Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
353 AM EDT Sun Sep 19 2021

Valid 12Z Sun Sep 19 2021 - 12Z Tue Sep 21 2021

...Strong to severe thunderstorms possible across portions of the Plains
and Midwest Sunday and Monday....

...Areas of heavy rain likely with flash flooding possible from the
Mid-South to the Southeast Sunday and Monday...

...Critical fire weather conditions possible for portions of Northern
California beginning late Sunday...

A strong cold front will continue to push across the western into the
central U.S., with below-normal temperatures and wet conditions spreading
from the Northwest into the northern Rockies on Sunday.  Showers and
storms are forecast to develop along the front as it moves into the
northern Plains and Upper Midwest, with scattered strong storms expected
across portions of the eastern Dakotas and northwestern Minnesota late
Sunday afternoon into the evening.  Ahead of the front, daytime
temperatures are expected to climb well into the 80s/90s across the Plains
and Midwest on Sunday -- more than 20 degrees above normal for portions of
the Upper Midwest.

The front will push farther east into the upper to mid Mississippi and
lower Missouri valleys on Monday.  Storms are expected to develop once
again along the front, with strong thunderstorms possible from portions of
the Upper Midwest and the northern Great Lakes to the lower Missouri
Valley and central Plains Monday afternoon and evening.  In addition to
damaging winds, heavy rains with isolated flash flooding are possible.

Meanwhile in the West, the front is expected to push south into the
Southwest by Sunday, with high pressure settling in over the Great Basin
and Rockies Monday and Tuesday.  This will support offshore winds across
California, with temperatures quickly rebounding across much of the
western U.S. Monday and Tuesday.  A Fire Weather Watch beginning late
Sunday is in effect for portions of Northern California.

Mid level disturbances associated with the remnants of tropical cyclone
Nicholas will continue to interact with a very moist airmass that remains
in place from the Gulf Coast into the Southeast, and the Tennessee and
lower Ohio valleys.  These are expected to produce additional rounds of
heavy rain across the region.  Flash flood watches are in effect from the
Mid-South to portions of eastern Tennessee and western Georgia.  Given the
recent heavy amounts that have already occurred over the past day, WPC has
highlighted portions of northern Alabama and Middle Tennessee with a
Moderate Risk for Flash Flooding on Sunday -- indicating that numerous
flash floods are likely in the region. 

As the threat for heavy rain and flash flooding is expected to continue
across portions of the Tennessee and lower Ohio valleys, upper level
disturbances moving farther to the east are forecast to support an
increasing threat for heavy rain and flash flooding along the Southeast
coast from North Florida to South Carolina on Monday.   

Pereira

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