Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 111138 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
538 AM CST Mon Dec 11 2017

Issued at 532 AM CST Mon Dec 11 2017

Aviation discussion updated below for 12Z TAFs.


.SHORT TERM...(Today and Tonight)
Issued at 319 AM CST Mon Dec 11 2017

Strong winds are beginning to affect the western CWA and have
decided to go with a Wind Advisory through the morning hours. In
fact, went with one across the whole CWA for the morning, with the
southern CWA expiring at 21Z. Although, feel the strongest of winds
will be over the western CWA and in the Coteau region. 0.5km winds
of 50kts currently moving across the western CWA and will spread
east over the next couple hours. The central CWA may be more
marginal with speeds, but it should be close or either short lived
criteria anyway. As far as precipitation with this area of low
pressure, currently seeing scattered rain showers mainly as this
system rotates through. Rather amazing to see temps this mild in the
middle of the night in December with readings in the 30s in 40s -
even well upstream temps are still mild. Most obs upstream have been
mostly rain and have been adjusting weather grids accordingly based
on hourly temps trends. Temperatures do appear to max out this
morning for eastern areas. Then, colder air begins to surge
southward across the Red River valley later this morning then
eventually spreads over the eastern CWA. 925mb temps take a tumble
through the day, so will see falling temps as the day progresses.

Low temperatures tonight are a bit tricky. We do see a weak surface
ridge axis sliding across, with winds going fairly light. Although,
models are in pretty good agreement in bringing a band of low clouds
across the CWA. Clouds will counter any appreciable temps falls
tonight as the winds go light.

.LONG TERM...(Tuesday through Sunday)
Issued at 319 AM CST Mon Dec 11 2017

The recent positive phase of the Pacific North American pattern
(PNA) is expected to continue through the long term, but should
under go a bit of weakening, transitioning to a less amplified long
wave pattern. It looks to be a fairly active period with occasional
s/ws moving through the fast flow pattern. The most obvious waves
both sfc/aloft swing through on Wednesday and again Friday night, as
well as Sunday night. Each system will have the potential to produce
some light pcpn across the region. There are some differences in
timing between the long range models, so overall confidence in the
forecast details is only about average. With a lack of any decent
cold air feed nearby, temperatures through the period should average
out near to above normal.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 532 AM CST Mon Dec 11 2017

MVFR CIGs are moving into the region this morning and will affect
TAF sites through most of the day. It appears there will be a bit
of breakup of clouds late this afternoon or evening before more
MVFR CIGs move in later tonight. Evolution of all this is a bit
unclear at this time and will fine tune TAFs as appropriate.
Otherwise, gusty northwest surface winds gusting over 40 knots at
times will affect TAF sites this morning, before a slow and
gradual drop off in speeds occurs through the afternoon and
evening. KATY may be affected by -SN this morning as well, with
periodic VSBY reduction to around 2SM at times.


SD...Wind Advisory until noon CST /11 AM MST/ today for SDZ003>005-

     Wind Advisory until noon CST today for SDZ006>008-011-018>023.

     Wind Advisory until 3 PM CST /2 PM MST/ this afternoon for

MN...Wind Advisory until noon CST today for MNZ039-046.



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