Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 241953
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
253 PM CDT Wed May 24 2017

.SHORT TERM...(This evening through Thursday)
Issued at 253 PM CDT Wed May 24 2017

Quiet and mostly dry conditions prevail as an upper ridge builds in
over the area. Cloud cover will gradually diminish through sunset,
yielding to a partly clear night. With increasing southerly flow and
theta-e advection, a mild night is expected with lows in the mid 40s
east to I-29 to lower 50s west.

As the upper ridge axis slides east of the forecast area tonight, a
surface low pressure centered in central SD will be moving eastward
into southeast SD early in the morning. The mid to low level
moisture is limited, but isolated showers cannot be ruled out ahead
of the surface front, and on the nose of the LLJ. This will allow an
increase in cloud coverage again throughout the day. Mostly cloudy
skies in combination with breezy southerly winds ahead of the front,
will bring warmer and near seasonal temperatures. Highs will be in
the lower to mid 70s.

.LONG TERM...(Thursday night through Wednesday)
Issued at 253 PM CDT Wed May 24 2017

Overall the chance for showers and thunderstorms will be pretty low
Friday and Saturday. There will be an upper level wave that passes
through Nebraska so a small threat along the Missouri River into
northwest IA during this time. Friday should prove to be the nicer
day with more sun and a bit warmer temperatures. Highs Friday in the
70s with highs on Saturday in the upper 60s to lower 70s.

The latest trends in the model output for Sunday into Wednesday is
to come a little closer to the GFS output of the last couple of
days. This unfortunately leans towards below normal temperatures
during this time. So, while it will not be a complete washout/freeze
out Sunday and Monday like some past Memorial Weekends, it will tend
towards the cool side with highs Sunday and Monday from the mid 60s
to lower 70s with morning temperatures from the upper 40s to lower
50s. Unfortunately there will also be a chance for showers both days
as well, but as stated before at this time not looking like a
pattern that supports an all day washout. In fact both days look
very much like surface based, instability driven showers with
nothing more than about 100-500 J/kg CAPE to work with. So nothing
severe but definitely the potential for a few brief downpours.

By Tuesday and Wednesday a bit drier air moves into the mid and
lower levels which will reduce the threat for diurnal Cu and shower
activity. However the air mass itself not a whole lot warmer so
still on the cool side.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1225 PM CDT Wed May 24 2017

VFR to low end MVFR ceilings continue as scattered low to mid
cumulus develop through sunset. VFR conditions will prevail for
the remainder of the TAF period. The only concern will be gusty
winds on Thursday as a high pressure settles in across the area.
LLJ of 40 knots possible at KHON early in the morning.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...05
LONG TERM...08
AVIATION...05


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