Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 232013
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
313 PM CDT Wed Aug 23 2017

.SHORT TERM...(This Evening through Thursday Afternoon)
Issued at 311 PM CDT Wed Aug 23 2017

Forecast challenges involve temperatures and precipitation chances
tonight.

Other than some scattered mid-level accas clouds across the bottom
half of the cwa, sunshine prevails this afternoon as temperatures
warm into the 70s and 80s. Winds are generally light out of the
south or southeast.

Watching the accas field into early this evening as short range
guidance maintains that there could be a shower or two developing
over Hand/Spink/Clark/Hamlin/Codington/Deuel counties where the nose
of a weak low level jet will coincide with the strongest low level
moisture and warm air advection. Also, overnight, an area of low
pressure dropping south out of Canada may drag enough mid-level
forcing/lift into far northeast South Dakota/west central MN to
promote a few showers or weak thunderstorms there. MUCAPE is less
than 500j/kg, while deep layer shear is 40 to 50 knots. Timing being
what it is (night-time occurrence), not really expecting much more
than for the far eastern edge of the cwa to be on the western edge
of any precipitation developing/moving through the region tonight in
association with this area of low pressure (currently over southern
Manitoba). Otherwise, the rest of the cwa should be dry tonight and
Thursday, while an airmass supporting seasonal temperatures is in
place.

.LONG TERM...(Thursday Evening through Wednesday)
Issued at 311 PM CDT Wed Aug 23 2017

Convection Friday through Saturday will be the main forecast
challenge in the long term.

The period begins with a weak upper level ridge over the region with
an upper level trough over Alberta. The upper level trough will
progress eastward into the western Dakotas Friday evening with
thunderstorms developing along a surface front. This surface front,
along with an area of low pressure will spread thunderstorms across
the eastern Dakotas Friday night, fueled by a 30-40 knot llj. The
llj shifts into southwest Minnesota by Saturday morning with
convection possibly ending for this CWA by then. While strong to
severe storms are possible, locally heavy rainfall could be the
bigger threat Friday night. With PWATS exceeding 1.5 inches and slow
storm motion, localized rainfall amounts of 2+ inches will be
possible. At this time, the heaviest rainfall will occur south of
Highway 12, or closer to Highway 14.

A surface high pressure, along with northerly flow aloft will bring
dry conditions for the start of the next work week. Temperatures
through the period will range around normal for this time of year.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1242 PM CDT Wed Aug 23 2017

Presently, good VFR is the expected prevailing flying weather
condition at all four terminals over the next 24 hours.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

SHORT TERM...Dorn
LONG TERM...SD
AVIATION...Dorn


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