Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 211505

Area Forecast Discussion
National Weather Service Aberdeen SD
905 AM CST Tue Nov 21 2017

Issued at 900 AM CST Tue Nov 21 2017

Wind speeds continue to diminish this morning with the best
pressure rises overhead and moving south, and the
thermal/pressure gradient tightest to the south. Mixing will
result in continued gustiness, however BUFKIT mixed winds do show
a general downward trend through the day. Therefore have cancelled
the remains of the wind advisory.


.SHORT TERM...(Today through Thursday Afternoon)
Issued at 343 AM CST Tue Nov 21 2017

The combination of cold air advection and 6 hour pressure rises of
+12 mb is producing gusty northwesterly winds this morning. Several
locations are reporting sustained winds of 30 mph with gusts of 40
to 45 mph. The strongest winds after 12Z should occur over
northeastern SD and western MN where half km winds are between 35 to
40 knots. Winds should subside after 18Z.

High pressure slides southward across the region late this afternoon
through tonight. As winds become light and variable, temperatures
will fall quickly with lows in the single digits and low teens. Warm
air advection will develop on the back-side of the surface high
over western SD with temperatures possibly warming before sunrise.

An area of low pressure will cross the region on Wednesday with
bring breezy southerly winds along with warmer temperatures. This
system could bring light pcpn, mainly in the form of rain to far
northeast SD and western MN during the afternoon hours. Winds
shifting to the northwest behind the surface low will mix down warm
temps aloft to produce highs in the 50s and low 60s along and west
of the Missouri Valley.

Upper level ridging building into the region on Thursday, along with
southwesterly winds should bring much above normal temperatures into
the region. Highs should range from the lower 40s, in western MN, to
the mid 60s, west of the Missouri Valley. These readings are 5 to 25
degrees above normal for this time of year.

.LONG TERM...(Thursday Evening through Monday)
Issued at 343 AM CST Tue Nov 21 2017

With the exception of Friday and Monday, the forecast area resides
underneath northwest flow aloft. So, the general trend of a dry
weather forecast continues. Over the past several nights,
deterministic/ensemble models have not lent much in the way of
forecast confidence to precipitation chances on Friday. Tonight,
there is, once again, a "hint" of some light precipitation potential
showing up briefly on Friday in some of the models, and some rather
low end pops managed to find their way into the extended forecast
this morning for Friday. As for early next week, the models have
displayed varying results, in terms of run-to-run consistency and in
comparison to each other in handling the strength/track of a
potential low pressure system. There has been, and continues to be
some indication that some shortwave energy will cross over the
Rockies and impact the plains region of the country early next week.
However, there are still way more questions than answers regarding
how this potential day 7/day 8 weather scenario will play out. Will
continue to monitor forecast trends for early next week.

As far as temperatures go, if the 00Z deterministic/ensemble output
is halfway accurate, much of the forecast period should be as warm
as, if not warmer than late November climo normal. The lone
forecast period that, currently, looks like temperatures will dip
to near normal or perhaps a few degrees below normal will be
Saturday/Saturday night.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday Morning)
Issued at 513 AM CST Tue Nov 21 2017

There were some sct/bkn MVFR cigs around a short while ago at the
KABR/KATY terminals. But, per satellite night-time microphysics
imagery, those clouds appear to be dissipating at this time. So,
TAFs are starting out at 12Z valid time VFR everywhere and set to
remain so at all four terminals throughout the next 24 hours.
While surface high pressure builds into the region today, boundary
layer moisture continues to be scoured out of the region, and
part of that process may translate into some mixing/heating of the
day strato-cu.




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