Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
216 PM EST Sun Dec 08 2024

Valid 00Z Mon Dec 09 2024 - 00Z Wed Dec 11 2024

...Heavy rain threat emerges across the South late Sunday into Tuesday...

...Periods of mixed rain and snow linger across Interior New England
through tonight...

...Unsettled and windy weather spreading across the Pacific Northwest this
weekend will reach into the northern Plains as snow/wintry mix by Monday...

...Well above average temperatures will overspread the central and eastern
U.S. as cold air surges into the western U.S....

..Strong Santa Ana Winds result in Critical Fire Weather day starting
Monday across Southern California...


The last vestiges of cold air are being dispelled out of New England for
the remainder of today into tonight with some lingering snow showers still
possible across far Interior New England.   Clearing skies and return flow
ahead of the Pacific System sliding through the Rockies, combining with
warmer/moist air returning out of the Western Gulf ahead of an average
upper-level trough; will result in well above temperatures today across
the Northern Plains and Midwest, shifting to the eastern half of the
country on Monday, and finally east of the Mississippi into Tuesday ahead
of the Pacific cold front.  Today, 20-30 degree departures will exist in
the Plains and temper a bit to 15-25 degrees above normal overnight
through Tuesday morning.  Increased moisture through the lower Mississippi
River Valley will have some stronger showers and possible thunderstorms
closer to the Gulf of Mexico.  Rain-rates may result in a few widely
scattered incidents of flooding across the Delta Region into SW LA today,
shunting south to the Central Gulf Coast Monday into Tuesday.  The Weather
Prediction Center has issued a Marginal Risk for today; and upgrades to a
Slight Risk (level 2 of 4) on Tuesday across south-central LA to Mobile
Bay mainly for risks near susceptible urban locations along I-10/12.

The aforementioned Pacific airmass/frontal zone has cross much of the
northern Rockies and has already developed a stronger surface low just
north of the U.S. Canada border.  Associated strong winds and snows from
overnight is resulting in dangerous travel conditions across E Montana
with a Blizzard Warning still in affect across far east-central MT until 6
pm MST today.  Downstream warm air advection will over-top some remaining
colder air across northern MN into the Western Great Lakes tonight. 
Winter Storm Warnings and Advisories are in effect across the norther Red
River Valley into northern MN where 4-7" of snow are expected. Strong
onshore flow off Lake Superior will further enhance local snow totals
across the Arrowhead of MN range with 9-12"+ totals expected. 

Behind the cold front a combination of cold air off the Pacific, as well
as from eastern AK, Yukon will continue to filter southward directed
through the Intermountain Region and Great Basin over the next few days. 
Below average temperatures will also bleed out in the Plains by late
Monday into Tuesday with a classic 'Blue Norther' cold front driving well
through the Southern Plains into northern Mexico by Tuesday.  High
temperatures will be about 5-10 degrees below normal across much of the
Rockies, Southwest and eventually into the Plains. 

Perhaps most impactful, is the surge directed through the Great Basin into
the Lower Colorado River Valley will result in well above average high
pressure that should allow for the front to cross the Peninsular Range
Monday.  This will bring very strong Santa Ana winds across southern
California on Monday and given dry/low humidity conditions already in
place; Red Flag Warnings have been issued for the eastern Transverse and
all Peninsular Ranges from Monday into mid-week; as well as a Critical
Fire (level 2 of 3) from the Storm Prediction Center.  Winds of 35 to 45
mph in the valleys and gusts of 50 to 65 mph in the mountains will help
expand any fires that do develop quickly and may reduce visibility with
blowing smoke and dust adding to travel concerns in the region. 

Gallina


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