Wednesday, April 6, 2011

April 7-10 Severe Weather Outbreak: Overview (April 6)

There is a very concerning risk over the West IL and North MO areas this weekend for a severe weather event. At this time, long lived tornadoes, violent tornadoes and extreme severe weather are still on the table.
I am here to asses this situation.

THE SET-UP
In the hours leading up to the outbreak, a disorganized cap will set-up, providing some instability. Contributing more so to the instability will be the advection of warm air into the Midwest Region.
There will also be diverging jet stream winds. When that happens, this means air rising is forcing the jet stream to separate, which is hard to do.
12z GFS data indicates the jet stream will be splitting up, mainly around the areas to the east of the outbreak.
The lower level jet stream will also be present in the area forecasted for the tornado outbreak.
Temperatures will be very high proceeding this event. Below is the forecasted maximum temperatures.


THE TORNADO THREAT
The images about to be posted are from the 12z GFS.

These images are from the Significant Tornado Parameter. It does appear there will be a sudden and intense risk area over the Midwest and Lower Great Lakes.
By analyzing these images, it appears that the jet stream may be the controlling factor in this risk.
However, this far out, it is too unsure to be sure.

INSTABILITY
Another piece to bring up is CAPE values of instability. Below is an image from the 12z GFS of CAPE values.
CAPE values of 4000 are extremely unstable. Anyone within the region of 3000 j/kg and above are in an intense risk of severe storms due to these high values.

THE WEATHER CENTRE'S RISK AREA FOR THIS WEEKEND
The Severe Weather Center page will be under renovations today, April 6, 2011.

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