Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 101952

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
252 PM CDT Thu Aug 10 2017

.SHORT TERM...(This evening through Friday)
Issued at 252 PM CDT Thu Aug 10 2017

Early afternoon satellite imagery with surface obs and radar
identified a cyclonic circulation over the Upper Midwest, with
shower and a few thunderstorms  over Minnesota and Wisconsin. This
precip should reach its maximum intensity later this afternoon, and
then wane towards sunset as the boundary layer stabilizes. SPC
Mesoanalysis showed an uncapped environment with a few hundred J/kg
of MLCAPE, which was enough to produce some deep convection and
lightning, but not enough to support strong updrafts.

Over the next 24 hours subsidence associated with the H500 height
rises will lead to surface high pressure building across the region,
which will mean light winds and clear skies to start the day on
Friday, with some patchy fog in the morning. Forecast soundings do
show the potential for some afternoon cumulus development, but it is
possible the large scale subsidence will win out and could end up
with mostly sunny skies. Afternoon highs will be in the 70s.

.LONG TERM...(Friday night through Thursday)
Issued at 252 PM CDT Thu Aug 10 2017

In the longer term the guidance suggests the large scale pattern
will evolve from the current western ridge/eastern trough (with
northwest flow over us) into more of a zonal flow by the middle to
end of next week. The western ridge will initially start to work
east, but strong flow across the Pacific looks to work into the
continent and flatten the ridge as it tries to push into the
central part of the continent. Overall, this suggests that near to
below normal temperatures will transition to near to above normal
temperatures by the end of the period, with less confidence in
precipitation chances and timing by that point given faster
westerly flow.

High pressure will provide fair and dry weather from tomorrow
night into Saturday. However, some precipitation chances will
exist across the west, closer to the main baroclinic zone, later
Saturday and Saturday night, and chances for showers and a few
storms look to work across most of the remainder of the area
Sunday into Sunday night as better low level moisture tries to
work into the area and a shortwave trough rotates through the
region. Things then appear to be quiet Monday and Tuesday, before
getting more unsettled and less predictable Wednesday into
Thursday as the flow turns more zonal.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 145 PM CDT Thu Aug 10 2017

VFR/MVFR conditions this afternoon with a few scattered showers
and thunderstorms across the region. Precip should taper off after
sunset, and should see skies clear across western MN, with some
lower clouds hanging on across eastern MN, and especially western
WI. Areas that clear out are at more risk for fog, and areas that
don`t clear could could see MVFR/IFR clouds overnight. VFR
conditions should return Friday morning.

A few showers are possible this afternoon at KMSP. There is also a
small chance for a thunderstorms, but at this time confidence is
too low to include thunder in the TAF. Should see skies start to
clear overnight, with VFR conditions expected to last through
Friday as well.

Sat...VFR. Wind NE 5 kts.
Sun...VFR. Slight Chc SHRA/TSRA afternoon. Wind ESE 5 kts.
Mon...VFR. Wind SE at 5 kts.




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