Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 PM EDT Thu Apr 10 2025

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

...Overview...

Guidance shows a fairly progressive pattern for the Sunday-
Thursday period. An upper low anchoring an amplified East Coast
trough as of early Sunday will lift away while the next trough
initially over the northern Rockies amplifies into the Plains and
then eastern U.S. An upper low within the latter trough should
track near the Canadian border and provide the dynamic support for
a Plains through Upper Great Lakes and eastern Canada surface low
that will push a cold front through the eastern half of the
country. The combination of northern stream Pacific energy and what
is left of a weakening upper low coming into the Southwest around
Tuesday may reach the Plains/Mississippi Valley by next Thursday
and reflect at the surface as one or more waves/frontal systems.
Confidence in details is on the lower side though. Also at that
time another upper low should reach offshore southern California
while some ridging builds over the western U.S. into Canada. Most
precipitation with the above systems should be light to moderate
and confined to locations east of the Rockies, with the relatively
higher totals over the far northern tier on Sunday and parts of the
central/south-central Plains into Mississippi Valley mid-late
week.

...Guidance/Predictability Assessment...

There is reasonable clustering in principle for the system
departing from the East Coast and the next feature emerging from
the Rockies/Plains. Dynamical and machine learning (ML) models and
ensembles show rapidly increasing spread for some aspects of larger
scale flow across the western half of the country by next
Wednesday/Thursday.

The departing East Coast system continues to exhibit some detail
differences, with the most notable being the GFS leaning to the
northern extreme of the spread (more in the 12Z run versus the 06Z
version). Farther west, GFS/CMC runs have been gradually trending
northward toward the remaining dynamical/ML consensus for a
developing upper low to track near the Canadian border.
Interestingly the 00Z/06Z GFS actually briefly opened the upper
system over the Upper Midwest by Monday while remaining guidance
has been advertising a consistent signal for an upper low near the
northern Minnesota border. Thereafter, guidance exhibits typical
spread for upper/surface low specifics and good agreement for the
upper trough reaching the eastern U.S. A majority/consensus
approach among the 00Z/06Z operational models looks good for the
depiction of these systems.

Guidance has been having more difficulty in resolving specifics
over the eastern Pacific into western North America, with varying
amounts of trough energy splitting while nearing the West Coast.
Solutions are clustering toward one upper low coming into the
Southwest around Tuesday while weak shortwave energy reaches the
Pacific Northwest and western Canada. Then by Wednesday-Thursday
latest trends are for the Southwest upper low to open up but with
the remaining shortwave maintaining some definition as it crosses
the Rockies/Plains while the northern energy begins to amplify
downstream from a ridge that builds into and north of the western
U.S. There is a minority ensemble cluster and a couple ML models
that show significantly more trough amplification over the Interior
West or Rockies though, and the 00Z AIFS mean hints at a
combination of these ideas. Meanwhile another upper low should
reach a position offshore southern California by next Thursday. A
trend toward half models and half means (06Z GEFS/00Z ECens) by
late in the period provides a reasonable account for latest
operational model trends but lower than average confidence in some
of the specifics at that time. At the very least, even with the
guidance spread there is a decent signal for a general axis of
lower surface pressures over the Plains by next Thursday with
GEFS/ECens ensembles showing the general idea of an east-central
U.S. rain area.

...Weather/Hazards Highlights...

Eastern parts of New England should see lingering rainfall on
Sunday with the system tracking away from the East Coast. Meanwhile
the developing northern Plains into Upper Great Lakes system
should bring a band of enhanced rainfall with the possibility of
some pockets of snow across parts of North Dakota and Minnesota,
with some rain/snow continuing across the Great Lakes/Northeast
through the first half of next week. Best potential for some snow
accumulation should be over the U.P. of Michigan and to the lee of
the eastern Great Lakes and high elevations of the Northeast. There
will also be some rainfall along the system's trailing cold front,
but likely with light to moderate amounts. Note that the Storm
Prediction Center is monitoring the potential for some strong
convection over parts of the Ohio Valley on Monday (mostly wind
threats). Expect rainfall with the above systems to stay light
enough not to present flash flood concerns, so the Days 4-5 EROs
depict no risk areas. Flow behind the northern tier storm should
produce strong and gusty winds over the northern/central Plains
Sunday into Monday, with some brisk winds reaching into the Great
Lakes/Northeast thereafter.

A weakening upper low reaching the Southwest by Tuesday may
produce some very scattered and light precipitation. Depending on
the definition and surface reflection of this energy farther
eastward, there may be a band of rainfall with varying intensity
from parts of the central/south-central Plains eastward through the
Mississippi Valley by Wednesday-Thursday.

The mid-upper level ridge axis across the Plains on Sunday will
support widespread above normal temperatures (plus 10-25F
anomalies) 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. Some daily records are
possible on Sunday, especially over the southern High Plains. The
warmth will moderate as it continues eastward into Monday and early
Tuesday. Then the cold front pushing across the eastern half of
the country will bring near to below normal readings, with highs up
to 10-15F below normal over parts of the East around midweek.
General mean ridging aloft over the West will support an expanding
area of above normal temperatures over the West and eventually
including the Plains Monday onward, with fairly broad coverage of
plus 10-20F anomalies.

Rausch/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