Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 181142

Area Forecast Discussion
National Weather Service Sioux Falls SD
642 AM CDT Tue Oct 18 2016

.SHORT TERM...(Today and Tonight)
Issued at 413 AM CDT Tue Oct 18 2016

Main upper lift forcing has passed the area overnight, and remains
but a weak mid-level wave cycling in behind this feature in
confluent cyclonic flow.  Clouds along with this mid-level wave are
a bit more extensive and persistent than previous models were
indicating, and a fairly solid consensus at this point that at least
a mostly cloudy condition will linger across much of the area this
morning before moisture works to erode via mixing and advection.
There remains a cluster of weakening light showers pushing into
central South Dakota associated with the mid-level wave, and despite
a gradual diminishing trend, almost all hi-resolution solutions
indicate potential for at least a few sprinkles with this feature
through mid-morning toward the James valley.  Once this feature
dissipates and clouds erode, it will be a fairly pleasant autumn day
with high pressure sliding south of the area and winds mixing to a
10 to 20 mph pace. Temps will be a bit above normal, mainly lower to
mid 60s.

Quiet conditions with generally clear conditions during the evening
leading into an increase in clouds from the southwest as strong
impulse currently pushing into northern CA emerges from the central
Rockies. Frontogenetic forcing scoots out in the mid levels with
increasing moisture, and will generate enough lift for a chance of
light rainfall by very late tonight along the South Dakota/Nebraska
border.  Otherwise, northern stream energy will drive a cold front
southward toward the far northern CWA by 12z Wed. Winds fairly
light, and with clear skies, will be a seasonably cool night.

.LONG TERM...(Wednesday through Monday)
Issued at 413 AM CDT Tue Oct 18 2016

Wednesday into Wednesday night will likely see showers develop south
of Interstate 90 as an upper level wave brings a decent shot of mid
level moisture, but fairly weak mid level forcing and fairly
inconsequential instability. Increased the chance for rainfall near
the Missouri River Wednesday afternoon and early evening but
anticipating rainfall amounts of a tenth of an inch or less.
Temperatures will be somewhat uniform across the area with cooler
low level temperatures north of Interstate 90 and a little more
sunshine while to the south clouds will be thicker and not allow the
area to take advantage of mixing potential. Aiming for lower 60s in
northwest Iowa to right around 57 down highway 14. If clouds and
rainfall can move in a few hours earlier then temperatures south of
Interstate 90 will be 2-4 degrees cooler.

The threat for precipitation will shift south Wednesday evening
allowing cooler air to filter in from the north. This will set up
cool mornings both Thursday and Friday with lows in the 30s while
highs Thursday will be in the 50s.

Flat ridging expected to become more pronounced Friday through
Monday which should mean above normal temperatures and dry conditions. See
no reason to argue with the grids that have been loaded, especially
given low standard deviations during this time. Do not doubt that
there will be a day when temperatures climb into the 70s but given
that yesterday the models had Friday warmest, while today they are
leaning towards Saturday, confidence is not high enough to pick
which day these warmer temperatures will occur.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 642 AM CDT Tue Oct 18 2016

Some brief lower MVFR to IFR ceilings will occur near the western
Missouri River corridor, but generally will see only patches of
VFR ceilings this morning, and a scattered flat cumulus field
with VFR heights this afternoon.




SHORT TERM...Chapman
AVIATION...Chapman is the U.S. government's official web portal to all federal, state and local government web resources and services.