379
FXUS02 KWBC 081829
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
229 PM EDT Tue Jul 8 2025

Valid 12Z Fri Jul 11 2025 - 12Z Tue Jul 15 2025


...Pattern Overview...

An upper low with several waves of embedded shortwave energy will
propagate across south-central Canada and the northern/central tier
of the U.S. over the next week. A pair of surface cold fronts will
move through the Plains and Midwest respectively, acting as a focus
for storms. A retrograding subtropical ridge will keep things
warmer than average across the southern tier.

...Guidance/Predictability Assessment

00z/06z suite of models are in reasonable agreement on the upper
level pattern over the CONUS, with differences around timing and
placement of shortwaves spinning through the base of the parent
low. The 06z ECMWF AIFS is notably more extreme than the rest of
the guidance when it comes to Max/Min Ts, while the 00z CMC has a
much higher magnitude qpf footprint than the GFS/EC/UK suite over
the Plains and Upper Midwest throughout the period.

A general model blend consisting of similar parts 00z EC/CMC/UKMET
and 06z GFS were used through day 4. The 06z GEFS was introduced to
the blend on day 5 to reduce the overamplification of a shortwave
over the Central/Southern Plains found in the 06z GFS. The 00z
CMCE/ECE were introduced to the blend on day 6 and the ensembles
make up the entire blend by day 7 due to the pattern becoming
weak/zonal across much of the lower 48.

...Weather/Hazards Highlights...

Scattered convection anticipated to fire ahead of, and along progressive
cold fronts, stalled boundaries and round the upper high in the
Southern Rockies. The exact location of anticipated higher QPF
amounts remain a bit uncertain given persistent model differences,
nevertheless, there is potential for isolated instances of
excessive rainfall and localized flash flooding-- including areas
from the Corn Belt into the Midwest and Ohio Valley, Appalachians,
and Mid-Atlantic.

For Day 4, there is broad Marginal Risk area for the Upper
Mississippi Valley/Midwest, a broad Marginal Risk stretching from
interior portions of the Deep south to the Mid-Atlantic coast, and
a Marginal Risk covering portions of eastern Colorado, Kansas,
Oklahoma and Texas Panhandle. For Day 5, there is a Marginal Risk
for eastern New Mexico and parts of the Oklahoma/Texas Panhandles
and from the Central/Southern Plains to the Ohio Valley.

Many locations will have daily maximums climbing well into the
100s at lower elevations across the Southwest and mainly dry
conditions, except for perhaps far southeastern Arizona into New
Mexico where some monsoonal moisture may be present. Experimental
HeatRisk values may rise to Major or Extreme levels (3 out of 4 or
4 out of 4) from the California deserts into southern Nevada, Utah,
and Arizona.


Kebede/Campbell

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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