While many may think tornadoes are mostly relegated to the Plains States, it is important to know that the Northeast is not immune to the phenomenon. In fact, tornadoes as strong as EF-3 (winds of 136 – 165 mph) can impact the region. Springfield, MA experienced one such tornado back on June 1, 2011, which was on the ground for over one hour, left a scar 39 miles long and up to ½ mile wide across south-central MA! While the Springfield tornado is uncommon and typically twisters of EF-0 and EF-1 magnitude occur, it is crucial to realize the danger these storms pose.
The Northeast (MD to ME), typically averages 46 tornadoes annually, a large number of which occur over MD, western/central PA and across upstate New York. For those who live around the I-95 corridor, that number is likely more in the 12 – 15 range, with the majority occurring in MD. June and July are by far the most active months with respect to tornadoes and generally coincides with the peak of Northeast severe weather season. The peak in activity is in large part due to more common occurrences of humid, Gulf air streaming northward, destabilizing the atmosphere more often. Add a cold front to the mix and strong thunderstorms are bound to fire.
One more ingredient is needed for tornado development and that is wind shear (winds turning with height). The proper wind shear (typically S to SE at the surface and westerly aloft), can form rotating, supercell thunderstorms which may spawn tornadoes. The Northeast is particularly fickle with having all these ingredients in place at the same time. One big issue is the proximity of rather cool ocean waters, which tend to allow cooler, stable air to funnel in on a tornadically favorable south - southeast wind. This air is typically detrimental in maintaining strong, supercell t-storms in effect saving the I-95 corridor from tornado outbreaks. However, on occasion, these storms hit the southeast winds formed by sea breezes and continue to spin, spawning a few isolated, weak twisters.
Although tornadoes are not typically favored in the Northeast, they can and do happen. Remember, if a tornado watch is issued for the area, don’t panic. The watch just means that the atmosphere is primed to produce supercell thunderstorms capable of producing a tornado. In other words, “keep an eye out.” If a tornado warning is issued for your town, this means a tornado has been detected by radar or that someone has spotted one on the ground. In this case, please seek immediate shelter preferably in a basement or at very least a lower-level interior room. For more on watches and warnings, visit Nick Troiano's blog.
