Tuesday, June 22, 2010

Time Lapse, and Tornadoes Tomorrow?

Well here we go, Andrew is gungho again. It's been one of those years. I poo-poo events and they go berserk, and then I finally get gungho about an event and am quickly nailed with a forecast bust. This forecast should be taken for what it's worth considering the above disclaimer!

Tomorrow is really peaking my interest now. I should be sitting pretty here in DeKalb for at least one round of significant severe weather, if not two. The obvious threat, is the potential for significant wind damage across Iowa early, moving into southern Wisconsin and here in northern Illinois thru the early morning hours. It appears this may take some time to organize out west early tonight, but may move into the Mississippi River valley by 4 AM. Associated with the 50 knot H5 trough ejecting out of the northern plains, a long-lived forward propagating MCS appears the likely end scenario with scattered reports of potentially significant wind damage possible likely along and north of Interstate 80. The most likely area to see significant damage from this complex may be along and near Interstate 88 from the Quad Cities towards the Chicago area in the early morning hours.

While some questions still exist, it is appearing increasingly likely that the air mass in the wake of the morning MCS will recover over northern Illinois and southern Wisconsin ahead of the final approaching wave and cold front moving in from Iowa. Shear profiles should be largely unidirectional across most of the warm sector, however given the presence of one or more outflow boundaries and enhanced low level shear along the warm front near the Wisconsin and Illinois borders, a tornado threat should exist early in storm evolution. The most likely area for tornadoes at this time appears to be from the Quad Cities towards Rockford, IL north to Madison, WI. Should the air mass recover enough and significant instability can be realized, given the much stronger speed shear compared to previous days any storm that is able to root to one of the aforementioned boundaries early in evolution may hold a strong tornado risk. That detail remains to be seen and will not be evident until tomorrow afternoon. This risk again would be along the Interstate 88 corridor into southern Wisconsin. It should be noted, that given a sufficient cold pool with early convection, the outflow boundary and warm front may both be shoved further to the south, and the target area for tornado development could shift further towards the Interstate 80 corridor. That will also be determined tomorrow.

As for yesterday's supercell, I did go ahead and upload a brief time lapse showing the at time significant rotation, but then later the storm struggling with it's outflow thus undercutting the updraft and effectively choking off any potential tornadogenesis.

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