Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 142035

Area Forecast Discussion
National Weather Service Sioux Falls SD
335 PM CDT Sat Oct 14 2017

.SHORT TERM...(Tonight)
Issued at 333 PM CDT Sat Oct 14 2017

Strong mid and upper wave will be moving eastward across the
forecast area tonight, exiting our far eastern zones between 06Z and
09Z. The wave is strong, with -24C noted at 500mb and a 120 knot jet
accompanying it. A second round of light rainfall is probable this
evening and overnight, lifting from southwest to northeast with a
band of rainfall currently in central SD. This is along the strong
surge of PV and is likely to fill in as it moves eastward. So thus
kept likely or categorical pops going this evening generally along
and north of I 90 where moisture depth is robust, with less pops
warranted south of I 90 as the mid and upper levels are much drier.
Additional rainfall amounts will be light, and areas of drizzle are
still warranted ahead of the wind shift with the aforementioned dry
mid and upper layers in our southern zones until very early this
evening. But as the deep layer northwest and northerly winds move
through, the drizzle threat will end, or at least visibility
reductions due to drizzle. It continues to look windy tonight behind
the wind shift due to cold air advection and a strong surge of PV.
Wind speeds of 20 to 35 mph are quite likely for several hours
behind the wind shift, but mixed layer winds suggest speeds below
wind advisory criteria. For lows, bias corrected readings looked
good for our western zones where the winds will become pretty light
and skies will clear first. However in the east, manually raised
lows a few degrees east of I 29 due to winds and cloud cover hanging
on much longer.

.LONG TERM...(Sunday through Saturday)
Issued at 333 PM CDT Sat Oct 14 2017

Sunday begins the trend of a pleasant week of weather coming up. It
still looks dry through the week, with no mention of rainfall until
possibly next Saturday east of I 29, and across the area Saturday
night. On Tuesday, Wednesday and Friday, raised highs a category
over superblend readings given the 900-850mb thermal regime. In
addition, there appears to be a lack of southeast winds which could
hold down temperatures those three days, with wind directions more
from the south or southwest.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 117 PM CDT Sat Oct 14 2017

Widespread IFR, LIFR and even some VLIFR conditions plague most
areas near and south of I-90 at early afternoon, trending to
mainly MVFR ceilings toward KMML/KBKX/KHON. Lower ceilings will
continue to expand northward ahead of inverted trough/frontal zone
near the James River valley. Has been some drizzle and a few
showers south, but the main widespread rainfall is expected north
of I-90 through the afternoon and early evening. There could even
be a rumble of thunder, but coverage/confidence will keep below a
mention in the KHON TAF. As the frontal zone works through the
area during the afternoon and early evening, will gradually see
any IFR ceilings raise to MVFR, but northwest winds will become
quite strong behind the front from late afternoon well into the
night, gusting 25 to 35 knots at times. Winds will decouple first
around KHON by 08-09z, then KFSD and KSUX toward daybreak.




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