Public Information Statement
Issued by NWS Little Rock, AR

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Public Information Statement
National Weather Service Little Rock AR
200 PM CST Mon Nov 29 2021

...Winter Weather Awareness Week in Arkansas...

November 29th through December 3rd is Winter Weather Awareness
Week in Arkansas. The purpose of this week is to remind people
what winter weather can bring, and how to deal with
hazardous winter conditions. Now is the time to prepare
for the upcoming winter season.

Today`s topic is the outlook for the upcoming winter.

Overall, winter around here has not exactly been cold in the
last thirty years. Since the winter of 1990-91, temperatures
were below average by at least a degree only seven times. Readings
were above average by a degree or more fifteen times.

Temperatures last winter were below normal. That is mainly due
to Arctic air that plunged southward through Arkansas all the way
to the Gulf Coast in mid-February. Two big storm systems arrived
from the 14th through the 18th, and deposited more than twenty
inches of snow in central and southern sections of the state.

Weather can vary quite a bit from winter to winter, so
forecasting what will happen is a challenge. The forecast
usually starts with looking at water temperatures along
the equator in the Pacific Ocean.

If the water cools, we trend toward La Nina. If warming occurs,
then it`s El Nino. Both variables have a say in how the weather
behaves across the country, especially when they become dominant.
In the coming months, the pendulum will swing toward La Nina,
which favors warmer and drier conditions across much of the
southern United States this winter.

This will be a moderate /versus weak/ La Nina, which not only
boosts the confidence in the forecast, but also increases the
chances of extreme weather such as severe storms and tornadoes.
Such was the case in 1999 and 2008, and eventually 2011 after
a cold and snowy start to the year.

While La Nina will likely be the most influential variable that
governs the weather pattern this winter, there are other factors
to consider such as the Arctic Oscillation /AO/. In the strongly
negative phase of the AO, pressure is higher toward the North
Pole, and this sets up a blocking pattern. Cold air traversing
Canada is forced to the south, and our temperatures drop.

In the winter of 2010/2011, there was a long term negative AO,
and that led to one cold blast after another. On February 9th in
2011, one to two feet of snow blanketed the Ozark Mountains. Six
to eight inches of powder accumulated in the Little Rock /Pulaski
County/ area. It was a top ten snowy winter locally.

Ten years later, the AO took a similar dive last winter, and that
led to the already mentioned cold and snow in February.

Such a lengthy negative AO is rare. Usually, AO phases are of
short duration /days to weeks/, and are tricky to forecast compared
to a much more stable El Nino and La Nina /months/.

Whatever happens, we all know that the weather can be all over
the place in this part of the world. It can feel like spring in
January, and it can get really cold. That is an ordinary winter
locally. Do not expect anything different this time around.

If more precipitation falls than expected, we will have to
watch for three things. If we are in the midst of a warm period,
be wary of severe thunderstorms, which are not unusual. If there
is a lot of rain, then flooding can become a problem. Finally,
given a well timed shot of subfreezing air, that is a recipe
for a big snow or ice storm.

&&

Additional information on the winter outlook from the Climate
Prediction Center can be found at:

https://www.noaa.gov/news-release/us-winter-outlook-drier-warmer-
south-wetter-north-with-return-of-la-nina

$$

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