Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 222116

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
416 PM CDT THU SEP 22 2016

.SHORT TERM...(This evening through Friday)
Issued at 415 PM CDT Thu Sep 22 2016

Warm front this afternoon has made it down to about I-80 in Iowa. It
will begin lifting back north tonight. This will maintain the cloud
cover overhead through the night and the day on Friday, but precip
fortunately looks to be lacking. There are a couple of reasons for
this. One, we have building heights at h5. Two, the 925-850 winds
will be diverging over the region with a weak segment going from
Iowa toward southern WI and the main push going from the eastern
Dakotas to the western Dakotas. This 925-850 setup looks to stay
with us through the day on Friday with the models showing their
primary focuses for precip through Friday across northeast Iowa into
southern WI and way out in the northern high Plains. As a result,
cut back considerably on PoPs tonight through Friday, with most of
the area remaining dry through the short term. Isolated activity in
the form of mostly showers as opposed to thunderstorms, is looking
to be the best we see as the boundary lifts back north.

.LONG TERM...(Friday night through Thursday)
Issued at 415 PM CDT Thu Sep 22 2016

We will finally get the upper trough to our west out of here by the
end of the weekend, but until then we`ll have a few more periods of
precipitation with which to contend. It appears most activity will
be to our north Friday night with the warm front and better
isentropic lift located there, although some low PoPs for part of
the area are still warranted. The western upper trough will start to
shift east on Saturday, helping the surface low lift north to near
the North Dakota/Canada border and push the cold frontal boundary
east toward Minnesota. We should see fairly SHRA/TSRA develop in a
north-south axis across the area during the afternoon as some upper
divergence and DPVA work into the area and help take advantage of
decent moisture and some instability. Although the cold front will
certainly not be a fast mover, it should move quickly enough to
avoid any widespread flooding issues. But, any additional
precipitation will certainly be problematic at this point, and it
looks like we could have some areas with over an inch of rain from
Saturday afternoon through Sunday morning, and it will unfortunately
be over the central and eastern portion of the area which has seen
substantial rain of late. The cold front will push east of the area
by Sunday evening, but we will then have the upper low and low level
cyclonic flow linger into Tuesday. So, although the widespread
precipitation will be done, we`ll likely see scattered showers
Monday into Tuesday with cool temperatures. Things then dry out and
start warming up for Wednesday and Thursday as the upper low shifts
east and a surface high and rising heights work into the area.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 123 PM CDT Thu Sep 22 2016

Main question this period is how much influence will dry air from east
winds emanating from a Hudson high influence the area. The hrrr
is the most aggressive with pushing MVFR or lower cigs southwest
of the MN river, with most terminals going vfr late this afternoon
and remaining there through much of the night. SREF probs are
similar as well. Was not quite that aggressive with the TAFs, but
did introduce significant VFR periods to WI terminals who will be
closer to the high and was conservative with keeping IFR
conditions tonight confined to RWF. Also kept TAFs dry, with most
models indicating we`ll see two focused areas of precip through
Friday morning. One down toward northeast IA into southwest WI and
the other way back in the western Dakotas.

KMSP...CIGS are the main issue here. We may see a passing shower
Friday afternoon as the warm front lifts back north, but this TAF
period is looking to bring a much needed 30 hour break from
precip. For CIGs, LAMP maintains an MVFR cig the whole period,
which is plausible, but the SREF and HRRR have MSP going VFR
tonight. Of course we could always head the other direction as
east winds are a favorable direction for getting low CIGs, which
is why we split the difference for now and went with a low MVFR
cigs returning tonight.

Sat...VFR with MVFR/TSRA likely late. Wind SE at 10g15kts.
Sun...VFR. Wind W-SW 10g20kts.
Mon...Chc mvfr/-shra. Wind SW 5-10kts.


.MPX Watches/Warnings/Advisories...


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