Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Fri Aug 14 2020

Valid 12Z Fri Aug 14 2020 - 12Z Sun Aug 16 2020

...Strong to severe thunderstorms across the northern Plains into the
upper Midwest will result in locally heavy rainfall through Friday...

...Increasing threat of heavy rain expected from the central/southern
Appalachians to the Mid-Atlantic during the weekend...

...Record heat becoming less intense over the southern Plains but
spreading into the interior Pacific Northwest and Great Basin during the
weekend...

A low pressure system developing along a cold front with fairly vigorous
dynamics will support the development of strong to severe thunderstorms
across the northern Plains and the upper Midwest through tonight.  In
addition to the anticipation of severe weather, heavy downpours associated
with the thunderstorms could lead to flash flooding for portions of these
areas.  The threat of severe weather and heavy rainfall should diminish on
Saturday as the low pressure system moves away into Canada.  Cool air
ushering in behind the cold front will drop temperatures appreciably into
the 50s across the northern Plains by Saturday morning.

Meanwhile, a warm and moist air mass trapped to the south of a slow-moving
frontal system will continue to provide a good chance of scattered
thunderstorm activity from the lower Mississippi Valley eastward into the
Mid-Atlantic and interior Southeast.  As a weak low pressure system is
forecast to form and then track slowly across the southern Appalachians,
the threat of heavy rain is expected to increase across the central and
southern Appalachians into the Mid-Atlantic during the next couple of
days.  On Friday and into Saturday, the central and southern Appalachians
eastward have Slight Risks of flash flooding in place as upslope flow
could enhance rainfall totals in the mountains, and much of the
Carolinas/Mid-Atlantic have seen heavy rainfall recently so the ground is
saturated.

Meanwhile farther west, hot and mainly dry conditions are expected, though
afternoon isolated storms could occur in the Southwest to the
Southern/Central High Plains. Excessive Heat Warnings and Heat Advisories
stretch from California through the Desert Southwest and into the Southern
Plains, as temperatures above 100 degrees will be widespread, with
temperatures over 110 degrees in the Desert Southwest. Dozens of record
high minimum and maximum temperatures should be tied or set for those
areas through the weekend (and beyond). After a cool day today in the
northwestern U.S., the upper-level ridge building will mean hot
temperatures spread to the Pacific Northwest especially by Saturday.
Another threat expected is fire danger, and Elevated to Critical Risks
have been outlooked by the Storm Prediction Center for portions of the
Great Basin into much of Wyoming through Friday. Red Flag Warnings are
also in effect.

Kong/Tate

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