Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Thu Apr 10 2025

Valid 12Z Sun Apr 13 2025 - 12Z Thu Apr 17 2025

...General Overview...

An amplified upper level trough will be in place across the East
Coast for the upcoming weekend, with a surface low moving offshore
the Mid-Atlantic coast that will track in the general direction of
Nova Scotia by early next week. Meanwhile, an upper ridge will be
in place across the Midwest states on Sunday 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 with a cold front crossing the
Intermountain West. The cold front should then reach the Deep
South by Tuesday morning with surface high pressure building in
behind it. Another trough is likely to reach the Western U.S.
during
the middle of next week, with a potential closed low near southern
California by Thursday morning.

...Guidance/Predictability Assessment...

The 00Z model guidance suite features good synoptic scale agreement
for Sunday across the country. By Monday, the GFS is slower and
more amplified with the low crossing the northern Plains, with a
stronger surface low crossing the Great Lakes. The GFS is also
quicker to move the coastal low near the Northeast offshore. By the
end of the forecast period next Thursday, model spread increases
substantially across the Pacific Northwest with additional Pacific
shortwave moving in, and the closed upper low near California has
trended farther west compared to the 12Z guidance.

The WPC fronts and pressures forecast was derived from a multi-
deterministic blend for Sunday, and then mainly GFS/ECMWF/CMC and
the ensemble means going forward into the first half of next week,
with means up to about 50% by Thursday.

...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 New England on Sunday, and widespread cloudiness from the
Mid-Atlantic to the Northeast. Similar to yesterday's forecast, it
does not appear likely that any areas will having flooding concerns
during the Day 4 and 5 time period (Sunday and Monday), so no risk
areas are currently warranted in either outlook. Having said that,
there will likely be a corridor of moderate to locally heavy
rainfall extending from central North Dakota to northern Minnesota
and across the Upper Peninsula of Michigan during this time period
as the main surface low crosses the region. Rainfall rates should
be modest with that event and not enough to cause flooding issues.

Elsewhere across the Continental U.S., several inches of snowfall
is likely across portions of the Montana Rockies through the
weekend as the upper low moves across the region. The front moving
across the central Plains and Midwest to the Ohio Valley will not
have much moisture or instability to work with, so rainfall
associated with it should be mainly light. However, breezy
conditions are likely behind the front and especially across the
Great Lakes region and northern Plains where the pressure gradient
will be stronger.

The mid-upper level ridge axis across the Plains on Sunday 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. The cold
front then brings cooler conditions back to the Eastern U.S. for
the middle of the 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