Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
347 AM EDT Tue Apr 18 2023

Valid 12Z Tue Apr 18 2023 - 12Z Thu Apr 20 2023

...Snow over the Cascades on Tuesday and Wednesday; moderate snow over
parts of the Northern Plains on Wednesday...

...There is a Slight Risk of severe thunderstorms over parts of the
Central/

 Southern Plains into the Middle Mississippi Valley on Wednesday...

...There is a Marginal Risk of excessive rainfall over parts of the
Central Plains, Upper/Middle Mississippi Valley, and Upper Great Lakes on
Wednesday...

On Tuesday, a front extending from the Northern Intermountain Region to
Central California will move eastward and merge with a weak front over the
Rockies by Tuesday evening. The front will continue to move eastward to
Middle Mississippi Valley and southward to the Southern High Plains by
Thursday morning. On Tuesday, the system will produce snow over parts of
the Northern Intermountain Region and the Northern Rockies.

In addition, moisture will flow northward over the Southern/Central Plains
into the Northern High Plains. As a result, on Tuesday, showers and
thunderstorms will start to develop over the Northern High Plains. By
Tuesday afternoon, showers and thunderstorms will develop over parts of
the Southern Plains. Moreover, overnight Tuesday, showers and
thunderstorms will develop over parts of the Northern/Central Plains into
parts of the Middle Mississippi Valley. Also, overnight Tuesday, snow will
develop over parts of the Northern High Plains, becoming light to moderate
on Wednesday.

On Wednesday, showers and severe thunderstorms will develop over parts of
Oklahoma to Iowa as the front moves onto the Plains. Therefore, the SPC
has issued a Slight Risk of severe thunderstorms over parts of the
Central/Southern Plains into the Middle Mississippi Valley from Wednesday
into Thursday morning. The hazards associated with these thunderstorms are
frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes.

Furthermore, moderate to heavy rain will accompany the thunderstorms over
parts of Kansas northward to Minnesota and Wisconsin. Therefore, the WPC
has issued a Marginal Risk of excessive rainfall over parts of the Central
Plains, Upper/Middle Mississippi Valley, and Upper Great Lakes from
Wednesday into Thursday morning. The associated heavy rain will create
localized areas of flash flooding, affecting areas that experience rapid
runoff with heavy rain. Moreover, showers and thunderstorms will move into
the Great Lakes overnight Wednesday.

Meanwhile, on Tuesday, weak onshore flow and upper-level energy will
create coastal rain and higher elevation snow, in the Cascades, over the
Pacific Northwest and Northern California, with snow extending into parts
of the Sierra Nevada Mountains. However, the snow over the Sierra Nevada
Mountains will begin to taper off overnight Tuesday. In contrast, the
coastal rain and higher-elevation snow will continue over the Pacific
Northwest through late Wednesday afternoon and begin to taper off on
Thursday morning. Elsewhere, lake-effect snow will develop downwind of the
Great Lakes on Tuesday into late Tuesday evening.


Ziegenfelder


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