The Weather Prediction Center

Short Range Forecast Discussion

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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

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

...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 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.


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Last Updated: 439 AM EDT Fri Aug 14 2020