238
FXUS02 KWNH 070625
PREEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
225 AM EDT Mon Jul 7 2025

Valid 12Z Thu Jul 10 2025 - 12Z Mon Jul 14 2025

...Hazardous heat and humidity continues for parts of the East
while the heat builds over the West...


...Pattern Overview...

Quasi-zonal flow to become more amplified as ridge builds over the
West/Southwest and troughing over the north-central states and
Northeast. This setup will continue to favor widespread heat and
humidity for the Southwest and surrounding locations. A low
pressure system will advance through the northern/central states
toward the Northeast and will be the focus for scattered showers
and thunderstorms.

...Guidance/Predictability Assessment

The past few runs of guidance have trended toward a stronger
shortwave with potential closed low for the north-central states
for the first half of the extended period. There continues to be
pronounced differences by the weekend and into early next week for
southern Canada and for the upper level ridge setting up over the
West/Southwest. WPC utilized a similar approach as the previous
forecast by starting with a general blend of the
ECMWF/GFS/CMC/UKMET and increasing inclusion and weighting of the
GEFS mean and ECMWF ensemble means through the middle and latter
periods.

...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 higher QPF is less certain
however there is the potential for isolated instances of flash
flooding-- including areas from the Corn Belt into the Midwest and
Ohio Valley, Appalachians, Mid-Atlantic, and Northeast. There is a
Marginal Risk for portions of the Northern Plains, Upper
Mississippi Valley and Midwest for Day 4 and 5. Marginal Risks in
place for portions of the Mid- Atlantic into North Carolina and the
southern Appalachians for both days 4 and 5 for an axis of heavier
rainfall that is likely south of a frontal boundary. There is a
Marginal Risk for the Texas/Oklahoma Panhandles and into southwest
Kansas for convection exiting the Southern Rockies into the
adjacent plains on Day 5.

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. Extreme Heat Watches have been raised for parts of
Arizona through at least Thursday.


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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