285
FXUS02 KWNH 010700
PREEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Fri Aug 1 2025

Valid 12Z Mon Aug 04 2025 - 12Z Fri Aug 08 2025


...Overview...

A cooling upper trough set to settle into eastern third of the
nation will be reinforced into next week by disturbances dropping
southeast across the Plains on the eastern edge of an upper ridge
over the Southwest which is forecast to build and expand by the
middle of next week. A wavy stalled front will support heavy rain
threats mainly near the coastal sections of the Southeast early
next week, but as a Bermuda High begins to build westward, wet
weather is forecast to spread gradually northward up the eastern
U.S. through mid-later next week. Meanwhile, upper troughing is
forecast to push through the Northwest with fronts forecast to
move into the northern Rockies/Plains to fire local thunderstorms.

...Guidance/Predictability Assessment...

The WPC medium range product suite was primarily derived from a
broad composite blend of overall well clustered guidance from the
latest runs of the GFS/ECMWF/UKMET/Canadian and GEFS/ECMWF/Canadian
ensemble means along with a compatible National Blend of Models and
machine learning guidance. This soluiton maintains good WPC
product continuity in a pattern with above normal predictability.

...Weather/Hazards Highlights...

A rather expansive cool air mass will settle into the eastern U.S.
for the first week of August. High moisture content and instability
near a front on the leading edge of this airmass will focus some
localized heavy rain to raise flash flooding risks given wet
antecedent conditions. WPC Excessive Rainfall Outlook (ERO)
Marginal Risk areas are in play Day 4/Monday and Day 5/Tuesday.

Farther west, shortwaves rounding into the eastern edge of the
upper ridge from the Rockies/High Plains are forecast to interact
with a downstream frontal zone. By early next week, there is a
some trend for the Ohio/Tennessee Valleys to see increasing rain
and storms. Rain and storms are generally forecast to overspread
the east-central U.S. Tuesday and the East mid-later next week.

Elsewhere, lingering rain and convection is possible over the
Interior Northwest into Monday coincident with the upper trough.
Lead moisture and instability will be above normal for the
northern Rockies/Plains. A Marginal Risk is depicted in the Day
4/Monday ERO for northwestern Montana as the shortwave moves
through and provides lift. Rain and thunderstorms are expected to
continue from southern central Canada down into the northern Plains
Tuesday where a Day 5 Marginal Risk ERO area was introduced, with
activity likely to spread over the Upper Midwest mid-later next
week. Meanwhile, the Four Corners states could see some increasing
monsoon showers underneath the broad ridge, amid the relatively dry
monsoon season especially across Utah/Arizona.

It mainly remains the case that cooler than average temperatures
are likely on the cool side of the main frontal system early next
week. The Southeast and much of the central U.S. can expect highs
of 5-10 degrees below average, with locally greater anomalies, as
highs only reach the 70s and low 80s for parts of the Southeast.
These temperatures should gradually warm closer to normal as the
week progresses. The Northwest will also generally be cooler than
average under rounds of troughing. The main hotspot for
temperatures will be across the Southwest, where lower desert areas
can expect highs 105-115F, and temperatures will be warming above
normal into the southern and central High Plains as the upper ridge
expands. HeatRisk from the Southwest into Texas shows some Major
(level 3/4) areas. Some record high temperatures there could be
challenged by next Wednesday. Florida is forecast to see seasonable
temperatures in the 90s, but with ample humidity allowing for some
areas of Major HeatRisk there as well.

Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw











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