Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 090524 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1124 PM CST Thu Dec 8 2016

Issued at 1122 PM CST Thu Dec 8 2016

See updated aviation discussion below.

UPDATE Issued at 913 PM CST Thu Dec 8 2016

Skies have cleared across most of the CWA this evening, with the
exception of areas along the Missouri River where lake effect
low cloud cover lingers. No changes made to winds or temperatures
at this time.


.SHORT TERM...(This Evening through Friday Afternoon)
Issued at 258 PM CST Thu Dec 8 2016

Some strings of lake effect clouds and possible light snow showers
remains off of Lake Oahe. The main impact at PIR has been BKN-OVC
sky cover at 1.3kft.

The Arctic sfc ridge over the western half of the of South Dakota
this afternoon will slowly edge across our entire forecast area by
09Z Friday. The high will still be over ND through. The initial
weather change will continue to be the diminishing cloud cover this
afternoon, and weakening pressure gradient. After nearly 3 days, the
gusts over 25kts have finally ended. PW values overnight will fall
to 0.08 to 0.12 inches, before rebounding slightly southwest of PIR.
The main concerns for a well below normal temperatures close to the
MEX guidance (with -10F at ABR) will be the nearing mid to high
clouds currently over WY, and the fact at least at ABR that below
normal temperatures with little to no snow on the ground is a rare
event. Low level moisture just below 900mb also increases overnight
through the mid morning hours Friday. Went with temps overnight
ranging from the single digits above 0 over our MN counties, to the -
10 to -15 range across north central MN. With winds in our coldest
areas generally less than 5mph and only a few pixels getting to the -
25F criteria, will not issue a Wind Chill Advisory for the area. the
best chance would be over northern Corson County from 05Z-15Z

Otherwise, the main story for this period will be light snow over
central SD on Friday, with totals generally around half an inch or
less. Expect highs in the single digits above zero northwest, up to
around 15 degrees elsewhere. This will be still around 15 degrees
below normal for this time of year.

.LONG TERM...(Friday Evening through Thursday)
Issued at 258 PM CST Thu Dec 8 2016

Fairly flat and fast flow is expected to continue across the region
for much of the period. The wave expected to bring snow to the area
on Saturday has now trended down in intensity somewhat, although mid
level frontogenesis progs still indicate some potential for a
banded snow event somewhere in the region.  Exactly where this might
set up is still somewhat up in the air, but there has been a slight
shift south of the low/mid level baroclinic zone in the CMC/GFS such
that they look more like the ECMWF. The ECMWF is the lightest as far
as QPF is concerned. Another stronger wave moves mostly south of the
region on Sunday into Sunday night.  Most of the measurable pcpn
from this system should be south of the ABR CWA. Other weak waves
are forecast during the period, but not much pcpn is expected until
perhaps late next week as the pattern begins to buckle.  Both the
GFS/ECMWF start to dig a western conus trof at that time.  As for
temperatures, they should remain below normal through the period
with a couple scheduled arctic outbreaks during the period.


.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1122 PM CST Thu Dec 8 2016

IFR/MVFR cigs will linger along the Missouri River tonight and
into the day Friday, affecting both KMBG and KPIR. For the most
part, VFR conditions will prevail elsewhere, but a few area of
MVFR cigs may drop out of North Dakota and across the eastern CWA
during the overnight hours into early Friday morning.




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