150
FXUS21 KWNC 151801
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 15 2026

SYNOPSIS: Persistent mid-level high pressure over the Four Corners provides a
good set up for monsoon rains over the Southwest, particularly early in the
period, leading to a risk of heavy precipitation and flooding. A more
progressive area of mid-level high pressure remains forecast over the
south-central contiguous U.S. (CONUS) occurring near the peak of summer
bringing the risk of extreme heat to the region. Above normal temperatures
bring a continued risk of Rapid Onset Drought to parts of the Northern Plains.

HAZARDS

Moderate risk of extreme heat for parts of the Southern Plains and the Lower
Mississippi Valley, Thu-Fri, Jul 23-24.

Slight risk of extreme heat for parts of the Central and Southern Plains, Lower
Mississippi and Tenneesee Valleys, and Southeast U.S., Thu-Wed, Jul 23-29.

Slight risk of extreme heat for Interior Washington, Thu-Sat, Jul 23-25.

Moderate risk of heavy precipitation for parts of western Colorado and the
Mogollon Rim of Arizona, Thu-Fri, Jul 23-24.

Slight risk of heavy precipitation for much of the Desert Southwest and
southern Great Basin, Thu-Mon, Jul 23-27.

Flooding Possible for parts of western Colorado and the Mogollon Rim.

Rapid onset drought (ROD) possible for portions of the Dakotas.

DETAILED SUMMARY

FOR SATURDAY JULY 18 - WEDNESDAY JULY 22:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR THURSDAY JULY 23 - WEDNESDAY JULY 29: Multiple model ensembles depict
anomalous mid-level ridging persisting over the western and central CONUS
through much of week-2, with a closed 594-dm contour remaining near the Four
Corners. There is increased support for a period of transient subtropical
ridging to build into the south-central CONUS at the end of week-1 and into
week-2. This particularly stands out in the normalized 500-hPa height anomalies
where 1 to 2 standard deviation anomalies are forecast at the climatological
peak of summer. Generally southerly flow off the Gulf of America is favored to
boost dewpoints east of the Rockies, resulting in potentially hazardous heat
index values for much of the Great Plains and along the Gulf Coast.



The potential for extreme heat continues to be supported by a variety of
forecast tools with elevated forecast confidence over parts of the Southern
Plains and Lower Mississippi Valley. The GEFS-ECWMF combined extreme heat tool
shows widespread 20 to 40% chances of either maximum temperatures or heat index
values to exceed the 90th percentile at some point during the week-2 period for
most of the CONUS except along the Northern Tier. Additionally, probabilities
exceed 40% and as high as 60% for the same threshold across parts of Texas and
the Lower Mississippi Valley. When considered individually the two models
disagree somewhat with respect to regions affected and signal strength but have
good agreement where the signal is strongest across this region. Given all
this, a moderate risk of extreme heat is posted for parts of the Southern
Plains and the Lower Mississippi Valley covering Jul 23-24. A broader slight
risk of extreme heat remains posted for much of Central and Southern Plains,
Middle and Lower Mississippi Valley, Tennessee Valley, and Southeast for all of
week-2.



A slight risk of extreme heat remains posted for Interior Washington for Jul
23-25, consistent with increased signal from the extreme heat tools. Guidance
from the uncalibrated and PET tools show elevated signals across the Pacific
Northwest early in the week-2 period.



Above normal temperatures are likely to persist across the Northern Plains,
although these temperatures are less likely to reach hazardous thresholds.
However, the combination of anomalous warmth, near to below normal
precipitation favored during week-2, and antecedent dryness supports an
enhanced risk of ROD across portions of the Northern Plains.



Model ensembles are showing continued enhanced signals of enhanced
precipitation stemming from the southwestern monsoon. Dynamical models are
depicting a potential enhancement of monsoon convection through the middle of
week-2, with uncalibrated probabilities from the ECWMF and GEFS indicating
widespread 50% chances of 3-day precipitation totals to exceed half an inch,
with some locations seeing 20% chances of 1 inch accumulations along with
higher probabilities centered over the Central Rockies and Mogollon Rim. A
moderate risk of heavy precipitation remains posted for portions of the Central
Rockies valid Jul 23-24. A corresponding moderate risk was added today for
portions of the Mogollon Rim across Arizona. A slight risk of heavy
precipitation remains valid for much of the Desert Southwest and southern Great
Basin and is forecast for Jul 23-27. This region is prone to flash flooding
with relatively small precipitation accumulations especially along dry creek
beds and in canyons and extreme caution should be exercised in such areas
should thunderstorm activity initiate nearby. As such, a pair of flooding
possible shapes have been added corresponding to the moderate risk area.
Monsoonal thunderstorms can also produce dry lightning, resulting in increased
wildfire risk.

FORECASTER: Ryan Bolt

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