Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 200514

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1214 AM CDT Thu Jul 20 2017

.UPDATE for 06z aviation discussion below..


.SHORT TERM...(This evening through Thursday)
Issued at 424 PM CDT Wed Jul 19 2017

Ongoing severe MCS will exit to the southeast quickly late this
afternoon. The forecast then becomes quite uncertain for this
evening and overnight with convective redevelopment possible
across central Minnesota. The atmosphere seems to be recovering
somewhat across South Dakota and there have been a few cells over
west central MN this afternoon. The HRRR would imply an east-west
line of storms developing between 02-03Z across central MN and
progress southeast for the rest of the evening into the early
overnight hours. This activity would contain a large hail threat,
although some damaging wind gusts are also possible. The biggest
threat will be heavy rainfall with training cells, but CAMs seem
to keep the line progressing southward which would limit flash
flooding potential.

.LONG TERM...(Thursday night through Wednesday)
Issued at 445 PM CDT Wed Jul 19 2017

For the extend, we`ll see our zonal flow transition over to
northwest flow this weekend, before going back more zonal by the
middle of next week. Most concerning period looks to Thursday night
into Friday, when another round of severe weather and heavy rainfall
looks possible.

Our dry weather Thursday will be short lived as moisture quickly
returns Thursday night from Nebraska toward southwest MN. Most of
the guidance is in agreement with an elevated band of thunderstorms
working into southwest MN. This will push the warm front back into
southern MN Friday afternoon, and guidance is in good agreement on
storms firing off along this front and heading southeast toward
Chicago Friday night. Some discrepancies with how far north this,
but we followed the more southern solutions for QPF Friday, like the
GFS for Friday as what are seeing today has tracked south of even
what the southern models had. Moisture, instability, and shear
parameters all look similar to what we are seeing today, so all
modes of severe weather will be possible, but upscale growth to an
MCS looks likely, probably tracking from south central MN over
toward southern lower Michigan.

For the weekend, it is looking up weather wise, as a secondary
shortwave in the increasingly northwest low drops across northeast MN
toward the U.P. of Michigan, with the majority of activity Saturday
night into Sunday staying off to our northeast.

We`ll have dry weather to start next week, but by Tuesday, moisture
will be surging back north across the Plains, with thunderstorm
chances returning Tuesday night into Wednesday as a front works into
the area.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1215 AM CDT Thu Jul 20 2017

Still have WAA wing of convection from the metro east into
western WI. This may linger much of the night. Some convection to
the southwest as well...and there is an outflow boundary that
developed from the earlier convection around the metro...that
worked to the KMKT area. This may interact with the southern
activity during the night and if this did develop further would
impede some of the better WAA into the eastern area. Expect some
MVFR cigs and some BR to develop over the central areas during the
night as the convection moves east and lower levels remain nearly
saturated. THis should all burn off through 13z with some high
clouds around into Thursday evening. Winds will be generally n-ne
during the period generally less than 10kts.

Could still see a threat of thunder through 07z-08z but most HIRES
solution exit it to the est and south. Still could see some MVFR
cigs and BR in the wake of the system but should become VFR
through 13z Thu.

Fri...Mainly VFR. -SHRA/TSRA likely. Winds SE 5-10 kts.
Sat...Mainly VFR. Chc MVFR in -SHRA/TSRA. Winds lgt and vrbl.
Sun...VFR. Wind NW 10 kts.


WI...Flash Flood Watch until 6 AM CDT early this morning for

MN...Flash Flood Watch until 6 AM CDT early this morning for



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