Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 151127 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
627 AM CDT Fri Sep 15 2017

.SHORT TERM...(Today through Sunday Afternoon)
Issued at 411 AM CDT Fri Sep 15 2017

Stratus deck has quickly slid southwest through the night and now
covers the entire CWA. Also seeing some fog in the Coteau region as
moist upslope flow aids its formation. Several models picking up on
this very well and went with a CONSSHORT feel for VSBY/WX grids as
far as fog is concerned. Also watching the first batch of
precipitation moving north out of NE and into southern SD, just
about ready to move into the southwest CWA counties. Updated the
near-term POP grids to reflect likely/categorical as this MCV moves
into the CWA. CONSSHORT/ECAM/HRRR POPs look pretty good in the short
term, and through much of the day in fact, so leaned heavily towards
these models while blending/smoothing out in the appropriate places.
Seems as if this first batch of precip will roll through the CWA
this morning. Then, there may be a break by mid day or early
afternoon while we await the main surface low/front which will
likely trigger another round of showers and storms. Parameters do
support potential for some strong to severe storms across the
eastern CWA today, so will have to keep an eye on that. There should
be quite a temperature contrast across the area today, as warm air
surges northward ahead of the low - reaching the southeast/far east
counties. While cool highs in the upper 50s to around 60 degrees
will be felt over north central SD, readings could soar well into
the 80s over east central SD.

The surface low departs on Saturday, but upper level shortwave
energy will likely bring some scattered showers and storms once
again to the area. Cool temperatures will also be felt with highs
mainly in the 50s and 60s.

Surface high pressure settles in by 12Z Sunday, and remains in place
through the better part of the day. Could be looking at chilly
temperatures Sunday morning, and currently have readings in the
upper 30s and 40s. Would not be surprised if these numbers come down
a bit more over the next few forecast shifts. Conditions finally dry
out by Sunday as well with the high pressure in place.

.LONG TERM...(Sunday Evening through Thursday)
Issued at 411 AM CDT Fri Sep 15 2017

Southwest flow aloft will be in place at the start of the period.
This means some warmer air will move into the region on return flow
around the sfc high to the east. Temperatures will be above normal
until at least mid week when a deep upper trough fully transitions
into the northern Plains.

Rain chances will be the big question through the extended. Lee side
troughing at the start of the period at the sfc will have some
shortwave energy to work with to enhance lift and set off some
showers and thunderstorms. Both the ECMWF and the GFS are indicating
the development of a potent, well stacked low sometime mid to late
next week. The GFS brings the front into the Plains and really slams
the Dakotas with storm chances. The ECMWF pulls the core low farther
north into Canada and the majority of the resulting precip, as well.
For now, have kept the slight chance to chance pops that the
consensus models show for Wed and Thurs.


.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 625 AM CDT Fri Sep 15 2017

A mix of MVFR/IFR cigs will briefly improve behind the first round
of showers and thunderstorms this morning in the west. However,
any heavier rain will result in MVFR/IFR vsby. Another round of
thunderstorms is possible near KABR and KATY late this afternoon
and evening. Cigs will fall to MVFR and IFR again at all sites
this afternoon.




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