623
FXUS02 KWBC 280714
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
314 AM EDT Sat Jun 28 2025

Valid 12Z Tue Jul 01 2025 - 12Z Sat Jul 05 2025


...Guidance/Predictability Assessment...

Latest model and ensemble guidance in this generally progressive
summertime pattern continues to seem reasonably well clustered for
mid-larger scale features through the upcoming medium-range
timeframe in a pattern with seemingly above normal predictability.
Blending the 18 UTC GFS/GEFS mean and 12 UTC ECMWF/Canadian/UKMET
and ECMWF ensemble mean should tend to separate more widespread
smaller scale differences out from the noise as consistent with
individual system predictability. This plan maintains very good
WPC product continuity as overall in line with the 01 UTC National
Blend of Models, machine learning tools and newest 00 UTC models.

...Weather/Hazards Highlights...

Organized thunderstorms with favorable moisture/instability and
ample right entrance region upper jet lift will fuel locally heavy
convective downpours to florish ahead of an upper trough and a
well defined for summer surface frontal boundary to progress into
the East and South/Southeast by Tuesday and into late next week. A
elongated WPC Day 4/Tuesday Excessive Rainfall Outlook (ERO) Marginal
Risk area remains from the Northeast/Mid-Atlantic back through the
Appalachians and broadly across the South. An ERO Marginal Risk
area has also been introduced for Day 5/Wednesday with focus
across the Southeast. One area of focus with for some heavier rain
is across the central to eastern Gulf Coast region. Areas will dry
out and moderate to the north post-frontal, but activity will
linger along/ahead as the front slows and slowly loses influence
across the South/Southeast into late next week. Even before the
front nears, moist scattered thunderstorms are likely farther south
in the broad warm sector as well. There will initially be less
forcing for organization and sustaining of storms deeper down
across the southern tier away from the upper jet, but instability
could allow for heavy rain rates that may cause localized flash
flooding, as likely dependent on smaller scale boundaries.

Monsoonal moisture with some connection to possible Pacific
tropical development is likely to increase next week in the
southern Rockies/High Plains with southerly flow under the upper
ridge, thus increasing coverage of rain amounts in storms. Marginal
Risks remain planned there for Day 4/Tuesday and also for southern
Arizona into Day 5/Wednesday. Areas like the Sacramento Mountains,
where the steep terrain and burn scars cause the area to be
particularly sensitive to rain and most vulnerable to potential
flash flooding, especially with wet antecedent conditions there.

Elsewhere, afternoon and nocturnal storm clusters may develop from
the Northern Rockies Tuesday onward across the northern Plains and
Upper Midwest Wednesday into Friday as moisture/instability pool
along/overtop a retreating front. A Day 5/Wednesday WPC ERO
Marginal Risk area has been introduced there to start given
potential for training of these strong to severe cells.


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 (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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