Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Tue Oct 24 2023

Valid 12Z Tue Oct 24 2023 - 12Z Thu Oct 26 2023

...A significant early season winter storm will bring heavy snowfall later
Tuesday through Wednesday across portions of the Northwest, Northern
Rockies, and Northern Plains...

...Heavy rainfall and some areas of flash flooding will be possible for
portions of the Southern Plains and Great Lakes...

...Much above average temperatures for much of the central and eastern
U.S. mid-week...

An upper-level low dropping southeastward over the northwestern U.S. will
help drive a significant early season winter storm from the Northwest
through the Northern Rockies and into portions of the Northern Plains
beginning Tuesday night. With cold air already in place, the falling
heights and secondary surge of cold air will help to bring snow levels
down so that heavy snowfall is expected for lower elevation valleys and
the Plains in addition to the mountains. Forecast storm total snowfall
ranges between 5-10", locally 12", from western North Dakota and eastern
Montana into the lower elevations of western Montana, with as much as 1-2
feet for the mountains of the Northern Rockies and northern Cascades. Snow
may mix in for lower elevations of the interior Northwest but little to no
accumulations are expected, while some accumulating snow will likely
spread further eastward into eastern North Dakota and northern Minnesota
by Wednesday night, continuing beyond the current forecast period. In
addition to the snow, the falling temperatures will feel like an early
winter blast, with highs only into the 20s and lows in the teens by
Wednesday from the Northern Rockies into the Northern High Plains.
Temperatures will be chilly but a bit more moderate in the Northwest, with
mostly 40s and low 50s expected.

To the east, showers and storms are expected to continue from the Plains
into the Midwest/Great Lakes as a broad warm sector remains in place ahead
of a pair of frontal systems. A deep upper-trough that has dug into
northern Mexico will continue to help support widespread storms ahead of a
Pacific front pushing into the Southern Plains. Anomalously high moisture
aided from the remnants of Norma will lead to some locally heavy
downpours, with repeated rounds of storms under broad southwesterly flow
increasing the potential for heavy rainfall totals. Slight Risks of
Excessive Rainfall (level 2/4) have been issued for both Tuesday and
Wednesday from the Texas Big Bend northeastward into Oklahoma where the
highest potential for this heavy rainfall and some scattered flash
flooding exists, particularly as some of these areas see repeated rounds
of rainfall over multiple days. Further north, a secondary local maxima of
heavy rainfall potential is expected across portions of the Upper Great
Lakes where moist southerly flow meets a quasi-stationary frontal boundary
draped over the region. Energetic upper-level flow parallel to the
boundary will help lead to repeated rounds of heavy rainfall. A Slight
Risk of Excessive rainfall is in place for Tuesday with a Marginal Risk
Wednesday as some isolated to scattered instances of flash flooding are
possible here as well.

In contrast to the frigid temperatures from the Northwest into the
Northern High Plains, an amplifying ridge to the east will help continue
much above average highs for the central U.S. and bring warmer
temperatures back to the Northeast. After a chilly morning many locations
dropping into the 30s for the Northeast, highs will warm into the 60s
Tuesday with 70s by Wednesday. Highs in the 70s to low 80s are forecast
from the Central Plains into the Midwest, with 80s from the Southern
Plains into the lower Mississippi Valley. Highs will be closer to average
from the Southeast into Florida, with 70s and 80s forecast. Conditions
will also be near average for California into the Great Basin, with 60s
and 70s expected, and 80s for the Desert Southwest. 

Putnam

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