056
FXUS21 KWNC 081846
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 08 2025

SYNOPSIS: Mid-level high pressure is predicted over the western Contiguous U.S.
(CONUS) favoring an increased risk of extreme heat over much of the Interior
West during the first half of the week-2 forecast period. Extreme heat is also
possible over the Northeast, exacerbated by high humidity levels favored. With
the subtropical high pressure predicted to be centered over the Four Corners,
shower and thunderstorm activity is favored to ramp up across the Desert
Southwest during the middle and latter portions of the forecast period.

HAZARDS

Moderate risk of heavy precipitation over the lower Four Corners region,
Sat-Tue, Jul 19-22.

Slight risk of heavy precipitation over southern and western Arizona, and
southern New Mexico, and western Texas, Fri-Tue, Jul 18-22.

Slight risk of extreme heat for Californias Central Valley and much of the
Interior West, Wed-Fri, Jul 16-18.

Slight risk of extreme heat for the Northeast coastal plain, Wed-Thu, Jul 16-17.

DETAILED SUMMARY

FOR FRIDAY JULY 11 - TUESDAY JULY 15:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR WEDNESDAY JULY 16 - TUESDAY JULY 22: A mid-level ridge accompanied by
maximum mid-tropospheric heights near 594 dm and small positive height
departures (+30 meters) are forecast across the western CONUS early in week-2
by the GEFS, ECENS and CMCE ensemble models. As week-2 progresses, the heights
fall slightly to near-normal. A slight risk of extreme heat is posted for much
of the interior West, including the Central Valley of California, through at
least July 18th. Actual air temperatures are predicted to range from the mid
90s for most of this area to near 110 deg F in the Desert Southwest, as
supported by the deterministic 0z ECMWF and 6z GFS model runs. Though this is
not considered to be an unusually high-end or high-impact heat event, it
nevertheless warrants a slight risk designation. Another mid-level ridge is
forecast over the Northeast and Upper Mid-Atlantic, supporting a slight risk of
extreme heat over the coastal plain from July 16-17. The deterministic models
noted above predict air temperatures in the low to mid 90s throughout this
heavily-populated urban corridor from near Philadelphia northeastward through
eastern Maine. Forecast uncalibrated ECENS dewpoint temperatures of at least 70
deg F would elevate the heat index values into the mid and upper 90s for at
least 2 days, which satisfies the criteria for extreme heat in this area. The
PETs support a very slight reduction of this largely humidity-driven heat event
each day during the remainder of the week-2 period (after July 17).



In the Southwest, the center of the subtropical ridge is forecast to drift
around the Four Corners area during week-2. This puts the ridge center in a
favorable position for increased shower and thunderstorm activity associated
with the summer monsoon. This is consistent with the evolution of the week-2
ECENS precipitation Probabilistic Extremes Tool (PET) and to a significantly
reduced degree, the GEFS PET. In percentile space, the ECENS PET depicts a 30%
chance of exceeding the 85th precipitation percentile, with even better support
from the week-2 statistical precipitation analogs from the manual height blend.
On the other hand, the GEFS is significantly less bullish, supporting only a
slight risk of heavy precipitation and also lower actual rainfall amounts
across the monsoon domain. After considering various model precipitation
guidance and the overall predicted evolution of the subtropical ridge over the
Southwest, it was decided that a moderate risk of episodic heavy precipitation
was still warranted over portions of the lower Four Corners region, July 19-22.
A slight risk of heavy precipitation remains posted for a somewhat broader area
than what is covered by the moderate risk, July 18-22. During monsoon season in
the Southwest, it is imperative for people (especially campers and hikers) to
be aware of the potential for flash flooding, especially in low-lying arroyos.



With 1.5-4.0 inches of rain predicted by WPC in the week-1 period over the
Mid-Atlantic (related to Post-Tropical Cyclone Chantal), any additional
rainfall received during week-2 may result in renewed flooding. The potential
for renewed flooding will also need to be monitored in central Texas. In
addition, CPCs Global Tropics Hazards (GTH) product forecasts a slight chance
(20%) of tropical cyclone development over the northern Gulf of America during
week-2. Though the risk is considered slight at this time, it is recommended
that residents and mariners near the northern Gulf Coast stay up-to-date on the
latest weather forecasts from local news media and from the National Hurricane
Center.

FORECASTER: Anthony Artusa

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