Thursday, August 17, 2017

Two Tornadoes Near Freeport Wednesday Evening

The atmospheric setup Wednesday evening was not in favor for widespread severe weather, let alone tornadic storms.  But that's what occurred just a little before 7:30pm Wednesday evening west of Freeport.


It's important to keep in mind that the Quad Cities National Weather Service radar beam, when looking at storms this far east, is not able to view the lowest part of a thunderstorm.  The radar is actually looking at the storm roughly 7,000ft above the surface.  Tornadoes that go 'undetected' on radar don't happen very often, but if they do, the tornadoes are usually fairly weak.  That's because strong tornadic thunderstorms have noticeable rotation not only at the lowest part of the storm, but also at the mid-levels.


The storm that moved near Freeport Wednesday evening had very little, if any, lightning detected with it.  What little rotation that was showing up was extremely weak and did not indicate that a tornado was going to, or in the process of, forming.  What likely happened Wednesday evening was the rain interacted with an approaching warm front in such a way that it allowed rotation to occur in the atmosphere, causing two brief spin up tornadoes.  Any stronger rotation may have very well formed below where the radar was viewing the storm.  This is why having trained weather spotters and 'ground truth' are so important to meteorologists.  It allows us know and verify what is occurring down near the surface.


Below are the findings from the damage survey from the National Weather Service:







First survey tornado path:
Rating: EF-1
Peak wind: 90 mph
Path length: 2.84 miles
Path width: 75 yards


This tornado started at 7:21pm 5 miles west/southwest of Freeport and ended around 7:28pm 4 miles west/northwest of Freeport





Second survey tornado path:
Rating: EF-0
Peak wind: 80 mph
Path length: 3.31 miles
Path width: 20 yards


This tornado started at 7:28pm 5 miles west/northwest of Freeport and ended around 3 miles west/southwest of Cedarville.

No comments:

Post a Comment