823
FXUS21 KWNC 211917
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 21 2025

SYNOPSIS: Mid-level high pressure is predicted across much of the contiguous
U.S. (CONUS) excluding the West Coast and much of the Northeast early week-2,
slowly amplifying westward through at least mid-week. This translates to
increased chances for extreme heat for many areas east of the Rockies, and in
the Southwest. Heat index values exceeding triple digits (deg F) are possible,
and could be widespread. The heat threat decreases after the first half of
week-2 as the ridge stops building, but at least a slight risk exists across a
large part of the CONUS all week. Along the northern periphery of the mid-level
high pressure, periods of showers and thunderstorms are possible all week from
the northern Plains through the western Great Lakes, with a moderate chance for
heavy precipitation in the center of this region around mid-week. Possible
surface low formation over the Gulf of America increases the likelihood for
heavy precipitation in parts of the central and eastern Gulf Coast. Timing is
uncertain, so the risk extends through all of week-2. Dry soils and anticipated
dry, hot conditions support a risk of Rapid Onset Drought (ROD) over Kansas.

HAZARDS

High risk of extreme heat for portions of the Great Plains and Mississippi
Valley, Tue, Jul 29.

Moderate risk of extreme heat for part of the South Atlantic Region, Tue-Wed,
Jul 29-30.

Moderate risk of extreme heat for areas from the High Plains to near the
Appalachians, Tue-Fri, Jul 29-Aug 1.

Moderate risk of extreme heat in part of the Desert Southwest, Tue-Fri, Jul
29-Aug 1.

Slight risk of extreme heat for a large part of the eastern, central, and
southwestern CONUS, Tue-Mon, Jul 29-Aug 4.

Moderate risk of heavy precipitation from northeastern Montana through western
Wisconsin, Thu-Sun, Jul 31-Aug 3.

Slight risk of heavy precipitation from the Northern Plains through the western
Great Lakes, Tue-Mon, Jul 29-Aug 4.

Slight risk of heavy precipitation for the central and eastern Gulf Coast
Region, Tue-Mon, Jul 29-Aug 4.

Rapid onset drought risk for parts of Kansas.



DETAILED SUMMARY

FOR THURSDAY JULY 24 - MONDAY JULY 28:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR TUESDAY JULY 29 - MONDAY AUGUST 04: The GEFS, ECENS, and CMCE all show an
evolving mid-level pattern featuring a mid-level ridge across much of the CONUS
from the Rockies to the Appalachians early week-2. This feature drifts westward
while nominally amplifying, peaking in strength over the central CONUS mid- to
late-week before settling into the Rockies toward the end of the period,
potentially broadening eastward again, though this is far from certain.
Meanwhile, a mid-level trough near the West Coast slowly deamplifies, and
another mid-level trough digs southward along the Eastern Seaboard in response
to the westward drift of the mid-level ridge. This pattern enhances the risk of
extreme heat for a large part of the CONUS from the Rockies eastward, and the
Desert Southwest, with the focus of extreme heat slowly pushing westward until
around mid-week. A high risk of extreme heat (>60% chance) is designated for
portions of the Middle and Lower Mississippi Valley, the central and southern
Great Plains, and the lower Ohio Valley Jul 29. A fairly broad area is
highlighted with a moderate risk (40-60% chance) of extreme heat,  many areas
from the central and southern Plains eastward through the Mississippi,
Tennessee, and lower Ohio Valleys until the middle of week-2, and a separate
area is posted over the Desert Southwest for the same time frame. With high
dewpoints expected - at least from the Mississippi Valley eastward - heat index
values are expected to exceed the 90th percentile compared to climatology and
triple digits deg F. The heat risk appears to wane by mid-week as uncertainty
increases regarding the evolution of the mid-level ridge. A moderate risk of
extreme heat is posted in parts of the Southeast Jul 29-30, after which the
greatest risk drifts farther west before uncertainty increases late in the
period.



Along the northern periphery of the mid-level ridge, periodic shower and
thunderstorm activity increases the threat for heavy precipitation from the
northern High Plains eastward into the central Great Lakes region. These
features are inherently difficult to forecast more than a few days into the
future, so the persistence of the mid-level ridge keeps at least a
marginally-increased threat of heavy precipitation throughout week-2. The
operational deterministic models are in slightly better agreement with the
intensity and placement of heavy precipitation around mid- to later week-2, so
a moderate risk of heavy precipitation is posted for this period from part of
the northern High Plains through much of the Upper Mississippi Valley.
Currently, there is too much uncertainty to highlight any particular region
with an elevated risk of flooding, but streamflows in parts of the northern
Plains and Upper Mississippi Valley are already above normal, and significant
additional rainfall could exacerbate the situation.



Surface low formation is possible over the Gulf of America at any time week-2,
which could support areas of heavy precipitation along part of the Gulf Coast.
There is a lot of uncertainty regarding the timing, location, strength, and
nature of any surface system that could form, so a slight risk of heavy
precipitation is posted for the central and eastern Gulf Coast for the entire
period. The Probabilistic Extremes Tools (PETs) are not particularly bullish on
this, but the ensemble means and deterministic models show one or more periods
of potentially heavy precipitation in this region. There is too much
uncertainty to highlight any particular region with an elevated risk of
flooding.



Anomalously dry soils and expected hot, dry conditions support a risk of Rapid
Onset Drought (ROD) for parts of east-central Kansas. There was heavy
precipitation over the weekend in eastern Kansas, so the risk area has been
trimmed out of this area.

FORECASTER: Rich Tinker

$$