There were quite a few storm reports in southeast Pennsylvania last week, starting on Tuesday (when I had that awesome lightning storm in State College) and going on through Friday (an unusually long streak for Pennsylvania). There were 79 storm spotter reports and 67 storm warnings issued in Pennsylvania during the four days. This was caused by an unsual amount of warm, unstable air in the region (unusual especially considering how cool the summer had been).

LINKS TO INTERACTIVE MAPS FROM NWS: TUE 18th | WED 19th | THU 20th | FRI 21st

On Thursday, the NWS is showing this photo of a purported funnel cloud in Dauphin County from a TV meteorologist in their report on the Thursday storms:

The photo does look a lot like a funnel cloud, but I've said before you can't determine that from a photo. (Note that they also credit another photo to the meteorologist but this video

credits it to "Billy Shaub").

On Friday, the wind damage report pinpoint (on the map above) west of Carlisle, PA was where my boss' sister's barn (no kidding) sustained severe damage near(technically it's West Pennsboro Township, but townships aren't recognized by online maps). You can see the video of her, and the damage, here.

Was it a tornado? Local residents thought so, because the damage was severe and there was a sound "like a freight train" that you often hear associated with tornadoes. Given all the damage reports over the 4-day period (and what NWS admits were multiple funnel cloud reports Thursday, though they only show one on the map) I'm really surprised they visit the area for multiple storm surveys, which are the only way to guarantee whether or not there really were tornadoes (In a storm survey they typically view the damage from the air to see if there are swirling patterns - if not, it's "straight-line winds" which can do as much or more damage than weak to moderate tornadoes - this NOAA site provides a good illustration of both, and says that hearing a freight train sound could be either).

Here's the radar image when the warning was issued (from IEM Cow), around the time the storm had hit the barn (left blue pushpin).

(maps by Google Maps, data by NWS, annotation by me)DOWLOAD RADAR LOOP | VELOCITY | STORM-RELATIVE VELOCITYCOURTESY PLYMOUTH STATE

I have annotated it to show what I believe to be a "bow echo," where the storm bows outwards in the direction of travel. These are notorious for straight-level high winds, especially near the tip of the bow, where the barn stood. If this is true, that could be evidence that the damage was from straight-line winds. The radar velocity animations also showed rotating winds (a mesocyclone, common in severe thunderstorms) but that could have produced either a tornado or a downburst (which would contain the straight line winds).

Like a typical meteorologist, I have not committed to either theory, and in fact we may never know what tore apart my boss' sister's barn, but nonetheless the damage was done. With his help, they started picking up the pieces this weekend though there is still much repair to be done.

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