions often serve as "real time" learning tools
when an event is approaching.**

**Given the rapid advances in science and technology, this intense
training regime is critical to the accomplishment of the NWS mission.**

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height="11.157638888888888in"}**IMET Program Goes All-Hazards**

Traditionally, the role of the Incident Meteorologist has been to deploy
to remote locations and to provide weather forecast support to
firefighters as they battle a forest fire's flames. However, times are
changing and as they change, so does the focus of the mission. In the
interests of Homeland Security, the program has undergone a
metamorphosis and has embraced an all hazards philosophy to better serve
our customers. Now, IMETs are available for dispatch to incidents like:
Chemical, Biological, and/or Radiological Releases, oil spills, and also
to significant events (like political conventions.)

The new mission focus was put to the test almost immediately in 2003,
when the space shuttle Columbia disintegrated upon reentry to the
Earth's atmosphere. IMETs from the southeastern offices were dispatched
to provide forecast support to the various agencies that were conducting
recovery operations.

In Alaska, and also along the West Coast, IMETs have been dispatched on
several occasions to provide forecast support to those who are trying to
clean up oil spills. Recently, IMETs were dispatched to both the
Republican and Democratic conventions.

As the expanded mission focus continues to take root, new partnerships
are being formed. The Southern Region of the National Weather Service
has taken the lead in this area and is in the process of building
relationships with the Nuclear Regulatory Commission (NRC), the
Department of Homeland Security (DHS), and the Centers for Disease
Control (CDC).

As the relationships continue to evolve, so do the training requirements
and roles of the IMET. A comprehensive, new training plan is being
adopted on the National and Regional levels. The new plan incorporates
not only the past training program, which was geared primarily toward
the Fire Weather program, but now includes specialized tracks. For
example, an IMET may choose to focus on marine hazards, like oil spills.
In this case, he/she will take a core set of courses that pertain to the
IMET-Marine Hazards track. Another IMET may choose to focus on Chemical,
Radiological, and Biological hazardous releases. In this case, he/she
will take a set of courses that pertain to the All-Hazards track.
Finally, a third IMET may choose to focus only on Fire Weather. This
IMET will take additional Fire Weather-related courses.

By completing the additional training, the IMET will become even more
qualified and able to provide an enhanced service to the customer.
Perhaps, the end result will be an increase in the numbers of lives and
property saved.

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height="8.196527777777778in"}**ReachOutReach**

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Recently, members of the outreach teams at WFO Jackson met to develop an
expanded vision for the office outreach program. In expanding the
vision, it was determined that we needed to find innovative ways to
reach new customers while maintaining and deepening existing
relationships with the current customer base. By the end of the meeting,
it was determined that the outreach program needed to be expanded into
three arenas. First, it was determined that we needed to reach out to
the non-English speaking community. Secondly, we wanted to develop new
partnerships with other government and private agencies (such as DHS,
NRC, and area hospital emergency managers). Finally, we wanted lay
groundwork in reaching out to travelers that drive through the forecast
area on the local interstates. By the end of the meeting, we realized
that we had quite a task ahead of us. How did we plan to accomplish
these innovative goals? The following discussion highlights the plan
that was laid and the course that we have since chartered.

Research was done to estimate the first non-English speaking ethnic
group to reach out to. Based on US Census Bureau statistics, it was
shown that the non-English speaking Hispanic community was the people
group that needed to be reached first. In an effort to launch the
outreach program in this arena, numerous brochures written in Spanish,
relating to weather safety, were ordered. Next, the diversity team
created a Spanish translation of our office brochure. With the help of
MIC Alan Gerard, it was determined that the best way to reach the
non-English speaking Hispanic community was to target area missions. A
plan has since been developed to travel to the various missions across
the state in order to raise awareness to issues like, tornado safety,
flooding, and lightning. Some interest has been expressed in developing
a Spanish version of the NWS Jackson website.

The concept of developing new partnerships with other agencies could not
have come at a better time. Unknowingly, the office outreach teams
tapped into a new vision that was in the process of making its way down
for the national headquarters. The national vision was to expand the
Fire Weather program to become an All-Hazards program. This meant that
Incident meteorologists (IMETs) could now be dispatched to incidents
other than wildfires. In other words, an emergency manager was now able
to request the dispatch of a forecaster to a significant event such as a
large-scale chemical release to provide forecast support. In order to
accomplish this expanded mission, new partnerships were forged with
agencies like the Nuclear Regulatory Commission (NRC) and the Department
of Homeland Security (DHS) to not only advise them on products and
services that were now available to them, but to obtain needed training
in regard to the expanded role of the IMET.

Furthermore, it was determined that we needed to develop a partnership
between our office and the emergency managers at local hospitals.
Shortly after realizing the need, the tornado outbreak of November
23^rd^ and 24^th^ occurred. That night, a tornadic supercell moved
through Hinds county toward Madison county. The path of the storm came
dangerously close to Saint Dominic hospital (within about 6 miles.)
While the storm was moving through the county, the emergency manager
from the hospital telephoned us with us many times. Listening to every
word that we said, she determined the next courses of action to take in
order to provide the best safety possible for her staff and patients.
Needless to say, this event accentuated a very important need for a new
relationship.

Finally, the expanded vision wanted to reach out to those traveling on
the roads and highways that stretch across the area. Given the high
frequency of severe weather in the Ark-La-Miss, it was determined that
travelers are often unknowingly at risk while driving on area roads and
highways. Using the innovative technological tool Hun-TV, which was
created at WFO Huntsville, Alabama, a plan was developed to install
Hun-TV at the welcome centers across the state. (Hun-TV is a program
that flashes the current weather maps, watches, and warnings across a
television screen.) In doing this, drivers would have a heads up on any
inclement weather that they were about to drive through. Details on how
to get Hun-TV installed are still in the works, but should be resolved
over the next several months.

![](media/image15.jpeg){width="7.993055555555555in" height="1.7625in"}As
WFO continues to expand the outreach horizon, the formation of these new
relationships should enhance the products that are provided to you, the
customer. Through the establishment of these new communication lines,
not only will the quality of our products continue to improve, but also
the timeliness of the relay of critical information (like storm reports)
will improve also.

*Weather Trivia*

Courtesy of the Southeast Regional Climate Center

*Are you looking for some strange discussion topics to talk about around
the old water cooler at work? If so, check out these strange
factoids...*

Just like warm air ascending mountain slopes can create clouds as it is
cooled, the pyramids of Egypt have been known to generate clouds from
hot air rising up along their sides.

Although we rely on oxygen to survive, only about 21% of the air we
breathe is oxygen. The majority of our atmosphere (78%) is made up of
nitrogen. The remaining 1% is a mixture of other gases, such as argon,
neon, and helium.

Cars can be carried away in only two feet of water.

Lightning has been known to kill people talking on the telephone.

Although it poses the most danger to people, cloud-to-ground lightning
represents only about 20 percent of all lightning strikes.

The wettest city in the United States is Hilo, Hawaii, averaging 128
inches of rain annually.

Tornadoes have been known to occur on every continent except Antarctica.

Believe it or not, humid air is lighter than the same volume of dry air
because water vapor molecules are less dense than the nitrogen and
oxygen they displace.

A cyclical increase in solar activity occurs as the sun\'s magnetic
field reverses every 10 or 11 years. Besides causing blackouts and
blocking radio communications, solar flares occurring during peaks of
solar activity can also contribute to the formation of the Northern
Lights.

German physicist Gabriel D. Fahrenheit developed the temperature scale
that bears his name in 1714. The \'zero point\' on his scale was the
lowest temperature he could attain with a mixture of ice, water and
salt.

Believe it or not, it has been hotter in North Dakota than it ever has
been in Florida. North Dakota\'s all-time record high temperature is 121
degrees F, while the highest temperature ever recorded in Florida is 109
F.

The deadliest Atlantic hurricane to occur in the 20th century struck
Galveston, TX on September 8, 1900, claiming 6,000 lives.

The reason why we have seasons is that the earth\'s axis of rotation is
tilted 23.5 degrees off its orbital plane. This means that when the
Northern Hemisphere is tilted more toward the sun, its summer here,
while in the Southern Hemisphere its winter and vice versa.

The earth\'s atmosphere is estimated to weigh about 5 million billion
tons. This weight exerts an average of about 14.7 pounds per square inch
of pressure on the surface of our planet, which is equal to about 29.92
inches of mercury in a standard barometer.

How much does a cloud weigh? That depends on the size and type of cloud,
but a 1 km x 1km x 1km (0.6 miles x 0.6 miles x0.6 miles) cumulus cloud
weighs about 1.4 billion lbs.

Tornadoes in the United States have an average path length of about 5
miles and an average width of 160-170 yards.

One unusual tornado story from 1894 tells of a twister that struck a
farm, hurling a chicken coop into the air and wedging it between two
trees. When people arrived to clean up the mess, they found all of the
chickens alive and well and not a single egg broken.

Keraunophobia, also known as brontophobia, is the irrational fear of
thunder and lightning.

Although it seems much wider, the current channel of a typical lightning
bolt is only about the size of a pencil.

Hurricanes never form within 5 degrees latitude of the equator. Although
the ocean waters near the equator do get warm enough to fuel hurricanes,
the effect that the earth\'s rotation has on winds and ocean currents,
known as the Coriolis effect, is too weak near the equator for
hurricanes to form.

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**The Next NEXRAD**

The WSR-88D (NEXRAD) will undergo some improvements in the next few
years. Perhaps the most significant will be an upgrade to
dual-polarimetric Radar.

The WSR-88D system is a network of over 150 Doppler weather radars
jointly developed and operated by the National Weather Service (NWS),
the Department of Defense (DOD), and the Federal Aviation Administration
(FAA). The word Radar is an acronym for Radio detection and ranging.
Therefore, as implied by the name, energy transmitted by weather radars
is essentially a radio wave with a frequency at the high end of the
radio spectrum. The radio wave frequency used by weather radars is
specifically chosen for its ability to \"interact\" with cloud and
precipitation particles. Radio waves with lower frequencies, such as
those transmitted by radio stations, tend to pass through clouds.
Therefore, they are not well suited for weather radar applications.
Currently the WSR-88D receives radio waves with a single, horizontal
polarization. However, dual polarimetric radars transmit and receive two
polarizations of radio waves, and are thus referred to as
dual-polarization radars. These polarimetric radars transmit and receive
both horizontal and vertical polarization radio wave pulses. Therefore,
they measure both the horizontal and vertical dimensions of cloud and
precipitation particles.

The accurate estimation of precipitation type and accumulation has been
a long standing problem for operational meteorologists who use the
current version of Doppler radar. The Dual Polarimetric radar will help
with both of these problems. Since the Dual Polarimetric Radar measure
the reflected power returned from both horizontal and vertical pulses,
these reflected power returns are measured in different ways thus, we
are able to obtain information on the size, shape, and ice density of
cloud and precipitation particles. By measuring the raindrop in both the
horizontal and vertical we can use this information to get a measure of
the average drop shape and, in turn, dominant drop size. This
information will enable the forecaster to give better rainfall
estimates. With better rainfall estimates the forecaster will be able to
better predict areas of flash flooding during heavy rain events. Also
the River Forecast units will get more accurate rainfall estimates into
there computer models to better predict river flooding events.

In addition to better rainfall estimates there are also several
potential applications of this information including:

1.  Improved estimation of rain and snow rates.

2.  Discrimination of hail from rain and possibly estimating hail size.

3.  Identification of precipitation type in winter storms.

4.  Identification of electrically active storms.

5.  Identification of aircraft icing condition.

Another problem that frequently plagues radar measurements is the
presence of anomalous propagation (commonly referred to as AP). AP
refers to a \"ground return contamination\" that sometimes occurs in the
radar data when a warm layer of air forms above a cold layer of air.
This phenomena, which is called an inversion layer, essentially bends
the radar beam back towards the ground resulting in a ground return
contamination that makes it very difficult, at times, to distinguish the
location and intensity of clouds and precipitation. Polarimetric radar
signatures also aid in the elimination of AP.

While deployment of the dual polarization Doppler radar is still a few
years away, it arrival is expected to yield a significant step toward
accomplishing the mission of the National Weather Service which is
protecting your lives and property.