Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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071
FXUS63 KFSD 200814
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
314 AM CDT Sat Oct 20 2018

.SHORT TERM...(Today and Tonight)
Issued at 314 AM CDT Sat Oct 20 2018

The latest water vapor imagery shows a strong upper level jet max
diving south through the eastern Dakotas and western MN early this
morning. This will bring a quick change to colder conditions today,
but luckily this will be a short lived cool down as southerly flow
brings warmer conditions back for Sunday.

An increased pressure gradient and fairly strong cold air advection
will create breezy conditions this morning, but winds will gradually
diminish through the afternoon as high pressure builds south. The
brunt of the coldest air will remain east of the area so expect a
normal diurnal rise in temperatures. Highs will only reach the 40s
in most locations while some lower 50s will be possible in central
SD. Some fragmented stratocumulus and a few flurries or sprinkles
will be possible before about 15z today, but any one location will
likely not see these clouds for more than about 3 hours. Most of the
high resolution models are dry with this frontal passage as well as
the lower resolution models, with only the NMM and ARW producing
some very light precipitation in southwest MN.

By tonight the surface high pressure will quickly shift east, but
winds will be on the light to calm side along and east of Interstate
29 through about 9z. This will allow for some radiational cooling
and lows in the upper 20s. Southerly return flow will set up from
west to east through the night and help modify any falling
temperatures, and likely bring a small rise in temperatures to those
locations that drop off the most. Lows from the upper 20s in
northwest IA to near 40 in south central SD.

.LONG TERM...(Sunday through Friday)
Issued at 314 AM CDT Sat Oct 20 2018

Sunday night into Monday will see the right entrance region of the
upper level jet shift east and drop a cool front into the area. Some
winds will hang on through the night so Monday morning lows will
likely be in the lower to mid 30s. Temperatures will mix fairly
nicely with a very dry environment, so looking at upper 50s to lower
60s.

Weak upper level ridging will provide a low amount of cloud cover
and fairly light winds Monday night into Wednesday. By Wednesday
afternoon into Wednesday night a weak southern stream cut off low
pressure will drift into the area and bring with it a chance for
showers. This chance will linger into Thursday. Friday right now
looking fairly quiet and mild as upper level energy passes to the
north but this of course could change quite a bit by the time next
Friday becomes reality.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1032 PM CDT Fri Oct 19 2018

VFR conditions through the TAF period. Low level wind shear will
develop at all TAF sites overnight. Northwesterly winds will pick
up on Saturday morning, gusting 20 to 30 kts into the afternoon.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...JM



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