Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 252054

Area Forecast Discussion
National Weather Service Sioux Falls SD
254 PM CST Sat Feb 25 2017

.SHORT TERM...(This evening through Sunday)
Issued at 250 PM CST Sat Feb 25 2017

Upper trough crossing the Northern Plains will bring a limited
chance for very light precipitation into the evening hours across
the highway 14 corridor. Scattered strato-cu snow/rain showers
continue to rotate across north western South Dakota this afternoon
and will slowly pivot eastward this evening. Any impacts should be
limited to the far northwestern portions of the CWA, and
precipitation amounts will be very light.

Mid-level clouds will stream across the remainder of the region into
the overnight hours, holding temperatures into the teens to lower

The aforementioned trough will move east of the area by Sunday
morning, leaving a poorly defined frontal boundary across the CWA.
Light warm advection aloft combined with southerly winds should push
high temperatures into the 30s in most areas. The impact of snow
cover has been marginal today, and would expect that to be the case
again on Sunday, but will again hold temperatures a couple degrees
cooler in the deeper snow pack areas.

.LONG TERM...(Sunday night through Saturday)
Issued at 250 PM CST Sat Feb 25 2017

Sunday night will transition from a west-northwest flow aloft to a
southwesterly flow as a Pacific trough digs into the Northwestern
US. This flow will direct a shortwave into the region Monday night
into Tuesday morning, followed by the main upper trough arriving
Tuesday night. With southerly surface winds and warm air advection
arriving Monday and Monday night, temperature profiles will be
particularly tricky. Recent snowpack and increasing cloud cover will
limit temperatures, but readings should manage to reach within a few
degrees of 40.

Precipitation will hold off until Monday evening, as the southerly
flow taps into increasing moisture and the shortwave approaches the
region. Still, there will likely be a substantial warm and dry layer
aloft to overcome, therefore think that measurable precipitation
chances remain quite slim. Precipitation type will also be difficult
to pin down, given the uncertainty of how much temperatures will
warm aloft and how deep the subfreezing temperatures will be near
the surface. Would prefer to limit mention of mixed precipitation at
this point, but have left in some freezing rain mention briefly
across northwest Iowa around daybreak Tuesday. At this point, it
does not look like freezing rain will be a major impact, with near
zero QPF values. In fact, the GFS keeps the forecast area dry
Monday night, while the NAM and ECMWF paint only some very spotty
QPF. Precipitation exits the area by midday Tuesday. Highs on
Tuesday will warm back into the upper 30s to lower 40s.

Northwest flow will bring in slightly cooler temperatures Wednesday
and Thursday, however temperatures will remain seasonal with highs
in the 30s. A shortwave drops across the northern Plains on
Thursday, which will bring gusty northwest winds and increasing
clouds. Models bring a fast moving swath of light precipitation
through the area, mainly in the afternoon, with the best potential
across the Highway 14 corridor into the Iowa Great Lakes area.
Temperature profiles are cold enough for snowfall, while
temperatures hold right around freezing.

Late week pattern transitions to upper level ridging/more zonal flow
pattern. Expect a nice warming trend with dry weather during this


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1130 AM CST Sat Feb 25 2017

VFR conditions will persist through the evening hours. System
moving through the Upper Plains will bring slightly lower ceilings
though the overnight hours and perhaps a few sprinkles near Huron,
but no large scale impacts to the region.

Clouds will again thin into Sunday morning.




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