898
FXUS02 KWBC 151828
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
228 PM EDT Wed Jul 15 2026

Valid 12Z Sat Jul 18 2026 - 12Z Wed Jul 22 2026


...Dangerous heat could continue across the north-central U.S.
through the weekend...


...Overview...

A strong upper ridge over the central U.S. could continue to cause
dangerous heat across the north-central Plains and Midwest through
the weekend. The eastern portion of the ridge likely joining up
with a subtropical Atlantic ridge should lead to hot temperatures
in the southeastern U.S. and Mid-Atlantic as well. An upper trough
poking into the Northeast and deepening should gradually shift the
heat southward and bring relief to northern areas into early next
week. Shortwaves moving through that trough will promote rounds of
rain and thunderstorms in parts of the central and eastern U.S.
this weekend and early next week. Additionally, ample monsoonal
moisture will continue to stream into the Southwest and
Intermountain West, producing rounds of showers and thunderstorms.


...Guidance/Predictability Assessment...

Model guidance continues to be reasonably agreeable on the large
scale pattern, including the upper ridge atop the Rockies to Plains
and stretching into the southeastern U.S. as the period begins
Saturday. Recent guidance has trended toward keeping the ridge in
place in the north-central U.S. through the weekend, maintaining
hot temperatures, as a first shortwave stays east of the region
more in the Great Lakes. Meanwhile a second shortwave, with better
agreement on timing compared to previous day, should round the
northern side of the ridge in southern Canada this weekend, and
then drop into the Upper Midwest/Great Lakes region early next week
(pressing a cold front/fronts south). This works to deepen the
eastern trough and push the upper ridge axis westward a bit into
the Intermountain West. Plenty of uncertainty in the details of
these individual shortwaves which would have implications on
frontal positions and QPF.

Elsewhere, model signal seems to be improving for a possible
northeastern Gulf tropical low. Much of the deterministic guidance
now shows, with the exception of the GFS, a weak low developing in
the Gulf this weekend and drifting across northern Florida and up
the Southeast coast. These join with AIFS ensemble members and
increasing numbers of Google DeepMind members and EC ensemble
members which have been showing this potential for several runs
now. There remains a lot of uncertainty with the track, strength,
or even presence of anything tropical related with this system, but
the National Hurricane Center is tracking this with low
probabilities of development at this time. Continue to monitor
forecasts from the NHC for the latest.

The WPC forecast was based on a multi-model blend early in the
period, with increasing proportions of the ensemble means to half
by Day 7.


...Weather/Hazards Highlights...

Hazardous heat is showing more potential to hang on into the
weekend in the north-central U.S. under the upper ridge. Persistent
well above normal maximum temperatures nearing/exceeding 100F and
warm minimum temperatures could cause continued Major to isolated
Extreme HeatRisk in the northern/central Plains and Midwest. WPC
continues to update Heat Key Messages for this event, which can be
found on our homepage. The hot conditions should slowly ease in the
northern states and shift southward into early next week. Farther
east, the upper ridge combining with subtropical Atlantic ridging
in the Southeast and Florida will promote warmer than average
temperatures for the southeastern U.S. to Mid-Atlantic this
weekend. This heat should also become more limited to southern
areas as the period progresses and cold fronts track south.
Temperatures a few degrees above already warm averages combined
with high humidity could lead to increased HeatRisk in the Lower
Mississippi Valley and Gulf Coast states.

Meanwhile, the southwestern to south-central U.S. could see
slightly below average temperatures as ample moisture leads to
clouds and rain/thunderstorms. Continued southerly flow under the
broad upper ridge will draw significant monsoonal moisture into the
Southwest and Intermountain West to Rockies. This moisture will
lead to scattered to numerous showers and thunderstorms with the
potential to produce heavy rainfall and localized flash flooding.
Sensitive places such as burn scars, steep terrain, etc., would be
the most vulnerable to any flooding concerns that may develop.
Broad Marginal Risks of excessive rainfall are in place from the
Southwest across much of the Intermountain West for Day 4-5
(Saturday-Sunday). Coverage of showers and thunderstorms should
gradually increase eastward over the Rockies and High Plains early
next week.

Multiple rounds of rain/thunderstorms are also possible from the
Great Lakes and Ohio Valley to the East Coast as shortwaves and
frontal systems focus moisture through the period. A Marginal Risk
of flash flooding is delineated for portions of the Great
Lakes/Ohio Valley and Northeast/Mid-Atlantic on Saturday. Rain
should mostly clear out of the Northeast on Sunday, but the
southeastern U.S. could still see convection with troughing and
tropical moisture in place (even if there is no true tropical low),
leading to possibly heavy rainfall threats. Into the workweek, the
next shortwave supporting surface fronts should cause another bout
of rain for the Ohio Valley and Great Lakes, spreading into the
East on Tuesday.


Santorelli/Tate


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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