691
FXUS21 KWNC 251812
PMDTHR
US Hazards Outlook
NWS Climate Prediction Center College Park MD
300 PM EDT July 25 2025

SYNOPSIS: Developing mid-level low pressure over eastern North America late
next week is expected to bring a welcomed cooldown for many parts of the
central and eastern Contiguous U.S. (CONUS) experiencing extreme heat
conditions. Potentially stalled frontal activity favored over the lower Eastern
Seaboard supports an increased risk for heavy precipitation over the Gulf
states and the Southeast. Associated with mid-level high (low) pressure favored
over the Great Plains (West Coast), periods of elevated winds are possible over
the western CONUS, as well as heavy precipitation over parts of the Great
Plains and Mississippi Valley which could trigger localized flooding over parts
of the lower Missouri River basin.

HAZARDS

Moderate risk of heavy precipitation for parts of the Southeast and lower
Mid-Atlantic, Sat-Sun, Aug 2-3.

Slight risk of heavy precipitation for parts of the Lower Mississippi Valley,
Southeast, and Mid-Atlantic, Sat-Tue, Aug 2-5.

Slight risk of heavy precipitation across parts of the Great Plains and
Mississippi Valley, Sat-Sun, Aug 2-3.

Slight risk of high winds for many parts of the western CONUS, Sat-Mon, Aug 2-4.

Flooding possible over the lower Missouri River basin.

DETAILED SUMMARY

FOR MONDAY JULY 28 - FRIDAY AUGUST 01:
https://www.wpc.ncep.noaa.gov/threats/threats.php

FOR SATURDAY AUGUST 02 - FRIDAY AUGUST 08: The week-2 hazards perspective
remains on track, as dynamical models continue to favor an anomalous ridge
center over central Canada, with a pair of mean troughs over eastern North
America and over the northeastern Pacific heading into the first weekend of
August. Over the past few days, the overall mid-level height pattern has
trended negatively in anomaly space across the CONUS, which has resulted in a
weaker and zonally narrow ridge axis across the central U.S, with broader mean
troughing across the eastern U.S through the middle of the period. This latter
mid-level feature looks to remain responsible for a welcomed cooldown to the
extreme heat conditions favored during week-1, and likely keep any renewed heat
risks at bay east mainly east of the Rockies in the outlook. Much of the
cooling is expected to be underway leading into week-2 associated with a large
frontal boundary extending from the Southern Plains into the western Atlantic
on day 7 (Aug 1). By day 8, Probabilistic Extremes Tools (PETs) indicate weak
chances for any lingering extreme heat, and the corresponding slight risk area
is removed in the outlook.



Later in the period, ensembles continue to point to the mean ridge retrograding
into the Interior West along with a deamplification of the mean trough over the
northeastern Pacific. This pattern shift being advertised has been somewhat
dubious, given that the models have varied on the strength of the ridge and
timing of this evolution in recent runs. Regardless, above-normal temperatures
are favored to develop over much of the Interior West, where if any extreme
heat conditions were to emerge, the Central California Valley, portions of the
Great Basin, and the Desert Southwest would appear most likely based on the raw
temperature tools. While PETs show increased chances for maximum temperatures
exceeding the 85th percentile, there are only modest chances for actual
temperatures exceeding hazard criteria and no associated heat hazards are
issued. This potential will continue to be reassessed in upcoming outlooks.



Tied to the aforementioned frontal boundary of the eastern CONUS, there
continued model support for this feature to slowly advance over the
southeastern CONUS, bringing a potentially prolonged period of enhanced
precipitation to portions of the lower Eastern Seaboard and into the central
and eastern Gulf states. The GEFS PET remains comparably weaker than the ECMWF,
but both show 20-30% chances for 3-day amounts exceeding the 85th percentile,
with the wettest signals along the coastal Southeast and just offshore in the
Atlantic. The uncalibrated ECMWF remains the most robust with the heavy
precipitation risk. This tool has slightly backed off of the threat over the
coastal Carolinas, but now shows elevated chances (30-50%) of heavy
precipitation further south into Georgia and into the Gulf region. Due to this
uptick in potential, and continued agreement in regards to the evolution of
this surface feature, a moderate risk of heavy precipitation remains issued
with its coverage shifted southward, and valid through Aug 3. Even with soils
expected to become drier associated with the heat event favored across parts of
the southeastern CONUS during week-1, urban flash flooding is still possible
with the highlighted moderate risk area. Consistent with recent rainfall events
with this synoptic setup, surface low formation also remains possible along a
stalled frontal boundary, which could gain tropical characteristics should any
development occur offshore and this potential will continue to be monitored in
upcoming outlooks.



Along the northern periphery of the mean 500-hPa ridge over the central CONUS,
episodic shower and thunderstorm activity may bring locally heavy precipitation
amounts across the Great Plains and parts of the Mississippi Valley. This
potential remains supported in the PETs through early week-2, with good
consistency indicating increased chances for amounts exceeding three quarters
to an inch across much of the Missouri River Basin. Therefore, a slight risk of
heavy precipitation remains issued for the Central and Northern Plains and
portions of the western Mississippi Valley, valid through Aug 3 before the mean
ridging begins to slide westward. Due to high rainfall surpluses over the past
few weeks (several areas have registered more than two to three times their
normal rainfall accumulation over the past 14 days), as well as potentially
heavy rainfall forecast during week-1 across the southern periphery of the
slight risk area, a flooding possible hazard is added to the outlook over the
lower Missouri River Basin for week-2.



Upstream, enhanced onshore flow tied to a 500-hPa trough near the West Coast is
anticipated to bring above-normal precipitation into much of the northwestern
CONUS. Although there are elevated probabilities for 3-day amounts exceeding
the 85th percentile in the PETs, actual totals are expected to remain below
hazard thresholds. Periods of elevated winds are however, a concern at or near
the base of the mean troughing aloft, and a slight risk of high winds is posted
(Aug 2-4) for much of the western CONUS where PETs maintain increased signals
for wind speeds exceeding the 85th percentile. The combination of elevated wind
speeds, low humidity and high temperatures increases the risk for wildfire
activity across parts of the West.



The enhanced mid-tropospheric moisture tied to the mid-level troughing as well
as a growing potential for renewed tropical cyclone activity favored in the
eastern Pacific is expected to bring increased precipitation amounts into the
southwestern CONUS towards the end of July. Based on the WPC week-1 QPF and
week-2 precipitation tools that are trending drier, any heavy precipitation
risk looks to have timed off into week-1, and the slight risk area for heavy
precipitation is discontinued in the outlook over Arizona and New Mexico.



No hazards are issued over Alaska. Although amplified troughing is favored over
the Gulf of Alaska to promote increased winds and enhanced precipitation
amounts over the Southeast, tools indicate amounts remaining below hazard
thresholds.

FORECASTER: Nick Novella

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