Chris Nuttall
EF5
Those are issued in Southern Region offices. It's not specific to Tulsa.
http://www.nws.noaa.gov/directives/sym/pd01005017s052003curr.pdf
Increase in hail size for warning criteria
- Thread starter Andrew Pritchard
- Start date
Those are issued in Southern Region offices. It's not specific to Tulsa.
http://www.nws.noaa.gov/directives/sym/pd01005017s052003curr.pdf
Matt Gingery
Personally, I think that warnings are issued for cells that are capable of producing severe weather. I understand that the entire warned area doesn't usually recieve the full impact of the cell, but sometimes it is difficult to tell where the FFD will be strongest so SPC does the best job that they can in order to cover all the bases. They have recently improved the area warnings as of late. Instead of issuing a warning for the entire county they issue it for the storm base track. In a cyclic cell the updraft is continuously overshooting the tops and being knocked down by the UA winds. As the updraft gets knocked down this sinking motion can produce severe winds and hail. The timing of this happening holds some uncertainty. A cell can produce 70mph winds in one area with large hail, and not match that level for 10 miles, but once the cell cycles again it will once again produce the severe level impact. SPC has many tools at their disposal, and I feel that they really do the best job that they can do with what they have to work with. It is the same with tornadoes in cyclic supercells, they issue the warning and if a tornado ropes out there is still strong rotation in most cases but not always confirmed touchdowns. I feel the warning is designed to warn the public of the potential hazards that should be expected, and in most cases severe weather usually occurs somewhere within the warned area, but not everywhere. Issuing watches is the area that I feel needs more research and development, i.e. convective outlooks, improving models. Given enough time and we always see improvement on a yearly basis.
rdale
EF5
SPC doesn't issue warnings - they do the watches. Local offices issue warnings. And you are correct - the goal is to issue for cells that will produce severe weather, but you can't always reach that goal. Sometimes the severe weather happens first.
Jeff Richardson
EF2
Thanks for the link, that was really informative. I've heard Significant Weather Alerts issued from other offices Southern Region offices in the past. Anyway, was just curious about those advisories and the reasoning behind them. That pdf file explained a lot to me. Thanks!
Chris Bowman
EF0
There are a few offices, at least, in Central Region that utilize the SWA for what they think is sub-severe. I have seen them issued as a "heads up" for a county before a warning would be needed. It's an effective tool for the offices that use them to say yeah that storm is out there, it's being monitored and if needed a warning will be issued.
The increase in hail size to one inch will really reduce the amount of warnings that are issued during pulse thunderstorm events unless the warning person feels that high winds are also a threat. I would have to double check as I don't have the numbers available readily, but I believe, and Rodney pointed this out, that Wichita issued something like 30 to 35% fewer warnings. This has resulted in warnings carrying more weight and the media doesn't need to cut into programing as much.
The increase in hail size to one inch will really reduce the amount of warnings that are issued during pulse thunderstorm events unless the warning person feels that high winds are also a threat. I would have to double check as I don't have the numbers available readily, but I believe, and Rodney pointed this out, that Wichita issued something like 30 to 35% fewer warnings. This has resulted in warnings carrying more weight and the media doesn't need to cut into programing as much.
rdale
EF5
Is it that fast of a process? The public has ignored SVR's for years, and probably has no idea of the increased criteria. I don't think this is an instant sort of thing, it may be too late to catch their attention for a long time yet.
Kiel Ortega
EF4
- Joined
- Jun 9, 2004
- Messages
- 325
While 1"+ hail for SVR warnings might decrease the number of warnings, I think it's important to remember that storm-based/polygon warnings have significantly increased the number of warnings (see below; apologies for the formating). Below are the warnings and verification for FY 2005-2008 in KS (wind speed in kts; penny means reports b/w 0.75 and 1 inch). FYI, 1" criteria were introduced during the FY 2006 (March 2006, I believe). I thought it was interesting that wind verification remained more or less the same even after the 1" criteria and polygon warnings were introduced. However, as you can see the introduction of polygon warnings (FY08), the # of warnings increased greatly. Also, you can see that penny-sized hail reports in KS remained the same (as I understand the directive, KS WFOs were to still collect penny reports), however the number of quarter+ reports nearly doubled. Really, I don't think there will be any significant impact in warnings from adopting 1" criteria, just an increase in # of 1" hail reports.
Year warnings penny hail quarter+ wind: 50 wind: 51 wind: 52 wind: 53 wind: 54 wind: 55 wind: 56+
2005 1559 513 880 27 7 223 7 5 19 320
2006 1667 517 816 19 5 256 13 1 12 440
2007 1299 405 643 24 5 185 7 2 4 218
2008 3192 573 1246 30 11 326 6 6 16 396
Year warnings penny hail quarter+ wind: 50 wind: 51 wind: 52 wind: 53 wind: 54 wind: 55 wind: 56+
2005 1559 513 880 27 7 223 7 5 19 320
2006 1667 517 816 19 5 256 13 1 12 440
2007 1299 405 643 24 5 185 7 2 4 218
2008 3192 573 1246 30 11 326 6 6 16 396
Chance Hayes
Many KS offices had already begun to issue polygon warnings or storm based warnings prior to 2008. I would chalk up the increase in number of warnings to a busier severe weather season. Though I won't argue that an increase in the number of warnings will occur, they will, just not by the amount depicted.
The increase in reports should also correlate with a busier season as well. The KS offices are still required to report any and all 3/4 inch reports that are received.
All posts and thoughts are mine and do not represent any agency or employer.
The increase in reports should also correlate with a busier season as well. The KS offices are still required to report any and all 3/4 inch reports that are received.
All posts and thoughts are mine and do not represent any agency or employer.
Greg Stumpf
EF5
But verification was still county-based during the test period (or so said my source at a CR WFO).
But there will be a lot less "huniting for dimes" since that will no longer be required to verify SVRs. Therefore, there will be fewer <1" reports. Will there be fewer reports overall? Unknown, as the "hunt" may be for nickels now.
Me too!
Mike Smith
As a Kansas meteorologist, far as I am concerned the 1" criteria has been a big success. Would like to see it nationwide.
Greg Stumpf
EF5
I vote for 1.5"-1.62" (golfball), nationwide.
rdale
EF5
It took nearly 20 years, over strenuous objections from USAF & EM, to get 1" into the system. And it's still not nationwide. I'd vote for golf balls too, but we'll be retired before that can happen 
V. Gensini
EF1
I personally think the 1" criterion would better suite the goals of the National Weather Service, as well as cut down the number of "That was a severe thunderstorm?" from the general public. 3/4" hail really doesn't do damage to property unless it is wind driven at speeds over 60 mph, in which case the svr warning verified for damaging wind!
Tim Shriver
EF4
3/4", I think is a good standard.
It is a good indicator that the cell can produce large
hail and has a good chance of producing
even larger hail.
1" is thought to be the beginning size of "damaging hail"
But I also think a hard (not slushy or soft) 3/4" hail
stone with some wind behind it can also do some damage.
If you get enough 3/4" hail you can start seeing some
crop damage.
This is a big concern for farmers etc. and the $$$'s in damage
can add up quickly.
Tim
It is a good indicator that the cell can produce large
hail and has a good chance of producing
even larger hail.
1" is thought to be the beginning size of "damaging hail"
But I also think a hard (not slushy or soft) 3/4" hail
stone with some wind behind it can also do some damage.
If you get enough 3/4" hail you can start seeing some
crop damage.
This is a big concern for farmers etc. and the $$$'s in damage
can add up quickly.
Tim
Steven Williams
EF2
I agree with Tim, 3/4" hail can be damaging to cropping, especially if there is some wind behind it. Horticultural crops in particular are very vulnerable to damage to hail of that size.
