NWS Little Rock, AR - Text Viewer

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Public Information Statement
National Weather Service Little Rock AR
600 AM CST Mon Nov 27 2023

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

November 27th through December 1st 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 or so. 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 seventeen times. 

Temperatures last winter were well above normal (by four to five
degrees). It was about the same the previous winter. But in the 
winter of 2020/2021, readings were colder than usual. That was 
due to Arctic air plunging southward through Arkansas all the 
way to the Gulf Coast in mid-February of 2021. 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 strongly toward El 
Nino, which favors warmer and drier conditions across the northern 
states, and a wetter scenario farther south. Confidence in 
temperatures across the south are more uncertain.

Across Arkansas, precipitation was above to well above average 
during most moderate to strong El Ninos going back forty years 
(into the early 1980s). Statewide amounts were on the plus side of 
normal in four out of five winters, and there was a surplus of 
liquid by more than two inches in three of those winters.

El Nino Years         Precipitation         Departure

2015/2016                12.89"               +0.77"
2009/2010                14.22"               +2.10"
1997/1998                15.17"               +3.05"
1991/1992                11.86"               -0.26"
1982/1983                16.97"               +4.85"

Temperatures were largely warmer than usual. Readings were more 
than two degrees above average in three of five winters. The outlier 
was the winter of 2009/2010, which was colder than normal by over 
four degrees! That's because El Nino was overwhelmed by the effects 
of a long term negative Arctic Oscillation (AO).

El Nino Years         Avg Temperature        Departure

2015/2016                 45.5°                +4.2°
2009/2010                 37.0°                -4.3°
1997/1998                 43.7°                +2.4°
1991/1992                 44.8°                +3.5°
1982/1983                 42.8°                +1.5°

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 2009/2010, there was a long term negative AO, and 
that led to one cold blast after another. In early February, a 
powerful storm brought as much as three feet of snow to the 
mid-Atlantic region (called "Snowmageddon"). By the 12th, there was 
at least some snow on the ground in 49 states (including Arkansas).

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-wetter-south-warmer-north

$$

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