Area Forecast Discussion
Issued by NWS Aberdeen, SD

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000
FXUS63 KABR 231154 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
654 AM CDT Sun Apr 23 2017

.UPDATE...
Issued at 640 AM CDT Sun Apr 23 2017

See below for an aviation forecast discussion for the 12Z TAFs.

&&

.SHORT TERM...(Today through Tuesday Afternoon)
Issued at 326 AM CDT Sun Apr 23 2017

The cold front extends to the county lines of Beadle and Spink,
extending northeast and northwest from there. CAM solutions are
generally agreed that this feature will move back to the north
during the day - though the finer details of the end destination vary
slightly. This will have a huge impact on the temperature forecast
for locations such as Aberdeen - where the going high is around 70
with NAM BUFKIT soundings mixing us up to 750mb - however if the
front fails to make it this far north - we could be seeing highs
that struggle to make 60. This example plays out across the northern
tier of counties for South Dakota today.

A low will develop along the front tonight across western South
Dakota. As this low moves east during the day, we develop a stronger
push of colder air southwards on the west side of the low. Milder
air will remain just to the east however, so again there will be a
strong contrast in temperatures even through Monday.

As for precipitation, the fairly aggressive GFS CAPE values peak
around 700mb into eastern counties. The GFS soundings don`t really
support this however, and much like the NAM BUFKIT soundings -
suggesting around 300 j/kg elevated/skinny cape, anticipate more of
a showers/rumble of thunder type environment.

Cold air will dominate conditions Tuesday, with 925mb temperatures
down to around +2C and 850mb temperatures between -6 and -4C.
Another system moves across the southern tier of the CWA. Profiles
support a rain/snow mix or possibly all snow along the northern edge
of this system with some wet bulb effects. With ground temps in the
40s to around 50, this should help melt off any accumulation so long
as the snow intensity remains light.

.LONG TERM...(Tuesday Evening through Saturday)
Issued at 326 AM CDT Sun Apr 23 2017

Compared to 24 hours ago, the 00Z deterministic solutions are 1-3C
cooler with their 925hpa thermal progs for Tuesday night through
Wednesday night with meager (at best) temperature recovery Thursday
and Friday. Again, Superblend is too warm for the middle of the
week. Eventually, forecast lows and highs through that period will
need to be lowered a solid category or more of temperature, if these
low level thermal progs continue. Between Tuesday night and Saturday
night, the only timeframe where there is any semblance of model
agreement is Saturday/Saturday night when the potential for a large
sw conus upper low is forecast to lift north-northeast across the
plains. Otherwise, spotty chances for precip from hit-or-miss
transient shortwaves in split flow upper level pattern continues.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 640 AM CDT Sun Apr 23 2017

Continuing to closely monitor the position of a cold front splayed
out west to east over the state. It pretty much bi-sects the
state and appears to be slowing down (still north of KPIR). KABR
is into IFR stratus now on the cold air side of this boundary, and
it appears stratus is about to overtake KATY. Expecting some low
clouds to show up soon at KMBG as well. Short range flight
category guidance continues to have trouble resolving the low
clouds/low level saturated or nearly saturated air. Daytime
heating is supposed to erode the southern edge of the low clouds,
perhaps all the way back into far southern ND this afternoon. Will
continue to monitor. At this point, KPIR continues to maintain the
highest probability of remaining VFR for the entire TAF valid
period. Also, later tonight after 03Z, precipitation chances (in
the form of rain showers, and perhaps a weak thunderstorm) begin
to increase at KMBG and KPIR, but especially at KMBG.

&&

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

$$

UPDATE...Dorn
SHORT TERM...Connelly
LONG TERM...Dorn
AVIATION...Dorn


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