Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 2:28 PM GMT on March 04, 2008
Two tornadoes touched down in Mississippi yesterday, and the record early season onslaught of tornadoes in the U.S. is expected to continue today. An unconfirmed tornado hit Camp Shelby, a Joint Forces Training Center 75 miles northwest of Mobil, Alabama at 11:25 pm CST Monday, injuring 14 National Guardsmen. A second tornado briefly touched down near Cary, Mississippi, and golf ball sized hail and damaging thunderstorm winds were plentiful across Mississippi, Louisiana, and Arkansas yesterday.
Another volley of tornadoes is possible over the eastern portion of North Carolina, South Carolina, and Virginia this afternoon. The Storm Prediction Center has placed this region under its "Moderate Risk" target today--one level below the maximum "High Risk" threat level. A powerful low pressure system will pass north of these states, dragging a strong cold front through. Strong EF2 and EF3 tornadoes are possible along this front, and the action may move into Maryland and Delaware late tonight. Tornado watches have already been posted for portions of Georgia, Florida, Alabama, and Tennessee this morning. The tornado page is a good place to track the tornadoes as they occur today, along with our severe weather page.
2008 sets early tornado season records
The year 2008 smashed the record for most January and February tornadoes, with 368. The previous record was set in 1999, with 235 January/February tornadoes. Reliable records extend back to 1950. The 232 tornadoes reported in February of 2008 was a record for the month of February. Second place goes to 1971, with a relatively paltry 83 tornadoes. Each of the past three years has seen an unusually early start to tornado season (Figure 1). One would expect to see a shift in tornado activity earlier in the year in a warming climate, along with an earlier than usual drop off in activity in late spring. We can see that in both 2005 and 2006 that tornado activity dropped off much earlier than usual, and it will be interesting to see if 2008 follows a similar pattern. Note that there is a very high natural variability in tornado numbers, and the record for fewest ever January and February tornadoes was set just five years ago in 2002, when only four twisters occurred. It will be at least ten more years before we can say with any confidence that a warming climate is leading to an earlier peak in tornado season.
La Niña to blame?
There does seem to be a tendency for more early season tornadoes during La Niña years--four of the five years that had January/February tornado counts above 75 were all La Niña years (1971, 1975, 1999, and 2008). The only exception was 1998, which was an El Niño year, and had 118 January/February tornadoes. However, connection between La Niña and enhanced tornado activity is a controversial area of active research, and we don't know enough about the matter to blame this season's early tornado activity on La Niña.
Figure 1. Tornado reports so far this year have totaled 368 for the months of January and February, by far the greatest number of tornadoes observed so early in the year. Image credit: NOAA Storm Prediction Center.
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