Posted at: 06/21/2013 11:22 AM
Updated at: 06/21/2013 5:01 PM
We had a pretty interesting morning (and the official start of summer) throughout the area, as a Mesoscale Convective System (a large cluster of strong/severe storms, MCS for short) developed across NW MN, tracked SE through the Twin Cities, and had enough strength to reach us in SE MN and northern IA. That was round one of severe weather. Several more rounds of severe weather is expected later today, lasting through the weekend. Here's the breakdown...
Friday afternoon: Skies clear up a little this afternoon/early evening. Sun comes out for a little bit, before more storms fire up in the eastern Dakotas once again later today, getting here later this evening.
Friday night: Models still disagreeing with one another as to exactly WHEN storms fire up and WHERE. Current thinking is it will be earlier than last night’s event, with the possibility of a couple rounds of strong/severe storms. Could see a few fire up shortly before 7 pm in SW MN, advancing east, with another round coming our way between 10-3 pm (earlier, but very similar to last night’s). We will be watching the eastern Dakotas very closely here over the next several hours, to see if any thunderstorm activity does indeed develop for that first round. If it doesn’t, it still looks like overnight strong/severe storms will be possible. Strongest of the overnight storms look to rock the Twin Cities area once again. Hail/strong wind/very heavy rain all the threats once again this afternoon/evening/tonight/Saturday morning. And just like today, the storms clear up by midday Saturday.
Saturday: Forecast confidence still up in the air for Saturday afternoon storm chances. One model solution has storms firing up farther north, the other has them firing up for us. Overall thought is to keep the chance there for more storms to fire Saturday night (10 pm and on) into Sunday morning. The later forecast models should have a better handle on it with the afternoon/evening model runs.
Sunday: Forecast models are still differing with one another for Sunday’s storm chance, in regards to position of storms. Have a slight agreement that they will be a Sunday night/Monday morning event…once again. Hail/wind/heavy rain all being the main threats.
Flooding Potential: This morning’s round of storms produced (reports so far as of 10 a.m.) between 0.25” – 1.25” throughout the area, with radar estimates in the 2”+ range across Winnebago, Worth, & Freeborn Counties. With a few more nights of storm clusters possible, heavy rain will continue to be likely. I can’t rule out up to 5” (2 night storm totals) possibly by Saturday morning in some areas. Some locations are pretty saturated after this morning, so a few locations will have to worry about Flash Flooding, but not everyone.