Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 282310

Area Forecast Discussion
National Weather Service Sioux Falls SD
610 PM CDT SAT MAY 28 2016

.SHORT TERM...(This evening through Sunday)
Issued at 416 PM CDT Sat May 28 2016

Upper low still spinning over northwest Iowa late this afternoon,
triggering isolated funnel clouds and even a very brief touchdown
along boundaries extending east and south from the surface low
center just south of Sioux Falls. This funnel cloud activity
could continue into the very early evening, with the lingering
showers continuing to move very slowly east out of the area by
06Z. Clearing and light winds expected during the overnight, and
with the recent rain, could possibly see some patchy light fog
develop after midnight in areas near/east of the James River.
Confidence not high in any significant fog development at this
point, so did not include mention in this forecast, but something
for the evening shift to monitor.

Sunday still looks to be the nicest day of the holiday weekend,
with plenty of sunshine, light winds, and high temperatures a
couple of degrees either side of 80.

.LONG TERM...(Sunday night through Saturday)
Issued at 416 PM CDT Sat May 28 2016

Could see elevated storms by late Sunday night between the
Missouri River and I-90, as 850mb warm front begins to lift
northward ahead of next mid-upper level trough approaching the
area. Soundings somewhat capped along/northeast of Huron-Sioux
Falls-Storm Lake line, so have limited extent of pops to areas
southwest of this line late Sunday night into Monday morning. More
robust lift moves across the area late Monday into Monday night,
which should lead to increasing coverage of showers/thunderstorms.
GFS looks to be overdoing instability based on pushing surface
dew points to near 70 by late Monday afternoon. Still likely
looking at MLCAPE values of 1000-1500 J/kg. Deep layer shear
marginal, but fair amount of directional shear in the lower 3km
which could be locally enhanced near any boundaries. Thus cannot
rule out isolated severe threat along with locally heavy rain
late Monday afternoon into the early evening.

Longer range models more consistent in pushing the cool front and
associated rain east of the forecast area by late Tuesday, leaving
cooler and dry conditions across our forecast area for mid-late
week as the upper level low moves east from the Canadian border
into Ontario, and upper ridge builds over the Rockies. Subtle wave
slips southeast around the fringe of the upper ridge toward next
weekend which could trigger a few showers or thunderstorms, though
timing is uncertain at this range.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 605 PM CDT Sat May 28 2016

Showers and isolated thunderstorms will come to an end this
evening, with decreasing clouds and dying winds by late evening.
With the recent rain, there is a possibility of patchy fog
development overnight, though models have backed off on fog
potential so did not include in tafs.


.FSD Watches/Warnings/Advisories...


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