818
FXUS21 KWNC 071932
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST February 07 2025

SYNOPSIS: Predicted enhanced onshore flow leads to an increased chance of heavy
precipitation and heavy mountain snow across the West. In the East, heavy
precipitation is most likely across the Ohio and Tennessee Valleys, the Lower
Mississippi Valley, and the interior Southeast. Models have come into better
agreement today on a low pressure system tracking through/near the Northeast,
with the potential for heavy snow and gusty winds. Arctic high pressure is
favored to maintain much below-normal temperatures across the northern Great
Plains and Upper Mississippi Valley.

HAZARDS

Moderate risk of heavy snow for the Cascades and Sierra Nevada Mountains,
Sat-Mon,  Feb 15-17.

Slight risk of heavy snow for the Cascades, Klamath Mountains, and Sierra
Nevada Mountains, Sat-Wed, Feb 15-19.

Slight risk of heavy snow for the northern and central Rockies, Sat-Mon, Feb
15-17.

Slight risk of heavy snow over the Northeast, Sun-Mon, Feb 16-17.

Moderate risk of heavy precipitation for the Ohio and Tennessee Valleys, and
parts of the Southeast, Sat-Sun, Feb 15-16.

Slight risk of heavy precipitation for much of California and the Pacific
Northwest, Sat-Wed, Feb 15-19.

Slight risk of heavy precipitation for parts of the Ohio and Tennessee Valleys,
Lower Mississippi Valley, and interior Southeast, Sat-Sun, Feb 15-16, and
Wed-Fri, Feb 19-21.

Slight risk of episodic high winds for the West and central to southern High
Plains, Sat-Wed, Feb 15-19.

Slight risk of high winds over the Northeast, Mon-Tue, Feb 17-18.

Slight risk of much below-normal temperatures for the northern Great Plains,
and Upper Mississippi Valley, Sat-Mon, Feb 15-17.

Possible flooding for parts of Kentucky, Tennessee, West Virginia, Lower
Mississippi Valley, and parts of the interior Southeast.

DETAILED SUMMARY

FOR MONDAY FEBRUARY 10 - FRIDAY FEBRUARY 14:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY FEBRUARY 15 - FRIDAY FEBRUARY 21: Model solutions remain
consistent that the strongest onshore flow and storm track shifts northward
along the West Coast during week-2. A moderate risk (40-60% chance) of heavy
snow is posted for the Cascades and Sierra Nevada Mountains from February
15-17, due to good model agreement and consistency along with the GEFS PET
depicting an elevated chance of 3-day snowfall amounts of 1-2 inches, liquid
equivalent. A broader slight risk for heavy snow, valid February 15-19, is
highlighted in this region. A slight risk of heavy snow is posted for the
northern and central Rockies, Feb 15-17.



During the past several days, Integrated Vapor Transport (IVT) model guidance
converged on a pair of low pressure systems affecting the West Coast with an
initial one over California at the very beginning of week-2, and a second one
taking a more northerly track across Northern California and the Pacific
Northwest around days 9-11, February 16-18. Based on these two low pressure
systems and support from the GEFS PET, a slight risk of heavy precipitation is
designated for the northern two-thirds of California and the Pacific Northwest
from February 15-19. Due to expected fluctuations in modeled tracks of these
low pressure systems at this time range, a moderate risk of heavy precipitation
is not designated at this time. Most of California and the Pacific Northwest
averaged below-normal precipitation during the past 30 days which would limit
the risk of widespread flooding. The enhanced Pacific flow and a mean 500-hPa
trough support a slight risk of episodic high winds across the West from
February 15-19. This wind hazard extends eastward to the central and southern
High Plains as the GEFS and ECENS depict lee-side cyclogenesis across eastern
Colorado.



The upstream 500-hPa trough is likely to maintain an active pattern across the
east-central CONUS through mid-February. Based on 24-hour precipitation amounts
from the GEFS and ECENS, a moderate risk of heavy precipitation is posted for
the Ohio and Tennessee Valleys and interior Southeast from February 15-17. An
interesting development today in the models favors the passage of a mid-level
trough through this region during the days 9-10 time frame, followed by a
possible brief drying out period. After this predicted brief respite, another
mid-level trough is forecast to dig across the west-central CONUS, followed by
eastward propagation into the central and eastern states. This second trough is
expected to promote the resumption of moderate to heavy rain to the region
during the last 3 days of the week-2 period. Accordingly, a broad slight risk
of heavy precipitation is posted for the Ohio and Tennessee Valleys, Lower
Mississippi Valley, and interior Southeast from February 15-16, followed by the
possible return of heavy precipitation to this area from February 19-21. A
possible flooding hazard continues for parts of Kentucky, Tennessee, West
Virginia, the Lower Mississippi Valley, and interior parts of the Southeast due
to frequent rainfall during the next week to ten days. 28-day average stream
flows are running above the 80th percentile across eastern Kentucky and
southern West Virginia.



The winter storm risk across the Northeast continues to be very challenging and
is associated with low confidence. Todays GEFS/ECENS models forecast a
significant winter storm for February 16-17, therefore a slight risk of heavy
snow is posted for portions of the Northeast for the dates mentioned.
Initially, both solutions favor a primary low tracking through the Ohio Valley
(though the GEFS is weaker), but with time a secondary low is forecast to
develop near the New Jersey coast and move northeastward. Its very difficult
to predict snowfall amounts with this system, but it does appear to be a
significant snow-producing cyclone for parts of the Northeast. As the low
pressure center intensifies off the coast, it may produce gusty northwesterly
winds across the Northeast and northern Mid-Atlantic regions. Accordingly, a
slight risk for high winds is posted for February 17-18.



Arctic surface high pressure is forecast to remain entrenched from Canada
southward into the north-central U.S. through approximately the first half of
week-2. Based on the GEFS PET, a slight risk of much below normal temperatures
is posted for the northern Great Plains and Minnesota, Feb 15-17, where there
is at least a 20 percent chance of minimum temperatures falling below the 15th
percentile and -10 degrees F. Any enhanced winds could result in wind chill
values below -25 or -30 degrees F, the cold advisory criteria. Although
below-normal temperatures are favored for northern New England, temperatures
are expected to remain above cold advisory criteria.



No hazardous weather is expected throughout Alaska during week-2 as surface low
pressure remains sufficiently south and west of the state. Only a slight lean
towards below-normal temperatures is forecast across southeastern parts of the
state. Over the Aleutians, in much closer proximity to predicted storm tracks,
wind speeds of at least 40 mph are forecast, but this does not reach or exceed
hazardous thresholds at this time.

FORECASTER: Anthony Artusa

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