Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 171828
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
128 PM CDT Sat Jun 17 2017

.SHORT TERM...(Today and Tonight)
Issued at 342 AM CDT Sat Jun 17 2017

Latest water vapor and RAP data shows strong 100 to 120 knots upper
level jet spreading into western SD early this morning. This was
allowing a weak mid level trough of low pressure to work into
western and central SD. With increasing mid level moisture
precipitation returns have been on the increase in these areas, but
so far has remained pretty light. Suspect that this trend of fairly
light rainfall will continue through the morning and afternoon
across eastern SD, southwest MN and northwest IA. While some very
minor amounts of elevated instability should exist it should do
nothing more than bring a few pockets of moderate to briefly heavy
rainfall and possibly a few lightning strikes. Suspect that
something close to a quarter inch of rainfall is likely north of
Interstate 90 with decreasing amounts south of the Interstate.

The rainfall should come to a quick end from west to east late this
afternoon into the evening as the main upper level support shifts
east and strong subsidence develops.

As for temperatures, with the precipitation and clouds lowered highs
a bit with lower 70s north of Interstate 90 and mid to upper 70s to
the south. Mild lows in the 50s overnight with a combination of
cooler and drier air but still some cloud cover hanging in.

.LONG TERM...(Sunday through Friday)
Issued at 342 AM CDT Sat Jun 17 2017

Relatively cool temperatures aloft on Sunday will lead to well
below normal temperatures across the area.  Steep lapse rates from
850-700 mb may result instability showers/isolated thunderstorms
through the peak heating of the day.  Have some 20-30 pops across
the east, where the change in temperature with height is most
significant.

Strong mixing could result in an isolated showed/thunderstorm Monday
afternoon across the east.  Limited instability, shear and lack of
moisture is not supportive of severe weather, but could get outflow
with strong inverted V profile.

Dry conditions are expected Tuesday with upper level ridge across
the west.  More unsettled conditions are expected Wednesday through
Friday as upper level northwest flow transitions to more zonal with
a few short waves working through. With the potential for good wind
shear, could have some severe weather especially on Thursday as a
cold front works into the region.

Cooler temperatures expected to round out the week behind the front.
 Have raised winds some behind the front on Friday into Friday
night.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 123 PM CDT Sat Jun 17 2017

Main concern for aviation area scattered showers and thunderstorms
through 03Z and the 2500-4000 foot ceilings coming into the area
after midnight.

With a strong upper wave moving across the area this afternoon and
evening and much colder air aloft, even the limited solar heating
is resulting in the development of showers and thunderstorms. With
a dry air mass, expect ceilings with the showers and storms to
remain VFR. However, there could be some small hail or wind gusts
to 45 kts with a few cells along and north of I-90. Both of these
conditions will be isolated enough that we have not put them in
the TAF. These showers will slowly dissipate after sunset as the
wave moves east. After skies briefly become BKN-SCT, expect
stratus to move southward after midnight into southwest MN and
east central SD as far south as FSD. Ceilings with the stratus
will be around 3000 feet prior to sunrise but with heating should
rise back above 3000 feet by late Sunday morning. At this time
expect the stratus to remain east of KHON and north of KSUX.

&&

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

$$

SHORT TERM...08
LONG TERM...BT
AVIATION...Schumacher



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