Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 171750 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1150 AM CST Fri Nov 17 2017

Issued at 1150 AM CST Fri Nov 17 2017

18z aviation discussion updated below.

UPDATE Issued at 1038 AM CST Fri Nov 17 2017

Band of light rain/sprinkles in northeast SD/west central MN this
morning will disspate/move east into the early afternoon as the
jet streak lift moves on. Otherwise, new shower development is
expected later this afternoon west river as lift from the western
low pressure trough moves in. With weak caa along with mid and
high level clouds keeping skies mostly cloudy through the
afternoon, temperatures should only rise a few more degrees or so
by late afternoon. Made adjustments to the forecast.

UPDATE Issued at 511 AM CST Fri Nov 17 2017

See below for an aviation forecast discussion for the 12Z TAFs.


.SHORT TERM...(Today through Sunday Afternoon)
Issued at 346 AM CST Fri Nov 17 2017

Starting out this morning in between a 500mb ridge over the Great
Lakes and up through Hudson Bay, with a trough across western Canada
through the Pacific Northwest. With southwesterly flow overhead,
we`re already seeing several small disturbances near the area. At
the surface, at 09Z, an area of low pressure was set up across
Hyde/Hand/Buffalo Counties. This low will continue to sink
southeast, tracking across far southeastern SD by 15Z. Expect light
rain/snow currently being hinted at via radar returns over Corson
County to slowly sink southeast through the morning hours, with rain
becoming the dominant weather type. A little sleet will not be out
of the question.

We`re also watching a low over northern Lake Winnipeg early
this morning, that will be tracking northeast to Hudson Bay by the
end of the day. It will push a cold front across our area this
afternoon. Assisted by shortwave energy in the southwesterly flow
aloft, chance of light rain or snow across western and central South
Dakota this afternoon and evening. Little to no snow accumulation is
expected. The 500mb trough will be directly overhead 09-12Z
Saturday, with northwest flow then being the rule for the rest of
the forecast period.

High temperatures on Saturday will be in the 30s to low 40s, as
cooler air filters in on breezy northwest winds of 13-18kts and a
ridge of high pressure builds in from the west. Warmer air will
return for Sunday, with highs in the 40s and 50s, as southwest winds
return as high pressure exits across MN.

.LONG TERM...(Sunday Evening through Thursday)
Issued at 346 AM CST Fri Nov 17 2017

The forecast area is situated under northwest flow aloft, or some
derivation there of, for the entire forecast period. Persistent high
pressure ridging aloft over the western half of the CONUS should
result in mainly dry forecast conditions with an occasional cold
frontal passage.

Highlights: much above normal warmth will be felt on Monday, and
again Thursday, and possibly Friday. A cold front is progged to
sweep through the region Monday, with strong low level caa to follow
Monday night into Tuesday (below normal cold). Tuesday night begins
a period of low level waa that results in slightly warmer conditions
on Wednesday (back to near normal). Presently, the waa persists into
Thanksgiving Day, with all three 00Z GSM deterministic solutions
yielding a low level west-southwesterly boundary layer wind and
925hpa thermal progs ranging from around +11C to +17C. Thursday also
has the support of 1-2 standard deviation above normal 850hpa
thermal progs off the NAEFS S.A. Ensemble Table. Beyond Thursday,
the deterministic solutions begin to diverge on the timing of the
next cold frontal passage back-dooring its way southward at the end
of the week (the ECMWF being the fastest of the group). At this
point, still looks near to slightly above normal for temperatures
prior to Saturday.


.AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon)
Issued at 1150 AM CST Fri Nov 17 2017

VFR conditions are expected through tonight and Saturday for all
locations as mid and high level clouds stream over. With lift moving
into the Pierre area later this afternoon and early evening, expect
some light rain to develop and possibly affect Pierre. Dont expect
any vsby reduction with ceilings maybe getting into the 3-5KFt




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