237
FXUS21 KWNC 281815
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT August 28 2025

SYNOPSIS: Multiple models continue to indicate surface low pressure forming
near or over the Northeast at the beginning of week-2 and moving northeastward.
This feature could bring heavy high winds to coastal portions of the
Mid-Atlantic and Northeast. Farther south, a few waves of low pressure may form
along a wavering frontal system from central Texas through the central Gulf
Coast and the Southeast, keeping a risk of scattered heavy rainfall across
these regions from the middle to end of week-2. In the Southwest, potential
tropical cyclone development west of Mexico could enhance tropical moisture
pushing into the Southwest, increasing the potential for episodes of locally
heavy precipitation for the region. Mid-level high pressure is predicted for
the Northwest during the end of week-1 into week-2, which could support
lingering extreme heat into the onset of the period for parts of Washington,
Idaho, and Oregon. Downstream, mid-level low pressure across the eastern
contiguous U.S. (CONUS) may support much below normal temperatures for parts of
the Upper Mississippi Valley, and Great Lakes at the beginning of week-2.

HAZARDS

Slight risk of high winds for coastal portions of the Mid-Atlantic and
Northeast, Fri-Sun, Sep 5-7.

Slight risk of heavy precipitation for Florida,  the Gulf Coast, and coastal
portions of the Carolinas and Southeast, Sun-Thu, Sep 7-11.

Slight risk of heavy precipitation for parts of the Southwest, Fri-Sun, Sep 5-7.

Slight risk of extreme heat for interior portions of Washington, northern
Oregon, and northwestern Idaho, Fri, Sep 5.

Slight risk of high winds for parts of eastern California and central parts of
Washington and Oregon,  Fri-Sun, Sep 5-7.

Slight risk of much below normal temperatures for parts of the Upper
Mississippi Valley, and Great Lakes, Fri-Sat, Sep 5-6.

DETAILED SUMMARY

FOR SUNDAY AUGUST 31 - THURSDAY SEPTEMBER 04:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR FRIDAY SEPTEMBER 05 - THURSDAY SEPTEMBER 11: Surface low pressure is
predicted to form over the Northeast at the start of week-2. This low and its
trailing front may support high winds, continuing the slight risk of high winds
for coastal portions of the Mid-Atlantic and Northeast, Sep 5-7. The ECENS and
CMCE Probabilistic Extremes Tools (PETs) indicate at least a 20% chance of wind
speeds exceeding the 85th percentile climatologically and 25 mph.



A quasi-stationary front is predicted to extend from the southern Mid-Atlantic
region westward along or near the Gulf Coast. This front combined with moist
onshore flow associated with a subtropical high over the western Atlantic and
eastern CONUS may support periods of locally heavy precipitation across coastal
regions for these areas. There is still significant uncertainty regarding the
timing, location, and quantity of precipitation. Therefore a general area is
highlighted with a slight risk of episodic, locally heavy precipitation across
coastal portions of Florida, the Gulf Coast, and coastal portions of the
Carolinas and Southeast, Sep 7-11. The PETs show the possibility of 3-day
rainfall accumulations exceeding the 85th percentile and one inch during the
period for the highlighted risk areas, further supported by daily guidance in
the uncalibrated ensemble means, and recent deterministic guidance.



As of 5am PDT on August 28, the National Hurricane Center is tracking 2 areas
for possible tropical cyclone formation over the East Pacific in the next 7
days. At least one of these systems may track close to the Baja Peninsula.
Despite high uncertainty of the timing and possible impact of enhanced moisture
from possible tropical cyclones, a slight risk of locally heavy precipitation
is highlighted for parts of the Southwest, Sep 5-7, primarily based on guidance
from the PETs.



Across the Northwest, amplified mid-level ridging at the end of week-1 is
anticipated to linger into the onset of week-2, supporting increased chances of
lingering extreme heat for some of the region. A slight risk of extreme heat is
designated for interior portions of Washington, northern Oregon, and
northwestern Idaho, Sep 5, where PETs indicate at least a 20% chance of maximum
temperatures exceeding the 90th percentile and 90 deg F (95 deg F locally). The
potential for thermal low pressure forming across the West Coast states with
adjacent surface high pressure in the Northeast Pacific supports a slight risk
of high winds for parts of eastern California and central parts of Washington
and Oregon, Sep 5-7. Anticipated hot, dry conditions may lead to enhanced
wildfire risk across interior portions of the Northwest and northern California.



Amplified mid-level troughing is predicted downstream of the mid-level ridge,
over the eastern half of the CONUS from the end of week-1 into the beginning of
week-2. A slight risk of much below normal temperatures is designated for Upper
Mississippi Valley and Great Lakes, Sep 5-6, away from the lake shores.
Multiple PETs show at least a 20% chance of minimum temperatures falling below
the 15th percentile climatologically and below 40 deg F. The mid-level pattern
is expected to become more zonal by the middle of the period, favorable for
milder temperatures.



Mid-level positive 500 hPa height departures are predicted for the mean week-2
pattern for Alaska, supporting above normal temperatures for much of the state.
Although anomalously warm temperatures are anticipated, actual temperatures are
not forecast to reach hazardous thresholds.

FORECASTER: Melissa Ou

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