Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 232357 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
657 PM CDT Sat Sep 23 2023

Issued at 648 PM CDT Sat Sep 23 2023

Aviation discussion updated below for the 00Z TAFs.


.SHORT TERM...(This Evening through Sunday Night)
Issued at 300 PM CDT Sat Sep 23 2023

Key Messages

* An occluded low could bring strong to severe storms to eastern SD
  and west central MN this afternoon. Quick, low topped tornadoes
  will be the main threat, initially.

The upper and mid level low pressure centers have pushed into
northwest SD this afternoon. The associated warm front and
associated convection has pushed up into northeastern SD. Shear of
40 to 50 kts is expanding north behind the initial convective band.
0-1 km EHI of .5 to 1 from codington and Grant counties south
combined with the deep layer shear may be enough to set off a few
tornadoes, though cold, low-topped ones are in order with CAPE less
than 1000 J/kg.

There is still a lot of uncertainty in the CAMs regarding exactly
how far north the severe storms may reach later this afternoon and
early this evening. Most guidance keeps the worst of the instability
and severe storm threat to the south and east of this forecast area.
But, more unstable conditions could develop as there is some
clearing occurring behind the warm front convection.

As the low complex moves east through SD tonight, it will stall and
retrograde a bit in ND on Sunday bringing some wraparound showers
through Sunday night.

.LONG TERM...(Monday through Saturday)
Issued at 300 PM CDT Sat Sep 23 2023

The main challenge that will continue to present some uncertainty
into this portion of the forecast revolves around the timing and
movement of this closed upper level low pressure system that looks
to remain in the vicinity of our area at the beginning of this
period. Beginning Monday morning, this upper low is progged to be
centered over parts of northern and central MN. This stacked system
is expected to move ever so slowly south and east through the day
ending up across parts of southeast MN and eastern IA on Tuesday.
Holding onto PoPs across out eastern zones on Monday, basically
along and east of the James Valley, seem very prudent in keeping
that trend in place. Our western zones and the Missouri valley will
start to see improvement Monday with more sunshine possible and
rebounding temperatures. We`ll have to continue to watch trends for
Tuesday as some of the models are suggesting continued shower
chances in our far eastern zones, again all dependent on the
aforementioned system. At this point though, considering the
uncertainty, we`ll go for a mainly dry picture in the official

The remainder of the period will feature an incoming ridge of high
pressure aloft which will return our forecast area to a dry, sunny
and mild trend. Temperatures are likely to remain above normal with
highs in the 70s to low 80s and overnight lows in the 50s. An upper
level trough is progged to work into the western CONUS toward the
latter half of the work week. This will give our region south to
southwesterly flow aloft and the kicking out of a sfc low pressure
system and associated frontal boundary off the lee of the Rockies
and into the Plains. This could give some of our area an increased
opportunity for precipitation by late in this period.


.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 648 PM CDT Sat Sep 23 2023


Areas of MVFR/IFR CIGs across the region through the period as low
pressure spins overhead. Will continue to see -SHRA/SHRA across
the entire region, as well as some TSRA/+TSRA near the KATY area
at the start of the TAF period. VSBY may drop to IFR under any




LONG TERM...Vipond
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