What is "a developing tornado"

[rdale]

there were alot of tornado reports from the storm

Just to clarify - per the reports there were no tornadoes logged from that warning... There was an unrelated police report of a tornado with no damage on a separate cell in the county, but nothing from the warning I'm asking about.

And again it wasn't supposed to be a big deal. I asked what people think a 'developing tornado' is and consensus appears to be unreachable ;>

In my mind the NWS should report exactly what the spotter sees, but feel free to disagree.

 

[Jason Boggs]

I tell you what, the best instance of a "DEVELOPING TORNADO" that I have ever seen was over the town of Stinnett yesterday. In the 10 years of chasing for me, I have never seen such rapid tornadic rotation without actually producing a tornado. That tornadic wall cloud was very low to the ground and the use of developing tornado terminilogy would have fit perfectly. I don't care what anybody says, there was a developing tornado with that storm, it just never FULLY developed. I say that any funnel is a developing tornado. Now, whether it fully develops or not is another story.

 

[Danny Neal]

A few simple changes to the text can solve this dispute.....

OLD: "XXX indicates a developing tornado"


OR

SOLUTION: "XXX indicates a rapidly rotating wall cloud producing a numerous funnel clouds....a tornado may be imminent" / "XXX radar indicates a T-storm capable of producing a tornado" Its never a bad thing to be overly specific. Although when typing up the warnings I suppose you need to be as quick and precise as possible.

I guess using the phrase "indicated a developing tornado or spotters indicate a developing tornado" is such normal terminology that most people don't think too much into it. Although like numerous people have elluded too that could mean mid level/low level/funnel/actual dust whirl.

 

[Darren Addy]

I think it is worth noting that Greensburg was wiped out less than three weeks prior to this "event". In the wake of an F5, multiple fatalities, and the highly publicized destruction of a County Seat - even with the superb warning time given by the DDC office — I think that we can forgive NWS employees who may err on the side of caution and passing along any information that might lead to someone's life being saved. I doubt that there is time for a tremendous amount of debate and filtering, under the circumstances.

Certainly we can argue that if the public is going to take warnings seriously, we can't OVERPLAY events either (desensitizing them), but let's not forget how fresh Greensburg is in the minds of (not just the public) but the people on duty in the NWS offices across the country.

 

[David Drummond]

I tell you what, the best instance of a "DEVELOPING TORNADO" that I have ever seen was over the town of Stinnett yesterday. In the 10 years of chasing for me, I have never seen such rapid tornadic rotation without actually producing a tornado. That tornadic wall cloud was very low to the ground and the use of developing tornado terminilogy would have fit perfectly. I don't care what anybody says, there was a developing tornado with that storm, it just never FULLY developed. I say that any funnel is a developing tornado. Now, whether it fully develops or not is another story.

Actually it did go ahead and produce after it moved off NE of Stinnett. I managed to get part way down a backroad there and got a glipse of the edge of it, which looked to be pretty large, for about a minute before it disappeared into the rain.

As as certian fire chief I was was under once told me, "...when it comes to protecting people, it's better to overreact than to undereact."

 

[scott r currens]

Remember that a tornado is the wind, not the cloud. Funnel clouds touch down but tornadoes do not. A low-level circulation becomes a tornado when it contracts to the point that the wind speed reaches EF-0 criteria. Sometimes that involves condensation/debris at the ground, sometimes it does not. If condensation/debris is not present at the ground then visualy it is impossible to really know exactly when the circulation is strong enough to be considered a tornado. I say "developing tornado" when I strongly suspect that a circulation has reached EF-0 (65-85mph winds) but I don't have conclusive evidence. Many times this strong circulation “Developing Tornadoâ€￾ does not develop a debris cloud or condense to the ground before it weakens, other times it does. In my mind this is a bigger threat than your average rotating wall cloud, so I would report it as a possible or developing tornado.

I know what I have written is somewhat confusing so please view the following video clip to see what I mean by “developing tornadoâ€￾. It is a long clip that goes back and forth between three tornadic circulations. The middle circulation is the one that applies to this discussion. It's low hanging cloud mass had strong rotation for 10 minutes before it ever condenced to the ground.

http://www.violentplains.com/video/ScottCurrens20070423b.wmv

 

[Mikey Gribble]

The example Scott posted is exactly what I was talking about. That is just as likely, if not more likely, to become a tornado as any funnel is and reporting it as a rotating wall cloud would be an understatement. Lots of tornadoes form before there is a recognizeable funnel coming down from the cloud base. In circumstances like this I think calling it a "developing tornado" is accurate and appropriate. When you see rapid rotation and vertical motion that close to the ground it is more than likely going to become a tornado and reporting it as a "rotating wall cloud" just doesn't convey the seriousness of the situation.

 

[Kory Hartman]

Warning Dissemination

Various lines from the 1998 Spencer, SD NWS Asssessment:

(Keep in mind this was 9 years ago, before I-pods, satellite radio, and 800 DirecTV channels... and before additional wx radio transmitters were commissioned):

From all accounts obtained by the Service Assessment Team, the dissemination of critical severe weather information through the commercial media was excellent. Most of those in Spencer who were aware of warnings and ongoing severe weather received information through the commercial media. Sioux Falls television stations and two commercial radio stations in Mitchell were mentioned most often by those interviewed, however, other radio stations in the area, including those in Sioux Falls and Yankton, also played valuable roles in disseminating warnings.

The cable television provider for Spencer has 95 subscribers in town, however, there was no cable override system for local emergency management access.

Several residents of Spencer who knew the radio frequency used by local storm spotters kept themselves informed on the approaching tornado by listening to the spotter traffic on a scanner.

The NWR coverage on May 30 was not adequate to ensure reliable reception of severe weather information on standard, home-use receivers in Spencer.

In spite of the devastation inflicted on Spencer, many residents obtained sufficient warning information through media sources or by first-hand observation and avoided death or serious injury by taking appropriate precautions. There was, however, a significant segment of the small population who remained uninformed until the destruction began. With the volunteer fire department siren not functioning and the nearest NWR station essentially out of range, the only practical, readily available sources of warning information for most Spencer residents were television and commercial radio.

The Spencer tornado occurred when many people were watching television. Viewers in Spencer who were tuned to a Sioux Falls station were provided information on the 8:12 p.m. Tornado Warning for northern Hanson County and the 8:32 p.m. Tornado Warning for northern McCook County.

Residents who heard some type of warning in time to take precautions indicated Sioux Falls television stations or commercial radio stations as their source of warning information. Several residents of the area cited two radio stations in Mitchell, which included listener reports with warnings from NWSFO Sioux Falls.

 

[Gabe Garfield]

Just to clarify - per the reports there were no tornadoes logged from that warning... There was an unrelated police report of a tornado with no damage on a separate cell in the county, but nothing from the warning I'm asking about.

What reports are you looking at? From SPC Storm Data:

TORNADO:
0343 15 W LIPSCOMB LIPSCOMB TX 3623 10054 (AMA)

I saw the "developing tornado" that was spoken of in the warning. It eventually became a large multiple-vortex tornado.

I will reiterate Dan Dawson's post: it was a tornado.

Gabe

EDIT:
FWIW, I agree with rdale. It's very ambiguous language and should be made more clear.

 

[rdale]

What reports are you looking at? From SPC Storm Data:

TORNADO:
0343 15 W LIPSCOMB LIPSCOMB TX 3623 10054 (AMA)

I saw the "developing tornado" that was spoken of in the warning. It eventually became a large multiple-vortex tornado.

The warning I was referring to said a "developing tornado" was 14 miles southwest of Lipscomb at 0333Z and moving northeast at 25mph, so a tornado at 0343Z 15W of Lipscomb wouldn't match up. The SVS issued during the warning said that the initial storm dissipated but a new cell formed west of Lipscomb...

 

[Joe Zemek]

Referencing the Tornado Emergency discussion, do the terms "funnel" and "low level mesocyclone" carry sufficient semantic power to motivate the public to take precautions when they as a group have become comfortable with severe weather warnings in general? Though the phrase "developing tornado" is technically incorrect, everyone seems to grasp it intuitively as a situation involving strong low level rotation. If I were to use the phrase "developing tornado" I would probably mean "descending and intensifying funnel cloud" or "intensifying rotation in low wall cloud."

How about the word "potential"? It doesn't imply that a tornado must form, only that it seems likely to observers. It's not as strong a word.

potential-->imminent-->developing-->actual

(this scheme ignores "possible" which is already used in situations where poor visibility may conceal an actual tornado--a Schrodinger's Tornado, I suppose ).

In a situation where a persistent funnel or rapidly rotating wallcloud hovers above the surface with no spotted debris cloud, those in the area face a threat which is probably best described to them as a developing/imminent tornado. As others have said, better err on the side of caution.

 

[Mike Kruze]

Certainly we can argue that if the public is going to take warnings seriously, we can't OVERPLAY events either (desensitizing them), but let's not forget how fresh Greensburg is in the minds of (not just the public) but the people on duty in the NWS offices across the country.

EDIT: I just realized that I posted this as Mike Kruze. This is Joe Nield. I am using his laptop as we are driving near OKC to visit a friend in Norman.

Actually, sociologic research has found that, by and large, the "cry wolf" syndrome does not exist. Everyone essentially goes through a five step process that determines their reaction to a warning, and this occurs, almost without fail, every time a warning takes place, regardless of the number of previous warnings or prior false alarms. The steps (and I am paraphrasing):

1) Receive the warning
2) Understand the warning
3) Verify the warning (go outside, turn on tv/radio, call a friend)
4) Personalize the warning (feel that you are threatened)
5) Take action.

As I said in the Tornado Emergency thread a couple of weeks ago, this helps depict why response is arguably the most important and, frustratingly, the least controllable link in the integrated warning system chain. That is an entire topic unto itself, however.