Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 211757

Area Forecast Discussion
National Weather Service Aberdeen SD
Issued by National Weather Service SIOUX FALLS SD
1257 PM CDT Wed Mar 21 2018

Issued at 1255 PM CDT Wed Mar 21 2018

18z aviation discussion updated below.


.SHORT TERM...(Today through Thursday Afternoon)
Issued at 410 AM CDT Wed Mar 21 2018

Fog is fairly thin on satellite thanks to westerly flow west of the
Missouri valley, and just off the surface into the James valley. We
are also seeing the gradual erosion of cloud cover, which means
today will be fairly nice. Winds will weaken and shift to easterly
by this evening/overnight. As such, there is the potential for west
river/Missouri Coteau/Sisseton hill upslope fog/stratus to

.LONG TERM...(Thursday Evening through Tuesday)
Issued at 410 AM CDT Wed Mar 21 2018

The models have come into better agreement in the long term with the
upper level flow along with the individual short waves moving
through it. The models have continued to show a good band of
rain/snow developing Thursday night and moving east through Friday
night. Dont look for much freezing rain/sleet with this system as
the warmer air overrides the cooler air at the surface as it
retreats. With the warmer ground and the amount of time of snowfall
occurring, the amount of snow accumulating will be difficult to
determine. One to 3 inches at best seems okay for now. Also,
continued with windy conditions across the cwa on Friday with a good
surface pressure gradient. Otherwise, the models show a couple more
short waves coming across the region Saturday night through Monday
bringing in more good chances of rain/snow. The models then show a
large upper level low pressure area developing over the southwest
U.S. for Monday and Tuesday and it is not expected to affect our
region. We should be drying out with the northern stream westerly
flow aloft for Monday night and Tuesday. Temperatures through the
long term should be near to 10 degrees below normal. There will be a
good range in high temperatures on Friday and Saturday from the mid
30s northeast in the cwa to the lower 50s southwest in the cwa. For
Sunday through Tuesday, mainly 40s are expected.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
Issued at 1255 PM CDT Wed Mar 21 2018

MVFR to locally IFR ceiling band persists from the northernmost
James River valley through the Sisseton Hills at midday. While a
slow eastward erosion to the main area indicated by satellite
trend, look from above also reveals a tendency for the trailing
clearing to succumb for a time to some self destructive sunshine
with additional upper IFR to low-end MVFR ceilings redeveloping.
Will be more of a struggle to get clearing to push toward KATY
before terrain-supported clouds try to redevelop tonight. Fairly
high near- surface moisture in place as generally weak surface
flow this evening turns toward an easterly upslope component.
Would expect this should yield redevelopment of some patchy to
areas of fog tonight, most significant where supported by the
upslope component. Shallow nature suggests that widespread
ceilings may not accompany, and have only hinted at through
mention of scattered layer around or below 500 ft AGL. While
surface flow will take some time to respond, will get increased
gradient into central SD by late tonight and Thursday morning
which should reduce the threat for widespread lower visibility, as
well as tendency for some warm advective mid-level cloud to
develop toward central SD by late tonight and Thursday morning.




SHORT TERM...Connelly
AVIATION...Chapman is the U.S. government's official web portal to all federal, state and local government web resources and services.