096
FXUS02 KWNH 280759
PREEPD

Preliminary Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
357 AM EDT Tue Jul 28 2026

Valid 12Z Fri Jul 31 2026 - 12Z Tue Aug 4 2026

***Long duration heat wave expected for much of the Western U.S.
 and western High Plains***

...Pattern Overview...

An impressive 600 dm upper ridge will be large and in charge across
the Western U.S. for the end of the week and starting the month of
August, producing a widespread heat wave from the Desert Southwest
to the western High Plains. The ridge should break down a little
going into early next week with shortwave energy eroding the
northern periphery of the ridge, with a cold front passing from the
Pacific Northwest to the northern Plains, but remaining hot from
California to the central/southern Plains. General troughing is
likely to continue across the eastern U.S. as a second shortwave
trough amplifies from the Great Lakes to the Mid-South as the
coastal low departs New England. A more zonal flow pattern likely
develops by Tuesday and beyond with warmer temperatures likely for
the East Coast states.

...Guidance/Predictability Assessment...

The 00Z model guidance suite features good overall synoptic scale
agreement across the Continental U.S. to close out the work week,
with the best agreement noted on the closed upper high positioned
across the interior Western U.S. through the weekend. The majority
of the guidance agrees well with a shortwave trough tracking from
the Upper Midwest to the Tennessee Valley through early Sunday,
although recent runs of the UKMET have likely been too strong and
too far north with the surface low that develops, and therefore a
non-UKMET consensus was used for fronts/pressures. The CMC becomes
more amplified with the upper trough across the Northeast U.S. by
the end of the forecast period Tuesday, and the GFS has more of an
upper ridge trying to develop near the Southeast Coast. The
ensemble means were gradually increased to about 40% by next
Tuesday.

...Weather/Hazards Highlights...

The area with the heaviest rainfall to close out the work week
will likely be across the Midwest as a shortwave disturbance aloft
promotes the development of a surface low with mesoscale
convective complexes that will likely bring multiple rounds of
heavy rainfall and strong thunderstorms, with a Slight Risk of
excessive rainfall extending from Minneapolis to St. Louis.
Additional heavy rainfall is likely across portions of the Deep
South and Gulf Coast region going into the weekend as a surface low
develops along a frontal boundary that will be draped across the
region, and showers/storms become more widespread for the Eastern
U.S. by Sunday and into Monday. Daily afternoon and evening
thunderstorms are expected from the central Rockies to the Desert
Southwest through Saturday, with slightly less monsoonal moisture
expected into Sunday and Monday.

Widespread heat will continue to make weather headlines across a
large portion of the western and central U.S. as a large upper
ridge becomes parked over the southwestern quadrant of the country.
The most extreme heat is expected over the lower elevations of the
Desert Southwest through much of the forecast period, with highs
well into the 110s and approaching 120 degrees in some instances,
and readings near 100 degrees extending north into southern Idaho
and westward to include the Central Valley of California. Another
area of excessive heat is likely from Montana into western portions
of the Dakotas with highs reaching or surpassing 100 degrees next
weekend before a cold front passes through early next week. Hot and
humid conditions will continue through the end of the week across
the Gulf Coast region, with heat indices on the order of 100-110
degrees with dewpoints well into the 70s south of the stalled
front. A slight abatement in the heat is likely by the weekend with
more clouds and rainfall across the region.


Hamrick




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, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

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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