Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 041701 AAC
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1101 AM CST Sun Dec 4 2016

.UPDATE...
Issued at 1059 AM CST Sun Dec 4 2016

Updated the forecast to remove the mention of pcpn. Have also
decreased sky cover some through this afternoon.

&&

.SHORT TERM...(Today through Tuesday Afternoon)
Issued at 330 AM CST Sun Dec 4 2016

500mb wave moving overhead with a narrow ribbon of snow composed of
large dendrites was evident on Eureka KELO skycam. Speed and width
of band support just a quick light accumulation as the feature moves
east at a 30kt clip. Winds will shift to the west behind this
feature and the region will see favorable mixing conditions today.
Mixed temperatures down from 925mb for KABR are in the low 40s.
Ridge axis passes overhead today, and winds become more southerly
tonight ahead of our next approaching upper trough. The surface low
and trailing cold front will pass through the Dakotas during the day
Monday, with 850mb cold advection causing readings at that level to
drop from a balmy +2 to +5C at 12Z to -10 to -12C by 00Z, which is
only about a standard deviation below climo. The temperature drop
and pressure rises of +6mb/6 hrs will result in gusty winds, with
NAM BUFKIT mixed winds on the order of 25G35KT for KMBG. The
strongest mixed winds translate east for Tuesday.

As for precipitation chances, dynamically the system track favors
North Dakota. Steep low level lapse rates intermittently touch the
dendritic growth zone but its not consistent. Thus, there may be
some low stratus and snow falling in the cold advection regime,
but accumulation and impacts due to blowing snow will be limited.

.LONG TERM...(Tuesday Evening through Saturday)
Issued at 330 AM CST Sun Dec 4 2016

When the period opens Tuesday night, an arctic cold plunge is
underway on some rather uncomfortably strong northwest winds. Wind
chill values are expected to be hovering between 0F and -20F from
Tuesday night through Thursday night over much of the CWA.
Collaborated stronger wind speeds with all surrounding neighbors
than what initial gridded guidance gave for winds Tuesday night
through Thursday. Something for future shifts to try and uphold.
Found SCAVEC did a fine job blending official winds with 50-50
blend of CONSMOS and MOSGuide winds. Temperatures are expected to
moderate at least a few degrees when low/mid-level waa develops
out ahead of a low pressure system still progged to move across
the region by Saturday. Overall, temperatures are expected to be
below climo normal for the entire extended period. Prior to that
weekend system (and attending precip chances), the ECMWF (3rd
consecutive night) continues to point to some light/fine snow
potential on Thursday across the eastern forecast zones so
continued to mention pops there as well as heading into Saturday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 526 AM CST Sun Dec 4 2016

Good VFR is being observed at KPIR/KMBG on warming west winds.
Meanwhile, the atmosphere`s having trouble picking a p-type and
sticking with it further east at KABR/KATY. Smallish 15
mile-wide band of precipitation working into northeast South
Dakota this morning is apparently running into a deep enough sub-
freezing near-ground layer that p-type is pretty much running the
gammet of possibilities. Have observed light snow, light freezing
rain and ice/snow pellets here at the office (KABR). Fortunately,
just as quickly as this mess starts, it appears to be ending. The
southern edge of the precip band is working toward KATY airspace,
so have also introduced a "mixed bag" of p-type in TEMPO for an
hour at KATY as well as KABR. IFR cigs have not relinquished their
grip on flight cat at KATY yet this morning either. KABR may see a
brief dip into MVFR cigs this morning, otherwise VFR should
prevail there over the next 24 hours. KATY is expected to
eventually improve above IFR flying weather today, especially once
winds switch around to warming west mixing layer winds.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...SD
SHORT TERM...Connelly
LONG TERM...Dorn
AVIATION...Dorn



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