254
FXUS21 KWNC 311806
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT October 31 2025

SYNOPSIS: Mid-level low pressure forecast over the northeastern Pacific favors
an increased risk of heavy precipitation, high elevation snowfall, and high
winds over portions of the northwestern contiguous U.S. (CONUS) and
southeastern Alaska during week-2. Additional shortwave energy is predicted to
traverse the Northern Tier of the CONUS early in the period favoring enhanced
chances for high winds shifting east from the Great Plains into the East, along
with the potential for surface low pressure over the Great Lakes or Northeast.
Increasing model spread reduces forecast confidence during the second half of
week-2.

HAZARDS

Slight risk of heavy precipitation across portions of the Pacific Northwest and
northern California, Sat-Tue, Nov 8-11.

Slight risk of heavy precipitation across portions of the Northeast, Sat-Sun,
Nov 8-9.

Slight risk of heavy snow across portions of the Cascades, Sat-Tue, Nov 8-11.

Slight risk of heavy snow across portions of the Northern Rockies, Sat-Tue, Nov
8-11.

Slight risk of high winds across portions of the Pacific Northwest and northern
California, Sat-Tue, Nov 8-11.

Slight risk of high winds across portions of the northern and central Rockies
and Plains and the Upper and Middle Mississippi Valley, Sat, Nov 8.

Slight risk of high winds across portions of the Midwest, Ohio Valley, Great
Lakes, Appalachians, Mid-Atlantic, and Northeast, Sun-Mon, Nov 9-10.

DETAILED SUMMARY

FOR MONDAY NOVEMBER 03 - FRIDAY NOVEMBER 07:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY NOVEMBER 08 - FRIDAY NOVEMBER 14: The 0z GEFS, ECENS, and CMCE
models remain in good agreement regarding troughing across the northeastern
Pacific. While the exact trough axis positioning is uncertain given model
differences regarding the amplification of downstream ridging over the
west-central CONUS, the feature at times will be close enough to the West Coast
of the CONUS to result in enhanced precipitation, coastal high winds, and high
elevation heavy snow beginning in week-1 and persisting into at least the first
half of week-2. Both the GEFS and ECENS Probabilistic Extremes Tools (PETs)
indicate at a 20-30 percent chance 3-day precipitation totals exceed the 85th
climatological percentile and 1.5 inches early in week-2, with chances
decreasing later in the period. The ECENS Integrated Vapor Transport (IVT) tool
continues to indicate enhanced probabilities of IVT values exceeding 250 kg/m/s
through about day-11 (Nov 11), while the GEFS IVT weakens the signal a bit
earlier. This is consistent with the ECENS, and also the CMCE, showing another
weak trough feature near the West Coast around the middle of the period, but a
flatter pattern depicted in the GEFS. Based on the above guidance, there is
enough support to maintain the slight risk for heavy precipitation across the
Pacific Northwest and northern California through Nov 11. Any heavy
precipitation is likely to lead to increased streamflows and possibly isolated
urban flooding within the highlighted precipitation area.



A slight risk for high winds is also posted over coastal areas of the Pacific
Northwest and northwestern California, where the GEFS and ECENS PETs depict at
least a 20 percent chance wind speeds exceed 25-mph, along with an enhanced
signal for wind speeds exceeding 40-mph just offshore. Lastly, slight risks for
heavy snow are posted across the Cascades and Northern Rockies. Signals in the
models are marginal, but 24-hour amounts exceeding 4-inches are possible, with
higher totals favored over the northern Cascades. The aforementioned wind and
snow hazards are valid through Nov 11.



Downstream, another shortwave trough is forecast to amplify across the
north-central and northeastern U.S. There is good support from the uncalibrated
0z ECENS and GEFS regarding enhanced wind speeds across the Northern and
Central Rockies and Plains as this trough initially digs into the CONUS, with
an enhanced gradient due in part to higher pressures over the Intermountain
West. There is also more support for surface low pressure developing across the
Great Lakes or Northeast on the lee side of the troughing. As this feature
potentially strengthens, increasing winds are possible on its backside,
progressing eastward from the Mississippi Valley through the Atlantic Coast. As
a result, a slight risk of high winds is highlighted across portions of the
northern and central Rockies and Plains and the Upper and Middle Mississippi
Valley on Nov 8, and then shifted eastward over portions of the Midwest, Ohio
Valley, Great Lakes, Appalachians, Mid-Atlantic, and Northeast on Nov 9-10. The
PETs are also more robust with the precipitation signal across the Northeast
compared to yesterday, indicating at least a 20 percent chance 3-day
precipitation totals exceed the 85th climatological percentile and 1-inch early
in the period. Daily surface analysis from the 0z GEFS and ECENS depict
consolidation of precipitation across the Northeast around days 8 and 9 (Nov
8-9), with minimal return flow from the Gulf likely keeping areas of the
Southeast and Mid-Atlantic relatively drier. Therefore, the slight risk of
heavy precipitation is focused across the Northeast, Nov 8-9, with small stream
and urban flooding also possible over some areas, especially given antecedent
rainfall. The GEFS indicates another shortwave trough entering the East later
in the period, but this is more uncertain given less support from the ECENS.



As the initial surface low pressure system departs the Northeast early in
week-2, relatively colder air is likely to push into much of the eastern CONUS,
with the potential for near-freezing overnight temperatures extending over
portions of the Mid-South into the Mid-Atlantic, and the coldest temperatures
over Upstate New York and New England where overnight lows may dip into the
teens deg F. Given that most of these areas have already experienced a first
frost or freeze, and that these temperatures are on par with the
early/mid-November climatology, no related temperature hazards are posted. Snow
cannot be ruled out across the Interior Northeast as well, but totals are
likely to remain below hazards thresholds precluding a related hazard.



Across Alaska, periods of high winds and locally heavy precipitation are
possible over the Southeast associated with anomalous mid-level troughing over
the northeastern Pacific and Bering Sea. However PETs show precipitation
amounts and wind speeds likely remaining below hazard thresholds.

FORECASTER: Thomas Collow

$$