Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 212330

Area Forecast Discussion
National Weather Service Sioux Falls SD
630 PM CDT Fri Oct 21 2016

.SHORT TERM...(This evening through Saturday)
Issued at 250 PM CDT Fri Oct 21 2016

Quiet night ahead as fairly strong upper level ridging builds across
the Northern Plains. At the surface high pressure will allow
southerly flow to turn to the west and then weaken to light and
variable in many locations. While the air mass is a bit warmer than
this morning, do expect cool overnight lows in the 30s. There will
be a threat for some low lying fog late tonight and Saturday
morning, but not anticipating any widespread concerns.

Southerly flow will increase through the day as high pressure shifts
east. This will allow warmer air to move in and should set up a very
nice day. Highs will range from the mid 60s in southwest Minnesota
to 70 to 75 in south central SD.

.LONG TERM...(Saturday night through Friday)
Issued at 250 PM CDT Fri Oct 21 2016

Plains upper ridging will provide plenty of subsidence, dry air, and
mild temperatures for a couple of pleasant fall days after the short
wave passes well to the north along the Canadian border. Modest
cooling behind the wave will still allow for high temperatures in
the upper 50s to mid 60s Sunday and Monday. A northwesterly breeze
Sunday will be replaced by a southeasterly one by Monday afternoon,
but nobody will get blown off their feet, so it will be a couple
good days for late season golf or other outdoor activities.

The most significant weather feature of the coming week, a short
wave moving northeast from the southern CA coast, is being handled
fairly consistently by models, both from model to model and from run
to run. This includes the timing of its passage across SD/MN/IA/NE at
midweek, followed by its deepening over the eastern USA as it passes,
and a return to plains ridging by Thursday. This will bring a threat
of showers and possibly isolated storms Tuesday and Wednesday. Due to
the modest nature of instability, moisture inflow, and upper
dynamics, there should be little or no threat of severe storms or
heavy rain as far north as our area centered over Sioux Falls. Wind
should also be modest with the surface system. Temperatures Tuesday
and Wednesday will be similar to or slightly cooler than the start
of the week. Still very far from any winter precipitation threat
with this system.

A warmup will at least modestly start Thursday under the upper
ridging, with high temperature looking to be generally in the 60s.
The operational GFS and EC differ on whether or not this warmup will
continue into Friday, with the GFS bringing cooling from a Pacific
northwest short wave, and the EC making Friday warmer by steering
the short wave quite a bit further to the north. Will go with the
guidance solution which leans to the cooler GFS. The involved
uncertainty is not a critical factor, for even with the GFS
solution we are not looking at wintry temperatures. Also, the GFS
frontal passage Thursday night looks like a dry one.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 630 PM CDT Fri Oct 21 2016

VFR conditions through the TAF period.




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