The Weather Prediction Center

Short Range Forecast Discussion

[Abbreviations and acronyms used in this product]
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Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
423 PM EDT Sat Oct 23 2021

Valid 00Z Sun Oct 24 2021 - 00Z Tue Oct 26 2021

...There is a High Risk of excessive rainfall over the Sierra
Nevada Mountains and a Slight Risk of excessive rainfall over the
Middle Mississippi and Ohio Valleys on Sunday into Monday
morning...

...Heavy snow for the Sierra Nevada Mountains...

...There is a Slight Risk severe thunderstorms over the Central
Plains and Middle Mississippi Valley through Sunday morning...

A strong storm in the Eastern Pacific will impact the West Coast
over the next several days.  On Sunday, the associated front moves
into the West Coast, advancing inland to the Northern High Plains
to the Great Basin/Southern California by Monday evening. Moisture
will stream into Central/Northern California overnight Saturday,
turning into a powerful stream of moisture on Sunday.  On Monday,
the moisture stream will move southward along the coast while
weakening. There is a Marginal Risk of excessive rainfall through
Sunday morning. As the moisture stream increases, WPC has issued a
High Risk of excessive rainfall over parts of the Sierra Nevada
Mountains on Sunday into Monday morning.  With the High Risk,
significant, and potentially life threatening flash flooding is
expected.

On Monday, the excessive rainfall threat lessens to a Slight Risk
over parts of the Sierra Nevada Mountains with a Marginal Risk
over other parts of the Sierra Nevada Mountains and parts of the
Southern California Coast from Monday into Monday night.  Heavy
snow will develop over the higher elevations of the Sierra Nevada
Mountains on Monday as the front moves pass by.  Furthermore, on
Monday, spotty snow will develop over parts of the Cascades and
the Northern Intermountain Region Rockies.

Meanwhile, an area of low pressure over the Central Plains and
associated front will interact with moisture flowing northward
over the Plains/Mississippi Valley to produce showers and
thunderstorms over the region overnight Saturday into Sunday
morning, with some storms becoming severe.  Therefore, the SPC has
issued a Slight Risk of severe thunderstorms over parts over the
Central Plains and Middle Mississippi Valley through Sunday
morning.  The hazards associated with these thunderstorms are
frequent lightning, severe thunderstorm wind gusts, hail, and a
minimal threat for tornadoes. The low and associated front marches
eastward to the Lower Great Lakes. The trailing boundary extends
across the Mid-Atlantic into the Southeast, then westward to the
Southern Plains by Monday evening. As a result, the risk for
severe thunderstorms moves eastward, with the front impacting the
Middle Lower Mississippi Valley on Sunday into Monday morning and
into the Mid-Atlantic and the Central/Southern Appalachians and
parts of the Southeast on Monday. Moreover, as the system moves
east, heavy rain at times will develop over parts of the Middle
Mississippi and Ohio Valleys on Sunday into Monday. Therefore, the
WPC has issued a Slight Risk of excessive rainfall with these
areas of rain and thunderstorms.  The associated heavy rain will
create mainly localized areas of flash flooding, with urban areas,
roads, and small streams the most vulnerable on Sunday into Monday
morning.

Ziegenfelder




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




Last Updated: 423 PM EDT Sat Oct 23 2021