900
FXUS21 KWNC 011839
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT August 01 2025

SYNOPSIS: Mid-level high pressure is forecast to expand across the Four Corners
and southwestern contiguous U.S. (CONUS) during week-1 and persist into week-2.
This favors an increased risk for extreme heat extending from the western CONUS
eastward to the south-central CONUS, with record-breaking high temperatures
possible, particularly over the Southwest. A period of extreme heat is also
possible over portions of the northeastern CONUS early in week-2 tied to
anomalous mid-level high pressure predicted over eastern Canada. Elevated wind
speeds remain possible over parts of the Central and Southern Plains, which
when combined with the hot, dry conditions forecast, may increase the wildfire
threat over some of these areas. Enhanced onshore flow is likely to lead to
unsettled conditions across southeastern Alaska with periods of heavy
precipitation and gusty winds.

HAZARDS

Moderate risk for extreme heat for southern portions of the California Central
Valley, Desert Southwest, Southern Rockies, and Southern Plains, Sat-Sun, Aug
9-10.

Slight risk of extreme heat for much of the western CONUS, Central and Southern
Plains, and Middle and Lower Mississippi Valley, Sat-Fri, Aug 9-15.

Slight risk of extreme heat for portions of the Ohio Valley and Northeast,
Sat-Mon, Aug 9-11.

Slight risk of episodic high winds for portions of the Central and Southern
Plains, Sat-Mon, Aug 9-11.

Slight risk of heavy precipitation across coastal portions of southeast Alaska,
Sat-Mon, Aug 9-11.

Rapid onset drought risk across southwestern Oklahoma.

DETAILED SUMMARY

FOR MONDAY AUGUST 04 - FRIDAY AUGUST 08:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY AUGUST 09 - FRIDAY AUGUST 15: A highly anomalous ridge (597-600
dm) is forecast to build over the Four Corners region of the U.S. during week-1
and gradually weaken toward the outset of week-2. An extreme heat event is
likely to be ongoing across portions of the Southwest and south-central CONUS
tied to this ridge. While the hottest temperatures are likely to occur prior to
the start of week-2, the uncalibrated 0z ECENS and GEFS depict maximum
temperatures in the 110-115 deg F range over the Desert Southwest on days 8 and
9 (Aug 9-10). The ECENS and GEFS Probabilistic Extremes Tools (PETs) depict
probabilities of at least 40 percent for maximum temperatures exceeding the
85th climatological percentile across the Four Corners, with probabilities in
both PETs gradually decreasing thereafter. Additionally, the skill-weighted
calibrated heat risk tool depicts at least a 50 percent chance of temperatures
exceeding the 90th climatological percentile during week-2 over the Southwest.



Given these strong heat signals, especially early in the period, a moderate
risk of extreme heat continues across the Southwest and south-central CONUS
through day-9 (Aug 10) and includes the southern half of the California Central
Valley where temperatures in the 105-110 deg F range are possible, the Desert
Southwest and much of New Mexico corresponding to the highest probabilities in
the PETs, and parts of Texas and Oklahoma where triple digit temperatures or
heat indices are depicted in the model guidance. A slight risk for extreme heat
continues for all of week-2 across much of the western CONUS eastward to the
Central and Southern Plains and Middle and Lower Mississippi Valley. Humidity
is likely to be more of a factor across the eastern Great Plains and
Mississippi Valley, with skill-weighted heat risk guidance depicting 60 percent
or greater probabilities for heat indices exceeding 105 deg F. The 0z GEFS and
ECENS depict an upward trend in temperatures throughout week-2 across portions
of the Northwest, with a corresponding increase in percentile probabilities in
the PETs. Low elevation areas may experience temperatures upwards of 90 to 95
deg F supporting the northward expansion of the slight risk for extreme heat
compared to yesterday.



Positive mid-level height anomalies over eastern North America favor
anomalously warm temperatures returning to portions of the northeastern CONUS.
Both the GEFS and ECENS PETs depict probabilities of at least 20 percent for
maximum temperatures exceeding the 90th climatological percentile (increasing
to above 40 percent closer to the Canadian border). By mid-August,
climatologies begin to drop off particularly across New England, likely
inflating percentile probabilities. However, the uncalibrated 0z ECENS, and to
a greater extent the 0z GEFS, depict an elevated potential for maximum
temperatures exceeding 90 deg F over some areas of the Northeast and Ohio
Valley. Given extreme heat thresholds are comparatively lower (heat indices
95-100 deg F) in these regions compared to farther south, a marginal slight
risk of extreme heat is highlighted, Aug 9-11.



Models depict enhanced easterly winds over the western Gulf and extending into
southern Texas and the Central and Southern Plains throughout the forecast
period, associated with tropical flow and enhanced return flow around surface
high pressure over the eastern U.S. Therefore, a slight risk of episodic high
winds is posted over these areas, Aug 9-11. Elevated winds combined with the
hot conditions forecast creates a favorable environment for wildfires. Rapid
onset drought risk is indicated across portions of southwestern Oklahoma due to
relatively lower 30-day precipitation totals compared to surrounding areas.



Enhanced onshore flow is forecast across southeastern Alaska during week-2
leading to increased precipitation. The GEFS and ECENS PETs depict at least a
20 percent chance 3-day precipitation totals exceed the 85th climatological
percentile and 2-inches justifying a slight risk of heavy precipitation, Aug
9-11. Mudslides are a concern over more vulnerable areas. While gusty winds are
also possible, hazardous criteria for winds is not anticipated to be reached.
Across northern Mainland Alaska, periods of heavy snow are possible along the
Brooks Range.

FORECASTER: Thomas Collow

$$