Are there too many Severe Thunderstorm Warnings? Many meteorologists believe that people are desensitized to them because there are so many of them. And that is probably true. The criteria for a Severe Thunderstorm Warnings is hail 3/4 of an inch in diameter or greater and or winds of 58 mph or greater. The problem with this set of criteria is that 58 mph winds do not produce widespread damage, and 3/4 inch hail (the size of a penny) rarely causes much damage. The 3/4 inch threshold was actually created for aircraft, which can be damaged by such hail when flying at 200-300 mph. But pilots do not use Severe Thunderstorm Warnings anyway.
Why are there so many? I have read statistics that say that Severe Thunderstorm and Tornado Warnings have increased by 300% since the 1980s. We certainly have better technology, especially radar to help produce better warnings. While detection scores have increased, so have false alarm rates. This may be leading to a “cry wolf” syndrome where the public stops taking warnings seriously, which could endanger public safety. At the same time, severe weather reports have increased by 250%. This is already skewing the severe weather climatology database. There are not more incidents, we just have better spotter networks, lots of storm chasers and pressure within the NWS to verify their warnings so that verification scores will increase. Some say that there should be no process of verification, only periodic justification of reasoning behind warnings.
Some say the hail criteria should be raised to 1 inch in diameter (quarter size) or even golfball size (1.75 inch) and that the winds criteria should be raised to levels that are strong enough to create significant wind damage. Protection of the integrity of the database is the reason I have heard for not adjusting the criteria.
Some say there should be an enhanced Severe Thunderstorm Warning, such as a Very Severe Thunderstorm Warning. This warning would some with higher thresholds. These would be used only in cases where an enhanced threat to life and property is suspected to exist. Currently, NWS offices can use strong wording in their warnings to communicate especially dangerous situations. Now, what is your opinion? Please respond by posting your comment on the Weather Talk Blog...
Why are there so many? I have read statistics that say that Severe Thunderstorm and Tornado Warnings have increased by 300% since the 1980s. We certainly have better technology, especially radar to help produce better warnings. While detection scores have increased, so have false alarm rates. This may be leading to a “cry wolf” syndrome where the public stops taking warnings seriously, which could endanger public safety. At the same time, severe weather reports have increased by 250%. This is already skewing the severe weather climatology database. There are not more incidents, we just have better spotter networks, lots of storm chasers and pressure within the NWS to verify their warnings so that verification scores will increase. Some say that there should be no process of verification, only periodic justification of reasoning behind warnings.
Some say the hail criteria should be raised to 1 inch in diameter (quarter size) or even golfball size (1.75 inch) and that the winds criteria should be raised to levels that are strong enough to create significant wind damage. Protection of the integrity of the database is the reason I have heard for not adjusting the criteria.
Some say there should be an enhanced Severe Thunderstorm Warning, such as a Very Severe Thunderstorm Warning. This warning would some with higher thresholds. These would be used only in cases where an enhanced threat to life and property is suspected to exist. Currently, NWS offices can use strong wording in their warnings to communicate especially dangerous situations. Now, what is your opinion? Please respond by posting your comment on the Weather Talk Blog...
on February 27, 2005, 10:41 pm
I think the new polygon warning system that the NWS is experimenting with will help by narrowing the warning area. I have seen a lot of damage come from severe thunderstorms but have not seen a record of the exact wind speed of each situation. I vote to leave the parameters as they currently stand.
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