Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 251113

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
613 AM CDT Sun Jun 25 2017

.UPDATE...For 12z Aviation discussion below


.SHORT TERM...(Today and tonight)
Issued at 341 AM CDT Sun Jun 25 2017

Another shortwave drops across the Great Lakes today, although it
will be a bit weaker with a farther northeast track as compared to
Saturday`s wave. Therefore do not expect the threat for hail again,
and the prevalent convective mode points toward more of a shower
nature than thunder. Have therefore kept the thunder mention to
isolated and restricted mainly to the afternoon hours.

Today will be different in that we will start off with a stratus
deck overhead (instead of sunny at daybreak with diurnally-driven
stratocu development). Do expect peeks of sun by afternoon, with
cloud cover more correlated with shower activity. Scattered showers
over northern MN will sneak into central MN (north of I-94) this
morning, sliding into west central WI by early afternoon (when
isolated/embedded thunder will also develop). Another weak impulse
will generate isolated to scattered activity to the west along the
MN River Valley into eastern SD.

Temperatures today will be around 15 degrees below normal, mainly
topping out in the low/mid 60s. Lows tonight will follow suit, and
dip into the 40s across most of the area, excepting downtown

.LONG TERM...(Monday through Saturday)
Issued at 341 AM CDT Sun Jun 25 2017

The longer term looks similar to the past few days, with the
primary item of concern being the shortwave trough and associated
surface features that will impact the area during the Tuesday
night through Wednesday night time frame. There have been some
changes beyond that time frame, with today`s runs all looking less
bullish on re-developing a western ridge and re-establishing
northwest flow over our area toward the end of the period.
Solutions now seem to favor more of a zonal pattern across the
northern tier of the CONUS from late week into the weekend.

A ridge of high pressure will be building in from the west on
Monday, but it looks like we should still have sufficient lapse
rates and low-level cyclonic flow for some lingering diurnal
shower activity over the eastern part of the forecast area.
Ridging then looks to keep things dry through the day on Tuesday,
but warm advection will markedly increase by Tuesday night. The
850 mb theta-e ridge looks to work into the area from west to east
Tuesday night in conjunction with strong warm advection, which
should lead to widespread shower and thunderstorm development with
things getting to the I-35 corridor or so by Wednesday morning.
There may be some potential for severe weather overnight Tuesday
night into Wednesday morning given forecast MUCAPE AOA 2000 J/Kg
and effective shear likely AOA 35 kt for portions of the area. The
main concern would be hail given mainly elevated convection, but
winds could be an issue if an MCS of sufficient size develops.
Residual cloud cover during the day on Wednesday will likely keep
temperatures in check, although they should still get back up to
near normal. The cold front looks to push through the area late
Wednesday afternoon and evening, and although there should be
sufficient forcing for additional shower/thunderstorm activity, it
remains to be seen if the atmosphere can recover sufficiently for
any severe weather potential after the precipitation earlier in
the day. We look to dry out behind the front Wednesday night.

Things won`t be too much if any cooler behind the front on
Thursday given a fairly zonal flow and little push of cold air
(along with more in the way of sunshine). A surface low looks to
work east along the main baroclinic zone to our south later
Thursday into Friday, with the GFS, ECMWF, and Canadian models all
indicating an inverted trough extending north through our area.
This would provide another period of higher PoPs with showers and
thunderstorms Thursday night and Friday, with perhaps some spotty
activity persisting into Saturday as another weak shortwave trough
moves through the region.


.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 614 AM CDT Sun Jun 25 2017

An area of MVFR level clouds will drift across the sites this
morning, and shift eastward to primarily affect west central WI
this afternoon. Within that area, a sub-1500 ft deck exists, which
will affect KSTC-KRNH-KEAU and possibly KMSP as well this morning.
Ceilings improve this afternoon as the lower clouds shift east.
Expect most sites to be VFR by early afternoon. Vicinity shower
mentions have been included at KRNH and KEAU, but could near the
eastern fringes of KMSP. Northwest winds will increase this
morning, with 15-18 knots sustained and gusts to around 25 knots

MVFR cigs will prevail this morning. Ceilings will be primarily
2000-2500 ft, although there is a pocket of lower clouds circa
1500 ft that could briefly affect MSP this morning at times.
Currently expect the showers and isolated thunderstorm activity to
stay to the east of MSP.

Mon...VFR. Winds NW 5-10 kts.
Tue...VFR. SHRA/TSRA late, with MVFR cigs. Winds S 5-10 kts.
Wed...VFR/MVFR. Periods of SHRA/TSRA early. Winds SSW 10-15 bcmg W.




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