Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 192028

Area Forecast Discussion
National Weather Service Sioux Falls SD
328 PM CDT THU MAY 19 2016

.SHORT TERM...(This evening through Friday)
Issued at 328 PM CDT Thu May 19 2016

Warm and breezy through the remainder of the afternoon into the
evening. While some hit and miss sprinkles or light showers will be
possible across mainly southwest Minnesota, the model soundings
continue to hint that the little bit of surface based instability
that does exist may just remain capped. Suspect that the clouds will
decrease pretty quickly towards sunset. With the winds remaining in
the 10 to 15 mph range in most areas through the evening, lows
should be mild again and mainly 50 to 55 degrees.

A weak wave will approach from the west early Friday morning but at
this time a lack of moisture and unimpressive lapse rates should
preclude much in the way of showery activity. By mid afternoon as
the wave passes, mid and upper level lapse rates may be steep enough
to allow a few showers and thunderstorms to develop, so will have a
small chance for areas north of Interstate 29. There should be a
decent amount of cloud cover around so highs will be limited
somewhat, and will aim for the upper 60s to lower 70s.

.LONG TERM...(Friday night through Thursday)
Issued at 328 PM CDT Thu May 19 2016

Upper ridge axis continues scooting eastward across the Plains
on Saturday and Sunday, while a broad trough digs through the
Intermountain West. We can expect breezy to windy conditions this
weekend out of the south. Saturday will see winds around 15 to 25
mph, however winds increase further on Sunday as the gradient
tightens ahead of the approaching low pressure to our west. Winds
will be just shy of advisory levels at 20 to 30 mph with some higher
gusts. With warm air advection, gusty southerly winds, and mostly
sunny to partly cloudy skies, temperatures improve a few degrees
each day. Highs on Saturday will reach the mid to upper 70s and
improve to within a few degrees above and blow 80 on Sunday.

Moisture return begins in greater earnest Saturday night and Sunday
as flow begins to tap into Gulf moisture. The aforementioned trough
to our west lifts northeast through the region the first half of the
week with a few waves passing through the region during this time.
Showers and thunderstorms will begin forming in the High Plains on
Sunday, with precipitation shifting eastward in south central SD
Sunday afternoon and evening. It still looks as though some moderate
instability forms in the afternoon west of I29, however shear is
fairly weak and capping will be in place. Late afternoon and
evening, the capping weakens over south central SD and the bulk
shear increases as well as the wave approaches from the west. A few
isolated severe storms may be possible at this time mainly west of
the James River.

Showers and thunderstorms spread east across the remainder overnight
Sunday night into Monday, before largely ending Monday
afternoon/evening. Models suggest that some fairly high precipitable
water values can be expected. Locally heavy rainfall will produce
upwards of an inch under the more intense thunderstorm bands. While
flash flooding is not yet expected, will need to keep an eye on the
already high river levels in northwest Iowa.

Southwest flow mid to late week will keep the weather pattern
unsettled, however models start showing some significant differences
in the timing and track of waves. Did not alter the blended pops
given the uncertainty. Not enough to confidence to go completely dry
in any given period, so slight chance to chance pops continue
Tuesday through Thursday. Temperatures remain seasonally mild in the


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1228 PM CDT Thu May 19 2016

VFR through the period. Diurnally driven VFR ceilings through
sunset, then increasing clouds late tomorrow morning.


.FSD Watches/Warnings/Advisories...


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