Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 202042

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
342 PM CDT SAT AUG 20 2016

.SHORT TERM...(This evening through Sunday)
Issued at 342 PM CDT Sat Aug 20 2016

Early afternoon satellite imagery together with radar and surface
obs showed a large synoptic system across the Upper Midwest with
deformation rainfall over northern Wisconsin. Meanwhile a few
scattered showers and thunderstorms developed behind the surface
cold front as the cool air aloft together with mid-August sun
promoted instability and shallow convection.

These showers and thunderstorms will continue through the early
evening hours before dissipating. Clouds will dissipate as well, but
forecast soundings show the potential for redevelopment again by
late morning Sunday, so increased the clouds in the sky grids
slightly and decreased temperatures across eastern MN and western
WI. At this time it does not appear that the cumulus will be deep
enough to produce precipitation. Back to tonight, northwest winds
should keep the boundary layer mixed enough to prevent fog formation
despite the widespread rainfall today.

.LONG TERM...(Sunday night through Saturday)
Issued at 342 PM CDT Sat Aug 20 2016

High pressure over the Missouri Valley will slide east early next
week with strong warm air advection taking over by Monday. Gusty
south winds ahead of the approaching trough and mixing to 875 mb
will allow us to reach the mid 80s to lower 90s both Monday and
Tuesday, warmer day being Tuesday. Coordination with surrounding
offices led to increasing highs a few degrees above the standard
blend due to the good mixing. GFS and NAM forecast soundings show
potential for gusts of 30-35 mph.

Low pressure associated with the trough will track eastward across
the Dakotas into northern Minnesota Tuesday night. A trailing cold
front may spark off some thunderstorm activity across western MN
Tuesday evening. However, a developing low along the southern end
of the front over Kansas, with a surface warm front extending to
the east along the IA/MO border, may produce a cluster of storms
or an organized MCS along I-80 which could prematurely steer the
healthy 45-55 kt low level jet to the east. If that were to
happen, it would be tough to get widespread storms across MN and
WI, particularly being in the entrance region of a secondary LLJ
centered over northern MN. Kept PoPs around 50 percent for now.

Cooler and drier weather follows for Wednesday night through
Friday before the next system approaches Saturday.


.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 105 PM CDT Sat Aug 20 2016

Showers and a few isolated thunderstorms will continue across the
region today. The chance for thunder is too low to include mention
in the TAFs. MVFR ceilings will gradually lift later tonight,
with VFR conditions expected on Sunday.

The steady rain has ended at KMSP, but a few scattered showers an
even an isolated thunderstorm are possible this afternoon. The
MVFR Cigs are starting to take shape, so may need to include them
back in the TAF at KMSP through the evening hours. VFR conditions
are expected for Sunday.

Mon...VFR. Winds SSW at 20G25 kts.
Tue...VFR. Winds SSW at 15G25 kts.
Wed...VFR with -TSRA possible. Wind S at 10G15 kts.


.MPX Watches/Warnings/Advisories...


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