Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
309 PM EST Fri Dec 22 2023

Valid 00Z Sat Dec 23 2023 - 00Z Mon Dec 25 2023

...Heavy rainfall and flash flash flooding to impact parts of the
Southwest this evening; Southern Plains to see potential flooding impacts
on Saturday; Gulf Coast and Lower Mississippi Valley to see heavy rainfall
on Christmas Eve ...

...Mountain snow and valley rain anticipated from the Pacific Northwest to
the Intermountain West through Saturday...

...Snow is forecast to overspread the Central Rockies Saturday night
before expanding into the Northern and Central Plains by the morning of
Christmas Eve...

...Unusually mild temperatures with some pockets of record breaking warmth
likely in parts of the Plains and Midwest through the Christmas holiday
weekend...

The upcoming holiday weekend will be stocking-stuffed with unsettled
weather from the Southwest and the Rockies to the Heartland and Great
Lakes. The culprits responsible are two upper level disturbances; one in
the Pacific Northwest and a closed upper low tracking into southern
Arizona this evening. The disturbance over the Northwest will bring about
periods of mountain snow and valley rain from the Washington/Oregon coast
to the northern Rockies and northern Great Basin tonight. The more potent
of the two features is the closed low approaching southern Arizona as it
funnels rich subtropical moisture into the Desert Southwest. The Weather
Prediction Center has a Slight Risk for Excessive Rainfall in place from
far Southern California and the Lower Colorado River Valley to southeast
Arizona. A little farther north, heavy snow is expected in the higher
terrain of the Southern Rockies where over a foot of snow is possible
tonight and into Saturday. In the Great Lakes, a weak wave of low pressure
tracking along a stalled frontal boundary will generate showers from the
Middle Mississippi Valley to the Lower Great Lakes this evening and
overnight.

By Saturday, the two aforementioned upper level disturbances will begin to
merge, aiding in the development of low pressure over the Central Plains.
Snow will fall across the Rockies with locally heavy amounts in the
tallest peaks of Colorado, Wyoming, and southern Montana. Meanwhile, a
surge of Gulf of Mexico moisture along a warm front will prompt heavy
showers and thunderstorms to blossom over the Southern Plains. Excessive
Rainfall rates are possible particularly in north-central Texas and
southern Oklahoma where a Slight Risk is in place. Farther west, the Storm
Prediction Center has a Marginal Risk in place for severe weather as a
trailing cold front over West Texas could spark severe thunderstorms
Saturday afternoon and into the evening. The low pressure area in the
Great Lakes makes its way into the Northeast by Saturday evening with a
mix of rain and snow showers (little snowfall accumulation expected).

By the morning of Christmas Eve, the cold front in the Northern Rockies
will have made it into the Great Plains, forcing precipitation to fall in
the form of snow from northern Colorado to the Dakotas. Up to a few inches
of snow is possible in these areas, as well as minor ice accumulations
thanks to a wintry mix along the Columbia River in eastern Nebraska on
north into southwest Minnesota. To the south, the conveyor belt of rich
Gulf moisture will stretch from the central Gulf Coast to the Ozarks. WPC
has a Slight Risk for Excessive Rainfall in these areas, as well as in
both eastern Oklahoma and eastern Texas. By Christmas Eve night, both the
East and West Coast will generally be dry, while the Mid-South on north
through the central Plains and Upper Mississippi Valley can expect
unsettled weather. Motorists and reindeer should be sure that their
headlights and noses are lit up brightly in areas where snow and rain are
expected Christmas Eve.

Temperature-wise, it will not begin to feel a lot like Christmas for much
of the Heartland on east to the East Coast this holiday weekend. On
Saturday, many places in the Heartland can expect daytime highs that range
between 10-25 degrees above normal. Morning lows will even be milder with
a wide footprint of 20-30 degrees above normal temps from central Texas to
the Upper Great Lakes. By Christmas Eve, record warm minimum temps will be
common in the Midwest where many low temps will be considerably higher
than the average high temps for late December. The East Coast will not
witness quite the anomalous warmth that the Midwest will, but daily
average temps could still top 10-15 degrees above normal in parts of the
Northeast on Christmas Eve. By Christmas Day, the most unusually mild
temperatures are expected in the Great Lakes and Northeast where highs
could range between 10-20 degrees above normal. In contrast, the
central/southern Plains and central/southern Rockies will be the coolest
versus normal thanks to a recent cold frontal passage injecting the region
with an air-mass that feels a lot more like Christmas compared to their
neighbors on the East and West Coasts.

Mullinax


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php