Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 202337

Area Forecast Discussion
National Weather Service Sioux Falls SD
637 PM CDT SAT AUG 20 2016

.SHORT TERM...(This evening through Sunday)
Issued at 259 PM CDT Sat Aug 20 2016

A combination of steep low level lapse rates and upper cyclonic
circulation will keep the threat of scattered showers and isolated
thunderstorms going through late this afternoon. Primarily for areas
in east central SD, southwest MN, and extreme northwest Iowa.
Otherwise the precip threat will rapidly wane early this afternoon,
leaving clear or mostly clear skies to follow overnight and late
tonight. With clear skies and light winds, still looks like a chilly
night for this time of year. However many of the consensus guidance
values have caught up to this way of thinking, so upper 40s to
around 50 still look reasonable, perhaps some mid 40s in low lying

Sunday will be a very pleasant day with light winds and plenty of
sunshine. Highs did not need to be altered with mid 70s to mid 80s.
The warmest readings will be in central SD with the coolest readings
in southwest MN.

.LONG TERM...(Sunday night through Saturday)
Issued at 259 PM CDT Sat Aug 20 2016

Surface ridging continues to pull off to the east on Sunday night.
In an increasing southerly flow, it will be a much milder night with
lows in the upper 50s to lower 60s. An upper level ridge over the
western CONUS drifts eastward on Monday, leading to probably the
warmest day of the upcoming week with highs into the mid 80s east of
Interstate 29, to lower and mid 90s over the James River Valley and
south central SD. With an increasing gradient as a surface trough
slides out onto the western High Plains, it will become windy on
Monday afternoon. With breezy conditions remaining on Monday night,
lows will only drop into the upper 60s to lower 70s.

Tuesday looks to be another hot day in a strong southerly flow as a
cold front approaches from the west. It will be another windy day,
with highs again mid 80s to lower 90s. Thunderstorm chances then
increase for Tuesday night into Wednesday as a shortwave lifts out
of southern Nebraska and the aforementioned cold front swings
through the region. Models are in decent agreement with timing the
frontal passage, exiting our CWA by 18z on Wednesday. With cooler
air beginning to filter in behind the front, highs on Wednesday will
run upper 70s to lower 80s.

The remainder of the extended period will be characterized by below
normal temperatures, with highs in the 70s and lows in the 50s for
Thursday through Saturday. With increasing moisture on a returning
southerly flow, rain chances will go back up for Friday into


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 635 PM CDT Sat Aug 20 2016

VFR conditions are anticipated for the majority of the overnight
period, once lingering diurnal CU dissipates. Winds will gradually
settle down this evening, turning variable after 4am. With
crossover temperatures very warm this afternoon, will need to
watch out for fog development by daybreak, especially in any
valley or sheltered area.

VFR conditions will prevail for Sunday, with a rather light wind.


.FSD Watches/Warnings/Advisories...


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