Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 031106

National Weather Service Sioux Falls SD
606 AM CDT Mon Aug 3 2020

.SHORT TERM...(Today and Tonight)
Issued at 400 AM CDT Mon Aug 3 2020

Northwesterly flow remains overhead as a surface high pressure
begins to slide southwards off to our east. This will keep
temperatures well below our seasonal normal, with afternoon highs in
the mid to upper 70s. Due to some elevated moisture above the 800 mb
layer, diurnal heating will likely result in a cumulus field
developing in the afternoon. The possibility of showers look slim
for today, as elevated instability is not looking likely aside from
occurring in the NAM based CAMs. As the wind profile is no longer
unidirectional, surface winds will be much calmer today with wind
gusts struggling to get above 10 mph.

As the aforementioned high pressure continues to slide southwards
overnight, surface winds will advect cooler and drier air into the
region. Without much moisture and lack of lift, skies will become
quiet clear. Combination of these factors will bring another cool
night, with overnight lows in the 50s and some even approaching the
upper 40s.

.LONG TERM...(Tuesday through Sunday)
Issued at 400 AM CDT Mon Aug 3 2020

Winds on Tuesday will start off weak, but as the surface pressure
gradient tightens from the west, winds will increase for areas west
of the James River Valley. Winds will be turning southerly during
the morning hours, which will begin to advect more moist air to the
region. By the afternoon, an upper level wave will be moving across
central South Dakota and is expected to reach those along the
Missouri and James River Valley by the early evening hours. MLCAPE
values of up to 1000 J/KG with bulk shear values approaching 40
knots could allow for some organized convection, but will be
dependent on the final track of the upper level wave.

Periods of scattered showers and thunderstorms will remain possible
on Wednesday, as the upper level wave travels eastwards and elevated
frontogenesis will keep rain chances possible throughout the day. As
the aforementioned surface high pressure moves eastwards, southerly
flow at the surface will bring warm and moist air into the region.
Afternoon highs will be in the mid 80 on Thursday, climbing into the
upper 80s and lower 90s by the weekend. With dewpoints in the 70s,
heat index values will be in the upper 90s.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 606 AM CDT Mon Aug 3 2020

VFR conditions expected during the TAF period. Wind will remain
light today, turning clockwise throughout the day ending
east/southeastwards by sunset. A scattered cumulus field will likely
develop by the afternoon, which will be dissipating after the
sun sets.




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