Thursday, July 10, 2008

Is it a tornado? Is it a dust devil? No, it's a gustnado!

Interesting phenomena going on this afternoon. The NWS-Memphis has issued a couple of Special Weather Statements (SPS's) alerting the public to the possibility of non-tornadic funnel clouds emanating from airmass, or pop up, thunderstorms. Earlier in the afternoon, one was issued for central Mississipi County, AR, and at 2:56pm, an SPS was issued for SE Fayette County and SW Hardeman County, TN. The NWS wording was "DOPPLER RADAR INDICATED A THUNDERSTORM CAPABLE OF PRODUCING SMALL SPIN UP CIRCULATIONS ALONG A GUST FRONT. THESE SPIN UP CIRCULATIONS MAY FOCUS GUST FRONT WINDS TO SPEEDS NEAR 50 MPH."

Commonly refered to as gustnadoes, this phenomena looks similar to dust devils or funnel clouds in appearance and are typically found along thunderstorm outflows, commonly called gust fronts. It is rare (around here anyway) to see the NWS alerting the public to these, but obviously there are reports of funnel clouds coming in to them. Obviously they are not as destructive as tornadoes and they are also very often short-lived and small in size. Their main distinction from tornadoes is that they are not usually attached the the base of a parent thunderstorm, more often just "spin-ups" along an outflow boundary. For more on gustnadoes, visit the Wikipedia site on them or see this YouTube video.

No comments: