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Wisconsin Weather

SEP 12, 2019 | Strong T-storms Possible with Cold Front Tonight

LAST UPDATE : SEP 12, 2019

Cold front will kick off scattered thunderstorms tonight, traveling northeast through WI overnight.
Cold front will kick off scattered thunderstorms tonight, traveling northeast through WI overnight.

9:00AM THU - No big changes to the outlook(please see previous updates below for more details) I pushed the target zone east slightly so that it touches the Mississippi River area in SW WI. A few storms in NE IA/SE MN could become severe. Again looking at a low grade damaging wind threat for much of Wisconsin given organization and strengthening wind fields.

On the heavy rain potential; really not too concerned about creating new problems. The big message is that it will aggravate pre-existing issues. I think one or two spots could get over 1.5" with t-storm activity. Typically cold front passages not the ideal situation for heavy rain due to it being a moving target. Despite this; not out of the question that moisture will get pinched in or south of La Crosse.

10:15AM WEDS - the morning round is likely to peak west of Wisconsin. During the evening/overnight Thursday I'm highlighting most of Wisconsin for a widespread low grade wind gust threat as the cold front sweeps through. The best instability will remained locked in Iowa. Elevated instability and strengthening wind fields should allow numerous storms to cross through the state. The surface will be cool, but not too cool which should allow wind gusts to cycle down.

JP

PREVIOUS UPDATE - On Thursday a cold front will sweep through the region. It won't make it into Wisconsin until THU night at the earliest. It may not completely pass through until Fri.

Thunderstorms will likely move into Minnesota or Iowa during the morning hours. How far east they get before weakening is not totally certain; but suspect it probably will be near to Minneapolis. In Wisconsin the surface warm front will get pushed south; perhaps south of Dubuque even.

During the afternoon the warm sector and reservoir of instability will build across Iowa/SE MN.Question is how far north can it get? My guess is not far; that the 12K high res NAM is pretty close. As for severe potential; it has all the pieces. Everything in the right spot and at the right magnitude - except for wind shear which is a bit weak for this time of year. My other knock is that the warm sector becomes very tiny 22-00Z and that it wouldn't be hard for early aft convection along the warm front to contaminate it. Mainly a function of that warm front becoming stationary and somewhat reinforced from the northeast.

Thursday PM warm sector and warm front position per the darker shades of red in southern WI.
Thursday PM warm sector and warm front position per the darker shades of red in southern WI.

JP

Forecast Maps

Storm Details

Hazards
Strong Thunderstorms, Heavy Rain
Start
THU 6:00 AM - Sep 12, 2019
End
FRI 3:00 AM - Sep 13, 2019
Confidence Level
Storm Class

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