Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 232340 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
640 PM CDT Mon Oct 23 2017

Issued at 631 PM CDT Mon Oct 23 2017

See below for an aviation forecast discussion.


.SHORT TERM...(This Evening through Tuesday Afternoon)
Issued at 329 PM CDT Mon Oct 23 2017

Some weak cape across central SD late this afternoon along with some
lift was bringing scattered sprinkles/light showers to the region.
Several of the cam models show these continuing to develop east into
the early evening. Thus, added in scattered sprinkles into the
forecast. There may be some measurable amounts up to a hundredth or
so. Otherwise, the wind advisory looks good with northwest winds of
25 to 45 mph continuing into the early evening. Expect the winds to
fall off into the late evening but with a strong enough surface
pressure gradient, stay breezy through the night. Expect the mixed
layer clouds to also dissipate into the evening leaving mostly clear
skies. Breezy northwest winds will continue into Tuesday with mostly
sunny skies as the surface high pressure ridge drops in from the
northwest. Winds should decrease later in the afternoon. It will
also be slightly cooler across the region.

.LONG TERM...(Tuesday Evening through Monday)
Issued at 329 PM CDT Mon Oct 23 2017

First area to highlight in the extended period is the brief surge of
warm air on Wednesday, out ahead of the approaching cold front. The
models still show 850 mb temps warming into the teens Celsius along
and west of the James River by 00Z Thursday. Highs will warm into
the 60s and 70s with breezy winds. Once again, fire danger will be a
concern over central South Dakota as RH`s fall to around 20 percent
west of the Missouri River. Although, wind speeds look a bit
marginal for headlines.

Strong cold front moves through the area Wednesday night, with gusty
northwest winds developing and a good shot of cold air advection.
850 mb winds from 40 to 50 knots will be over the area Wednesday
night, with these speeds shifting east over the CWA through the day
Thursday. Increased wind speeds a bit during this time, above what
SuperBlend gave - which is likely too low. Could very well need a
Wind Advisory by that time as current forecast has low end or
marginal criteria. 850 mb temps plunge to -6C to -9C by 12Z Friday,
so highs on Thursday will only top out in the 40s.

The big question is what will happen with the low pressure that
moves through the region Thursday night through Friday. The GFS and
GEM continue to be more progressive with this system, thus allowing
for the pocket of cold air associated with this wave to push east
and out of the area much faster. The 12Z EC on the other hand, has
flipped back to its solution it had a couple days ago, with a
stronger and slower moving wave over the region. This particular
outcome keeps cold air over the area longer through the day Friday
with much colder 850 mb temps compared to the more progressive
models. Also, the EC is back to bringing some light snow accums
across the far eastern CWA late Thursday night into Friday morning.
Inherited SuperBlend POPs do have small chances over the far east
for this time, but if the other models start to revert back to the
EC-looking solution, these POPs will have to be increased further
west with QPF/snow accums beefed up as well. For the time being,
will accept SuperBlend highs for Friday until a better consensus can
be reached in the models.

After this system moves out, probably looking at a night or two of
pretty cold temps if we can get into ideal radiational cooling
conditions as the surface high moves through. Lows in the teens and
20s are what we would be dealing with. Looking ahead to the weekend,
conditions appear to be mostly dry for the time being, with slowly
warming temps compared to Friday - although staying on the cool side.


.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 631 PM CDT Mon Oct 23 2017

bkn-ovc VFR cigs over the region right now will clear off over the
next few hours, leaving a mostly clear VFR sky in place through
Tuesday afternoon. Northwest winds are beginning to decrease in
speed and should settle into the 10 to 20 knot range by midnight
and remain so until picking back up again on Tuesday.


SD...Wind Advisory until 7 PM CDT /6 PM MDT/ this evening for

MN...Wind Advisory until 7 PM CDT this evening for MNZ039-046.



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