780
FXUS02 KWBC 161858
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
258 PM EDT Wed Jul 16 2025

Valid 12Z Sat Jul 19 2025 - 12Z Wed Jul 23 2025

...Central Gulf Coast heavy rain threat may linger into Saturday...

...Potential for multi-day heavy rain and flash flooding threat
from portions of the Midwest to the central Appalachians Saturday
into Sunday...


...Overview...

The medium range period will continue to feature an expansive and
building upper ridge stretched across the southern U.S. and
progressive upper shortwaves moving through the northern tier
states. Convection will be plenty across much of the nation east of
the Rockies, but especially along a west to east oriented nearly
stationary frontal boundary draped from the Midwest to the central
Appalachians this weekend. Lingering tropical moisture along the
Gulf Coast may bring one more day of heavy rain threats on Saturday
before dissipation within a larger scale ridge. Meanwhile,
monsoonal moisture will be in place through at least this weekend
in the Four Corners states to the south-central High Plains. Upper
ridging from the southern Plains to the Southeast will promote
summer heat into next week.


...Guidance/Predictability Assessment...

Model guidance continues to advertise an overall progressive
synoptic pattern dominated by a strengthening subtropical ridge
across the southern U.S. and a fairly fast moving jet and wave
train across the north. Model agreement remains reasonable for most
of the medium range period, aside from the typical small scale
differences in timing and amplitude of individual shortwaves. Some
additional uncertainty about how strong the southern ridge will be
and also reinforcing energy out West. The WPC forecast used a
blend of the deterministic guidance the first half of the period,
trending towards a 50/50 split between deterministic guidance and
the ensemble means of the EC and GEFS by day 7.


...Weather/Hazards Highlights...

The National Hurricane Center continues to monitor the potential
for tropical system development across the northern Gulf in the
short range period. The remnants of this energy (regardless of
development) may linger into the weekend, and could bring locally
heavy to excessive rainfall into at least Saturday. Despite the
relatively light QPFs forecast by the models, continued to maintain
a small slight risk across northern Louisiana given the available
anomalous moisture and the forecasted heavy rains in the short
range.

A series of shortwaves and associated surface fronts through the
northern tier will continue to support showers and thunderstorms
from the northern Plains eastward to the Mid-Atlantic. This entire
area is encompassed by a broad marginal risk on the Excessive
Rainfall Outlooks (EROs) with the warm and very moist airmass in
place. There is greater and increasing concern for significant
rainfall and the potential for flash flooding from portions of the
Midwest to the Central Appalachians through the weekend. For both
EROs on Day 4 and 5, decided to broaden/expand the existing slight
risks across portions of the Midwest, Ohio Valley, and the central
Appalachians. This is looking like a favorable setup that has the
potential to produce significant rainfall and flash flooding
somewhere in the region given abundant moisture (PWs nearing 175%
of normal) focused along a nearly stationary west/east oriented
front. Additionally, while not a super strong signal at the moment,
the ECMWF EFI is at least showing some values above 0.5 with shift
of tails 0+. Analogs have also pointed towards some significant
events in the past as well. Taken altogether, these slight risks
are considered "higher end" slight risks, with the potential for
upgrades to moderate risks in future updates. Elsewhere, activity
east of the Rockies may overall shift east with a building ridge
over the Central U.S. but daily shower and thunderstorm threats
will continue into next week across the Great Lakes region and the
East.

Farther south, ample monsoonal moisture will be in place across
the Southwest/Four Corners/southern Rockies region this weekend.
Marginal Risks remain across much of Arizona and New Mexico and
stretching into parts of Colorado and Utah. Areas like burn scars
and urban areas would be of greatest concern for flash flooding.
Monsoonal moisture may continue, but possibly slightly weaker, into
next week.

Temperatures in the High Plains to the northern/central Plains
looks to remain near or below normal (on the order of 5-10 degrees)
for this time of the year through much of the period, with some
moderation at times. Elsewhere, despite temperatures being only
modestly above normal, the persistence of ridging over the
Southeast along with elevated humidity will keep a moderate to
major HeatRisk in place for the region, with localized extreme
impacts this weekend. This expands westward into the
Tennessee/Mississippi Valley and Central Plains next week, kicking
off what is likely to be an extended period of persistent and
possibly dangerous heat through mid to late July.


Miller/Santorelli


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


















$$