An NWS storm survey team confirmed that a tornado touched down in McMinnville, OR this afternoon. They have yet to say what rating the tornado was on the F-scale, but there was significant damage to some buildings.
I have heard there is video of the whole thing, but I’ve yet to see it. I will post a link when it comes out. However, I did find this photo of a funnel cloud from Harrisburg, OR this afternoon:
Funnel cloud from Harrisburg, OR today (13Jun2013)
Tornado confirmed and a cool photo of a funnel cloud…in western Oregon no less! Check.
Of course, that’s not enough for me. I like to investigate why these things happen (not surprising, I suppose, since it is my job to forecast these things). Here are the radar images from around the time of the reported tornado in McMinnville:
KRTX 0.5 degree reflectivity valid 13Jun2013/2333Z
The cell that caused the twister is fairly obvious. It had a ~60dbz core which is pretty good, but at this distance from the radar, we are sampling at ~3,700 feet above ground level. In other words: we’re not seeing much, if any, of the portion of the cell that contained the tornado.
The cell also had a **very** weak rotation at that level. Green indicates movement toward the radar (which is located in Portland – toward the upper right) and red is away. The values in there are pretty lame, like 10 knots in each direction, but that rotation is cyclonic. Again, though, we’re overshooting most of it at this range.
Finally, here is the sounding from Salem, OR. It is quite close by and, as luck would have it, taken at right around the same time:
There is some **weak** cyclonic rotation on this sounding as well – notice how the wind barbs show southerly wind at the surface and then it gradually turns toward the west/northwest with height (called veering). It’s also pretty moist in the low levels and there is some very marginal instability.
None of this information screams tornado, and I never would have forecast it to occur based solely on what I’ve seen so far. But it’s not hard to see how it happened in hindsight.
This is yet another learning experience and a pretty unusual and neat occurrence to boot.