082
FXUS21 KWNC 291812
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 29 2026

SYNOPSIS: A restrengthening area of mid-level high pressure forecast supports a
renewed and expanded risk of extreme heat conditions for many parts of the
western contiguous U.S. (CONUS) during week-2. The combination of anomalously
warm and drier than normal conditions is expected to enhance the risk for
wildfire activity where numerous wildfire incidents have been reported within
highlighted heat risk areas.  Antecedent dryness along with the likelihood of
above-normal temperatures and below-normal precipitation during the next two
weeks supports an increased risk for the Rapid Onset of Drought to parts of the
Great Plains and Corn Belt. A more favorable monsoonal circulation supports an
increased and potentially prolonged risk of heavy precipitation across the
Desert Southwest and lower Four Corners.

HAZARDS

High risk of extreme heat for portions of California, the Great Basin, and
adjacent parts of the Rockies, Thu-Fri, Aug 6-7.

Moderate risk of extreme heat for portions of the High Plains, Southwest, Great
Basin, Rockies, Northern Intermountain, Northwest, and California, Thu-Sat, Aug
6-8.

Slight risk of extreme heat for most of the western two-thirds of the CONUS and
Southeast U.S., Thu-Wed, Aug 6-12.

Slight risk of extreme heat for parts of the Ohio Valley, Appalachians, eastern
Great Lakes, Mid-Atlantic, and Northeast, Thu, Aug 6.

Slight risk of heavy precipitation for parts of the Desert Southwest and
adjacent regions, Thu-Wed, Aug 6-12.

Rapid Onset Drought (ROD) possible for parts of the Great Plains, Middle
Mississippi Valley and Great Lakes.

DETAILED SUMMARY

FOR SATURDAY AUGUST 01 - WEDNESDAY AUGUST 05:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR THURSDAY AUGUST 06 - WEDNESDAY AUGUST 12: The week-2 hazards outlook
perspective generally remains on track. Dynamical models continue to advertise
the reamplification of a 500-hPa ridge centered over Interior West resulting in
an elevated risk of extreme heat over many parts of the western CONUS by the
middle of next week. In addition, the amplifying ridge looks to be in a more
favorable position for the advection of monsoonal moisture, supportive of a
potentially prolonged heavy precipitation risk across the southwestern CONUS
during the outlook period. Downstream, a fairly shallow mean mid-level trough
remains favored to deamplify and lift out over southern Canada, with an
accompanying frontal system bringing cooler temperatures for portions of
northeastern CONUS early in the period. As the mean mid-level troughing
gradually shifts eastward over southern Canada, much of the mid-level ridging
initially established over the eastern U.S. looks to ease but become more
confined over the Southeast towards the middle of week-2. Concurrently, much of
the anomalous ridging over the western CONUS is favored to subside but begin to
slightly shift eastward, where there is some model support for the linkage
between both of the 500-hPa ridge centers later in week-2. If realized, the
pattern would support widespread above-normal temperatures throughout much of
the CONUS, with increased risks for extreme heat along a merged ridge axis from
the Interior West eastward into the Southeast.



Underneath the amplified 500-hPa ridge favored in the West where both the ECMWF
and GEFS feature 596 and 595 dm mean heights, respectively, a high risk of
extreme heat remains posted for parts of California, Great Basin and adjacent
Rockies, and is extended through Aug 7. Coverage is expanded to include
adjacent portions of the Northern Intermountain, and reduced along the southern
periphery of the high risk area based on cooler trends in the temperature tools
associated with increased monsoonal moisture and precipitation across the
Desert Southwest. Within the highlighted high risk area, Probabisitic Extreme
Tools (PETs) indicate 30-50% chances for daytime temperatures exceeding the
85th percentile, with the probabilistic NWS Heat Risk Tool favoring increased
chances for purple level (extreme) categorical values. The continuation of a
high risk of extreme heat is also supported by a number of locations in the
National Blend of Model (NBM) that are forecast to approach and/or break
records for daytime maximums and nighttime minimums, implying little overnight
relief to the heat. A broader moderate risk area of extreme heat remains
posted, and is adjusted to include more the Central and Southern Plains and
Mississippi Valley due to better support in the calibrated heat index tools,
and increasing chances for heights exceeding 597dm in the latest ECMWF ensemble
over this part of the country. The moderate risk remains valid through Aug 8
before much of the ridging aloft deamplifies. The combination of anomalously
warm and drier than normal conditions is expected to be favorable for wildfire
activity where numerous wildfire incidents (both contained and ongoing) have
been reported within these elevated heat risk areas.



Surrounding these elevated risk areas for heat, a slight risk area of extreme
heat is designated throughout week-2 (Aug 6-12) for much of the western
two-thirds of the CONUS, with an extension throughout the lower Gulf States and
Southeast where enhanced subtropical ridging looks to remain a factor. This
extension is supported by the calibrated heat tools which depict increased
chances for heat index values above 105 and 110 deg F driven by elevated
dewpoints.  Prior to the development of more mid-level troughing and cooler
temperatures favored further north later next week, the separate slight risk
area of extreme heat remains posted (Aug 6) and now covers a smaller portion of
the northeastern CONUS relative to yesterday. Calibrated heat tools continue to
show increased chances for heat index values exceeding the 90th percentile in
advance of a frontal boundary by the outset of the period.



A Rapid Onset Drought (ROD) risk remains posted over the Plains and Mississippi
Valley over areas with antecedent dryness and near to below normal
precipitation is favored to prevail over the next few weeks. According to the
U.S. Drought Monitor valid July 21, abnormal dryness (D0) and moderate drought
(D1) expanded this past week across the Dakotas implying that ROD is underway.
Despite the cooler temperatures favored early in week-2, any renewed warmth
combined with dry conditions enhances the risk for wildfire activity.



Across the Southwest, deterministic and ensemble based ECMWF solutions continue
to point to increased dewpoints and total precipitable water content
overspreading the Sonoran Desert, consistent with a Gulf of California moisture
surge event by late next week. Given that tropical cyclone activity in the
eastern Pacific is favored to calm down in the wake of Genevieve, any gulf
surge potential is most likely tied to the precursor pairing of a strong
thermal low established over Arizona and easterly wave activity moving off of
the Sinaloa Highlands of western Mexico to initiate a moisture event. Based on
raw and calibrated precipitation tools, a slight risk of heavy precipitation
remains posted and continues to be valid for all of week-2 due to the
persistence of wet signals in the ECMWF PET associated with a favorable
monsoonal circulation where additional gulf surge events are possible later in
the period.

FORECASTER: Nick Novella

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