Day 3: 2009 Severe Weather Watch Overview

Posted by on 3 Jan 2010 | 4 comments

Deviating from the cold theme of the past two days (mainly because I just got back from a walk and am freezing…), today’s map deals with severe thunderstorms and tornadoes.

Every year the National Weather Service’s (NWS) Storm Prediction Center (SPC) issues approximately 850 severe thunderstorm and tornado watches combined.  Greg Carbin, the Warning Coordination Meteorologist (WCM) at the SPC, put together a graphic that contains the number of watches issued per county during 2009 (valid through October).

A couple of things stand out about the geographic distribution of this year’s convective watches.

  1. Central Oklahoma had the most watches (~35) of anywhere in the United States.
  2. There are few watches issued west of the Continental Divide.
  3. East of the Continental Divide, only four areas did not record a single convective watch: far western Texas (El Paso area), far southern Texas (Brownsville area), east central Wisconsin (Green Bay area), and eastern Maine (Portland and Jonesport areas).
  4. There is a relative minimum in watches from southwest to north central Kansas – right in the middle of theVORTEX II domain.
  5. There is a relative maximum in watches from northeast Colorado into eastern Wyoming and western Nebraska – several of which were issued during VORTEX II.  (VORTEX II’s only significant tornado intercept occurred nearLa Grange, Wyoming, near the border of Wyoming and Nebraska.)
  6. The lack of repeated land-falling tropical systems resulted in no coastal areas having a pronounced maximum.

Day 3

(Image courtesy of the NWS SPC.)

  • Zac

    Now do you have a companion graphic that shows verified thunderstorm/tornado warnings? It would be interesting to see if the same distribution exists.

  • http://www.patricktmarsh.com pmarsh

    It would be difficult to create a map of severe thunderstorm/tornado warnings because there is no fixed shape to them. However, if we assume the old “county-based” warnings, something could be constructed for all *issued* warnings. Verified warnings will be a little harder to put together. Namely because there are so many warnings that one would have to “verify”.

  • DJ

    Has the SPC done the same graphic over a multi-year period? I am kinda curious to see if the watch density has a similar distribution to the tornadic supercell track density maps I made for Oklahoma.

  • http://www.patricktmarsh.com pmarsh

    Not that I’m aware of. However, the code is written in such a way that I believe we can go back to the past few years and create them. Also, maps were created that break down the total number of watches into only tornado watches and only severe thunderstorm watches.