Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
318 AM EDT Sun Apr 20 2025

Valid 12Z Sun Apr 20 2025 - 12Z Tue Apr 22 2025

...Light to moderate snow over parts of the Cascades, Northern
Intermountain Region, Northern Rockies, and Upper Great Lakes on Sunday
and Monday...

...There is a Slight Risk of excessive rainfall over parts of the Middle
Mississippi Valley and the Southern Plains on Sunday...

...There is an Enhanced Risk of severe thunderstorms over parts of the
Middle/Lower Mississippi Valley on Sunday...

A wave of low pressure over the Southern Plains on Sunday will move
northeastward to into western Quebec, Canada, by Tuesday. The associated
front will move from the Southern Plains to the Northeast to the
Mid-Atlantic and then southwestward to the Southern Plains by Tuesday as
well. Moisture from the Gulf of America will stream northward over the
Plains and intersect with the boundary, producing showers and severe
thunderstorms over the Middle/Lower Mississippi Valley. Therefore, the SPC
has issued an Enhanced Risk (level 3/5) of severe thunderstorms over the
Middle/Lower Mississippi Valley through Monday morning.  The hazards
associated with these thunderstorms are frequent lightning, severe
thunderstorm wind gusts, hail, and a few tornadoes.  Furthermore, there is
an added threat of EF 2 to EF 5 tornados over the Middle/Lower Mississippi
Valley.

In addition, the showers and thunderstorms will produce heavy rain over
parts of the Middle/Lower Mississippi Valley and the Southern Plains on
Sunday. Therefore, the WPC has issued a Slight Risk (level 2/4) of
excessive rainfall over parts of the Middle/Lower Mississippi Valley and
the Southern Plains through Monday morning.  The associated heavy rain
will create mainly localized areas of flash flooding, with urban areas,
roads, small streams, and low-lying areas the most vulnerable.

On Monday, the threat of severe thunderstorms and excessive rainfall
reduces. However, showers and thunderstorms will continue along and ahead
of the front from the Great Lakes/Ohio Valley into the Tennessee Valley,
Lower Mississippi Valley, and the Western Gulf Coast. The threat of
excessive rainfall associated with these storms is not expected. 

Early Monday morning, wet snow will develop near the western third of Lake
Superior. By Monday evening, the swath of wet snow will move eastward over
parts of the Upper Peninsulas of Michigan, moving into Canada by Tuesday
morning. Rain with embedded thunderstorms will move into the Northeast
overnight Monday. Showers and thunderstorms will continue along the front
overnight Monday into Tuesday morning from parts of the eastern
Ohio/Tennessee Valleys into the Lower Mississippi Valley and Central Gulf
Coast. 

Meanwhile, on Sunday, upper-level energy will move onshore over the
Pacific Northwest overnight, developing a front over the Northern
Intermountain Region. The energy will produce rain and highest-elevation
snow over parts of the Northwest into the Northern Intermountain Region
and the Northern Rockies.

On Monday, the front consolidates over the Northern Rockies/Northern
Intermountain Region and moves eastward to the Northern/Central Plains
across the Central Rockies into the Great Basin by Tuesday. The system
will create highest-elevation snow and lower-elevation rain over parts of
the Northern Intermountain Region/Northern Rockies. Rain will begin to
develop over parts of the Northern High Plains on Monday afternoon into
evening. The rain will move into parts of the Northern Plains/Upper
Mississippi Valley by Tuesday morning.


Ziegenfelder


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