Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 010939

Area Forecast Discussion
National Weather Service Sioux Falls SD
339 AM CST Wed Mar 1 2017

.SHORT TERM...(Today and Tonight)
Issued at 339 AM CST Wed Mar 1 2017

Main issues over the next 24 hours will continue to be
precipitation. Isentropic lift developing ahead of an upper trough
moving through the area this morning will result in light snowfall
along and east of the James River Valley this morning. Lift really
decreases by mid to late morning, so expect most of the
accumulations with this disturbance to be done by then.
Accumulations will be relatively light, but may total up to around
an inch.

This afternoon, could see some scattered snow showers develop as
some weak CAPE develops at the top of the mixed layer.  NAM is
slightly more unstable than the GFS as is super adiabatic near the
surface.  Still some question as to whether the dendritic layer will
saturate or not, so only have some 20 pops for this at this point
across southwest Minnesota.

Another disturbance is expected to drop down in northwest flow
tonight. Have raised pops across southwest Minnesota after 09Z.
Questions still remain in terms of where the back edge of
precipitation shield will develop.

.LONG TERM...(Thursday through Tuesday)
Issued at 339 AM CST Wed Mar 1 2017

Thursday will see a threat for some light snow along and northeast
of a Huron to Storm Lake line. The EC/Canadian and GFS all fairly
agreeable on the path of the surface low, with the snowfall expected
to be northeast of the path, while the nam is a north outlier. So
will lean towards the EC/Canadian and GFS output which means that
some light snow will be possible. The precipitation and cloud cover
will keep temperatures in check with highs in the 30s.

Thursday night into Friday morning will see high pressure build
southeast and bring some chilly morning lows. Expecting these lows
to range from the mid teens to lower 20s. The surface high pressure
shifts quickly east and should allow for a fairly gusty south wind
to develop. Raised winds a bit and will shoot for about 15 to 30 mph
most locations.

An upper level trough will dig into the west coast which will allow
an upper level ridge to build across the Plains. This will bring a
warm and dry weekend to the area. South winds will be a bit gusty
again on Saturday but should not be quite as bad on Sunday. Highs
both days at least in the 50s with some 60s likely in central SD
down the Missouri River into northwest Iowa.

A fairly strong system will move through Sunday night into Monday
and will bring a chance for rain or snow to the area. While this
system will zip through the area another wave will dig onto the west
coast which will bring another period of upper level ridging to the
area. This will support above normal temperatures Monday and
Tuesday with very little chance for precipitation.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1018 PM CST Tue Feb 28 2017

Shortwave energy moving through tonight, poorly resolved by model
data. Have followed the 925:850 RH fields which suggest that a
period of light snow will cross the CWA from HON to FSD to SLB
into Wednesday morning.

IFR to LIFR conditions will persist, with visibility in snow as
low as 2 miles. Models also suggesting a rapid rise in ceilings
behind the snow, but this should be temporary as more instability
based strato-cu forms by mid-day and the afternoon. Winds will
turn gusty by mid-day Wednesday from the northwest.




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