Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 200246 AAB

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
946 PM CDT Wed Sep 19 2018

Issued at 921 PM CDT Wed Sep 19 2018

Other than isolated light rain showers, the CWA remains dry as of
230z. Redevelopment of more robust activity has focused across
southeastern South Dakota, nearer the surface front. That said,
another shield of moderate to heavy rain is still expected to
develop and track across the area later tonight into Thursday.
Fog, some dense, also remains fixed along the eastern Coteau this
evening as some upslope from northeasterly winds persists. Fog
can be expected through Thursday morning.

UPDATE Issued at 641 PM CDT Wed Sep 19 2018

See updated aviation discussion below.


.SHORT TERM...(This Evening through Thursday)
Issued at 327 PM CDT Wed Sep 19 2018

The potential for heavy rainfall tonight into Thursday morning will
be the main forecast challenge.

As of 20Z, a good portion of the CWA is seeing northeasterly winds
and dry conditions. Temperatures have not warmed much today with
current readings in the upper 50s and low 60s. A warm front is
advection northward some across eastern Nebraska where temps have
reached the upper 70s, to the mid 80s. The warm front may reach as
far north as Sioux Falls tonight. The front, along with an
increasing LLJ and an abundance of LLM should set the stage for
locally heavy rainfall across southeastern SD into southern MN. As
of now, the axis of the highest expected pcpn amounts should occur
just south of this CWA. Considered issuing a flash flood watch for
Hamlin, Codington, and Deuel Counties due to rainfall last night,
and the possibility for an additional 1 to 2 inches tonight. However
with the latest model trending south, decided to hold off at this

An upper level trough, currently over the Pacific Northwest, will
begin impacting the Northern Plains on Thursday. More widespread
rainfall can be expected with the upper level trough. By Thursday
afternoon, a surface low pressure system should be located over
northern Wisconsin, with dry northwesterly flow into the CWA. A few
models are showing precipitation ending sooner than expected in the
central portion of our CWA as well.

.LONG TERM...(Thursday Night through Wednesday)
Issued at 327 PM CDT Wed Sep 19 2018

High pressure quickly pushes through the area Friday leading to
southerly flow and  warming weather and dry conditions through the
weekend. Friday will be below average, with highs around 60, and
over the weekend temperatures will see an increase into the 70s.

Another cold front pushing through Monday morning will bring a
chance of showers and storms, specifically in the eastern part of
the CWA. One area of concern will be the timing of the front.
Gusty winds from the southeast ahead of the front could cause the
region to dry out if the front is slow to push through, making a
fire hazard for the region Sunday.


.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 641 PM CDT Wed Sep 19 2018

MVFR/IFR ceilings and occasional visibility conditions will
persist through the valid TAF period as the bulk of the system
that has brought recent rains and mist/fog begins to move in. Both
showers and thunderstorms are possible at all sites tonight into
Thursday, with the best chance for thunderstorms at site ATY.
Winds will remain out of the northeast until late in the period
when a change to the northwest is expected.




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