Latest Outlook to Next ThursdayJune 17th, 2014 at 12:05 pm by Chad Evans under Chad's WLFI Weather Blog
What is left of derecho is now in northern Michigan & Ontario with a few left-over showers near South Bend.
Thankfully, it stayed north & northwest of our northern counties overnight.
What a history it has had! From gust of 96 mph near Sioux Falls, South Dakota to gusts of 85 mph in Minnesota. Gusts over to 75 mph were measured in the Des Moines, Iowa area to significant damage in southern Wisconsin this morning to now Tornado Warnings in northern Michigan.
Widespread wind damage has been reported from northwest Illinois with many highways closed due to fallen trees & power poles/lines. Trees are also down in Milwaukee, Wisconsin.
Chicago appears to have escaped the brunt of it, but the northern suburbs to Wisconsin were hit.
The Canadian Weather Service (Environment Canada) has Severe T’Storm Watch out for southern Ontario for it as it is now nearly out of the U.S.
Isolated monster supercell that pop south of the derecho produced these twin wedge tornadoes in Nebraska yesterday evening:
It is already a hot day with humid conditions. We are capped as of 1 p.m. like a boiling pot on a stove. It is very unstable with up to 4000 J/kg of surface CAPE in the viewing area, but there is also CINH (cap).
If a storm could burst through, it looks like it could go severe (hail wind), given such instability with decent shear around.
So, again, for us today, we are capped & hot, but outflow boundary is laid across area from derecho to our north this morning. That said, if any storm would happen to pop through the cap it would be on that outflow boundary (again, could go severe if one can pop through). So, an isolated storm or two is possible today with 20% coverage. Highs of 90-93 are likely with heat indices of 96-101. However, the strong south to southwest wind to 35-40 mph will help to add at least some comfort.
It appears a new cluster of storms may form in northeastern Iowa/southeastern Minnesota/southwestern Wisconsin this evening. This will not be a true derecho, but it may evolve into an MCS or a complex of storms.
This could affect our areas along & of U.S. 24 by late tonight-tomorrow morning with a damaging straight-line wind threat. We will continue to monitor this.
On its outflow boundary, despite capping, a few storms may pop through the lid tomorrow afternoon-evening. Shear will be such that any storm could go severe with a wind, perhaps hail threat. However, this is only if the storms can pop through the cap.
Storms are possible Thursday & Friday. Although dynamics/shear will tend to be north of our area, popping storms’ outflow boundaries may form cold pools that form lines/clusters of storms with a few scattered severe wind gusts in our area. Unstable airmass may cause at least a few hailers.
Storms are possible Saturday & Sunday. Again, since main dynamics/shear will occur well north of the area, storms will only organize with their outflow boundaries/cold pools. Otherwise, the they will be more multi-cellular & pulsey. However, storms than can really pulse up &/or really organize would have potential of a few severe gusts, perhaps some hail.
Monday-Tuesday looks dry with highs in the 80s, lows near 60 to the low 60s after a stretch of upper 80s to lower 90s & lows near 71 this week & into the weekend.
Storms are possible again by next Wednesday-Thursday with hot & humid highs near 90 with lows near 72.