Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 110544

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1244 AM CDT Fri Aug 11 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 06Z TAFS through 06Z Friday night)
Issued at 1237 AM CDT Fri Aug 11 2017

Expect stratus out by EAU to remain in place through the rest of
tonight, but will quickly dissipate between 12z and 15z this
morning. Just west of this stratus, winds will begin to drop
overnight and there is potential for fairly widespread dense fog
along the MN/WI border, which could be an issue for RNH. Also for
fog, we are already seeing br/fg in central MN and this may
become an issue at STC, where some vsbys between 1sm and 3sm are
expected in the morning. Also went a bit above guidance for winds
east, as forecast soundings at EAU show some winds in the 15-20kt
range getting mixed down this afternoon. Otherwise, no additional
concerns this period, with a few-sct cu field expected in the 5k-
6k ft range.

KMSP...There will likely be fog in the MN River Valley this
morning, but this is not expected to directly impact the field.

Sat...VFR. Wind light/variable.
Sun...VFR. Wind SE 5 kts.
Mon...VFR. Wind SE at 5 kts.




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