Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 191622 AAB

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1022 AM CST Fri Jan 19 2018

Issued at 1021 AM CST Fri Jan 19 2018

Increased sky cover across the region today and tonight. Muck like
yesterday, satellite shows a continuous feed of high clouds over
the area. Therefore, also lowered temps a degree or two to better
resemble yesterday`s slightly moderated highs.


.SHORT TERM...(Today through Saturday Afternoon)
Issued at 426 AM CST Fri Jan 19 2018

A weak frontal boundary associated with an area of low pressure will
bring northwesterly winds into the CWA today. The shift in wind
direction will help mix down warm temperatures aloft to produce
highs in the upper 30s and 40s today.

A strong upper level jet, along with southwesterly flow aloft will
spread across the region tonight into Saturday. With upper level jet
support, we should see mostly cloudy skies on Saturday. A few hi-res
models develop pcpn in southwest SD during the morning hours. This
pcpn slowly spread east into central SD during the afternoon hours.
With temps around 40s, the dominate p-type, if any, will begin as
all rain before transition over to snow.

.LONG TERM...(Saturday Evening through Friday)
Issued at 426 AM CST Fri Jan 19 2018

Main forecast challenge in the long term continues to be the winter
storm which is expected to move into the northern plains in the late
Saturday through early Monday time frame. Latest models have trended
toward a more southerly solution, keeping the heaviest snowfall
south of our CWA.

The long wave trough is expected to track across the southwest
CONUS, closing off and moving into the central plains by late
Saturday. This will place the northern plains region in a southwest
flow/WAA pattern. Previous runs were showing some snowfall
development along with this initial WAA push, but recent runs have
really have backed off on this. Sunday the low pressure system
begins to lift northeast, tracking from the OK panhandle toward the
NE/KS/MO/IA border, across IA and southern WI and toward the Great
Lakes. Previously the NAM was the outlier as compared to the GFS/EC
and held on to a more northern solution, but now, even the newest
06Z NAM run has come around to a more southerly solution. This track
leaves the best forcing and heaviest snowfall south of our CWA.
Winds do pickup as the pressure gradient tightens on the backside of
the system late Sunday into Monday morning, but with temperatures in
the 20 and 30s and snow ratios in the 12:1-14:1 range, uncertain of
the extent of blowing snow as well. Overall forecast confidence
remains low. A watch was issued, but for counties south of our CWA --
still plenty of time to adjust if models were to flip-flop and start
trending further north again.

High pressure, dry conditions, and seasonal temperatures are
generally expected through Thursday. The next hint at any type of
precipitation will be associated with a low pressure system moving
in sometime in the late Thursday/Friday time frame.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 532 AM CST Fri Jan 19 2018

VFR conditions will prevail. A weak surface trough will slide
across the region today resulting in a wind shift to the west
northwest. Wind speeds will be less than 10 kts however. No
reduction to CIGS or VSBYS is anticipated.




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