Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 272018

Area Forecast Discussion
National Weather Service Sioux Falls SD
318 PM CDT WED JUL 27 2016

.SHORT TERM...(This evening through Thursday)
Issued at 318 PM CDT Wed Jul 27 2016

A weak cool front surging south through the area this afternoon not
likely to produce anything of significance. Could still be an
isolated shower or thunderstorm in mainly northwest Iowa but with
CAPE values around 500-1000 J/KG severe storms are not expected.
After the diurnal cycle runs its course any shower or thunderstorm
activity will be over. The next area of interest turns to a couple
of waves which were located in western SD and central MT at 19z. The
first will move across the area overnight but appears to be lacking
in some lower to mid level moisture. The wave on water vapor
looks more impressive than the models are indicating so will have
a small chance for showers and thunderstorms west of the James
River Valley through about midnight as it approaches but believe that
a combination of the waning diurnal cycle and the likely lack of mid
level moisture will allow activity to falter during the late
evening. The next wave will move into central SD Thursday afternoon
but at this time the better moisture and forcing looks to hold off
until later into the evening, so no mention of rain or thunderstorm
chances Thursday either.

Lows tonight will be very pleasant as high pressure sags in to the
James Valley. Will have them range from the upper 50s near KHON to
the mid 60s over southwest Minnesota and northwest Iowa where clouds
and a little wind could hang in through the night. Also lowered
highs a bit near Jackson and Spencer as stratus could linger well in
to the afternoon. Highs should range from the mid 70s in northwest
Iowa and southwest Minnesota to the lower 80s along the Missouri
River Valley.

.LONG TERM...(Thursday night through Wednesday)
Issued at 318 PM CDT Wed Jul 27 2016

Thursday night looks to be a cool and dry night with the forcing
focused across central Montana into the western Dakotas. The short
wave train is expected to move from central South Dakota into
eastern Nebraska on Friday.  With these weak waves moving through
and moist adiabatic lapse rates, could see a shower or weak
thunderstorms across south Central South Dakota into northeast
Nebraska.  Clouds will likely keep temperatures down in the upper
70s to near 80.

GFS and NAM have another short wave tracking across the southern
edge of the forecast area Friday night into Saturday, while the
ECMWF is relatively dry.  Have started to focus pops closer to the
southern cwa, and reducing pops to the north.

Sunday the upper ridge starts to build into the region leading to
warmer more humid conditions. Still could see some showers and
thunderstorms develop Monday night into Tuesday as low level jet
develops across the plains.  Could see additional chances of
precipitation on Tuesday into Wednesday as moisture continues to
increase into a conditionally unstable atmosphere ahead of a cold
front that will work through the region next Wednesday. This front
will introduce much cooler air to the region, and knock highs back
into the 80s near seasonal norms.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1220 PM CDT Wed Jul 27 2016

For the most parts, VFR conditions through the period. Parts of
southwest Minnesota and northwest Iowa could see ceilings drop to
low end LVFR on Thursday morning, but at this time not expecting
widespread lower ceilings along and west of Interstate 29. Hit and
miss showers and thunderstorms possible this afternoon and early
evening mainly in northwest Iowa.


.FSD Watches/Warnings/Advisories...


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