Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
127 PM EST Tue Feb 04 2025

Valid 00Z Wed Feb 05 2025 - 00Z Fri Feb 07 2025

...Unsettled weather to persist across the Northwest U.S. through the
middle of the week much colder temperatures and heavy snowfall across the
Cascades and the northern Rockies...

...An atmospheric river will continue to stream across central California
today before ending early Wednesday  with additional heavy rains and
concerns for flooding...

...New storm system to bring a threat for light snow, sleet and freezing
rain to portions of the Ohio Valley and the Mid-Atlantic region by
Thursday...

...Record high temperatures are expected across much of the Southern U.S.
over the next few days...

A very stark separation of well below average and well above average
temperatures bisects much of the lower 48 states will a very strong
surface front.  No greater is this noticeable than across Montana into
Wyoming, where temperatures will range from below zero at the Canadian
border but rise in the 40s, 50s and even 60s across the central Rockies
states of Utah and Colorado.  Influence of a modest surge of cold air
yesterday across the Plains has dropped the cold front across into the
Southern Plains into West Texas where it is starting to stall and moderate
with clearing skies but today will be the last day of average to slightly
below average temperatures for this area.  The front is fairly stationary
through the Red River Valley, Tennessee Valley toward the central
Appalachians.  A slight dip in the jet stream has allowed a colder
surge/frontal push through the Mid-Atlantic into the Carolinas later today
and as far south as Georgia through mid-week.  Little moisture generally
as resulted in a dry frontal passage, with exception of a day or so more
of downstream lake effect snows across the Great Lakes into the Northeast.
Temperatures will start to become slightly below average across the
northeast/Mid-Atlantic through Wednesday but with increased sun it will
not be too bad. 

The active weather exists across the Western U.S. today associated with a
persistent, fairly stationary deep layer low off the Pacific Northwest
coast.  This low has been providing a strong gradient to its south
allowing for sub-tropical moisture to be directed as an Atmospheric River
across northern California.  This moisture surge will continue today but
with the cold front starting to drop south along the California coast,
heavy rainfall will continue to slide southward along the coast bringing
heavy rainfall to Santa Lucia Range (and downstream through the central
Sierra Nevada into the Intermountain West).  The AR will start to round
Cape Conception later today into the overnight period, but the connection
to the moisture stream will become severed and the plume will dry out
bringing only lighter showers into Southern California.  Rainfall totals
across the coastal range and lower slopes of the Central Sierra Nevada
will be in the 2-3" with spots of 4-5" in favored orographics.  As such,
the Weather Prediction Center has maintained a Slight Risk (level 2 of 4)
of Excessive Rainfall for today in the Sacramento Valley, San Francisco
Bay region and Santa Lucia Ranges; while the Marginal Risk extends to the
western Transverse Range. 

This surge of moisture is extending well into the Intermountain West aloft
and will start to stream over those areas of well below temperatures along
and north of the frontal zone.  As such, this will result in heavy
snowfall  to continue farther inland into the interior mountain ranges
such as the Sawtooth, Bitterroots, Tetons and Absaroka Range. Much of this
snowfall will be connected to the persistent and strong atmospheric river
that will continue to impact central California today into tomorrow.
Additional snowfall accumulations of 1 to 2 feet will be possible over the
Cascades and the northern Rockies with locally heavier totals through
early Thursday.  Meanwhile, for the highest elevations of the central and
northern Sierra Nevada, as much as 1 to 3 feet of new snowfall is expected.

This surge of moist Pacific air will continue quickly eastward, dry out
and descent through the Four Corners into the High Plains by Wednesday as
a strong surface cyclone develops across Southern Wyoming and a warm
frontal surge overtakes the southern Plains and lower Mississippi Valley
by Wednesday evening.  This will bring a strong dry line out through the
Staked Plains/Cap Rock and present an Elevated (level 1 of 3) of Fire
Weather Outlook for Eastern NM and portions of adjacent SE CO, SW KS,
OK/TX panhandles.  Temperatures of 15-20 degrees above normal will press
High temperature records today in the Four Corners states with
temperatures into the 70s-80s.  Wednesday, the 70s/80s reaches the
southern Plains and lower Mississippi River Valley with record potential
there too and by Thursday a large number of cites across Texas to KY/TN
and GA will also have a solid chance of record highs in the 70s and 80s.

This surge of above average air will come with some increased moisture
from the Gulf; which will move north-northeast lifting the warm front back
across the TN into Ohio Valley by Thursday, bringing some rain chances
across KY where grounds are fairly saturated and pose a low end, scattered
risk of Excessive Rainfall and WPC has issued a Marginal Risk to account
for such.   However, the greater concern is as the moisture lifts over the
front, the remaining cold air at the surface will pose a solid chance for
a broad area of freezing rainfall before the warmer air can reach the
area.   Eastern Central Plains (E KS/N MO) through the Mid-Mississippi
Valley will start to see the potential for ice starting midday Wednesday
with spots of .10" possible near St. Louis.  With strengthening
southwesterly flow and moisture, freezing rain areas will expand overnight
into Thursday across the Ohio Valley into southern Great Lakes Region and
across to the north-central Appalachians/Allegheny Plateau into Thursday
night.  Spots over .25" are becoming increasingly possible portions of W
Maryland, West Virginia Panhandle and central/southern Pennsylvania.  
Totals of .10-.25" are possible across N Indiana into Ohio, all making for
dangerous travel conditions.  Please keep advised through local forecast
office updates and forecasts.

Gallina


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