Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 150557 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1257 AM CDT Sat Jul 15 2017

.UPDATE...
Issued at 1257 AM CDT Sat Jul 15 2017

06z aviation discussion updated below.

UPDATE Issued at 902 PM CDT Fri Jul 14 2017

Convection earlier this afternoon over NoDak put out an outflow
boundary nearly the length of the state. Between the forcing from
the leading edge of the boundary and what presumably is the cold
pool left behind by all the convection, additional disorganized
clusters of thunderstorms have developed over portions of
southwest and south central NoDak and are moving south-southeast
into this cwa (mainly over north central SoDak). Negligible deep-
layer shear and negligible CAPE to work with downstream for this
disorganized convection to work into. About the only thing going
for it is its cold pool interacting with appx 20-25knots of 0-3km
shear, which may be able to help keep thunderstorms going for
another couple of hours. No low level jet tonight and the sun is
setting (loss of daytime heating). Caveat, the MO River valley
region of the CWA mixed deeply into a strong-wind-favorable
inverted-V-type environment (rather high DCAPE values currently).
So, strong winds (45 to 55mph) remain a concern for a little
while longer tonight. Meanwhile, forecast winds and temps are
still okay, so no major changes planned to the forecast tonight,
other than to perhaps extend in time and areal coverage the
thunder chances in the wx grids.

UPDATE Issued at 606 PM CDT Fri Jul 14 2017

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.SHORT TERM...(This Evening through Saturday Afternoon)
Issued at 315 PM CDT Fri Jul 14 2017

Upper level ridging will build over the Rockies and the Plains
states during the short term period, with just a weak shortwave set
to move through tonight. Surface high pressure currently to the east
of the region will slowly drift south late tonight and Saturday as a
weak frontal boundary tracks across the CWA. A 30-40 knot low level
jet develops over the western part of the state during the evening,
possibly helping the front to become the focus for a few showers or
thunderstorms. The northwestern CWA may see some of this
precipitation, but any storms that do develop will likely be
elevated under a +11 to +13 degree cap, and in an area with around
20 degree dewpoint depressions. Therefore, expect strong winds to be
the main threat should convection be able to get going. High
pressure drops back in behind the exiting front on Saturday. Big
question right now is how warm temperatures will be able to get
before winds shift around to the north. They struggled to reach
forecast highs today with most areas seeing more of a southeast
wind, so went ahead and lowered them some for Saturday.

Low temperatures tonight will be mainly in the 60s, with highs on
Saturday ranging from the mid 80s northeast to the upper 90s
southwest.

.LONG TERM...(Saturday Evening through Friday)
Issued at 315 PM CDT Fri Jul 14 2017

The period begins with an upper level ridge over the region. Surface
high pressure east of the region will produce southeasterly winds
over the CWA. Winds will be gusty in north central SD where the
pressure strengthens ahead of a low pressure system. The winds,
along with a dry airmass, will create fire weather concerns
Sunday afternoon. A fire weather headline maybe needed in the near
future.

An area of low pressure and associated cold front will cross the
region on Monday and Monday night. An abnormally warm airmass will
be in place ahead of the fropa with highs likely reaching the 90s
and low 100s. Showers and thunderstorms will be possible along
the front.

Forecaster confidence is low from Tuesday through Thursday. Models
are showing a frontal boundary displayed across the region with
temperatures possibly varying as much as 10 degrees depending on
convection. There is some support amongst models for northeast SD
and west central MN bearing the brunt of this pcpn.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1257 AM CDT Sat Jul 15 2017

Light rain showers (and an occasional rumble of thunder) at KMBG
should be dissipated by 07Z. Radar trends suggest convection could
reach all the way to and impact KPIR for a couple of hours, early
on, in the 06Z TAF cycle. Otherwise, dry and VFR describes weather
at all four terminals over the next 24 hours.

&&

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

$$

UPDATE...Mohr
SHORT TERM...Parkin
LONG TERM...SD
AVIATION...Mohr



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