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Area forecast discussion
National Weather Service Sioux Falls South Dakota
503 am CST Mon Dec 11 2017

Short term...(today and tonight)
issued at 331 am CST Mon Dec 11 2017

Satellite water vapor image showing a strong upper level shortwave
diving into ND very early this morning. This feature will continue
to quickly drop southward through the day, while surface low
pressure tracks across Minnesota, then into the central Mississippi Valley
by afternoon. Extending from that, a cold front will push across our
area, with the main cold punch coming in during the afternoon. With
the strong cold air advection/steep lapses rates/and a tightening
gradient, will see northwest winds increase through the morning and
become gusty into the afternoon. Soundings suggest winds at the top
of the mixed layer running from 40 to near 50 kts, so issued a Wind
Advisory for the entire area, ending from northwest to southeast
during the afternoon as winds begin to subside. Models are still in
agreement with light precipitation developing along and ahead of the
main cold push, though becoming more diffuse in the afternoon.
Thermal profiles would indicate that precipitation type would be
mainly snow, with a little rain mixing in where surface temperatures
climb into the upper 30s. In any event, any snow would be very light
(outside of a brief convective burst) with only a couple tenths of
accumulation mainly north of Interstate 90. While high temperatures
will be in the mid to upper 30s, temperatures will fall during the
afternoon as the colder air filters into the area.

By tonight, winds will subside and there will be a general decrease
in clouds in our north and east, with some cloudiness remaining in
our west as the front hangs up over that area. This will play a part
in a fairly wide range of temperatures across our area overnight,
with lows in the mid 20s over south central SD, to as low as the mid
teens east of I-29.

Long term...(tuesday through sunday)
issued at 331 am CST Mon Dec 11 2017

The cool down will be short lived however as temperatures rebound on
Tuesday as the flow takes on a more westerly component. Highs will
close in on 50 over south central SD, then tapering down to the east
with 30s from east central South Dakota into northwestern Iowa.

Another cold front slides through the region on Wednesday as an
upper level shortwave drops from the northern rockies into the
Central Plains during the day, with models disagreeing on the
strength and exact track of this system. As a result, there are
differences in the precipitation potential for our area, but at this
point consensus would keep it mostly dry. Confidence is higher
however with regard to winds, and it looks like another breezy day,
with highs 30s and 40s.

After a brief cool down on Thursday, temperatures rebound once again
for the end of the week as readings climb back to a good 10 to 15
degrees above normal for Friday through Sunday as the upper level
flow transitions to a less amplified pattern. Precipitation chances
look pretty minimal through the period, with the most enhanced
chance coming later on Saturday into Saturday night, though again
does not look to be anything significant. Models still indicating a
quick return to a more amplified pattern by the beginning of next
week as a a northwesterly upper level flow returns to the region -
maintaining the relatively benign weather of late.

&&

Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 500 am CST Mon Dec 11 2017

Northwest winds will ramp up quickly this morning with gusts of 40
to 45 mph expected through the day. The winds will taper off into
the evening, but remain a bit breezy through about 3z Tuesday.
MVFR ceilings will settle southward this morning, then VFR
conditions will return late afternoon into the evening. Spotty
light rain and light snow is expected but for now significant
reductions in visibility are not expected.

&&

Fsd watches/warnings/advisories...
South Dakota...Wind Advisory from 9 am this morning to 6 PM CST this evening
for sdz050-063>071.

Wind Advisory from 9 am this morning to 3 PM CST this afternoon
for sdz038>040-052>062.

Minnesota...Wind Advisory from 9 am this morning to 6 PM CST this evening
for mnz071-072-080-081-089-090-097-098.

Iowa...Wind Advisory from 9 am this morning to 6 PM CST this evening
for iaz001>003-012>014-020>022-031-032.

NE...Wind Advisory from 9 am this morning to 6 PM CST this evening
for nez013-014.

&&

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