Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 121156 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
553 AM CST Mon Feb 12 2018

Issued at 553 AM CST Mon Feb 12 2018

12z aviation discussion updated below.


.SHORT TERM...(Today and Tonight)
Issued at 326 AM CST Mon Feb 12 2018

Taking a look at the 500mb pattern today, much of North America
(minus eastern AK and western Canada) is under the influence of a
large trough extending from the main low over northern Canada. An
embedded low moved onshore over Oregon, and has been able to set up
across ID and northern NV early this morning. The result has been a
subtle ridge developing over WY/SD. Expect the 500mb low to sink
south to the NV/CA border by the end of the day, where it will spin
through Tuesday. The slight ridging will remain overhead through
today, and become surpressed tonight as the northern extend of the
western trough moves in.

Although much of the energy remains closer to the 4 corners area,
some moisture has already been able to slide across SD. Most of this
will be in the form of cloud cover, although a half in of snow can`t
be ruled out anywhere in the forecast area late this morning
through tonight.

Closer to the sfc, we`re still under the influence of a ridge of
high pressure, extending from northeastern MT/western ND.
Temperatures will top out near 10 degrees today, or about 15-25
degrees below normal (with the largest discrepancy west river).
Warmer air on the back side of the exiting high, on south-southwest
winds and still plenty of clouds, will keep temperatures from
falling too far tonight. Kept lows in the single digits. The focus
for light snow will shift to southern and eastern areas.

.LONG TERM...(Tuesday through Sunday)
Issued at 326 AM CST Mon Feb 12 2018

The models show two similar three day periods in the forecast from
Tuesday through Thursday and for Friday through Sunday. There is
expected to be two short wave troughs along with their surface cold
fronts dropping across our region from the northwest bringing a
couple chances of light snow  Tuesday and Wednesday will feature
south to southwest winds with waa with quite a warm up from Tuesday
to Wednesday. Tuesday is expected to be in the mid 20s to the lower
30s with 40s on Wednesday. An Arctic boundary then comes through
Wednesday night into Thursday bringing a big cool down along with
chances of light snow. Highs on Thursday are expected to only reach
the mid teens to the lower 20s. Again the winds will turn to the
southwest bringing warmer air back in for Friday and Saturday with
20s Friday and 30s for Saturday. Then another Arctic boundary comes
into the region Sunday and Sunday night bringing much colder air
along with chances of light snow. Sunday should get into the 30s
before temperatures fall.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 553 AM CST Mon Feb 12 2018

VFR waa clouds will stream over the cwa through today and tonight
along with areas of light snow/flurries. One area of light snow out
west this morning will lift northeast into the early afternoon and
should affect MBG with maybe vsbys down to 2 miles. Another area of
light snow will develop later this afternoon and lift northeast and
may affect PIR, ABR, and ATY into tonight.




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