60th anniversary of the Worcester, MA tornado: The "Granddaddy" of Southern New England tornadoes.

When one thinks of southern New England one does not think of strong/violent or killer tornadoes here, and for great reason, as they are not very common, though not unheard of.  In fact, just recently, on June 1st, 2011 we had a strong/killer tornado rip through New England.  This tornado was on the ground for 39 miles, beginning in a section of Westfield, MA and finally lifting back up in a section of Charlton.  During it's 39 miles, 70 minute journey, at the peak the tornado was rated as a high end EF3 tornado with maximum winds of 160 mph, just shy of EF4 status and killed 3 people and injuring 72.  Prior to this 2011 tornado you have to go back to May 29th, 1995 when an F4 tornado struck the town of Great Barrington, MA.  In the 10 minutes this tornado was on the ground, 3 people were killed.  Prior to 1995, there was another F4 tornado (although there are major uncertainties regarding whether or not this should have been rated so high) which struck Hamden, CT on July 10th, 1989.  While only on the ground for several minutes, it produced major damage and injured over 40 people.  Then we'll go back to 1979, on October 3rd an extremely rare October tornado struck Bradley Airfield in Windsor Locks, CT.  While this was yet another short-lived tornado, it produced extreme damage along with killing 3 and injuring over 500 people.  This was yet another F4...even borderline F5 tornado.  While there were a few other tornadoes with a rating of F3 or higher we'll get right to be the big one, the Worcester, MA tornado of June 9th, 1953.

Below is a projected surface map on the day of June 9th, 1953.  An area of surface low pressure (circled in black) moving through Quebec Provence in southeastern Canada is pushing a cold front (highlighted by the blue line) to slide eastward towards southern New England and allowing for a warm front (highlighted by the red line) to lift northward through southern New England.  As the warm front would lift through CT and MA into northern New England, this allowed much warmer and humid air to work into the region, becoming two contributors on what was going to make for quite the unstable airmass later that afternoon.

Below we will take a look into the 700mb and 500mb levels of the atmosphere, which is roughly anywhere from around 10,000ft above sea-level to around 18,000ft above sea-level.  First off, is an image of the 700mb pattern over the Continental United States and much of Canada.  The red arrows indicate where the weather pattern is deriving from.  As you can see by the arrows, our airmass at 700mb originated from the desert Southwest.  This is actually pretty significant as research done over he past decade has shown that an atmospheric setup like this is conducive into allowing an elevated mixed-layer to sustain itself from the southwestern United States all the way to southern New England.  We could go into lengthy discussion into what an elevated mixed-layer is, but too make matters simple, elevated mixed-layers just lead to extremely unstable atmospheric conditions which is a major ingredient towards severe thunderstorms.  We also take note of the wind direction/strength depicted by the wind barbs.  We notice that the winds at this level are coming more from the northwest 25-35 knots, with even 40 knots over Ohio.  As the area of low pressure continued moving northeastward and then eastward into and through Canada, the system continued to actually strengthen and this allowed the wind fields to increase at this level on the day of the event.  

  

Below is a reanalysis map of the 500mb pattern along with wind strength/direction for roughly 8:00 AM eastern time on the morning of the 9th.  Just like at 700mb, we notice a trajectory of the pattern with the airmass originating from the southwestern United States and we also note a westerly flow with 40-45 knows over southern New England, however, just further off to the west, winds increase to 50-60 knots, and this would arrive over southern New England later that afternoon.

With the surface pattern, 700mb pattern, and 500mb patterns looked into we can now put all of this together and explain why such a violent tornado occurred in a region where they are oh so rare.  

The 500/700mb pattern which had been in place across the region for several days allowed an elevated mixed-layer plume to eject from the southwestern United States and survive it's journey to southern New England.  When the approaching storm system from the west allowed for a warm front to push northward through southern New England.  When the warm front pushed through this allowed dewpoints to soar into the 80's across spots and dewpoints to climb into the 60's.  The combination of temps into the 80's, dewpoints and into the 60's along with the elevated mixed-layer lead to extreme instability across the region. The warmfront, also in close proximity to the region, also allowed for winds at the surface to likely be from a more southerly/southeasterly direction.  With winds at the surface from the south/southeast, turning to the west/northwest aloft in the mid/upper levels of the atmosphere this created large amounts of helicity, or directional wind shear across the region...an extremely important ingredient for supercells and tornadoes.  

As the afternoon went on and the cold front and energy aloft associated with the system progressed eastward, thunderstorms began to develop.  One thunderstorm in particular became extremely severe and reaching supercell status, a supercell is a thunderstorm with very strong rotation.  At the height of the storm, the supercell thunderstorm produced a tornado which too this day is known as the granddaddy of southern New England tornadoes.  Along it's path, the tornado was on the ground for 90 minutes, traveling 48 miles tracking through eight different towns in central MA.  The tornado produced F4 damage across six of the eight towns affected, and even producing borderline F5 damage in spots.  When all said and done, 94 people were killed and over 1,000 people were injured.  Thousands of buildings/structures were heavily damaged with many completely destroyed.  

This was not the only killer tornado this system would produce, however.  Just the day before, the same system produced an F5 tornado in the town of Flint, MI.  That tornado killed 116 people and injured over 800 people.  This storm system, which began producing severe weather across NE/IA/WI would end up producing a total of 46 tornadoes, with 13 of them F3 or higher.  To this day, this series of outbreaks remains one of the most devastating and deadly in recorded history.  

Below is a slideshow, created by the National Weather Service in Taunton, MA, which also explains more regarding the setup, as well as showing numerous photos of the damage produced by the tornado, and even some images of the tornado itself.

http://www.erh.noaa.gov/box/papers/WorcesterTornado53_files/WorcesterTornado53.html

*Data was obtained through various National Weather Service Products and the images were obtained from the reanalysis site from Plymouth State and the Daily Weather Map Archive's ran by NOAA.*