052
FXUS21 KWNC 021817
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 02 2025

SYNOPSIS: Strong mid-level high pressure results in the increased risk of
extreme heat across parts of the West next week. The greatest chance for
extreme heat is forecast for the Desert Southwest and San Joaquin Valley of
California on July 10 and 11. Although above-normal temperatures are likely to
persist across the West through the end of week-2, the chance for extreme heat
decreases by July 15. A slow-moving cold front is expected to be the focus for
locally heavy rainfall across portions of the eastern and central U.S. from
July 10 to 12.

HAZARDS

Moderate risk of extreme heat for the Desert Southwest and San Joaquin Valley
of California, Thu-Fri, Jul 10-11.

Slight risk of extreme heat for parts of the West, Thu-Mon, Jul 10-14.

Slight risk of heavy precipitation for southeastern Arizona and southwestern
New Mexico, Thu-Wed, Jul 10-16.

Slight risk of heavy precipitation for parts of the eastern and central U.S.,
Thu-Sat, Jul 10-12.

DETAILED SUMMARY

FOR SATURDAY JULY 05 - WEDNESDAY JULY 09:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR THURSDAY JULY 10 - WEDNESDAY JULY 16: The GEFS and ECENS depict a 500-hPa
ridge strengthening over the West during the early to middle part of next week.
Among the ensemble mean solutions, the ECENS remains the strongest with this
ridge as 500-hPa heights are forecast to peak at 597-dm across southern
California and the Desert Southwest on July 10. A moderate risk of extreme heat
(valid July 10 and 11) is posted for parts of the Desert Southwest and
southeastern California where the ECMWF Probabilistic Extremes Tool (PET) has
more than a 40 percent chance of maximum temperatures exceeding 110 degrees F.
Since the uncalibrated ECENS and GEFS have maximum temperatures at or above 110
(105) degrees F as far north as Las Vegas (San Joaquin Valley of California),
those areas are also included in the moderate risk area. Although anomalous
heat is also likely to affect inland areas of the West, only a slight risk
(20-40 percent chance) of extreme heat is warranted for a broader area through
July 14 as there is less forecast confidence that extreme heat thresholds would
be reached according to the PETs. Towards the end of week-2, the ensemble mean
solutions favor a weakening of the mid-level ridge and the slight risk of
extreme heat is discontinued after July 14. The anomalous warmth during the
early part of week-2 would lead to the additional drying of fuels and elevate
the wildfire danger across the Pacific Northwest and Northern Intermountain
West.



Following Hurricane Flossie in the East Pacific, the National Hurricane Center
states that there is a 50 percent chance of another tropical cyclone (TC)
forming in the East Pacific during the next week. Many of the GEFS ensemble
members have this potential TC taking a somewhat similar track to Flossie
towards the southern Baja Peninsula which could eventually lead to a surge of
enhanced low to mid-level moisture northward from the Gulf of California into
the Desert Southwest. However, the ECENS ensemble members are generally weaker
with any TC that develops and favor a more westward track with enhanced
moisture less likely to reach the Desert Southwest. Based on the wetter GEFS
PET, a slight risk of heavy precipitation is posted for southeastern Arizona
and southwestern New Mexico. Due to diverging model solutions on precipitation
amounts across the Southwest, the flooding possible hazard from previous
outlooks was discontinued.



A slow-moving front is forecast to be the focus for thunderstorms with locally
heavy rainfall from the Northeast and Mid-Atlantic westward to the Central and
Southern Great Plains. The spatial extent of the slight risk of heavy
precipitation, valid from July 10 to 12, is based on where the GEFS and ECENS
PETs have a 20 percent chance of 3-day precipitation amounts exceeding the 85th
percentile and 1 inch. Also, the slight risk area is supported by the
uncalibrated ECENS model output. Beyond the early part of week-2, any diurnal
convection is expected to become more scattered across the eastern U.S. which
precludes the continuation of the slight risk past July 12.



An amplified 500-hPa trough is forecast to become established over Alaska by
the beginning of week-2. This anomalous trough favors much cooler temperatures
and above-normal precipitation across much of Alaska. However, precipitation
amounts are not forecast to reach hazards thresholds.

FORECASTER: Brad Pugh

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