669
FXUS02 KWNH 010718
PREEPD

Preliminary Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
316 AM EDT Sat Nov 1 2025

Valid 12Z Tue Nov 04 2025 - 12Z Sat Nov 08 2025


...Overview...

Early next week, a closed upper low will be exiting the Southeast
while an upper level trough moves across the Northeast. By mid-next
week, the upper level pattern is expected to shift as a series of
strong upper level troughs move west to east across the country.
This will result in persistent stormy conditions across the
Northwest as Pacific frontal systems move onshore with widespread
precipitation chances. Periods of light to moderate precipitation
will also be possible across the Great Lakes and Northeast next
week and across the Ohio and Tennessee Valleys later next week.
Most of the Southern and Central U.S. should remain dry next week
under the influence of weak mean ridging.


...Guidance/Predictability Assessment...

After struggling for the past few days, model guidance is finally
coming into better agreement on the evolution of the low exiting
the Southeast early next week. Most model guidance is showing the
low being pulled out into the Atlantic as it interacts with the
upper trough exiting the Northeast. The latest 00Z runs of the
ECMWF, CMC, and GFS all show the low lingering briefly off the
Southeast Coast on Tuesday, then being pulled out into the Atlantic
by Wednesday morning. The 18Z GFS seemed to be an outlier, showing
a chunk of energy from the low splitting off and lingering over
the Gulf, which was not present in any other model solutions. Model
agreement is pretty good through the rest of the medium range
period, with an expected amount of spread in the timing and depth
of upper troughs moving into the West next week. There is some
uncertainty in the evolution of the troughs downstream over the
Great Lakes, which will be determined by how they interact with an
Arctic low/trough digging into Canada late next week.

WPC`s forecast blend was composed of majority deterministic model
guidance through the first half of the period, with very little
influence from the 18Z GFS outlier solution. Ensemble means from
the GEFS, ECENS, and CMCE were added in increasing amounts through
the rest of the period to help smooth out model differences, but
some deterministic influence was kept throughout to maintain some
detail.


...Weather/Hazards Highlights...

Precipitation chances will focus over the Northeast and Northwest
next week as a series of upper troughs and accompanying surface
low pressure systems move across the northern tier of the nation.
These systems should be fairly progressive, but repeated rounds of
precipitation over the terrain along the West Coast could result
in locally heavy precipitation amounts. A system mid-next week
will likely bring a brief atmospheric river event to northern
California and southwestern Oregon, with heavy low elevation rain
and heavy mountain snow in the Sierra Nevada and Cascades.
Isolated instances of flash flooding may be possible during this
event, especially near steep terrain or burn scar areas, and
therefore there are Marginal Risks of excessive rainfall in effect
for Tuesday and Wednesday. The focus for heavy precipitation should
shift north over western Washington and Oregon with the next
system moving onshore later next week.

Elsewhere, precipitation rates with these systems will likely be
light to moderate over the interior Northwest and Northeast, and
there will be winter weather potential in the northern Rockies and
northern New England. Periods of mountain snow are expected with
each passing system in the northern Rockies, and some wrap around
snow will be possible on the backside of these systems late next
week in northern New England. Snow amounts should be relatively low
in northern New England, but could be enough to shovel.

For the rest of the nation, the forecast looks to remain mostly dry
next week. There could be some isolated shower activity over the
Florida peninsula and along the Southeast Coast early next week as
the upper low exits the region, and precipitation chances may
increase over Florida again late next week as a cold front moves
south across the state. Precipitation chances will also likely
extend into the Ohio and Tennessee Valleys late next week as a low
pressure system strengthens over the region.

Above average temperatures are forecast across the Plains through
much of next week under the influence of weak upper level ridging.
High temperatures are forecast to run 10-20 degrees above average.
Elsewhere, temperatures should be near average.


Dolan


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 (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

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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