Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
439 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 under 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 track slowly across the interior Southeast, the threat of heavy rain
is expected to increase across the central and southern Appalachians
followed by the Mid-Atlantic during the next couple of days.  While the
heavy rainfall may not necessary be continuous through the period, any
additional downpours will raise the possibility of flash flooding from the
Carolinas to the Mid-Atlantic where the ground is already saturated from
recent heavy rainfall.  The low pressure system is forecast to edge slowly
eastward toward the coast by Sunday morning, with the heaviest rainfall
most likely moving across the interior Mid-Atlantic.

In contrast to the wet weather in the East, hot and mainly dry conditions
are expected to continue for the western U.S. under the dominance of a
warm ridge of high pressure.  A large area of Excessive Heat Warnings and
Heat Advisories is in effect from California through the Desert Southwest
and into the southern Plains where record high minimum and maximum
temperatures will be widespread.  Only some afternoon isolated storms are
forecast today for the interior Southwest to the southern and central High
Plains.  The heat is forecast to become less intense over the southern
Plains but will intensify quickly across the interior Pacific Northwest
and Great Basin during the weekend.  In addition to the heat, dry conditions
will promote fire danger across portions of the Great Basin into much of
Wyoming today.  Red Flag Warnings are also in effect.

Kong


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