Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 161140

Area Forecast Discussion
National Weather Service Sioux Falls SD
540 AM CST Thu Nov 16 2017

.SHORT TERM...(Today and Tonight)
Issued at 341 AM CST Thu Nov 16 2017

The main focus for today will be the windy and warmer conditions
across the area. Southeast winds this morning will quickly increase
shortly after daybreak in south central SD as the surface gradient
increases and a mid level trough begins approaching from the west.
Windy conditions will expand across the region through midday, with
gusts to 30 to 40 mph possible at times. With strong warm air
advection and increasing mid level moisture, skies will become
mostly cloudy, but could scatter out some in the afternoon across
southeast South Dakota. Despite the clouds, expect a much warmer day
across the board, with highs from near 40 in southwest MN where the
clouds will persist longest, to the mid 50s in south central SD.

Gusty winds will continue into the early morning hours, finally
diminishing late tonight for areas along and west of I-29. With
cross barrier flow developing in the Buffalo Ridge area, expect
local enhancement of wind speeds throughout the evening and
overnight hours. Southerly flow will result in milder overnight lows
mainly in the mid 30s to near 40. Temperatures in the Buffalo Ridge
area will likely see periods of warming overnight, with the enhanced
winds and persistent cloud coverage in that area.

.LONG TERM...(Friday through Wednesday)
Issued at 341 AM CST Thu Nov 16 2017

Main concern in the long term forecast is the potential for rain and
snow Friday night into early Saturday. Longwave positively tilted
upper trough will swing across the central and northern plains
Thursday night through Saturday morning. Trough at the surface will
reach central SD by Friday morning, driving quite a bit of moist
southerly advection and stratus along with it. The broad longwave
nature of the approaching trough will serve to limit our
precipitation chances outside of northwest Iowa by pushing the
lower level boundary southeastward before the most potent upper
level forcing arrives Friday night. Expect most of the lower
boundary related precipitation in NW IA to fall as rain as surface
and 925mb temperatures will be above freezing until after
midnight, after which some snow may mix in. Best shot for
precipitation in SE SD will be a frontogenetic band associated
with a secondary 700mb front that will swing through SE SD during
the 00z-06z Saturday timeframe. With the surface boundary well to
the southeast, expect any precipitation associated with this
feature to be snow. This band will have the paucity of low level
moisture to overcome, so not expecting anything more than a
dusting at this time.

As for other sensible weather during this period, have bumped up
winds between 18z Friday and 00z Sunday due to the decent pressure
gradient and cold advection aloft in the wake of the frontal passage.

Sunday through Thanksgiving: Models showing a series of sometimes
impressive upper waves translating across the northern CONUS next
week. General GFS/EC/CMC agreement on a wave Monday night with
slight disagreements in timing and depth. Nonetheless, each solution
doesn`t bring enough moisture to the CWA to warrant any mention of
precipitation at this time. Significant model disagreements take
hold after this period so have gone with consensus.


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 534 AM CST Thu Nov 16 2017

Band of low stratus less than 1000 ft agl continues to stream
across southwest MN, east central SD, and the Iowa Great Lakes.
The RAP has a good handle of this stratus which places the edge
just on the border of FSD through the 14Z or 15Z before rapidly
retreating the band eastward through 17z. Will go with a tempo
group at FSD with the potential for the stratus to remain just
east of the airport. Otherwise, high clouds will also spread
eastward across the region into this afternoon. Winds will be
quite gusty, averaging 15 to 25 kt with gusts to 35 kt into this
evening. Winds gradually decrease in the overnight hours, but will
remain gusty east of I-29 through the end of the TAF period.




LONG TERM...Ferguson
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