Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 112330 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
530 PM CST Sat Nov 11 2017

Issued at 528 PM CST Sat Nov 11 2017

Added some isolated rain showers to the forecast across south
central SD based on current temperatures and radar returns. With a
15 degree dewpoint spread there is still some drier air at the sfc
to overcome and some of these returns may be virga or result in
not much more than sprinkles for the next hour or two.


.SHORT TERM...(This Evening through Sunday)
Issued at 220 PM CST Sat Nov 11 2017

Main focus is on the left exit of an 80kt jet streak that pushes
across south central counties this evening into the early overnight
hours. Confidence continues to be low as to whether moisture will
materialize at all as its mainly up to the 12Z deterministic NAM
(and none in the 18Z) and about 1/3 or NSSLWRF ensemble members.
Other CAMs do or did support this feature as well, through with
varied intensity/placement. Will continue the low pops over
mainly Jones/Lyman counties. As for the precipitation type,
profiles show a layer aloft that is above freezing, but just
barely so, and wet bulb effect could result in snow reaching the
surface. Again, depends on intensity and small dendrites will
probably evaporate with that 6-8kft deep dry layer and/or melt
as it reaches the warm layer and just result in sprinkles. Worst
case (and what is looking more and more like lowest probability)
scenario is we get large dendrites with some intensity and the
resulting cool air manages to allow snow to reach the surface with
the potential for accumulation.

The wave upstream will continue to weaken and shear apart as it
moves into south central South Dakota, so we should see favorable
radiational conditions elsewhere. Return flow and warm advection
sets up for Sunday with a light southwest component for the James
valley - and as such tuned temperatures a bit warmer for our area.
Light winds in the northeast means readings will struggle more there
despite sunshine. Winds will be southerly and more breezy for the
Missouri valley portions of the CWA.

.LONG TERM...(Sunday Night through Saturday)
Issued at 220 PM CST Sat Nov 11 2017

Generally speaking, the flow pattern from Sunday night through
Saturday is an uneventful one; brief periods of zonal flow
punctuated by pendulum swings of northwest flow to southwest flow as
upper level ridges and trofs take turns over the western conus. This
translates into some fluctuations in temperature from near to a
little bit above normal early in the period to near or a little bit
below normal Tuesday/Wednesday, followed by another brief warm up
Thursday before more cold air sweeps into the region at the end of
the week. In this progressive flow pattern, there isn`t much of a
signal, currently, for precipitation chances; at least not until
late in the period when a notable pv anomaly may be working through
the region.


.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 528 PM CST Sat Nov 11 2017

VFR conditions with light winds are expected through the period.




SHORT TERM...Connelly
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