Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 162357

Area Forecast Discussion
National Weather Service Sioux Falls SD
557 PM CST Thu Nov 16 2017

.SHORT TERM...(This evening through Friday)
Issued at 211 PM CST Thu Nov 16 2017

A stalled frontal boundary and stubborn stratus have led to a much
cloudier and cooler day for portions of Minnesota and Iowa today.
Temperatures have been struggling to reach the freezing mark in a
few locations.  Meanwhile, south of the warm front across south
central SD and NE, temperatures have soared into the 50s and even
60s. Winds however have continued to howl this afternoon with 40 mph
winds west of the James River Valley.   Most of the active weather
in the seven day forecast continues to focus around the upcoming 48
hour period. Here`s a look at where the most modifications were
made to the forecast.

1. Adjusted diurnal temperature curve overnight into Friday.
2. Increased gradient winds overnight over higher terrain.
3. Stratus and fog additions into the forecast for Friday.
4. Precipitation chances Friday night into Saturday.

Tonight: For some areas, our temperatures will actually be a flop
from the daytime highs. With continued low-level warm advection
overnight and winds turning southerly as opposed to east
southeasterly, temperatures over Minnesota and Iowa will continue to
rise after sunset.   Further west, very little if any diurnal trend
is expected tonight, and temperatures may remain near 50 in the
higher terrain areas of the Missouri River valley.  With 925 mb
winds turning southwest, expecting continued high gusts along the
Buffalo Ridge areas of Southwest Minnesota.  Gusts up to 45 mph
could be possible. With the sharp turn in low-level flow, low-level
moisture field over Kansas/Oklahoma/Texas will rapidly advect
northward, with stratus moving into the area ahead of an advancing
frontal boundary. Looking at dProg/dT of soundings overnight shows
models have trended further west with stratus and fog potential.

Friday: Once stratus arrives, it is expected to remain in place for
much of the day.  This is especially true east of I-29, and could
have a more profound impact on temperatures. Have lowered highs
slightly in the eastern zones, but even with strong boundary layer
thermal advection highs should still reach near 50.  While not a
great dense fog setup, am still expecting areas of fog by or after
daybreak Friday with visibilities dropping below 1 mile in a few

.LONG TERM...(Friday night through Thursday)
Issued at 211 PM CST Thu Nov 16 2017

Friday Night-Saturday: A positive tilted shortwave pushes through
the region into Saturday. A somewhat disorganized system will
bring fairly weak forcing mechanisms as it moves through. Will
maintain low end PoPs, focused higher over the Highway 20 area and
again further west and northwest along a lingering 700 mb
frontogenesis band.

Northwest winds return for Saturday and with temperatures struggling
to reach 40 degrees, wind chills will be quite brisk through the

Sunday-Tuesday: A progressive parade of shortwaves continues to
start next week out, but with little in the way of moisture, not
anticipating much in the way of precipitation and our rollercoaster
ride of temperatures will continues.

Wednesday-Thursday: There still remains considerable disagreement in
the long range forecast for Thanksgiving.  Temperatures are very
uncertain with a nearly 6 to 8 SD in projected highs.  However,
ensembles are supporting minimal precipitation potential for the
Thanksgiving timeframe, with the latest GEFS only suggesting an 8%
probability for 0.10" QPF into Thursday.  So will trend with
temperatures towards the median given the uncertainty while
maintaining a dry forecast.


.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 552 PM CST Thu Nov 16 2017

Breezy conditions will persist through the evening hours. Stratus
is expected to move into areas along and east of I-29 near
daybreak Friday morning. Cold front is expected to move through
the region Friday afternoon, helping to shift the low lying
moisture and clouds east.




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