238
FXUS02 KWNH 070650
PREEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
249 AM EDT Mon Apr 7 2025

Valid 12Z Thu Apr 10 2025 - 12Z Mon Apr 14 2025

...General Overview...

The large upper trough that will be in place across the Northeast
U.S. early in the week is forecast to lift out of the region by
Thursday. An amplifying shortwave trough originating from south-
central Canada is expected to amplify as it drops southeast across
the Ohio Valley, and thus support a surface low from the Midwest to
the Mid-Atlantic coast to close out the work week and emerging off
the coast next Saturday. Meanwhile, an upper level ridge builds
across the Intermountain West and Rockies Thursday into Friday, and
then shifts eastward to the Plains by next weekend. With the ridge
departing the West, an upper trough approaches from the Pacific
Northwest and supports a cold front crossing the Intermountain West
to the central/northern Plains through next Monday.

...Guidance/Predictability Assessment...

The 00Z model guidance suite indicates good synoptic scale
agreement across the Continental U.S. on Thursday. There are still
some differences in the surface low evolution near the East Coast
and whether a secondary low will form and become the dominant low
by Saturday morning, but that is now looking more likely. The area
with the greatest model differences is across the West Coast region
going into Sunday and across much of the Western U.S. Monday in
regards to the evolution of the trough moving inland from the
Pacific. It is uncertain whether it will be a split upper flow
pattern, or just a main consolidated trough.

The WPC fronts/pressures forecast was mainly based on a multi-
deterministic blend on Friday, with gradually increasing
proportions of the NAEFS and ECENS through the weekend, reaching
about 2/3rds ensemble means by next Monday.


...Weather/Hazards Highlights...

The low pressure system crossing the Ohio Valley and then reaching
the East Coast to close out the week will be the next event to
monitor, with widespread showers expected from the Deep South to
the Great Lakes on Thursday. Even though forecast rainfall totals
are not expected to be heavy, the ground will likely still be quite
saturated for many of those areas affected by the prolific
rainfall lately, so that is something that will continue to be
monitored, but for now no risk areas appear warranted for the Day 4
excessive rainfall outlook. Colder high pressure held over the
Northeast interior in advance of the system may allow for some
terrain focusing snow chances. A deepening coastal low near the
Mid-Atlantic Coast on Friday and into early Saturday will likely
result in higher rain chances and breezy conditions from Virginia
to New England into next weekend. A Marginal Risk area will be
valid for Day 5/Friday-Friday night from NJ/PA northward to
southern New England with more of an enhanced QPF signal in the
deterministic guidance, with perhaps 1-2 inches of rainfall.

Elsewhere across the country, periods of moderate rain and
mountain snow return to western Washington and Oregon courtesy of
onshore flow and a shortwave passage Thursday, but this does not
look like a major event at this time. Light snow then reaches the
higher elevations of the northern Rockies by next weekend as the
moisture moves inland. Dry conditions are forecast from the
Southwestern U.S. to the central/southern Plains during the entire
forecast period.

In terms of temperatures, a moderating trend commences by the end
of the week across the Eastern U.S. as the upper trough lifts out
of New England. Looking ahead to next weekend, lows should be near
average while daytime highs remain slightly below average with
increased cloud cover. Meanwhile, a warm pattern is expected for
the Western U.S. through the end of the week with both daytime
highs and overnight lows about 10-20 degrees above average, with
the greatest anomalies over the Great Basin on Friday. These
milder conditions then reach the central and northern Plains by
next weekend as the ridge shifts eastward.

Hamrick


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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