Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 130019

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
719 PM CDT Tue Sep 12 2017

.Updated for 00Z Aviation Discussion...
Issued at 715 PM CDT Tue Sep 12 2017


.SHORT TERM...(This evening through Wednesday)
Issued at 1248 PM CDT Tue Sep 12 2017

Quiet weather continues across the region, as high pressure
maintains control across the upper midwest. The northern stream
jet is well to our north with zonal flow and plenty of warmth
across the region with the jet to our north. Increased wind speeds
mainly in western and central MN through the afternoon as deeper
mixing is achieved and gusts around 15-20 knots is likely in
western MN.

Expect dry conditions tonight for most of the area but a
developing system to the west with a frontal boundary could send
some decaying showers toward western MN. Expect that most
acitivity will not reach the forecast area. Farther east, clear
skies and light winds will lead to more fog in eastern MN and
western WI.

The thermal ridge leans in even farther tomorrow, so expect a few
degrees warmer than today, possibly reaching 90 degrees in
western MN.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 408 PM CDT Tue Sep 12 2017

A major pattern shift will take place Thursday with a deep trough
developing across the western U.S., and the semi-permanent
western ridge of late finally focusing over the east. Southwest
flow aloft will prevail into the weekend, with the baroclinic zone
nearly stationary from the central Rockies northeast to northern
Minnesota. Multiple waves of energy embedded in the southwest flow
will bring periodic thunderstorm chances Thursday through
Saturday night. Capping will limit the overall extent of activity
due to a dry boundary layer, and focus it where the deeper
moisture tongue will be found across central and western MN. The
best chances will be Friday night with a weakening mid level wave
and Saturday night with the surface front itself. Robust
instability due to very steep mid level lapse rates and a
moistening boundary layer may develop Saturday afternoon across
MN. Sufficient shear in place and decent forcing along the front
could bring a severe thunderstorm risk through the mid evening
hours. A cooling and stabilizing boundary layer will diminish the
severe risk in Wisconsin from late evening onward. Temperatures
through Saturday will average 10-15 degrees above normal, with
highs in the mid to upper 80s and lows in the mid 60s Thursday and

Cooler air follows for early next week before the trough/ridge
pattern reloads during the middle of the week. This should resume
the warmer and wetter pattern into late September.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 715 PM CDT Tue Sep 12 2017

VFR conditions across Minnesota, with patchy dense fog expected to
develop overnight across Wisconsin. Areas in eastern MN, like KMSP
and KMKT could see some fog development also, but confidence is
higher in visby restrictions at KRNH and KEAU. Expect VFR
conditions and southerly winds for Wednesday.

Could see some fog development again overnight, but not
anticipating any visby restrictions. Winds will be southerly and
around 05 kts.

Thu...VFR. Wind S 5-10 kts.
Fri...VFR. Slight chc of SHRA/TSRA. Wind S S 5-10 kts.
Sat...VFR. Chc of SHRA/TSRA late. Winds S 5-10 kts.




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