A Dead Heat

No, this blog isn't about political races -- I just thought I'd use this topical theme to refer to our tornado pace for the year. What I mean is that as of October 19, the year 2008 appears to be in a dead heat with 2004 -- and that was the year with the most tornadoes on record.

Through October 19, my preliminary tornado count for the year is 1633. That includes the 1390 tornadoes that the National Weather Service has confirmed through the end of July, plus the others that I've counted since then based upon NWS preliminary reports. There were exactly 1633 confirmed tornadoes through October 19, 2004.

2004 wound up with a record 1819 tornadoes, adding another 10 in the last part of October, a November record of 150, and 26 in December for a total of 186 more tornadoes. The average number of tornadoes between now and the end of the year is 121 (as shown below), so tornado activity will need to be 55% above average for the rest of the year to outpace 2004 and set a new record.

What are the chances that 2008 will break the 2004 record? We would need a lot of tornadoes, and at this time of year they tend to occur mainly in the brown-shaded areas below, sometimes called "Dixie Alley." 93 of the record 150 tornadoes in November 2004 came in one outbreak on November 23-24, and most fell in this area -- plus in a bit more of TX and in SC.

I would bet against 2008 setting a record, because unless the current weather pattern changes, there may not be enough instability present to bring so many tornadoes. That instability is present when warm, moist air pushes onshore from the Gulf of Mexico in an ample amount. Recently we've seen high pressure systems, like the one shown by the big H above, over the Southeast. That has featured a period of northeast flow that has pushed air offshore instead! The cold fronts and weather systems moving into the Southeast have encountered dry, relatively stable air and -- accordingly -- have not produced many tornadoes.

We've seen this pattern a lot of the time for the past couple of years, and it has led to the prolonged drought experienced in the Southeast. Of course, this pattern could break down and allow the Gulf of Mexico to open up. That would mean an active end of the year tornado-wise.

Even now, the year 2008 is in second place for tornadoes for a whole year. Let's hope the year ends up still in second place!