116
FXUS02 KWNH 020646
PREEPD

Preliminary Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 AM EDT Fri Oct 2 2026

Valid 12Z Mon Oct 05 2026 - 12Z Fri Oct 09 2026


...Lingering Gulf Coast/Southeast U.S. Excessive Rainfall/Flooding
threat Monday into Tuesday...

...Long Duration Late-Season Heat Wave Expected for California...


...Guidance/Predictability Assessment...

Models continues to maintain good agreement on the large-scale
evolution of a amplified northern-stream across eastern U.S., with
a series of frontal boundaries settling southward across central
and eastern states. Forecast uncertainty increases with the
positioning of the frontal boundary across the Gulf
Coast/Southeast, especially towards mid-week, which affects the
location for the heaviest precipitation. The ECMWF seems support a
faster southeastward progression of the precipitation axis, while
the GFS maintains the axis further north. Using a model blend of
the deterministic, ensemble, and AI guidance, seems to smooth some
of the timing and amplitude differences across the Gulf
Coast/Florida. Uncertainty grows towards late week on the evolution
of the frontal passage. Therefore, utilizing a blend with the NBM
and the ensemble means seemed to capture a middle ground between
the model differences.


...Pattern Overview and Weather/Hazards Highlights...

A broad trough extending across eastern U.S. will continue to
support a slow-moving frontal boundary along the Gulf Coast into
the Southeast. Deep moisture from the Gulf will remain pooled
along the boundary, supporting locally heavy rainfall across
central Gulf Coast into Florida. Repeated round of high rainfall
rates will lead to excessive rainfall/flash flooding threats across
south Texas and portions of the Gulf Coast into the Southeast and
northern Florida, which is reflected on Day4/Monday Excessive
Rainfall Outlook Marginal Risk area. Flood risk continues for
northern Florida through Day5/Tuesday. Towards mid-week, chances
for showers and thunderstorms continues as the frontal boundary
stalls across the Gulf Coast into Florida. The axis of greatest
rainfall will continue to gradually shift south and east as the
high pressure strengthens over the eastern states and dry airmass
builds behind the front.

Farther north, a series of northern-stream shortwaves will eject
frontal passages across the northern Plains, Midwest, Ohio Valley,
and Northeast. Towards mid to late week, the potential for
isolated
light showers may develop along the boundary, while cooler air
behind the front begins to spread into north- central and
northeastern U.S. Across the West, persistent upper ridging will
maintain above- normal temperatures across much of Western U.S.
into the work week. The greatest heat will remain concentrated
across California and Desert Southwest with daytime highs reaching
90s to low 100s. The prolonged heat will pose a risk for heat
related illness, especially for those without adequate cooling and
hydration. See WPC`s Key Messages for the California October Heat
Wave for additional information.



Oudit


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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