495
FXUS02 KWBC 150711
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
311 AM EDT Tue Sep 15 2026

Valid 12Z Fri Sep 18 2026 - 12Z Tue Sep 22 2026


...Hazardous Heat subsides over the South-Central U.S. late week
as heavy rain/strong thunderstorms threaten the Northern/Central
Plains, Upper Midwest/Great Lakes, Southwest and Southern Rockies...


...Overview...

An anomalous ridge which supported a heat wave in the Southern
Plains and Lower Mississippi Valley will weaken considerably under
the influence of an amplifying upstream trough as well as a closed
mid-level disturbance approaching from the Gulf later this week.
The upstream trough will produce heavy rainfall across portions of
the Northern Plains, Upper Midwest/Great Lakes and Northeast this
weekend. Meanwhile, the passage of the Central U.S. trough should
reduce heavy rainfall concerns over the Southwest/Southern Plains
this weekend before an East Pacific disturbance renews monsoonal
storms across the region early next week.


...Guidance/Predictability Assessment...

The deterministic GFS and Euro, as well as the AIGFS and ECAIFS are
in good agreement on the synoptic pattern evolution across the
CONUS on days 3 and 4. The GFS and AIGFS begins to diverge from
consensus by day 5 regarding the north-central U.S. trough so are
replaced by the GEFS and ECE means to mitigate some of the
uncertainty that arises with the Central U.S. trough amplitude. The
Euro suite is favored on days 6 and 7 due to inconsistencies/spread
in the GFS suite.


...Weather/Hazards Highlights...

A potent low pressure system will bring rounds of thunderstorms
and heavy rainfall to portions of the Central U.S. later this week.
Scattered showers and thunderstorms are expected to redevelop over
parts of the Upper Midwest, where a slight risk (at least 15%
chance) of excessive rainfall is in effect on Friday. Shower and
thunderstorm focus should spread across the Great Lakes, Ohio
Valley and Northeast over the weekend, before dropping south into
the Mid-Atlantic early next week.

Shortwave disturbances streaming north through the
Southwest/Southern Plains will generate a little bit more
convection over New Mexico on Friday before an amplifying trough
shifts the unsettled weather into the Central/Southern Plains this
weekend. An East Pacific trough dropping into the Southwest should
reignite monsoon storms across New Mexico by early next week. Slot
canyons and dry washes are especially susceptible to flash
flooding from any storms that develop.

Some record high temperatures remain possible across parts of the
South into late week, but a weakening ridge should gradually
moderate the heatwave into the weekend.


Kebede


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


























$$