726
FXUS01 KWBC 261931
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
330 PM EDT Sat Apr 26 2025

Valid 00Z Sun Apr 27 2025 - 00Z Tue Apr 29 2025

...Wet snow along the Sierra Nevada, parts of the Great Basin this
weekend, and then the northern Rockies Sunday night/early Monday...

...Heavy rainfall and snowmelt will lead to a risk of flooding for
portions of the northern High Plains of Montana Sunday...

...Outbreak of severe weather, including strong tornadoes,
expected for portions of the Midwest/Plains Monday...

...Much below average temperatures continue across California, the
Great Basin, and the Southwest with much above average
temperatures spreading from the Plains into the
Midwest/Southeast...

An active Spring weather pattern will continue across large
portions of the U.S. through the weekend. A deep upper-level low
has brought a period of unsettled weather to the West including
both rain and periods of snow given the much cooler temperatures
in place. Showers and some thunderstorms over California/Oregon
and into the western Great Basin today will spread northeastward
across the Great Basin and into the northern Rockies by Sunday.
Winter Weather Advisories are in place for higher elevations of
the Sierra Nevada and even for some of the ranges into southern
California for accumulations generally between 3-6", locally as
much as 8-12". Winter Storm Watches are also in place for portions
of the northern Rockies in Montana for accumulations as much as
6-12". Accumulating snowfall should be limited to higher
elevations, but the colder temperatures may result in some snow
mixing in for lower elevations of the Great Basin/northern Rockies
overnight Saturday and into Sunday morning.

A moist airmass along a quasi-stationary boundary already in place
across portions of the central/southern Plains ahead of the
approaching upper-low/trough has been responsible for multiple
days of locally heavy rainfall/flash flooding and severe weather.
An ongoing complex of storms across Oklahoma this afternoon as
well as the possibility of some additional storms later along the
periphery of the complex could lead to a few additional scattered
instances of flash flooding, with a Slight Risk of Excessive
Rainfall (level 2/4) in place. Storms ahead of the complex in
southeastern Oklahoma as well as another round of isolated
convection along a dryline further west over the southern High
Plains will also pose a severe weather threat, with a Slight Risk
(level 2/5) from the Storm Prediction Center for the threat of
very large hail, damaging winds, and a few tornadoes.

The boundary will finally lift northward as a warm front overnight
Saturday and into the day Sunday as the approaching
upper-low/trough begins to overspread the Plains. The surge of
strong, moist southerly flow northward and upper-level support
will lead to a broad area of showers and thunderstorms Sunday over
the northern Plains. A combination of moisture and upslope flow
along the Rockies will lead to widespread showers and
thunderstorms anchored along portions of the northern High Plains
of Montana. Locally heavy rainfall as well as Spring snowmelt
across terrain sensitive areas including burn scars has prompted a
Slight Risk (level 2/4) of Excessive Rainfall for the threat of
some scattered flash flooding. Additional storms are expected
further east, with sufficient CAPE and very strong dynamics with
the approaching trough leading to the potential of some severe
weather. A Slight Risk is in place along portions of the
northern/central High Plains primarily for the threat of large
hail. An eventual complex of storms moving through the Dakotas
late Sunday and into the early morning hours Monday may also lead
to some isolated flash flooding.

The upper trough and an accompanying surface low pressure/frontal
system will shift eastward from the Plains into the Midwest on
Monday. The continued impressive dynamics given the strength of
the trough, with strong winds at both upper- and lower- levels, as
well as the surge of a moist, unstable airmass northward will lead
to widespread, intense thunderstorms Monday afternoon and evening.
A Moderate Risk (level 3/5) is in effect for the Upper Mississippi
Valley where an outbreak of severe weather, including strong
tornadoes, is expected. A broader Enhanced Risk extends
southwestward into the Middle Missouri Valley with a Slight Risk
into the southern Plains where more potentially significant but a
bit more isolated instances of very large hail, damaging winds,
and tornadoes will also be possible.

Elsewhere, scattered showers and thunderstorms will continue this
afternoon ahead of a cold front across the Northeast/Mid-Atlantic,
with most storms coming to an end later this evening as the front
clears the coast. Storms will linger longer into Sunday over
portions of the interior Northeast/northern New England, with some
snow potentially mixing in for higher mountain elevations. Very
dry conditions, warm temperatures, and strong, gusty winds have
prompted a Critical Risk of Fire Weather (level 2/3) from the
Storm Prediction Center for northwestern New Mexico today. Even
stronger winds expected Sunday will lead to an Extremely Critical
Risk of fire weather (level 3/3) over portions of central and
southern New Mexico as well as far west Texas. The deep
upper-level trough over the western U.S. as well as a
corresponding upper-level ridge intensifying over the
central/eastern U.S. will lead to an increasing dichotomy in well
above average and below average temperatures this weekend and into
next week. Well above average temperatures over the Plains Sunday
will expand eastward across the Midwest and Southeast Monday, with
the Northeast/Mid-Atlantic also seeing above average highs.
California, the Great Basin, and the Southwest will see another
day of well below average highs on Sunday before conditions
moderate closer to average on Monday. Areas of the Pacific
Northwest and northern Great Basin will remain at or above
average.

Putnam


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
$$