Probably the most often asked question of the last 24 hours has been, “Can you redo the WFO counts without including 2011?” So, here are the WFO counts sans 2011. The top three have changed slightly
There were 83 tornado emergencies between 1999 and the end of 2010…
More graphics to come…
Last night I posted a call for help from fellow meteorologists and weather nerds to help me acquire the tornado emergencies that I was missing. Wow! Thanks to the help of Jason Kaiser, Daryl Herzmann from Iowa State, and Rick Smith from National Weather Service (NWS) forecast office Norman, I now believe I have all tornado emergencies in my possession! Now the fun part of analyzing them begins! Since many people are already aware of my project, I decided to go ahead and post two quick graphics that I think will be of interest.
First, a bit about my method. For this analysis I treat the tornado warning and all subsequent severe weather statements associated with the tornado warning as a single episode. Since a tornado emergency can be issued in the text of either a tornado warning or a severe weather statement, all tornado emergencies issued within a single episode is consider a single tornado emergency. Consider the following scenarios:
Scenario 1: A tornado warning is issued for 2 counties and does not contain the tornado emergency text. Subsequently 4 severe weather statements are issued. The second severe weather statement contains the tornado emergency language for county A but not county B. The fourth severe weather statement contains the tornado emergency for county B but not county A. How many tornado emergencies will this count as?
Using my definition, even though 2 tornado emergencies were technically issued, they are both contained within a single tornado warning and thus this is treated as a single tornado emergency.
Scenario 2: A tornado warning is issued for county A and does not contain the tornado emergency text. Subsequently 2 severe weather statements are issued. The second severe weather statement contains the tornado emergency language for county A. As the tornado moves into county B, the NWS issues a new tornado warning, without the tornado emergency language, for county B. Subsequently, the NWS issues three severe weather statements for county B, all three containing the tornado emergency language. How many tornado emergencies will this count as?
Using my definition, even though 4 tornado emergencies were technically issued, they are all contained within the framework of only two tornado warnings. Thus this is treated as two tornado emergencies — even though this is for the same tornado.
Scenario 3: A tornado warning is issued for county A and does contain the tornado emergency text. Subsequently 2 severe weather statements are issued, both of which contain the tornado emergency language. How many tornado emergencies will this count as?
Using my definition, even though 3 tornado emergencies were technically issued, they are all contained within the framework of a single tornado warning. Thus this is treated as one tornado emergency.
Does that make sense?
With that said, there have been 143 distinct tornado emergencies issued since the first one on 3 May 1999 for south Oklahoma City, OK. The chart below breaks them down into yearly counts:
Examining tornado emergencies by NWS forecast office, the top three are
This might be a bit surprising to many who typically think of “tornado alley” as being in the central United States. Unfortunately, or fortunately, you decide, many things go into the decision to issue tornado emergencies. Some of these things include population potentially impacted and local office policies. Remember, the tornado emergency is not a formal product. It wasn’t until the last year or two that local forecast offices has official guidance in place. Bottom line, not every office uses tornado emergencies. (Also, keep in mind the magnitude of the 27 April 2011 tornado outbreak and where that was located! However, to be fair, I will say that all of the top three offices had issued tornado emergencies prior to 27 April 2011.)
The rest can be found in the chart below:
In the coming days and weeks I will be doing more analysis on tornado emergencies and will post findings as they are completed. If there is something you would like to see, leave me a comment and let me know. If I don’t already have plans to examine your request, I’ll add it to my list!
In light of this year’s extremely violent tornadoes and the reaction to them amongst the meteorological, emergency management, and social science communities, I’ve spent a lot of time thinking about the National Weather Service’s (NWS) practice of issuing tornado emergencies. For those who don’t know, this product is, in theory, designed to serve as a “more severe” tornado warning. Essentially a tornado emergency is nothing more than a regular tornado warning with a variant of the phrase, “This is a tornado emergency,” contained somewhere in the text. This phrase could be contained somewhere in the initial tornado warning or in a follow-up statement known as a severe weather statement.
Over the last few days I have been working on putting together a collection of all tornado emergencies ever issued. The first one was issued on 3 May 1999, as a severe weather statement, as the Bridge Creek F5 tornado threatened downtown Oklahoma City. Since then this product has been issued over 100 times with varying success. Much like the success of the tornado emergency product, I have had varying levels of success in tracking down all the products ever issued. So far I am fairly confident that I have collected all of the tornado emergency statements since 2005. Unfortunately I have run into a problem with tornado emergencies prior to 2005. The problem stems from the fact that the, “This is a tornado emergency,” tagline can be placed in one of several NWS text products. All initial tornado warning statements that contained this tagline are archived and I am fairly confident I’ve retrieved them all. However, obtaining severe weather statements prior to 2005 have proven elusive. (The exception to this is the severe weather statements from the Fort Worth, TX office on 28 March 2000 when a tornado emergency was issued for downtown Fort Worth, which I have found.)
Please see the Tornado Emergency post for a listing of all known tornado emergencies. Subesquent posts will contain images.
The first tornado of the day is ongoing across portions of southwest Oklahoma. The tornado vortex signature (TVS) is located just to the northeast of Tipton, where the brighter reds and greens are side-by-side. Additionally, I should point out that the Oklahoma Mesonet has lost communication with the Tipton Mesonet station. With visual confirmation of a tornado in the vicinity, this would seem to suggest the tornado moved very close to, if not hitting, the Tipton Mesonet station. This would not be the first tornado to hit an Oklahoma Mesonet station this year. Back on 24 May 2011, the El Reno, OK EF-5 tornado moved close enough to the El Reno Mesonet station that debris wrapped around the Mesonet’s observing site. The strongest measured wind gust in Oklahoma history was recorded by the El Reno Mesonet station during the tornado’s passage.
Tonight, as many mourn the loss of Steve Jobs, keep in mind that the next person to change the world as he did might be you.