Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 140844

Area Forecast Discussion
National Weather Service Sioux Falls SD
344 AM CDT Mon May 14 2018

.SHORT TERM...(Today and Tonight)
Issued at 344 AM CDT Mon May 14 2018

Complex of storms has developed along stationary boundary to the
south of the forecast area.  Storms across Central Nebraska are
expected to lift northeast impacting the southern half of the
forecast area through the morning hours.  Weakly forced environment
will likely lead to additional rounds of convection through the
afternoon hours. Models indicate PV of varying strength across the
region, but may be convectively induced. Atmosphere is only weakly
capped, but moist adiabatic lapse rates will result in only a few
hundred J/kg of CAPE.  With meager instability and shear, general
thunder in SPC day 1 outlook looks very reasonable.  Atmosphere does
get a bit of a boost from weak upper level jet feature that develops
south of the area leading to enhanced upward vertical motion in the
left exit region of the jet. This is most focused across the
southern half of the forecast area through the afternoon into the
early evening hours.

As northerly flow develops tonight expect convective chances to
dwindle as moisture decreases.  This will gradually lead to
decreasing clouds across the area.  With clearing skies from
northwest to southeast, concentrated coolest lows across north
Central SD where radiative cooling could take place the longest.

.LONG TERM...(Tuesday through Sunday)
Issued at 344 AM CDT Mon May 14 2018

A few nice days with warm temperatures and dry conditions are in
store Tuesday and Wednesday. Northwest flow aloft will be replaced
by weak flow as ridging rebuilds across the Plains. The result will
be the return to mostly sunny skies and high temperatures rebounding
into the 70s Tuesday and low to mid 80s on Wednesday.

Pattern starts to transition to southwest flow aloft on Thursday, as
a slow moving trough over the Intermountain West drifts further
east. Shortwave ejects from the main low and tops the ridge in the
northern Plains on Thursday. South-southeast surface winds increase
ahead of the wave, with surface pressure deepening near eastern
Colorado. Surface boundary setting up to our west will allow some
scattered showers and thunderstorms to drift into mainly our western
and northern counties in the evening and overnight.

Models coming into a greater consensus with bringing a second
shortwave along with a surface boundary through the region Friday
afternoon through Friday night. Trailing mid level boundary could
keep unsettled weather in the picture on Saturday, however with
clouds and precipitation, temperatures will be much cooler Saturday.
Cool temperatures continue into Sunday but upper level ridging
attempts to rebuild in the Plains early next week. Monday looks dry
with slightly warmer temperatures.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1104 PM CDT Sun May 13 2018

Chaotic areas of MVFR ceilings remain at late evening across
southeast SD and into northwest IA, with VFR ceilings most other
locations. Trend in ceilings should be down into the MVFR and
some IFR conditions for most locations overnight with high degree
of low level moisture, and approach of convection toward the lower
Missouri River valley later tonight. Even with some breaks in MVFR
conditions, should get redevelopment of convective clouds heading
into the afternoon hours which will be marginally MVFR to VFR in
height, and should have a scattering of showers and thunderstorms
for KFSD/KSUX areas as weak mid-level wave moves across during the




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