Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 211705

Area Forecast Discussion
National Weather Service Sioux Falls SD
1205 PM CDT Tue Mar 21 2017

.SHORT TERM...(Today and Tonight)
Issued at 319 AM CDT Tue Mar 21 2017

A mid level shortwave will continue to slide along the South Dakota
and Nebraska border this morning. With a strong surface high to our
north, and northeast flow at the surface, this wave continues to
contend with drying air in the low levels. This will help hold off
any accumulating precipitation for a large portion of the forecast
area. Mid level frontogenesis is expected to set up along the
Missouri Valley around daybreak before quickly dissipating mid to
late morning. With modest forcing also moving into the Missouri
Valley area, expect the best chance for rain and snow to be focused
is south central SD and far southeast SD, moving into the Sioux City
and Storm Lake areas later this morning. Temperatures will hover
near freezing for the duration of the precipitation, with wet
bulbing over to snowfall likely in south central SD where the
precipitation chances are greatest. Expect locally around an inch or
two of wet snow in Gregory County and neighboring areas, otherwise
amounts will be minimal.

Drier air will diminish the snowfall by midday, however cloudy or
mostly skies will stick around for the bulk of the region through
the day. Temperatures will be colder than recent days, with highs
only in the upper 30s to mid 40s.

Second wave approaches from the west late tonight, with cloudy skies
persisting. Northeast winds turn southeasterly and increase
overnight as the gradient tightens. This will help keep lows from
dropping a great deal. Lows will be in the 20s.

.LONG TERM...(Wednesday through Monday)
Issued at 319 AM CDT Tue Mar 21 2017

Weak wave passing through upper level ridging will provide the next
chance for precipitation across the area.  Right now, it looks like
it will be in the form of snow and can`t rule the possibility of
a quick inch in some areas, but again moisture looks to be the
limiting factor. As earlier shift alluded too, it looks like a
cool damp day with breezy southeast winds.

After that, all eyes turn towards the Thursday/Friday event.  Models
continue to be consistent in widespread rainfall developing across
the area by Thursday afternoon and continue through Friday before
ending Saturday morning. Instability still looks borderline, but
can`t rule out the chance for a few Thunderstorms Thursday night
into Friday.  One thing for sure is that everyone should pick up a
decent amount of rain and some areas could even see an inch or two.
But trying to pick down those areas right now will be difficult.  I
don`t think the impacts will be that great as I think most areas
should be able to handle that amount of water with not much frost in
the ground at this time. Definitely will have to keep an eye on the
potential for heavy rain for messaging purposes.

Saturday and Sunday look relatively dry, but busy weather pattern
continues into early next week with another short wave forecast to
pass over the area. Right now the majority of that precipitation
should be in the form of rain.

Temperatures in the extended look pretty consistent with middle 40s
to middle 50s.  Nothing too warm and nothing too cool.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1204 PM CDT Tue Mar 21 2017

Some localized MVFR ceilings on the tail end of the exiting band
of light snow should be gone by 19z to 20z, if not sooner.
Otherwise expecting mainly VFR conditions. There will be a small
threat for another band of snow late tonight and Wednesday morning
which could briefly lower to MVFR but confidence not high enough
to include in TAF forecast.




LONG TERM...Heitkamp
AVIATION...08 is the U.S. government's official web portal to all federal, state and local government web resources and services.