702
FXUS21 KWNC 131859
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 13 2026

SYNOPSIS: Persistent mid-level high pressure over the Four Corners occurring
near the peak of summer brings the risk of extreme heat for much of the central
and southeastern Contiguous U.S. (CONUS) as well as portions of California
throughout week-2. Mid-level low pressure over the Northeast U.S. may result in
heavy precipitation for portions of the southern Mid-Atlantic region early in
the forecast period. Increasing inflow of tropical moisture is favored to
enhance monsoon rains over the Desert Southwest through the middle of week-2.

HAZARDS

Slight risk of extreme heat for the Central Valley of California, Tue-Mon, Jul
21-27.

Slight risk of extreme heat for much of the Southern Plains, Lower Mississippi
Valley, and Southeast U.S., as well as portions of the Central Plains and
Mid-Atlantic, Tue-Mon, Jul 21-27.

Slight risk of heavy precipitation for much of Virginia and the Carolinas, and
for adjacent portions of Georgia, Tue-Thu, Jul 21-23.

Slight risk of heavy precipitation for much of the Desert Southwest and
southern Great Basin, Tue-Sat, Jul 21-25.

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

DETAILED SUMMARY

FOR THURSDAY JULY 16 - MONDAY JULY 20:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY JULY 21 - MONDAY JULY 27: Multiple model ensembles depict anomalous
mid-level ridging persisting over the western CONUS throughout week-2, with a
closed 594-dm contour emerging over the Four Corners by the middle of the
forecast period. This pattern is highly favorable for above-normal temperatures
across much of the Lower 48, and when occurring near the peak of summer brings
a widespread risk of extreme heat, particularly for the western CONUS.
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, although a downward trend in signal strength has been noted
over the past few days. The Probabilistic Extremes Tool (PET) from the GEFS
indicates widespread 20% chances of maximum temperatures to exceed the 85th
climatological percentile for all but the northeastern portion of the CONUS
throughout the forecast period. The ECMWF PET is much more circumspect,
exceeding the above percentile threshold only over portions of the Pacific
Northwest and Southeast U.S. The GEFS-ECWMF combined extreme heat tool shows
widespread 20% or greater chances (as high as 50% for portions of the West) 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 the
Northeast and Desert Southwest. As with the PETs, when considered individually
the two models disagree widely with respect to regions affected and signal
strength. Given the continuing decrease in signal strength in general and an
increased signal for monsoon activity much of the Interior West is no longer
highlighted for extreme heat, however a slight risk of extreme heat remains
posted for the Central Valley of California, as well as much of the
southeastern and south-central CONUS, both valid for all of week-2. The
persistent Four Corners ridge is favored to induce anomalously warm
temperatures well north into the Great 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 increased signal 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. Given this, a slight risk
of heavy precipitation is posted for much of the Desert Southwest and southern
Great Basin, valid Jul 21-25. 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. Monsoonal thunderstorms can also produce
dry lightning, resulting in increased wildfire risk.



Tied to the troughing favored over the eastern U.S. early in week-2, ensembles
continue to point to surface low development along the Eastern Seaboard.
Relative to yesterday, models place the heaviest precipitation further eastward
with the bulk of potentially hazardous accumulation totals remaining offshore.
However, both the raw GEFS and ECMWF probability of exceedance tools remain
supportive of a heavy precipitation risk, depicting 20-40% chances of 3-day
amounts exceeding an inch over southern Virginia and the Carolinas. Therefore,
a corresponding slight risk for heavy precipitation remains posted in the
outlook valid Jul 21-23.

FORECASTER: Danny Barandiaran

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