125
FXUS21 KWNC 061859
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EST December 06 2025

SYNOPSIS: Mid-level low pressure across the northeastern Pacific and eastern
Alaska downstream from a strong mid-level high pressure ridge centered just
west of the Alaska Mainland are forecast to bring very cold air and dangerous
wind chills across central and southern Alaska, along with episodes of high
winds across southern Alaska from the Aleutians into Southeast Alaska. After a
brief lull at the beginning of week-2, the mid-level low pressure should
slightly enhance moist Pacific flow across the northwestern Contiguous U.S.
(CONUS) with increased chances of heavy snow and high winds redeveloping early
in week-2. In the eastern CONUS, an area of Arctic surface high pressure is
forecast to bring enhanced chances for much below normal temperatures for many
areas east of the Mississippi.

HAZARDS

Moderate risk of much below normal temperatures for most of Southeast Alaska,
Sun-Mon, Dec 14-15.

Slight risk of much below normal temperatures for much of central, eastern, and
southern AK, Sun-Wed, Dec 14-17.

Moderate risk of high winds across southern Alaska from the eastern Aleutians
through central Southeast Alaska, Sun-Sat, Dec 14-20.

Slight risk of high winds for southern Alaska from the central Aleutians
through Southeast Alaska, Sun-Sat, Dec 14-20.

Moderate risk of much below normal temperatures for parts of the Ohio and
Tennessee Valleys, and Appalachians, Sun-Mon, Dec 14-15.

Slight risk of much below normal temperatures for parts of the Mississippi,
Ohio, and Tennessee Valleys, Appalachians, Great Lakes, Mid-Atlantic, and
Southeast, Sun-Tue, Dec 14-16.

Slight risk of heavy snow across the northern Cascades, Mon-Tue, Dec 15-16.

Slight risk of heavy snow across part of the northern Rockies and adjacent High
Plains, Mon-Wed, Dec 15-17.

Slight risk of high winds for coastal regions of the Pacific Northwest,
Mon-Tue, Dec 15-16.

Flooding possible across parts of the Pacific Northwest.

DETAILED SUMMARY

FOR TUESDAY DECEMBER 09 - SATURDAY DECEMBER 13:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SUNDAY DECEMBER 14 - SATURDAY DECEMBER 20: The 0z ECWMF, GEFS, and Canadian
ensembles depict a highly-amplified mid-level ridge centered west of Alaska,
with a fairly amplified downstream mid-level trough established over
southeastern Alaska and the adjacent northeastern Pacific. This set-up favors
persistent surface high pressure across much of Alaska and the Yukon throughout
week-2. Conversely, mean low pressure is favored in the Gulf of Alaska. The
pressure gradient between these features brings increased chances for episodes
of high winds across much of southern Alaska between the eastern Aleutian
Islands through much of Southeast Alaska. High winds would be particularly
favored in gaps and inlets. Probabilistic Extremes Tools (PETs) show enhanced
chances of wind speeds exceeding the 85th climatological percentile. Therefore,
broad moderate and slight risks of high winds are posted for all of week-2 for
much of southern Alaska.



PETs continue to highlight enhanced chances for temperatures to fall to near
hazardous thresholds across Southeast Alaska and into the southeastern
Mainland. However, chances for hazardous much below normal temperatures are
reduced by the middle of week-2 and further reduced by the end of the period.
This is tied to the mid-level 500-hPa height pattern deamplifying over Alaska
through the period resulting in less northerly flow into the state. Therefore,
a moderate risk remains posted for Southeast Alaska for days 8 & 9, while a
broader slight risk is maintained for much of the interior, south-central, and
southeastern Mainland for days 8-11. The combination of very cold weather and
high winds along the southern tier of the state increases the threat for heavy
freezing spray at times near larger bodies of water.



In the wake of a strong mid-level trough progressing off the Northeast coast,
strong Arctic high pressure builds into the eastern CONUS by the end of week-1
and into week-2. PETs from the ECENS and CMCE indicate enhanced chances for
temperatures to fall below the 2nd percentile at the start of week-2 over the
Ohio and Tennessee Valleys. There is broad support among all three PETs for
minimum temperatures to fall below the 5th percentile across much of the
eastern CONUS. Therefore, a moderate risk of much below-normal temperatures is
forecast for parts of the Ohio and Tennessee Valleys for days 8 & 9. Enveloping
this moderate risk area, a broad slight risk of much below normal temperatures
is forecast for the Middle and Lower Mississippi, Ohio, and Tennessee Valleys,
Mid-Atlantic, and Southeast for days 8-10. The GEFS and ECENS indicate enhanced
probabilities for apparent temperatures to fall below 0 degF across much of the
northern half of the moderate risk area with near 0 degF wind chills over the
southern half of the region. Freezing temperatures are likely to extend to the
Gulf Coast and through much of the Florida Peninsula. Temperatures should
moderate relatively rapidly as we head into the middle of the period as the
high pressure shifts east, allowing return flow into central CONUS. Some tools
indicate there may be a renewed chance of cold temperatures by the end of
week-2, however.



A mid-level ridge over the Rocky Mountains has trended stronger and further
West relative to yesterday. This has reduced chances for enhanced onshore flow
into Northern California and the Pacific Northwest since yesterday`s forecast.
There is still some signal for enhanced moisture and wind into portions of the
Pacific Northwest and northern Rockies but there is significantly less
confidence. Therefore, a slight risk of high winds and heavy snow are posted
for coastal Washington and the northern Cascades, respectively, for days 9 &
10. A second slight risk of heavy snow is posted for the northern Rockies for
days 9-11 as the moisture moves inland. A flooding possible hazard remains
posted for portions of western Washington and northern Oregon, where any
additional precipitation may increase the risk for flooding and landslides as
the soil conditions will remain wet from an atmospheric river in week-1.

FORECASTER: Ryan Bolt

$$