911
FXUS02 KWBC 171958
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
358 PM EDT Thu Sep 17 2026

Valid 12Z Sun Sep 20 2026 - 12Z Thu Sep 24 2026


...Heavy rainfall threatens the Midwest and Northeast Sunday...
...Monsoon storms reignite over the Southern High Plains/Rockies
middle of next week...


...Overview...

A trough moving over the north-central plains looks to produce
heavy rainfall over portions of the Midwest through the Northeast
Sunday into Monday before a storm lingers off the Mid-Atlantic
midweek. A cold air damming ridge of surface high pressure builds
down east of the Appalachians and brings cooler/wet conditions for
the middle of next week. An East Pacific trough enters the West
Coast which will reignite monsoon storms over much of New Mexico
and the Texas Panhandle beginning on Tuesday. A weak disturbance
lingering around the Florida Peninsula will be responsible for
daily heavy rainfall potential.


...Guidance/Predictability Assessment...

12Z global models are in good agreement on the on the north-central
wave that lingers over the Great Lakes with cold air damming for
the East Coast and trough/low over California Mon/Tues. The 00Z
ECMWF/06Z EC-AIFS were preferred in the morning model blend with
preference a general model blend for Days 6/7. NBM QPF was
amended with the 00Z EC/06Z EC-AIFS for magnitude, including lower
magnitude for New Mexico Days 5-7.


...Weather/Hazards Highlights...

A low pressure system with attendant surface fronts draped across
the Central U.S., Midwest and East Coast will act as a focus for
scattered showers and thunderstorms over the Northern/Central
Plains and Northeast on Sunday into Monday. Some flash flood risk
is possible, please see the Excessive Rainfall Outlook through Day
5. Cold air damming develops midweek along the Eastern Seaboard
with below normal temperatures and onshore flow.

Elsewhere, a West Coast trough and retrograding Southern U.S. ridge
will create a corridor for monsoon moisture to lift north through
beginning Monday night. Storms should proliferate across New
Mexico and the Texas panhandle beginning on Tuesday and continuing
through the rest of the week. Isolated to scattered flash flooding
can be expected for those areas. Burn Scars in the Sangre de Cristo
and Sacramento mountains, as well as slot canyons, dry washes, and
recently saturated soils will be especially susceptible to flash
flooding from next week`s rounds of monsoon storms.


Jackson


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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