Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
334 AM EST Fri Nov 12 2021

Valid 12Z Fri Nov 12 2021 - 12Z Sun Nov 14 2021

...Snow and high winds over the northern Plains/upper Midwest gradually
subside today as locally heavy rain and strong thunderstorms move across
the Northeast and Mid-Atlantic...

...Flash flooding potential to continue over the Pacific Northwest into
early Saturday as onslaught of heavy rainfall continues...

...An Alberta clipper will deliver another around of snow/rain and gusty
winds across the northern Plains Saturday into early Sunday...

A large and energetic low pressure system that has brought snow and high
winds across the northern Plains and upper Midwest will steadily weaken
today as it moves across the Great Lakes and then retreats into Canada
tonight.  Nevertheless, very strong and gusty winds on the back side of
this system will initially bring blowing snow and reduced visibility over
portions of the northern Plains this morning before conditions steadily
improve later today.  In the mean time, a strong cold front associated
with this energetic system will sweep through the eastern U.S. today with
locally heavy rain and embedded strong thunderstorms.  These storms may
lead to local flooding issues later today across New England.  Chillier
and drier air will advance into the East Coast tonight behind the strong
cold front.  However, a reinforcing cold front will quickly spread a mix
of rain and snow from across the Great Lakes through the Appalachians on
Saturday and then across New England Saturday night with gusty winds. 
Strong west to northwest winds behind this front will usher in colder air
through the eastern U.S. Saturday night.

Meanwhile, persistent onshore flow from a modest atmospheric river will
continue to bring moderate to heavy rainfall into portions of the Pacific
Northwest.  Another 2-4 inches of rain have been forecast for the region
over the next 24 hours and rainfall rates over some areas may be as high
as 0.5-0.75 inches per hour.  Excessive rainfall will remain be a concern
this morning before the threat of heavy rain diminishes later tonight when
the main energy penetrates further inland to support a new low pressure
center over Albert, Canada.  This low pressure system is expected to
develop over the northern Plains/upper Midwest Saturday night into early
Sunday and deliver another around of snow and gusty winds across the
region, with rain showers farther south. 

In the Central/Southern Plains, dry and breezy conditions coinciding with
low values of relative humidity has prompted the issuance of an Elevated
Risk of fire weather by the Storm Prediction Center through Saturday
morning, as these conditions could allow any fires that ignite to spread
rapidly.

Temperature-wise, areas from the central Plains to the mid-Mississippi
Valley are expected to see temperatures falling into the 30s and 40s later
today, which are around 10 to 15 degrees below normal.  As the Plains warm
up on Saturday with the advancement of a warm front through the region,
cooler temperatures are expected to settle into the Tennessee and Ohio
Valleys behind the reinforcing cold front.  With temperatures sitting 10
to 20 degrees below normal, daily highs in these areas will be in the 40s
and 50s.

Kong/Zavadoff


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