941
FXUS21 KWNC 041907
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 04 2025

SYNOPSIS: From July 12 to 14, a strong mid-level ridge of high pressure results
in an elevated risk for extreme heat across the West. Beginning on July 14,
there is an increasing chance for extreme heat to affect the Northern Great
Plains as the western heat is expected to shift eastward with time. Following a
lull in the Monsoon, an increasingly favorable pattern for locally heavy
rainfall across the Desert Southwest is forecast during mid-July.

HAZARDS

Slight risk of extreme heat for the interior Pacific Northwest and Northern
Intermountain West, Sat, Jul 12.

Slight risk of extreme heat for the Central Valley of California, Great Basin,
and parts of the Desert Southwest, Sat-Mon, Jul 12-14.

Slight risk of extreme heat for the Northern Great Plains and Western Corn
Belt, Mon-Fri, Jul 14-18.

Slight risk of heavy precipitation for southeastern Arizona and southwestern
New Mexico, Sat-Fri, Jul 12-18.

Slight risk of heavy precipitation for central and western Arizona, and
adjacent areas of southeastern California and Nevada, Wed-Fri, Jul 16-18.

DETAILED SUMMARY

FOR MONDAY JULY 07 - FRIDAY JULY 11:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY JULY 12 - FRIDAY JULY 18: The GEFS and ECENS are in good agreement
that a 500-hPa ridge peaks in strength across the West prior to the start of
the outlook period on July 12. However, this anomalous ridge with 500-hPa
height anomalies of +30 to +60 meters continues to favor at least a slight risk
of extreme heat for much of the inland West through July 14. A slight risk of
extreme heat is posted for the interior Pacific Northwest on July 12, but a
shortwave trough is expected to progress inland and provide slight cooling
after that date. For the Great Basin, Central Valley of California, and parts
of the Desert Southwest, a slight risk of extreme heat is posted from July 12
to 14. The spatial extent is based on where the GEFS and ECENS Probabilistic
Extremes Tool (PETs) have a 20 to 40 percent chance of maximum temperatures
exceeding the 85th percentile and reaching extreme heat thresholds. A moderate
risk was considered for the Salt Lake City area, but the PETs have less than a
40 percent chance that maximum temperatures reach 100 degrees F. The anomalous
warmth during mid-July would lead to the additional drying of fuels and elevate
the wildfire danger across the interior Pacific Northwest and northern
Intermountain West.



The ensemble mean solutions are consistent that 500-hPa heights increase with a
warming trend across the northern Great Plains and Western Corn Belt later in
week-2. Based on the evolving longwave pattern, tendency for anomalous heat to
typically shift eastward from the West, and the calibrated heat index (HI) tool
having more a 20 percent chance of HI values to exceed 100 degrees F, a slight
risk of extreme heat is posted for the Northern Great Plains and Western Corn
Belt beginning on July 14.



As of 11am PDT on July 4, the National Hurricane Center is monitoring a
tropical wave a few hundred miles south of Mexico and states that there is a 80
percent chance of tropical cyclone (TC) development in the East Pacific during
the next week. Following this potential TC, many of the GEFS and ECENS ensemble
members favor additional TC genesis in the East Pacific during mid-July. The
continued active East Pacific with a model consensus for northwest tracks may
lead to enhanced low to mid-level moisture spreading northward from the Gulf of
California into the Desert Southwest. Unlike previous days, the model guidance
is in better agreement depicting the 500-hPa ridge axis shifting north over the
Four Corners region later in week-2. Given these favorable signs along with
support from the ECENS PET, the slight risk of heavy precipitation was
continued for southeastern Arizona and southwestern New Mexico for the entirety
of week-2 and expanded to include more of the Desert Southwest, beginning on
July 16. If good model continuity is maintained, a flash flooding hazard may be
added in subsequent outlooks.



An amplified 500-hPa trough is forecast to become established over Alaska
during the second week of July. This anomalous trough favors much cooler
temperatures and above-normal precipitation across most of Alaska. Unseasonably
cold temperatures and even snow may affect the Brooks Range and North Slope
during mid-July. Towards the end of this outlook period, the ensemble mean
solutions indicate that the amplified 500-hPa trough over Alaska weakens.

FORECASTER: Brad Pugh

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