Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 160337

Area Forecast Discussion
National Weather Service Sioux Falls SD
1037 PM CDT Sat Oct 15 2016

.SHORT TERM...(This evening through Sunday)
Issued at 344 PM CDT Sat Oct 15 2016

Lowest stratus has about cleared the forecast area as expected, as
winds become more southwesterly ahead of approaching surface trough.
However, fairly widespread mid-high clouds have held temperatures
down a bit from expected. These should continue to progress east
through the late afternoon, allowing for clear to partly cloudy
skies and light winds for most areas tonight. Exception will be in
our far south near the slowing boundary, where low level moisture
will persist and lead to potential fog/stratus redevelopment late

As the surface ridge shifts east on Sunday, southeast-south winds
will begin to increase fairly quickly Sunday morning, becoming gusty
by midday/afternoon. This could pull some of the stratus northward
toward I-90 through the morning, but also looks like another shot of
mid-high clouds, so overall looks like quite a bit of cloud cover
again for much of the area on Sunday. Strong warming aloft, but with
expected clouds, models trending a bit cooler despite what should be
decent boundary layer mixing. This especially evident east of the
James Valley, and knocked highs back a few degrees from previous
forecast. Will still be a mild mid-October day, though, with highs
in the 70s.

.LONG TERM...(Sunday night through Saturday)
Issued at 344 PM CDT Sat Oct 15 2016

Mid level short wave is still on target to impact our eastern zones
Sunday evening. Maximized near 700mb, it is basically lifting
northeastward along the southeast extension of low pressure in
southwest Canada. Strong warm air advection exists with this wave
with veering profiles. There will likely still be stratus to contend
with along I 29 and points eastward during the Sunday evening hours
coupled with plenty of mid and upper level moisture. However the
profile remains dry in the crucial 850-700mb layer. Therefore only
small pops are warranted Sunday evening from Marshall MN to near the
Iowa Great Lakes. Thunder is a question mark. It is quite capped
through 750mb, therefore effective shear is limited and there is no
level instability. The mid levels are more unstable then what it
was showing yesterday and last night. Therefore just included an
isolated chance for TSRA embedded in the shower activity.

Monday will be one more much above normal temperature day before it
begins to cool off. However there is a lot of model discrepancy in
the surface wind direction. The GEM and ECMWF hang onto northerly or
northeast winds behind Sunday nights short wave passage longer than
the GFS and NAM which turn the winds around faster. Therefore 925mb
temperatures are quite warm on the GFS and if verified, would likely
produce lower to mid 80s in a lot of locations. The ECMWF is cooler,
so for now just trended between the two as it is difficult to
ascertain the wind direction. But a stronger short wave moves
through late Monday and Monday night which will drag cooler air
into the region beginning on Tuesday. The overall moisture profile
with this wave is not very deep, so shower and thunderstorm chances
are limited mainly to our northern zones.

From Tuesday onward, the models are in much better agreement today
in showing an open upper trough moving through the plains during the
middle of the week which reinforces the cool air. Rainfall chances
will be very limited due to a lack of moisture, with temperatures
trending much closer to normal.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1035 PM CDT Sat Oct 15 2016

MVFR to IFR stratus and fog is expected to develop through the
KSUX to KSLB corridor late tonight. These low clouds will be
drawn northward on Sunday as the flow becomes southeasterly. This
will impact KFSD by late afternoon.




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