Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 100831

Area Forecast Discussion
National Weather Service Aberdeen SD
331 AM CDT Thu Aug 10 2017

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 331 AM CDT Thu Aug 10 2017

The strong shortwave (and weak surface low) that moved through the
region today has shifted east into Minnesota. While that
initially left the area dry last evening, have seen highs clouds
slide east into the area from a weak shortwave in Wyoming and low
to mid clouds and some showers wrap around the surface low and
SSE out of eastern North Dakota. These showers are tied to
shortwave seen on WV imagery and a 850-700mb trough and they
should continue southeast through the far NE part of SD and into
west central MN. Have seen a little bit of embedded thunder, due
to a pocket of 250 J/kg of MUCAPE and have included isolated
thunder near the ND border to account for that moving in over the
next couple hours. Upstream, seeing very isolated showers across
portions of eastern ND. Expect that potential (isolated) to
continue into the day today for areas east of Brown/Spink
counties. Elsewhere, models showing the clouds (llvl moisture) in
eastern ND dropping south along and east of the Missouri River for
the first part of the morning. Previous forecast had a good handle
on this cloud cover, so only made minor adjustments. Do have a
little bit of a concern there could be very isolated showers
farther west than the current forecast, based off some of the CAM
solutions (especially NSSLWRF Ensemble members) developing
isolated showers all of the way west to the Missouri river.
Looking at soundings, it appears that the moisture is shallower
as you go farther west, so opted to leave sprinkles or isolated
showers out of the forecasts. As high pressure builds east over
the area through the afternoon, expect some diminishment over
central SD, but areas farther east will likely stay mostly cloudy
through much of the day. Temperatures today will be below normal
with highs generally in the 70s.

High pressure will continue to push east across the Dakotas
Thursday night and remain through much of Friday (ridge axis
along the Dakotas/Minnesota border at 18Z). Thus, should see
skies clear out this evening as diurnal heating is lost. Will
probably see diurnal CU again on Friday ahead of the next series
of shortwaves moving through on Friday night into the weekend.

The first wave will likely produce thunderstorms in western SD on
Friday afternoon and should see them spreading east-southeast
into the southwest half of the CWA Friday night. While
instability is limited over western SD, decent shear and the
support of the shortwave may be enough for some severe storms.
But as they shift towards the CWA, the instability diminishes, so
would expect the severe threat to do the same (storms will likely
ride the better gradient just to the southwest of Jones county).
another shortwave and broad 700-500mb q-vector convergence
supports continuing to show high end chance PoPs across the area
on Saturday. The question is if the current PoPs are in the right
location. Latest trends from the models seems to point to both a
brief dry period over much of the area on Saturday morning and
also keeps much of the forcing/instability and in turn model pcpn
over the southwest half of the CWA. If this trend continues, will
likely need to shift the current broad brushed chance PoPs to the

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 331 AM CDT Thu Aug 10 2017

The models all continue to show a 50h low pressure trough off to our
northwest yet on Saturday night slowly making its way southeast
across the region through Sunday night. As a result, consensus
remains that good chances of showers/storms remain for Saturday
night across the cwa with residual chances remaining across the
eastern cwa for Sunday into Sunday night. Otherwise, the models all
show 50h heights building over the region into early next week as a
large upper low pressure area moves into western Canada.
Temperatures will be on the rise from Sunday into Wednesday from the
lower to mid 70s on Sunday to the lower to mid 80s by Wednesday
which is closer to normal. It looks like Monday and Tuesday will be
mainly dry with the models indicating a fast moving short wave
trough along with a surface front moving across the region Tuesday
night and Wednesday. This will bring in chances of showers and


.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1255 AM CDT Thu Aug 10 2017

MVFR stratus ceilings will be moving down from the north tonight
affecting all stations. These ceilings will then lift and become VFR
and scatter out/dissipate through the day. There will also be a few
showers at or in the vicinity of ABR early this morning.




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