Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Mon Apr 28 2025

Valid 12Z Mon Apr 28 2025 - 12Z Wed Apr 30 2025

...Additional rainfall and snowmelt bring flooding concerns to portions of
the northern High Plains of Montana early today...

...Outbreak of severe weather, including strong tornadoes, expected for
portions of the Midwest/Plains today, followed by strong to severe
thunderstorms possible for interior Northeast on Tuesday...

...Potentially significant flash flooding increasing across portions of
the southern Plains beginning on Tuesday...

...Warm air spreading eastward from the central U.S. to the eastern U.S.
heading into midweek...

During the course of the next couple of days, most of the active weather
associated with our ongoing Spring weather pattern is forecast to impact
the mid-section of the country.  A deep upper-level trough exiting the
Rockies is currently interacting with a cold airmass dipping south from
Canada into the northern High Plains.  This interaction is leading to the
formation of a low pressure system over the northern Plains.  With
additional lift provided by terrain interactions, the higher elevation of
southern Montana is expected to receive additional snowfall today while
the lower elevations in close proximity remain under the threat of flash
flooding due to the prospect of additional rainfall and snowmelt in the
vicinity.  The threat of flooding is expected to diminish by later today
as the mixed rain/snow spreads farther south into Wyoming before tapering
off tonight.  Across the northern Plains, however, an expanding area of
moderate to locally heavy rain is expected to spread quickly eastward as
the center of the intensifying low pressure system moves quickly into the
upper Midwest by this evening.  On the warm side of the system, the
building up of instability interacting with vigorous dynamics ahead of the
low pressure system will likely lead to an outbreak of severe weather over
the upper Midwest, especially by later today into the evening hours.  The
Storm Prediction Center anticipates a moderate risk of severe weather over
portions of the upper Mississippi Valley where strong tornadoes, very
large hail, and damaging winds are expected.  An enhanced risk of severe
weather extends southwestward ahead of a trailing cold front through the
Mid-Missouri Valley, with a Slight Risk extending further southwestward
through the southern Plains.  Locally heavy rainfall may also lead to some
isolated instances of flash flooding as well.  By Tuesday morning, as the
elongated low pressure system tracks into southern Canada, colder air
behind the system could change the rain to a period of wet snow across the
upper Great Lakes area.  Strong and gusty northwesterly winds will sweep
across the northern Plains today and then through the Great Lakes on
Tuesday.

Across the southern Plains, the trailing portion of the cold front is
forecast to stall later on Tuesday.  As residual upper-level troughing
ejects out of the southern Rockies, an episode of heavy rain is expected
to emerge over the southern Plains on Tuesday.  Repetitive rounds of
storms in vicinity of the stalling boundary over an already sensitive
region given recent rainfall is anticipated to result in a moderate risk
of excessive rainfall for portions of southwest Oklahoma and northwest
Texas with scattered to numerous instances of flash flooding possible by
later on Tuesday.  A broader Slight Risk extends northeastward towards the
Mid-Mississippi Valley and southwestward into the Texas Big Country for
additional scattered instances of flash flooding.  More generally,
scattered to widespread storms are expected along the cold front from the
interior Northeast southwestward through the Ohio/Middle Mississippi
Valley and southern Plains. The Storm Prediction Center has included a
slight risk of severe weather as some storms will be capable of large hail
and damaging winds, along with an enhanced risk across interior Northeast
for Tuesday evening ahead of an approaching cold front.  It appears that
additional rounds of heavy rain and embedded severe thunderstorms will
impact Oklahoma and vicinity Tuesday night into Wednesday morning near the
stalled frontal boundary, leading to a continued threat of flash flooding.

Elsewhere, very dry conditions along with strong, gusty winds will keep a
critical fire weather risk today across portions of New Mexico followed by
a gradual lessening of the threat on Tuesday.  Elsewhere, a
quasi-stationary frontal boundary across portions of the Southeast will
bring some showers and thunderstorms through today.  A Pacific system will
bring increasing precipitation chances into the Pacific Northwest by this
evening and then inland through the northern Great Basin and Rockies into
Tuesday, reaching into the northern High Plains Wednesday morning.  An
upper-level ridge building over much of the central/eastern U.S. will
bring well above average conditions to start the week.  Forecast highs in
the 70s and 80s will be common, including for more northern locations like
the Midwest and Northeast ahead of the cold front.  After a cool weekend,
temperatures will begin to return back closer to average over the West
today and especially into Tuesday, with highs generally ranging in the 60s
and 70s, with 80s into the Desert Southwest. 

Kong/Putnam


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