Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 230359 AAB

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1059 PM CDT Fri Sep 22 2017

Issued at 652 PM CDT Fri Sep 22 2017

Thought about extending the Heat Advisory for metro counties
through Saturday with heat indices possibly in the mid 90s again
and also sultry lows in the mid 70s tonight. However,
temperatures aloft won`t be nearly as impressive as today, there
will be more cloud cover, and the risk of outflows from the west
could negatively impact max heating. Will allow the current
advisory to expire at 7 pm.


.SHORT TERM...(This evening through Saturday)
Issued at 346 PM CDT Fri Sep 22 2017

The surface cold front is knocking on our doorstep late this
afternoon, with the thermal ridge ahead of it producing near-
record temps/dewpoints and attendant widespread heat indices in
the upper 90s to lower 100s across central/southern MN into west
central WI. As the low level jet re-intensifies tonight, expect
showers and thunderstorms to develop over far western Minnesota in
the vicinity of the front. As the front meanders slowly eastward
on Saturday, precipitation chances will inch toward central MN
throughout the day. With precipitable water values also nearing
record values, heavy rainfall will be of concern over western MN
given the front will be nearly stationary. Given east/south
central MN into west central WI will go most of the diurnal
heating period precip-free with decent mixing, expect highs in
the upper 80s to lower 90s. Meanwhile, temps over the western
forecast area will likely only moderate about 5 degrees (into the
mid 60s to lower 70s).

There will also be a small threat for severe storms Saturday
afternoon and early eve given the abundant moisture combined with
deep layer shear progged around 30 knots, although the fact that
the stronger flow aloft is displaced from the frontal boundary,
expect the threat to remain marginal in nature.

.LONG TERM...(Saturday night through Friday)
Issued at 346 PM CDT Fri Sep 22 2017

In the big picture, we`ll see the western trough ever so slowly
shift eastward over the weekend, with its associated frontal
boundary grudgingly moving along with it. With the heart of the
thermal ridge a bit farther east and more in the way of cloud cover,
we will be a bit cooler (but still well above normal) on Sunday. The
upper trough will work into the area for the first half of the week,
then we`ll start to shift into northwest flow by the end of the week
as ridging starts to develop over the western US.

Most of the precipitation with the frontal boundary to our west
looks to occur along and west of the front, meaning it will mainly
be the western and northwest portion of the area that will be
impacted through the weekend. We could see some activity as far east
as the Twin Cities metro, but it would be limited, with most of the
weekend looking dry from near I-35 eastward. The front will finally
move eastward Sunday night and Monday, bringing its shield of
showers and some embedded thunder along with it. We should see
precipitation end from west to east Monday night and Tuesday as the
frontal boundary moves into the eastern Great Lakes and high
pressure works into our area. Things look mainly dry through the
remainder of the week with temperatures near or slightly below
normal. The main chance of any precipitation after Tuesday looks to
be Thursday into Friday when we`ll see a cold front bring a
reinforcing shot of cold air, then wind up beneath the upper cold
pool while cyclonic flow lingers over the area.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1059 PM CDT Fri Sep 22 2017

VFR conditions expected through the period, except at AXN where
MVFR and possibly IFR cigs arrive behind the cold front late
tonight and Saturday. Thunderstorms will become more numerous
across western MN this evening, impacting only AXN. Wind shear
will develop mid evening with a strong 50+ kt jet streak around

KMSP...VFR expected. TS/SHRA activity expected to stay to the
west through Sunday.

Sun...Mainly VFR. Slight chance MVFR/TSRA. Winds SW 5-10 kts.
Mon...MVFR/TSRA. Winds S 5-10 kts.
Tue...Chc MVFR/TSRA early. Winds NW 5-10 kts.




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