Increase in hail size for warning criteria

[Chris Nuttall]

The current warning criteria for a SVR is 3/4" hail and/or winds that are gusting to or higher than 58 mph. There is not a criteria for lightning. If we're going to discuss the warning by the book, we should only be discussing the hail or wind. In this thread's case, it's the hail size threshold.

Lightning production in severe storms varies greatly. If warnings were issued on storms due to the lightning, the number of warnings would increase dramatically. FWIW, many offices already issue SPSs (Signficant Weather Alert) for strong storms that don't reach severe thresholds. If there's going to be a separate discussion on the merits or demerits of using lightning as a criteria, it should probably be in a separate thread.

 

[Dan Robinson]

FWIW some of the most intense lightning events I've witnessed have been in non-severe storms. Severe storms tend to have more frequent CG lightning, but not always. With the exception of a few (namely Mulvane and Kent County, TX), supercells tend to be very infrequent CG producers - when they do it's mainly in the forward flank precip area.

 

[Jason Boggs]

I agree with Chris Nuttall here. Lightning has no role in whether a storm is severe or not. Storms are not warned on because they have lightning. If they were, every thunderstorm would have to be considered severe.

I agree that the hail criteria should be "upped" to 1 inch for severe. .75 inch hail is not going to do a whole lot of damage for the most part. Yea, it hurts vegetation, but a farmer can't put his crop in the garage until the storm passes.

Again, I think raising the criteria would do a lot more good than bad.

 

[Andrew Pritchard]

Received this from Chris Miller at ILX...

This afternoon we received the official word that the minimum hail criteria
for Severe Thunderstorm Warnings will be increased to 1.00" effective
April 1, 2009. For an informational web briefing from our regional
headquarters about this initiative, go to the following link:

http://www.crh.noaa.gov/crh/One_Inch_Hail_Podcast.wmv

For "near severe storms" with hail 3/4" to less than 1", and wind gusts
less than 50 knots (58 mph) we will be using our Special Weather
Statement (SPSILX/WWUS 83 KILX) product. We also use this for reports
of cold air funnels. This product is available on our webpage in a number of locations,
or you can go there directly at:

http://www.crh.noaa.gov/product.php?site=ILX&product=SPS&issuedby=ILX

This change in hail criteria does NOT change the size of hail that we want you
to report to us. Hail reports of ALL SIZES are very important to our severe
weather operations. Let Ernie or me know if you have any questions.

 

[Jason Harris]

Interesting that currently in Sacto valley, (California) only the shorterm cast mentions nickle-size hail (.85) as possible but no special weather statement to that effect:

--

Short Term Forecast

SHORT TERM FORECAST...CORRECTED
NATIONAL WEATHER SERVICE SACRAMENTO CA
910 PM PST MON MAR 2 2009

***** CITY OF NIXON CORRECTED TO DIXON *****

CAZ017-018-030645-
SOUTHERN SACRAMENTO VALLEY-CARQUINEZ STRAIT AND DELTA-
910 PM PST MON MAR 2 2009

.NOW...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A LINE OF
HEAVIER SHOWERS WITH EMBEDDED THUNDERSTORMS IN IT. THE SYSTEM IS
MOVING NORTHEAST ALONG INTERSTATE 80 TOWARDS THE CITIES OF DIXON
AND DAVIS. HEAVY RAIN WITH NICKLE-SIZE HAIL AND GUSTY WINDS ARE
POSSIBLE WITH THIS SYSTEM. MOTORISTS TRAVELING WITHIN THIS REGION
ARE ADVISED TO SLOW DOWN AND INCREASE FOLLOWING DISTANCES...AND
WATCH OUT FOR PONDING OF WATER THAT CAN MAKE DRIVING DIFFICULT.

--
Earlier in day I heard a severe-t-storm warning for Amador and Calaveras county for similar situation. Where's the consistency?

Didn't see any reports either--despite the claim of a spotter here below. Maybe now that doesn't count as a report?

--
National Weather Service Issues Severe Thunderstorm Warning For The Mother Lode
Monday, March 02, 2009 - 03:20 PM
Bill Johnson
MML News Director
Monday Storm Drenches Sonora (03/02/09)

Sacramento, CA -- The National Weather Service has issued a severe thunderstorm warning for western Tuolumne County including Sonora and Calaveras County including San Andreas.

This warning will be in effect until 4pm.

Monday Storm Drenches Sonora (03/02/09)

At 3pm the N.W.S. Doppler radar indicated a line of severe thunderstorms capable of producting nickel size hail and gusty winds above 30 mph. These storms were located along a line extending from Grizzly Flat to Copperopolis to southeast of Waterford. The line is moving in a northeastly direction at 20 mph.

A spotter at Copperopolis has already reported nickel sized hail and wind gusts to 30 mph.

 

[Derrick Herndon]

what about newer cars?

As a car enthusiast I have to wonder what this new criteria will mean for dealerships and car owners. 3/4 inch is not enough to do significant car damage unless wind driven. However newer cars now have aluminum hoods, trunks and even roofs in order to reduce weight. The hood on one of my cars weighs less than 20 lbs. I believe this is an increasing trend. Are we going to see increasing hail damage claims in the future while the numbers of warnings decreases?

 

[beaudodson]

If we were warning on the "life threatening" part of the storm then lightning would be a criteria. How many people are killed each year by lightning? How many by hail?

I have never quite understand why the media reacts so "intensely" to certain storm types and not others. Flash floods and lightning kill more people than tornadoes in my region. By watching the local news you might not know that. A lot more attention is paid to "non-life threatening" events than life threatening events. I think it is a psychological issue with meteorologists. People get excited over tornadoes but "lightning" and "flooding" does not get the same attention. They should get as much if not more attention. They kill more people.

There is another poster on Storm Track that can discuss the same issue concerning "black ice" and how many people are killed in car accidents each year - weather related.

Winter storms kill more people each year than tornadoes and hurricanes combined. Winter storms won't receive wall to wall coverage, however, from FOX News or CNN. Winter storms can also cause a tremendous amount of property damage (see the 2005 Ohio Valley winter storm). However, winter storms are obviously not as dramatic as a land falling hurricane. I have yet to see Geraldo in the middle of a winter storm.

On the subject of hail - I like the change to 1" hail for severe thunderstorm warnings. Hopefully the public will take these warnings more seriously. Time will tell. This will also cut down on the number of times we send out our storm spotters. We normally send them out for all severe thunderstorm warnings. Granted most of the warnings in this region are for wind and not hail. Normally hail is included in the warning, but a lot of the warnings are mainly for winds greater than 58 mph.

 

[Jeff Duda]

Andrew and Chris, it is interesting what you posted/mentioned. This was recently posted on the DMX NWS site:

New One Inch Hail Criteria for Severe Thunderstorm Warnings

On April 1, 2009, the National Weather Service in Des Moines, IA will change its severe thunderstorm warning hail criteria to 1 inch in diameter instead of 3/4 inch. The wind component of the criteria will remain the same at 58 mph. For a detailed reasoning behind the policy change, please refer to the following webinar by clicking here.

Also on April 1, 2009, the National Weather Service in Des Moines, IA will start issuing Significant Weather Advisories (SWA) for thunderstorms approaching severe criteria. SWAs will be issued under the Special Weather Statement product. The SWA will be issued for thunderstorms which are producing or expected to produce at least 3/4 hail and/or 45 mph winds, but less than severe criteria. SWAs will be issued for specific storms and they will describe where the storm is, its movement, a short term forecast and its hazards.

Short Term Forecasts (STF) will be issued when thunderstorms are expected in the next hour. STFs will provide customers with general thunderstorm trends and expected weather hazards over the next 3 hours, regardless of intensity.

Questions about these changes should be directed to the National Weather Service, Des Moines, IA.

This confuses me because now it seems there will be an additional weather product issued (similar to Special Weather Statements) that do the same thing as what the ILX office is doing with their SWSs.

 

[Patrick Marsh]

If we were warning on the "life threatening" part of the storm then lightning would be a criteria. How many people are killed each year by lightning? How many by hail?

I have never quite understand why the media reacts so "intensely" to certain storm types and not others. Flash floods and lightning kill more people than tornadoes in my region. By watching the local news you might not know that. A lot more attention is paid to "non-life threatening" events than life threatening events. I think it is a psychological issue with meteorologists. People get excited over tornadoes but "lightning" and "flooding" does not get the same attention. They should get as much if not more attention. They kill more people.

There is another poster on Storm Track that can discuss the same issue concerning "black ice" and how many people are killed in car accidents each year - weather related.

Winter storms kill more people each year than tornadoes and hurricanes combined. Winter storms won't receive wall to wall coverage, however, from FOX News or CNN. Winter storms can also cause a tremendous amount of property damage (see the 2005 Ohio Valley winter storm). However, winter storms are obviously not as dramatic as a land falling hurricane. I have yet to see Geraldo in the middle of a winter storm.

On the subject of hail - I like the change to 1" hail for severe thunderstorm warnings. Hopefully the public will take these warnings more seriously. Time will tell. This will also cut down on the number of times we send out our storm spotters. We normally send them out for all severe thunderstorm warnings. Granted most of the warnings in this region are for wind and not hail. Normally hail is included in the warning, but a lot of the warnings are mainly for winds greater than 58 mph.

Ask anyone in your neighborhood or community which are they more afraid of: tornadoes, flash floods, or snow storms they will almost always respond with tornadoes. I know a lot of meteorologists who don't give a rats behind about tornadoes. It isn't some psychological issue with meteorologists. It's what the public wants.

I will say you are right about there being some psychological aspect, but it's the public's not the meteorologist's that is important. Right now, I bet a lot of people in northern AR and KY both fear ice storms more than tornadoes. Why? Because that is the most recent "big" disaster.

 

[Nick Smith]

In case anyone is wondering why the severe thunderstorm threshold is 3/4" hail and 58 mph wind, I'd recommend reading this paper by Joe Galway:

"The Evolution of Severe Thunderstorm Criteria within the Weather Service"

http://ams.allenpress.com/perlserv/.../1520-0434(1989)004<0585:TEOSTC>2.0.CO;2&ct=1

 

[beaudodson]

Ask anyone in your neighborhood or community which are they more afraid of: tornadoes, flash floods, or snow storms they will almost always respond with tornadoes. I know a lot of meteorologists who don't give a rats behind about tornadoes. It isn't some psychological issue with meteorologists. It's what the public wants.

I will say you are right about there being some psychological aspect, but it's the public's not the meteorologist's that is important. Right now, I bet a lot of people in northern AR and KY both fear ice storms more than tornadoes. Why? Because that is the most recent "big" disaster.

The problem is that often times some of these other weather events impact more people than the "highly visible tornado warnings". In actuality winter storms are going to cause a lot more impact in my region than a radar indicated tornado.

Having gone through the worst of the ice storm (Paducah, KY) I can tell you that people are hyper-sensitive to winter weather, at this time. Give it time and that will pass.

If we have a major tornado outbreak this spring then the sensitivity will shift to "severe" weather.

There are some good studies out there (one presentation at the eastern us weather conference) on the psychology of weather forecasting. How people perceive your forecast - how one or two changes in wording can change the way the forecast/warning is perceived. It is quite an interesting topic and I believe will become more and more important in the coming years (forecast changes). We can already see that by the new standards of forecasting for "impact" of weather events by the NWS. Example being the changes to winter weather warnings. Less is more.

Tornado warnings are important, obviously, however if a flash flood event is underway and is impacting hundreds or thousands of people then which is more important? A lot of times (I have noticed) that the tornado warnings will get all of the attention. A lightning "storm" - frequent cloud to ground lightning - might get very little weather coverage (no coverage) but if the NWS issues a severe thunderstorm warning for 1" hail then a channel will break in with wall to wall coverage. Which is more important? Again, the phsychology of weather warnings and meteorologists.

Interesting topic...

 

[rdale]

Good news! Southern Region and Eastern Region will start using 1" criteria on 1/5/10 at 0001Z and the CR/WR test will be over... It's all official!