697
FXUS02 KWNH 090648
PREEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
248 AM EDT Wed Apr 9 2025

Valid 12Z Sat Apr 12 2025 - 12Z Wed Apr 16 2025


...General Overview...

An amplified upper level trough will be in place across the East
Coast for the upcoming weekend, with a surface low off the Mid-
Atlantic coast that will track in the general direction of Nova
Scotia by early next weekend. Meanwhile, an upper ridge will be in
place across the Plains that will support warm conditions for this
time of year. An incoming upper trough across the northern Rockies
will then spur surface cyclogenesis across the central/northern
Plains by Sunday with a cold front crossing the Intermountain West.
The cold front should then reach the south-central U.S. by Tuesday
morning with the upper ridge breaking down. Another trough is
likely to reach the West Coast region during the Tuesday to
Wednesday time period, but uncertainty is higher on its evolution.

...Guidance/Predictability Assessment...

The 00Z model guidance suite has come into better agreement with
the trough axis crossing the northwestern states over the weekend.
The 12Z CMC was a slow outlier and not used beyond day 4 given its
timing differences, but the new 00Z run is in much better
agreement. This also holds true for the potential closed upper low
near the Desert Southwest late in the forecast period, but still
remains more uncertain than other parts of the country. For the
system across the East Coast this weekend, the GFS it a bit
farther northwest with the surface low across the northern Mid-
Atlantic, and the CMC more offshore, but otherwise good agreement
noted for this region.

The WPC fronts and pressures forecast was derived mainly from a
GFS/ECMWF/UKMET/previous WPC blend for this weekend, and then
mainly GFS/ECMWF and their respective ensemble means going forward
into the first half of next week, with means up to about 60% by
Wednesday.

...Weather/Hazards Highlights...

The low pressure system emerging off the southern New England coast
this weekend will likely keep widespread light to moderate rainfall
across the Northeast U.S., especially on Saturday with the
heaviest rainfall beginning to exit the Cape Cod region. Higher
elevation snow is likely for the northern Appalachians through the
weekend with several inches of accumulation possible. With most of
the heaviest rainfall expected on Friday, it appears unlikely that
there will be any excessive rainfall concerns going into
Saturday/Day 4, so no risk areas are warranted. An even less
eventful rainfall forecast is expected for Sunday/Day 5, and
therefore no risk areas are necessary as well, even though there
will likely be a swath of moderate rainfall across the northern
tier states with the surface low moving through.

Elsewhere across the Continental U.S., several inches of snowfall
is likely across the higher terrain of the Northern Rockies through
the weekend as the upper low moves across the region. The front
moving across the central Plains and Midwest will not have much
moisture or instability to work with, so rainfall associated with
it should be mainly light. There may be an increase in shower
coverage across portions of the southern Plains by the middle of
next week as a potential wave of low pressure develops along the
front, but does not look impressive at this time.

The mid-upper level ridge axis exiting the Rockies and across the
Plains through the upcoming weekend will support widespread above
normal temperatures from the Desert Southwest to the central and
northern Plains. Highs could reach into the 90s from western Texas
to eastern Colorado and western Kansas, before the cold front
brings readings closer to climatology for Monday. The warmth then
encompasses the Midwest to the Deep South to start the week and
then it reaches the East Coast by Tuesday, with highs about 5-15
degrees above average. However, widespread cloud cover over the
weekend will tend to keep things cooler than mid-April standards
across the Eastern U.S. before things moderate next week.

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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