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FXUS02 KWBC 251834
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
234 PM EDT Fri Sep 25 2026

Valid 12Z Mon Sep 28 2026 - 12Z Fri Oct 02 2026


...Early season New England Nor`easter lingers early next week...

...Multi-day Four Corners states to Plains/Mississippi Valley
heavy rain/runoff/tropical moisture connection threat next week...


...Overview...

An early season Nor`easter will linger off New England early next
week before exiting into the Canadian Maritimes. Strong/gusty winds
with potential for coastal flooding, beach erosion, and rip
currents are possible, along with heavy coastal rains. Meanwhile,
an upper trough will work through the West/Southwest early next
week and move east into the Plains midweek and beyond. Heavy
precipitation will be widespread ahead of this trough and with
lead/wavy multi- stream frontal system interactions. A tropical
moisture connection as East Pacific Hurricane Polo landfalls in
Mexico favors multiple days of rain/storms and some mountain snows
in the Four Corners states, with widespread heavy rainfall/runoff
issues spreading across the Plains and Mississippi Valley as next
week progresses.


...Guidance/Predictability Assessment...

The large scale forecast and evolution show reasonable agreement,
but there remains some considerable uncertainties on the smaller
scale, leading to notable and potentially high impact differences
in the sensible weather associated with systems. Forecast
confidence remains high with the development and lingering of an
early season Nor`easter, but models continue to come into better
alignment on how long this system may linger off the Northeast
coast. Certainly by early next week though, the system should begin
to push off towards the Canadian Maritimes.

Across the central U.S., there remains question on timing of a cut
off low over the Southwest and its progression into the south-
central U.S. next week. Regardless though, confidence is higher for
leading tropical moisture from East Pacific Hurricane Polo to
enhance rainfall across the Southwest into the Central U.S.. Recent
12z GFS run comes into better agreement showing an overall slower
trough progression and absorption of Polo into the larger flow
around Wednesday of next week. ECMWF remains a bit slower as well.
WPC progs favor the slower ECMWF/ECENS/EC-AIFS solutions which have
shown better run to run continuity and also is more consistent
with the official NHC track for Polo.


...Weather/Hazards Highlights...

The western Atlantic Nor`easter will lead to broad onshore flow
from the Mid-Atlantic to the Northeast, continuing early next week.
The lingering storm could lead to coastal flooding and beach
erosion, as well as marine hazards like rip currents and high surf.
Heavy rain could cause inland flooding across southeastern New
England. See WPC`s Key Messages regarding this coastal low for
further information.

Deep tropical Pacific and Gulf moisture should return ahead of the
large-scale troughing into an unsettled/cooled West, bringing
widespread rain to the Four Corners states northward and eastward
into early next week. Moderate to heavy rain spreads across the
Plains and Mississippi Valley into early-mid next week. A slow
moving upper low will interact with tropical moisture from Polo,
leading to heavy to excessive rainfall threats across the Four
Corners Monday to Tuesday/Wednesday. A WPC Excessive Rainfall
Outlook (ERO) Slight Risk area is in place for Monday. Vulnerable
soils from recent heavy rainfall could exacerbate flash flooding
concerns. Some snow is possible in the higher peaks of the
Intermountain West/Rockies with the precipitation, as the trough
pushes east into the Plains on Wednesday/Thursday and cools
temperatures. A Slight Risk ERO has also been introduced for the
south-central U.S. for Tuesday, with later week risks to monitor.

Meanwhile, a wet period for Florida is expected to linger into
early October as onshore moisture flow fuels enhanced daily rain
chances.

Warmer than average temperatures will persist in the south-central
U.S. into early next week under an upper ridging, and highs in the
90s are forecast through the southern Plains and Lower Mississippi
Valley. On the other hand, cooler than average temperatures
(especially for highs) are forecast for the West under troughing
aloft, gradually spreading eastward early next week and helping to
moderate temperatures in the Plains by midweek. Temperatures could
reach around 10 degrees above normal in the East ahead of the
trough Wednesday-Thursday.


Santorelli/Schichtel


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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