Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Mon Sep 20 2021

Valid 00Z Tue Sep 21 2021 - 00Z Thu Sep 23 2021

...There is a Slight Risk of excessive rainfall over parts of the
Southeast, Tennessee Valley, and the Southern Appalachians through Tuesday
morning...

...There is a Slight Risk of severe thunderstorms over parts of the
Upper/Middle Mississippi Valley through Tuesday morning...

...There is a Critical Risk of fire weather over parts of Northern
California through Tuesday morning...

Upper-level energy over the Lower Mississippi, Tennessee, and Ohio Valleys
and abundant moisture over the Southeast/Tennessee Valley into parts of
the Ohio Valley will produce showers and thunderstorms over the region.
Some of the thunderstorms will produce heavy rain. Therefore, the WPC has
issued a Slight Risk of excessive rainfall over parts of the Southeast,
Tennessee Valley, and the Southern Appalachians through Tuesday morning. 
The associated heavy rain will create mainly localized areas of flash
flooding, with urban areas, roads, and small streams the most vulnerable.
The excessive rainfall threat continues over parts of the Southeast and
Southern Appalachians on Tuesday into Wednesday morning.

Meanwhile, a front extending from the Upper Midwest roughly southwestward
to the Southern Rockies will move eastward to the Lower Great Lakes and
the Eastern Gulf Coast by Wednesday evening.  Showers and thunderstorms
will develop along and ahead of the boundary over parts of the Upper
Mississippi Valley/Upper Great Lakes, moving into the Great Lakes to
Middle Mississippi Valley by Tuesday morning.  Some of the thunderstorms
will become severe.  Therefore, the SPC has issued a Slight Risk of severe
thunderstorms over parts of the Upper/Middle Mississippi Valley through
Tuesday morning.  The hazards associated with these thunderstorms are
frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes.

On Tuesday, the severe thunderstorm threat decreasing, while the threat of
excessive rainfall develops over parts of the Great Lakes and Ohio Valley.
Therefore, the WPC has issued a Slight Risk of excessive rainfall with
these thunderstorms.  The associated heavy rain will create mainly
localized areas of flash flooding, with urban areas, roads, and small
streams the most vulnerable on Tuesday into Wednesday morning. As the
boundary moves eastward, the excessive rainfall threat moves into the
Lower Great Lakes/Ohio Valley and the Central Appalachians on Wednesday.

Elsewhere, gusty winds and lowering humidity over parts of Northern
California have increased the threat of fire weather over the area. 
Therefore, the SPC has issued a Critical Risk of fire weather over parts
of Northern California through Tuesday morning. As a result, Red Flag
Warnings are over parts of Northern California.  Additionally, Freeze
watches are over parts of the Northern/Central Rockies.

Ziegenfelder

Graphics are available at www.wpc.ncep.noaa.gov/basicwx/basicwx ndfd.php