335
FXUS21 KWNC 271836
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 27 2026

SYNOPSIS: Strong mid-level high pressure is forecast to bring a prolonged heat
wave to the West through the beginning of August. 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 renewal of an enhanced
monsoon during early August is possible following the prolonged heat wave.
Possible surface lows forming in the lee of the Rockies may support periods of
high winds across the Northern and Central Rockies at the beginning of the
period, which may lead to enhanced wildfire risk where hot and dry conditions
are anticipated.

HAZARDS

High risk of extreme heat for portions of the Great Basin, and adjacent
regions, Tue-Thu, Aug 4-6.

Moderate risk of extreme heat for portions of the Southern Plains, Southwest,
Great Basin, Rockies, and California, Tue-Fri, Aug 4-7.

Slight risk of extreme heat for most of the western two-thirds of the CONUS and
Southeast U.S., Tue-Mon, Aug 4-10.

Slight risk of extreme heat for the Middle and Upper Mississippi, and Ohio
Valleys, Great Lakes, Mid-Atlantic, and Northeast, Tue-Thu, Aug 4-6.

Slight risk of heavy precipitation for parts of the Desert Southwest, Tue-Mon,
Aug 4-10.

Slight risk of high winds for the Northern and Central Plains, Tue-Wed, Aug 4-5.

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

DETAILED SUMMARY

FOR THURSDAY JULY 30 - MONDAY AUGUST 03:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY AUGUST 04 - MONDAY AUGUST 10: The GEFS, ECENS and CMCE are in good
agreement and remain consistent in showing a highly amplified 500-hPa ridge
peaking in strength by the middle of week-1 when it becomes centered over the
western Contiguous U.S. (CONUS) before weakening towards the end of week-1.
However, tools are now showing an increase in strength of the mid-level height
anomaly moving into the middle of week-2. By day 10, the ECENS and CMCE support
a near 600dm ridge over the West. The increase in strength of the ridge moving
into the middle of week-2 supports a high risk  (>60% chance) of extreme heat
for portions of the Great Basin, Aug 4-6. A moderate risk (40-60% chance) is
highlighted across portions of the Southern Plains, Southwest, Great Basin,
Rockies, and California, Aug 4-7. The moderate risk is spatially reduced
relative to yesterday with much of the Southern Plains and lower elevations of
the Desert Southwest removed from the risk area today. A slight risk (20-40%
chance) is designated for most of the western two-thirds of the CONUS and
Florida. Heat tools indicate greater than 30-40% chances of actual temperatures
or heat index values exceeding 110 deg F across parts of the Desert Southwest
and California Central Valley and 100 deg F across portions of the Great Basin.
The National Blend of Models indicates near or record daily highs for parts of
the southwestern CONUS at the beginning of week-2, as well as near to record
nighttime lows across the southern tier of the CONUS, providing little to no
relief in these areas.



Surface low formation in the lee of the Rockies may help to propel a front
across the Plains and into the Great Lakes. Ahead of this system, warm moist
air from the Gulf of America may bring another round of extreme heat to
portions of the Upper Mississippi Valley, Great Lakes, Ohio Valley and into the
Northeast and Mid-Atlantic and adjacent areas. Therefore, an additional slight
risk of extreme heat is posted for these regions for Aug 4-6. Based on the
evolving mid-level pattern, this is likely to be a more transient heat wave
relative to the extreme heat ongoing this week. These surface lows may bring
enhanced winds to the region. A slight risk of high winds is designated across
the Northern and Central Plains, Aug 4-5, where wind gusts could exceed 34 kts
(~39 mph). Gusty conditions combined with hot, dry weather may enhance wildfire
risk for some of these areas.



According to the U.S. Drought Monitor valid July 21, abnormal dryness (D0) and
moderate drought (D1) expanded this past week across the Dakotas where a Rapid
Onset Drought (ROD) risk is underway. Increasing 30-day precipitation deficits,
high evapotranspiration rates, and the increased chance of above-normal
temperatures and below-normal precipitation during the next two weeks support
an enhanced risk of ROD across even more of the Great Plains and Corn Belt.



With extreme heat ongoing over the Southwest, and favored to continue through
much of the next 10 days, thermal low formation over the region, plus a
favorable location for the mid-level ridge as it weakens, would support a
resurgence of the Southwest Monsoon early in August. Above normal precipitable
water is favored over the Southwest by middle of week-2. Therefore, a
temporally broad slight risk of heavy precipitation is forecast over parts of
the Southwest, for all of week-2.

FORECASTER: Ryan Bolt

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