Guest post by Paul Homewood
The tornado season remained a quiet one in September. According to data from NOAA’s Storm Prediction Center, during September, there were 43 preliminary tornado reports. This is less than the 1991-2010 September average of 74 tornadoes, and marks the least active September in terms of tornado activity since 2009, when eight tornadoes were confirmed. The majority of the tornadoes were weak and associated with the remnants of Hurricane Isaac as it moved through the Lower Mississippi River Valley and into the Midwest early in the month.
There were also no tornado-related fatalities during September. The below-average tornado activity was similar to the rest of 2012 to-date. The preliminary number of tornadoes during the January-September period was 843 with 119 tornado reports still pending for July, August, and September, marking the lowest January-September tornado count since 2002.
Preliminary reports suggest that 2012 will finish with the lowest number of tornadoes since at least 2005. Up to July, the running total of EF1+ events was 301, and I would anticipate a final year total of just under 400.
Just how unusual would this be? Well, it turns out not very! Since 1970, there have been six years when EF1+ tornadoes totalled less than 400.
|Year||No of EF1+ Tornadoes|
In other words, a quiet year like this one comes along about every six years.
Confirmed numbers for May/June/July
NOAA have now issued final numbers for May through to July, as shown below.
The analysis shows that, not only were total tornado numbers well down on the long term average, but also that, as a proportion, there was a sharper decline in the stronger categories. EF0 storms were 63% of normal, whereas EF1+ were much lower at 26%.
This brings YTD numbers for EF1+ up to 301, as at the end of July, compared to the long term average of 383.
Next month I am planning to take a closer look at a state by state breakdown.
Remember that all tornado reports can be found on their own separate tornado page here.