Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 191654

Area Forecast Discussion
National Weather Service Sioux Falls SD
1154 AM CDT Mon Jun 19 2017

.SHORT TERM...(Today and Tonight)
Issued at 400 AM CDT Mon Jun 19 2017

Temperatures will rebound a few degrees today as the upper level jet
shifts east and takes some of the cooler air with it. With the loss
of this cooler air aloft the hit and miss instability showers and
thunderstorms will also be less likely. Will maintain a very small
chance along and east of the Buffalo Ridge this afternoon, but with
CAPE amounts only about 250-500 J/kg and the freezing level up
around 9000 feet, vs 8000 feet yesterday, suspect activity will be
isolated and not have any small hail.

With temperatures on the rebound aloft, surface temperatures should
climb into the mid 70s across southwest MN with 80 to 85 along the
Missouri River corridor into central SD.

A weak acceleration in the upper level jet will bring a small threat
for showers and thunderstorms to southwest MN late tonight but there
is a decent chance this activity could stay to the northeast of the
area and coverage will be marginal.

.LONG TERM...(Tuesday through Sunday)
Issued at 400 AM CDT Mon Jun 19 2017

Tuesday still appears to be a fantastic day across the area with
plenty of sun, low humidity and light winds as surface high pressure
builds into Minnesota and Iowa.  As the surface ridge shifts east,
25-35 knot low level jet increases and could see some elevated
storms develop on the leading edge of the low level jet.  Right now,
the model soundings would suggest these storms would be relatively
high based, around 800 mb or higher, limiting the wind shear
potential. Think the biggest concern would be wind with any storms
that develop as sub cloud layer remains quite dry.

Cold front moves through the area Wednesday afternoon and could see
storms with the frontal passage.  Atmosphere appears to be fairly
capped, so questions remain as to whether anything could develop in
the first place.

Cold air lags significantly behind the front but works into the
region on Thursday. Relatively strong wave moves across central
Canada on Thursday with trailing cold front working through the
region Thursday night into Friday morning.

Behind this front, much cooler air works into the region from the
north with 850 hpa temps falling into the single digits as the upper
level jet buckles south of the area.  While this occurs, a series of
waves are expected to move across in zonal flow potentially leading
to a cool and unsettled weekend next weekend.  Models have been in
fairly good agreement that the leading wave affecting the region on
Saturday will be strong and intensifying, but how it interacts with
successive waves is still up for debate.  Have raised pops for
shower activity next weekend, and kept temperatures abnormally cool
but still above record levels.

The pattern remains cool through the weekend, with the jetstream
lifting back to the north early next week as a ridge builds back to
the west.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1153 AM CDT Mon Jun 19 2017

Scattered diurnal based CU will persist through the afternoon
hours before dissipating later this evening. Winds will turn light
and variable overnight, before increasing in speed by mid-morning




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