223
FXUS02 KWBC 160721
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
321 AM EDT Thu Jul 16 2026

Valid 12Z Sun Jul 19 2026 - 12Z Thu Jul 23 2026


...Dangerous heat will gradually subside in the north-central U.S.
early next week...


...Overview...

An upper ridge over the western and central U.S. into Sunday will
continue to cause dangerous heat across the northern/central
Plains. The northeast side of the ridge will get gradually
suppressed by shortwave energy entering the Midwest/Great Lakes
into a northeastern U.S. upper trough, which will bring relief from
the heat to northern areas as the trough pushes cold fronts
through the region. The shortwaves and fronts in the broader trough
should also yield rounds of rain and thunderstorms in the Great
Lakes to East Coast 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
Sunday while a trough axis is atop the East. A shortwave should
round the northern side of the ridge and 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. The timing of this shortwave shows fairly good consensus
through early Tuesday, but after that there are model differences
with the speed of it and its associated surface fronts. Recent GFS
runs appear to be on the fast side by midweek as the AIFS, ECMWF,
and CMC are all slower.

Model differences persist with the potential for a tropical low in
the northeastern Gulf. Recent guidance is not particularly strong
with a low overall, and ensemble members are split with when/if a
low would track out of the northeastern Gulf across northern
Florida, Georgia, and South Carolina Sunday-Monday. Elongated
surface troughing may be in place regardless, which could enhance
rain amounts in Florida and the Southeast. The National Hurricane
Center is tracking the possible formation of a tropical system and
shows low probabilities for now. Continue to monitor NHC forecasts
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 around
half by Day 7.


...Weather/Hazards Highlights...

Another hot day is in store Sunday for the northern/central
Plains, as temperatures near/exceed 100F, yielding Major to
isolated Extreme HeatRisk. WPC continues to update Heat Key
Messages for this event, which can be found on our homepage. The
ridge influence farther south will also lead to generally Major
HeatRisk stretching into the central Plains and Middle/Lower
Mississippi Valley to Southeast. The hot conditions should slowly
ease in the northern states into the workweek, but be maintained in
the south. Temperatures a few degrees above already warm averages
combined with high humidity could lead to increased HeatRisk in the
south-central U.S. 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
(Sunday-Monday). Coverage of showers and thunderstorms should
gradually increase eastward over the Rockies and High Plains early
to midweek.

Elsewhere, southern stream energy is forecast to meander in the
northeastern Gulf in a moist and unstable environment early next
week. Troughing and tropical moisture in place (even if there is no
true tropical low) could lead to heavy rain, and Marginal Risks
are in place for portions of northern/central Florida for isolated
flash flooding on Sunday and Monday. Meanwhile the tail end of a
frontal boundary could hang up in eastern North Carolina and
Virginia and produce locally heavy rain on Sunday. The next round
of rain and thunderstorms is forecast to come through the Midwest
and Great Lakes early next week underneath a shortwave aloft. As
the shortwave and front move southeast, rain chances should
overspread much of the eastern U.S. for Tuesday-Wednesday.


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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