Wisconsin Weather

Heavy Rain Possible this Weekend Across Wisconsin

Friday PM, Saturday, and Sunday will bring multiple rounds of rain and storm activity to Wisconsin. There is disagreement on exactly where the heaviest rain will fall. It will depend on where each individual cluster of rain lines up. I think 2-4" is a realistic possibility for portions of Wisconsin by early Monday morning. Let's discuss what we know so far:

Long Duration Slow Moving Storm

A low pressure system will push multiple waves or precipitation over the warm front thru Saturday. Then finally on Sunday the low arrives and passes through. This low pressure system is well organized and paired with good upper level support.

NAM simulation of multiple rain chances between Fri PM and Sunday from tropicaltidbits.com
NAM simulation of multiple rain chances between Fri PM and Sunday from tropicaltidbits.com

GFS Latest Prediction

The GFS is the lowest of all rainfall predictions through the weekend. It appears to be on the low end compared with other models but demonstrates the widespread coverage.

12GFS rainfall accumulation simulation. This model is the lowest of all simulations and practically an outlier prediction.
12GFS rainfall accumulation simulation. This model is the lowest of all simulations and practically an outlier prediction. Image from pivotalweather.com

NAM Latest Prediction

The NAM is much wetter across southern & central WI with locally 4-5". I'm betting there is a bit too much convective contamination(overdoing t-storm activity). But this is essentially the upper bound.

12NAM rainfall simulation showing what can happen if rainfall clusters align over the same areas. 4-5 inches locally.
12NAM rainfall simulation showing what can happen if rainfall clusters align over the same areas. 4-5 inches locally? Image from pivotalweather.com

WIWX Heavy Rain Prediction

With the big difference in model simulations right now it wouldn't be possible to say exactly how much rain will fall by city. So instead I've broad-brushed an area I think is most at risk to get you on the right preparedness level. Just know there will need to be some adjustments in the coming days to fine-tune things!

Rainfall forecast for Friday PM, Saturday, Sunday. The system finally ends Monday AM.
Rainfall forecast for Friday PM, Saturday, Sunday. The system finally ends Monday AM.

This will be a long duration taking place over 2.5 days with some breaks here and there. Thus I'm not expecting a major impact right now in terms of major flash flooding. I expect there will be swollen streams, runoff, and some street flooding. We have time to take a conservative approach. If mother nature decides to follow the NAM simulation path then you will be prepared. The key thing is - no surprises! I will send out storm alerts on Friday once we've hopefully zeroed in on the details and location a little more.

Snow Chance North Sunday?

NAM and European models are hinting at snow chances in the far north on Sunday? It's pretty late in the season and these are early forecast simulations. Let's see how things evolve over the next couple days.

For more information, see our members only discussion for this event.

Thank you and stay tuned!

~ help spread the word~
  • Create
Write post here...
Sign in or register to join the conversation!
© 2019 Wisconsin Weather Group | All Rights Reserved
v8.21