Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 241130

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
630 AM CDT Sat Jun 24 2017

.Updated for 12Z Aviation Discussion...
Issued at 626 AM CDT Sat Jun 24 2017


.SHORT TERM...(Today and tonight)
Issued at 319 AM CDT Sat Jun 24 2017

Things will be somewhat similar today as they were yesterday,
except there is a stronger shortwave trough working through the
area, so expect to see more widespread showers and some
thunderstorms. The shortwave trough is quite evident in water
vapor imagery, currently dropping southeast through North Dakota,
and has a PV anomaly associated with it that the RAP indicates
down to around 500 mb. There is a band of mid-level clouds already
with this feature, and expect to see some SHRA develop with it
over the next several hours. It should work into the western
portion of the area this morning, then dive southeast through the
afternoon. Scattered showers and a few thunderstorms can be
expected given the large scale forcing and MLCAPE values of
200-500 J/Kg. A quick look at forecast NST parameter values from
the NAM suggest some potential for at least a few funnel clouds
from central/west central into south central Minnesota during the
afternoon hours, which isn`t surprising given the upper low,
associated cold pool, good low-level lapse rates, and pools of
cyclonic surface vorticity with an enhanced surface trough progged
to accompany the upper wave. We should see activity quickly wane
in the evening hours.

.LONG TERM...(Sunday through Friday)
Issued at 319 AM CDT Sat Jun 24 2017

On Sunday, we`ll still have some cyclonic flow in the boundary
layer along with cold air aloft, so some shower and thunderstorm
activity is expected once again, although with ridging starting to
work in from the west, would expect things to mainly be near and
east of I-35 on Sunday. Otherwise, the latter portion of the
forecast period still appears to be most interesting around
midweek when we`ll see the eastern trough shoved east while a
shortwave ridge and pronounced warm advection work into our area.
This looks to be followed by a brief period of westerly upper flow
before the western ridge re-asserts itself and we get back into
northwest upper flow by the weekend. Any lingering showers in
association with the upper low should be confined to the far
eastern portion of the area on Monday.

After that we should have sufficient ridging for dry weather
through the day on Tuesday. However, strong warm advection will
begin to setup Tuesday night as low pressure develops over the
Northern Plains. Expect to see elevated convection develop to our
west Tuesday night and work into the area overnight, perhaps
reaching the Twin Cities metro by Wednesday morning. The ECMWF has
come around more to the GFS and MPAS idea of tracking the main
surface low near the Canada/Minnesota border on Wednesday, with
the cold front moving through during the late afternoon/evening
hours. Given the amount of forcing and elevated instability
expected with the warm advection and moisture surge Tuesday night
and early Wednesday, it currently doesn`t look like we`d recover
too much from that round of showers/thunderstorms to have anything
significant in the way of instability when the cold front moves
through, but it`s a number of days away so certainly should be

A secondary and weaker shortwave trough will push east through the
region on Thursday, but it appears the main baroclinic zone should
be mostly south of our area by then, so PoPs will be confined
primarily across the south. However, a slightly stronger upper
wave looks to work into the area on Friday, which should lead to
more widespread chances of precipitation as the upper flow
transitions back to northwesterly by Saturday.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 626 AM CDT Sat Jun 24 2017

Primarily VFR conditions but a few MVFR showers and thunderstorms
are possible as an upper level shortwave move across the region
today. At this time the best chance for thunder is south of the
TAF sites, but can not rule out a thunderstorm at any location.
Just did not have the confidence to include mention in the TAFS.

Showers should approach the region by late morning. A few
thunderstorms are possible this afternoon, but they will be widely
scattered so did not have the confidence to include mention in
the TAFs at this time. Winds will be northwest with gusts near 25
kts this afternoon, and then tapering off after sunset.

Sun...VFR. Chc MVFR with p.m. -TSRA possible. Winds NW 10-15 kts.
Mon...VFR. Winds NW 5-10 kts.
Tue...VFR. -TSRA possible in aftn, likely late. Winds S 5-10 kts.




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