Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 142005 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
305 PM CDT Thu Sep 14 2017

.SHORT TERM...(This Evening through Friday Afternoon)
Issued at 302 PM CDT Thu Sep 14 2017

An area of low pressure is currently located over south central SD
with a cold front just north of Watertown. Warm 700 mb temps of +10C
is capping convection along the front. A weak upper level shortwave
currently over northwest SD will bring light showers to our
northwest through this evening.

The main upper level trough is located over the desert southwest.
This trough will lift northward tonight which will bring
increasing chances for showers and thunderstorms for locations
along and west of the Missouri Valley by Friday morning. There is
a potential dry slot moving into the eastern CWA during the mid
morning hours. If the dry slot does develop and skies clear off,
then highs in our eastern CWA will be warmer than expected.
Clearing skies and destabilization will play an important role in
strong storms. Went conservative with the severe threat as the
signal is not clear enough.

The western portion of the CWA should see a decent amount of
rainfall from this storm system. ESRL`s Extreme Probability page
shows accumulated pcpn for this CWA in the 90-95th percentile from
0Z Friday to 0Z Saturday. The western Dakotas are in the 99th
percentile for accumulated pcpn.

.LONG TERM...(Friday Evening through Thursday)
Issued at 302 PM CDT Thu Sep 14 2017

Pcpn chances/temps are the main issue during the time period. All
the preferred models are indicating a negative PNA pattern across
the conus, meaning west conus troffing, with east conus mid level
ridging. As for the deterministic details, the models are in fair
agreement until post 120 hours.  After that time period, s/w and
frontal timing becomes significantly different. Needless to say,
won`t change to much during that time period given the disparities,
and will stick fairly close to model blend. However, did bump up
overnight lows some Tuesday and Wednesday morning given LLJ across
the forecast area. Rain chances appear to be mostly confined to the
early part of the forecast (early this weekend), as well as toward
the middle of next week as energy lifts out of the western trof
northeast across the region. Temperatures will favor below normal
Saturday and Sunday, but then should trend back above normal next
week as warm air once again flows north into the Northern Plains.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1229 PM CDT Thu Sep 14 2017

Prevailing VFR conditions can be expected through this evening. An
area of low pressure will slowly cross the region tonight through
Saturday bringing showers and thunderstorms. The terminals of
KPIR, KMBG, and KABR will have the best potential of seeing pcpn
by Friday morning. The surface low will also bring low clouds into
the region with MVFR cigs possible for all terminals except KATY.




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