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Wisconsin Weather

OCT 22, 2020 | Heavy Rain, T-storms, and Snow Today

LAST UPDATE : OCT 22, 2020

THU 12:34PM - No changes.

WEDS - 12:00PM - Looking at the 12z model run (less ECMWF). The short range models show plenty of rain, t-storm/convective activity over southern Wisconsin...further south than the medium range models (GFS,EC). As a result I expect moisture flow to be delayed and probably not working into the system the way said med range models suggest. Confidence is low, consistency is just ok, and models are trending slightly south run to run. Preferred to take a conservative approach on the snow predictions.

NORTHERN WI - With main moisture surge coming up through the eastern side of Wisconsin and best banding into NE Minnesota, I predict northwest Wisconsin will tend to under-perform on snow amounts. Perhaps even a dry slot or emptiness in reflectivities as suggested by short range models. I went 3-6" up along the Lake Superior region...best chances across western Upper Michigan as rain transitions to snow THU PM. GFS goes big but I don't believe it yet.

SOUTHERN WI - Two or three periods of rainfall - starting THU AM - will bring 1-2" with a band of 2.0-2.5"ish *somewhere*. Narrow zone and consistency wasn't good enough to zone it in on the maps. The heaviest amounts depend on exactly where t-storm activity trains during the afternoon & evening and relative to morning period of rainfall. Again GFS/EC further north...I like the short range further south solutions.

NMMB 12z rainfall prediction for Thursday 10/22.
NMMB 12z rainfall prediction for Thursday 10/22.

TSTORMS THREAT - Have to assume early day t-storm/rain activity in southern WI will delay northward push of the elevated warm front. Redevelopment likely to be somewhere over southern WI again THU afternoon. NAM high res is interesting but preferred the other short range models collectively. Expect small hail with any thunderstorm activity. With very cold/stable boundary layer negating most other threats and bulk of instability above 500mb, weak low level thermodynamics. The surface warm front will make it close to the WI/IL border. Unlikely this setup comes together with forcing along the elevated warm front further north, storm motion perpendicular to the surface WF.

NEXT UPDATE - THURSDAY AM (by late AM)

Forecast Maps

Storm Details

Hazards
T-Storms, Snow, Heavy Rain
Start
THU 12:00 AM - Oct 22, 2020
End
FRI 6:00 AM - Oct 23, 2020
Confidence Level
Storm Class

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