525
FXUS21 KWNC 021835
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT September 02 2025

SYNOPSIS: At the outset of week-2, mid-level high pressure is forecast across
central North America favoring a pattern change with above-normal temperatures
returning across portions of the Great Plains and Midwest by the middle of the
period. Mid-level low pressure is forecast near the West Coast of the CONUS
favoring unsettled weather across the Pacific Northwest, and enhanced wind
speeds over coastal California, and extending through the Great Basin and Great
Plains. A stalled frontal boundary remains forecast along the East Coast and
northern Gulf resulting in enhanced precipitation chances, with uncertainty in
regards to the inland extent of the heaviest precipitation. Surface low
pressure is forecast to bring increased chances of heavy precipitation and
elevated wind speeds to south-central coastal Alaska early in the period.

HAZARDS

Slight risk of heavy precipitation across Florida, the eastern Gulf Coast, and
portions of the East Coast, Wed-Sat, Sep 10-13.

Slight risk of high winds across Florida, the eastern Gulf Coast, and portions
of the East Coast, Wed-Sat, Sep 10-13.

Slight risk of high winds over portions of the California Coast, Great Basin,
Rockies, and Great Plains, Wed-Sat, Sep 10-13.

Slight risk of high winds across coastal portions of southeastern Mainland
Alaska, Wed-Fri, Sep 10-12.

DETAILED SUMMARY

FOR FRIDAY SEPTEMBER 05 - TUESDAY SEPTEMBER 09:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR WEDNESDAY SEPTEMBER 10 - TUESDAY SEPTEMBER 16: Ridging and associated
positive 500-hPa height anomalies are forecast to expand across the
north-central U.S. early in week-2. This is likely to lead to a pattern change
with much warmer temperatures over portions of the Great Plains and Midwest
relative to earlier in week-1. Extreme heat is unlikely given the mid-September
temperature climatology, with most areas forecast to be in the 70s and 80s deg
F in the uncalibrated 0z GEFS and ECENS. Therefore, a related temperature
hazard is not posted.



Upstream of the aforementioned ridge, the 0z ECENS, GEFS, and CMCE depict
amplified troughing moving into the western CONUS. This feature is likely to
lead to some enhancement of precipitation, particularly across the Northwest
where the ECENS Probabilistic Extreme Tool (PET) depicts high probabilities
(greater than 60 percent) for 3-day precipitation exceeding the 85th
climatological percentile. However, probabilities in the GEFS PET are much
lower (20-40 percent), and actual 24-hour precipitation amounts are forecast to
be under a half-inch in the uncalibrated versions of both models. Higher
probabilities in the PETs are likely tied to the lower precipitation
climatology this time of year. While unsettled weather is possible across the
Northwest in association with the trough, hazardous conditions are not
expected, precluding a related precipitation hazard. The trough also favors
elevated wind speeds throughout much of the West and into the Great Plains. A
slight risk for high winds is posted over portions of the California Coast,
Great Basin, Rockies, and Great Plains, Sep 10-13, coinciding with the
strongest signal in the ECENS PET. Wildfire development and spread is the
primary concern due to soil moisture values in the lowest 10th climatological
percentile as of September 1. The wind threat is forecast to subside later in
week-2 as the troughing weakens.



A stalled frontal boundary remains forecast just off the East Coast of the
CONUS and into the eastern Gulf serving as focus for enhanced precipitation.
Uncertainty lies in how far inland the heaviest precipitation extends, with the
uncalibrated ECENS and GEFS generally keeping the highest week-2 precipitation
totals just offshore. However, the GEFS and ECENS PETs depict at least a 20
percent chance 3-day precipitation totals exceed the 85th climatological
percentile and 1-inch over much of the Mid-Atlantic and Southeast coasts, with
the ECENS PET extending these probabilities further north into the coastal
Northeast. The remnant low of Tropical Storm Lorena, currently over the Eastern
Pacific, is predicted to become embedded within the mean westerly flow across
the CONUS, and ultimately may have some interaction with this frontal system
around the start of week-2. A slight risk of heavy precipitation is highlighted
across Florida, the eastern Gulf Coast, and portions of the East Coast, Sep
10-13. Surface high pressure across the Northeast also favors enhanced easterly
flow along much of the Eastern Seaboard, with the ECENS PET depicting wind
speeds having a 20 percent chance of exceeding the 85th climatological
percentile and 20-mph. This supports a slight risk of high winds, also for Sep
10-13. While the National Hurricane Center is monitoring an area of disturbed
weather in the Atlantic Main Development Region with high chances for tropical
cyclone development in the next week, the majority of model guidance and
ensembles favor a recurving track away from the East Coast at this time.



Troughing and associated surface low pressure across the Bering Sea and western
Alaska are forecast to bring periods of heavy precipitation and high winds to
south-central coastal Alaska early in the period. The ECENS PET depicts at
least a 20 percent chance wind speeds exceed the 85th climatological percentile
and 40-mph across southeastern coastal Mainland Alaska supporting a slight risk
for high winds, Sep 10-12. A related precipitation hazard is not issued at this
time given totals may not reach hazards criteria over most areas.

FORECASTER: Thomas Collow

$$