836
FXUS02 KWBC 110624
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
224 AM EDT Mon May 11 2026

Valid 12Z Thu May 14 2026 - 12Z Mon May 18 2026


...Guidance/Predictability Assessment...
Guidance seems reasonably clustered with the overall larger scale
upper pattern from late week into the weekend as highlighted by a
warming ridge that slides eastward into the Central U.S. as an
amplified downstream trough shifts over/offshore the East. Noteably
however, the greatest source of uncertainty continues to surround
the upstream evolution and timing of a main closed low from the
eastern Pacific to advance inland over the West then downstream
along with advent of additional Pacific shortwave energies to
subsequently drive less amplified flow later weekend into early
next week. Models continue to especially struggle with the main
Pacific closed low track/timing inland, with abysmal agreement both
run-to-run and within the larger modeling suite as a whole and
continuing with the latest 00 UTC guidance cycle. Even so, there
was enough agreement overall to favor a composite of otherwise
compatible GEFS/ECMWF/Canadian ensemble means through this forecast
period. This plan seemed to best preserve WPC product continuity
and maintain reasonable 01 UTC National Blend of Models integrity.

...Weather/Hazards Highlights...

It generally remains the case that an eastern Canadian closed
upper-level low/trough will help support longwave troughing down
over the eastern U.S. through late week. Impulses will lead to the
progression of a wavy frontal systems and showers/thunderstorms
through the East. System progression to the Atlantic will spawn
moderate coastal cyclogenesis with wrapping moisture/rains lifting
up/off the East Coast as a maritime threat. Troughing breaks down
by the weekend as low amplitude ridging builds in from the west.

Upstream, an eastern Pacific closed low is slated, still with much
uncertainty, to advance inland mid-late week to focus organized
light to moderate precipitation most likely across portions of the
northern Great Basin, Pacific Northwest, and northern Rockies.
Surface lows and frontal boundaries will form downstream, bringing
weekend shower/thunderstorm chances broadly from the central U.S.
to the Midwest/Great Lakes/East. Farther upstream system energies
with some showers will subsequently work inland into the West and
downstream over the lower 48 with uncertain timing in an overall
more benign weather pattern in increasingly zonal flow aloft.

Temperatures for the eastern U.S. will be below normal into late
week before moderating with upper trough ejection to the Atlantic.
Meanwhile, an eastward shifting upper ridge will gradually spread
well above normal temperatures across the Central to East-Central
U.S. that may produce several summertime high temperature records.


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




$$