Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EST Sun Dec 04 2022

Valid 00Z Mon Dec 05 2022 - 00Z Wed Dec 07 2022

...Snow and rain chances continue across the West with accumulations
expected for the mountains and northern valleys...

...Heavy rain and the risk for scattered flash flooding for the Tennessee
Valley Monday...

...Widespread showers likely ahead of a cold front for the East Coast on
Tuesday...

Pacific moisture will continue to flow across the West as an upper-level
trough moves very slowly down the West Coast. The moisture as well as
associated surface frontal systems will promote widespread snow showers as
well as lower elevation/valley rain across the region. The heaviest totals
should remain localized to the Sierra Nevada and mountain ranges of the
northern and central Rockies. Another 5-10 inches of snow will be possible
overnight for the Sierra Nevada where snow totals have been measured in
feet. However, there will still be accumulating snow for the lower
elevations/valleys in the cooler air located in northern portions of the
West. Winter Weather Advisories remain in effect for portions of the
Pacific Northwest through the northern Great Basin and into the northern
Rockies for snow totals between 1-3 inches, locally higher in the northern
Rockies. Snow will taper off first for the Pacific Northwest while lasting
into the day Monday further east in the northern Rockies. Temperatures
will remain below normal while winds will also be a bit blustery along the
front of the Rockies.

Warm, moist air will be funneled northward from the Gulf across the South
following a warm front early Monday. Widespread shower and thunderstorms
are likely from the Lower Mississippi Valley east through the Tennessee
Valley into the southern Appalachians and Carolinas. There is a Slight
Risk of Excessive Rainfall (level 2/4) currently centered on northern
Alabama, south-central Tennessee, and northwest Georgia where an axis of
heavier rainfall is expected as storms move roughly parallel to the slow
moving warm front. The axis of heaviest rainfall has been shifting a bit
run-to-run in the guidance so the Slight Risk may still shift before
tomorrow. A Marginal Risk of Excessive Rainfall (level 1/4) is in place
for Tuesday as the showers are expected to taper off through the day and
rainfall totals should remain lower compared to Monday. High temperatures
will be running 10-20 degrees above average south of the warm front with
highs in the 60s and 70s from the Southern Plains to the Southeast Monday
and Tuesday. Meanwhile, to the north, bitterly cold air will spread south
from Canada into the Northern Plains and Upper Midwest. Highs near the
Canadian border will be in the single digits with wind chills running
below zero.

Temperatures will be around average on Monday along the East Coast before
a warm up ahead of a cold front on Tuesday. Highs will be in the 40s in
the Interior Northeast, 50s for the coastal Northeast and Mid-Atlantic,
and 60s and 70s into the Carolinas. Widespread showers will proceed the
front throughout the day and into the evening. A wintry mix is possible
for higher elevations in the Interior Northeast and Appalachians where
temperatures will be a bit colder.

Putnam
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
133 PM EST Sun Dec 4 2022

Valid 12Z Wed Dec 7 2022 - 12Z Sun Dec 11 2022

...Heavy rain threat from the southern Plains to the Mid-South
midweek to the central Appalachians/Mid-Atlantic later week in
active flow across much of the nation...

18Z Update: The 12Z model guidance suite initially has good
synoptic scale agreement on Wednesday across the continental U.S.,
but timing differences become apparent by Thursday with the
shortwave exiting the Rockies and crossing the central Plains to
close out the work week. The CMC and the UKMET remain on the
slower side of the guidance spread, whereas the GFS has a stronger
and more progressive solution. There was less ensemble support
for the slower CMC/UKMET solutions. The WPC forecast was
primarily derived from a GFS/ECMWF blend with some previous WPC
continuity and 20% ensemble means through Thursday, and then
increased use of the ensemble means along with some previous WPC
continuity going into the end of the week and into next weekend.
The QPF forecast was derived from a roughly 40% NBM 4.0/40% NBM
4.1/10% GFS/10% ECMWF blend for most of the U.S., and slightly
reduced totals across the Pacific Northwest late in the period
where the blend appeared too high. The potential exists for 2 to
locally 4 inches of rainfall from eastern Oklahoma to parts of
Tennessee and Kentucky as moisture is lifted over a
quasi-stationary frontal boundary with waves of low pressure, and
a Slight Risk of excessive rainfall is maintained for the Day 4
period across northeastern Oklahoma into north-central Arkansas
and western Tennessee. The previous forecast discussion is
appended below for reference. /Hamrick
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