254
FXUS02 KWNH 300713
PREEPD

Preliminary Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
312 AM EDT Thu Jul 30 2026

Valid 12Z Sun Aug 02 2026 - 12Z Thu Aug 06 2026


***Heat wave likely to continue from California to the
 Intermountain West into next week***

...Pattern Overview...

The large upper ridge that will be governing the overall weather
pattern across the western half of the country will start to break
down a little starting Sunday and into Monday. This will be due to
a strong closed upper low/trough moving inland across southwestern
Canada, with a trailing cold front bringing a welcomed cool down
from the Pacific Northwest to the northern Plains after a very hot
stretch of weather. Meanwhile, an amplifying trough over the
Midwest and then the Mid-South will lead to increased showers and
thunderstorms from the Gulf Coast to the Northeast Sunday into the
beginning of next week, thus keeping temperatures close to seasonal
averages through mid-week. However, excessive heat will continue
across the southwestern quadrant of the country as the upper level
ridge remains in place.


...Guidance/Predictability Assessment...

The 00Z model guidance suite features good overall synoptic scale
agreement across the Continental U.S. going through Tuesday, with a
general deterministic model compromise serving well as a starting
point for fronts and pressures. There are still some modest model
differences on exactly how the trough axis across the Ohio Valley
and Mid-South evolves, and whether it closes off into a weak closed
upper low. The ECMWF and CMC show hints of this happening Tuesday
morning, whereas the GFS features more of an open trough, but
overall does not appear to be a highly impactful weather event at
this time. More substantial model differences emerge across the
northwestern quadrant of the country by Wednesday as trailing
shortwave energy moves across this region, and even more so by
Thursday across the northern tier of the country, although there is
still good overall agreement on the ridge across the Southwest
states. The ensemble means were gradually increased to about 40-60%
by the Wednesday to Thursday time period.


...Weather/Hazards Highlights...

Showers and thunderstorms are expected to increase more broadly
across the East Coast states in general for Sunday into Monday as
deeper moisture is advected northward ahead of the upper trough
across the Mid-South. The rainfall could be potentially more
concentrated across Upstate New York into Vermont where interaction
with a cold front could enhance coverage of showers and storms.
Rainfall likely lingers across portions of the Mid-Atlantic into
the Southeast U.S. through Tuesday.

There will likely be widespread record heat across much of the
interior Western U.S. going into Sunday. The hottest readings for
the weekend will be across the lower elevations of the Desert
Southwest where widespread 110s are forecast. Montana likely has
cooler temperatures by Sunday, followed by the Dakotas on Monday as
the cold front moves through. Record high overnight lows are also
likely, including locations farther to the east across Texas with
lows struggling to get below 80 degrees. It will remain
uncomfortably hot going into the first half of next week from
California to Utah and southward to Arizona where the upper ridge
persists the longest. Hot and humid conditions will continue across
the Gulf Coast region with heat indices likely exceeding 100
degrees most days.

Elsewhere across the Continental U.S., most of the monsoonal
rainfall should be confined to eastern Arizona and into central New
Mexico, with scattered convection reaching into portions of Utah
and Colorado. A corridor of showers and storms is likely ahead of
the front that crosses the Dakotas and into Minnesota early in the
week, and this may also be accompanied with some severe weather.
The Pacific Northwest will likely have some slightly below average
temperatures this weekend before a gradual warm-up ensues next
week, and generally close to average for the eastern U.S.

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




$$