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