Area Forecast Discussion
Issued by NWS Aberdeen, SD

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297
FXUS63 KABR 130347 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
947 PM CST Tue Dec 12 2017

.UPDATE...
Issued at 947 PM CST Tue Dec 12 2017

Clipper system in southern Canada will be moving quickly across
our region tonight bringing mid and high level clouds along with
very strong northwest winds. Northwest winds will pick up through
the night into early Wednesday across the region with a Wind
Advisory in effect. Some mixed light rain and light snow could
also develop tonight east in the cwa with the strong lift in
advance of the clipper. Updated forecast.

UPDATE Issued at 553 PM CST Tue Dec 12 2017

00z aviation discussion updated below.

&&

.SHORT TERM...(This Evening through Wednesday Afternoon)
Issued at 322 PM CST Tue Dec 12 2017

The main challenges in the very near term of the forecast are winds
and precipitation chances late tonight into the day Wednesday. A
clipper low will drop out of Canada and across the far eastern
Dakotas and Minnesota tonight. Still some disagreement in the models
with the potential for precipitation, both type and amounts. The GFS
and NAM are much less aggressive with amounts, with little in the way
of accumulations, while the ECMWF and Canadian indicate up to one
tenth of an inch possible late tonight or early Wednesday morning
across the east. A few of the models hang on to lingering light
precipitation through the day as well across the far eastern CWA.
Model soundings don`t show a great potential for freezing
precipitation, but temperatures may be just below freezing at times,
so left the mention in as was indicated by the in-house model blend.
Again, amounts will be light, so impacts should be minor. A fairly
strong gradient sets up on the back side of the clipper, which will
result in very windy conditions developing from west to east late
tonight through the day Wednesday. A Wind Advisory has been issued
to account for this.

Low temperatures tonight will range from the upper 20s east to the
mid 30s west, with highs on Wednesday ranging from the mid 30s to
the mid 40s.

.LONG TERM...(Wednesday Evening through Tuesday)
Issued at 322 PM CST Tue Dec 12 2017

Northerly flow aloft will dominate the long term portion of the
forecast.

The period begins with a clipper system dropping southward across
the western Dakotas. This system will bring breezy conditions, along
with a chance for snow. Like most clipper systems, this one lacks
significant moisture with minor snowfall amounts expected. Another
low pressure system will cross the region Friday night through
Saturday with light snow possible. However the latest model guidance
brings this upper level trough through most of the CWA dry.

Models are suggesting a pattern change developing early next week
with an upper level trough of low pressure moving over the Pacific
Northwest. This area should see dry and mild conditions through
the first half of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 553 PM CST Tue Dec 12 2017

A strong Alberta Clipper system will drop quickly across the region
tonight and early Wednesday. This will bring mainly very strong
northwest winds later tonight and Wednesday of 25 to 40 knots. Along
with the winds will come low VFR/MVFR ceilings to all locations for
Wednesday. Otherwise, expect some scattered rain/freezing rain/snow
showers to develop tonight and continue into Wednesday. These may
affect ABR and ATY for a time.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 3 PM CST /2 PM MST/ Wednesday for SDZ003-004-
     009-015-016-033>035-045-048.

     Wind Advisory from 6 AM to 3 PM CST Wednesday for SDZ005>008-010-
     011-017>023-036-037-051.

MN...Wind Advisory from 6 AM to 3 PM CST Wednesday for MNZ039-046.

&&

$$

UPDATE...Mohr
SHORT TERM...Parkin
LONG TERM...SD
AVIATION...Mohr



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