Thursday, June 1, 2017

Special Report- June 1, 2011 From A Meteorologist's Perspective

YouTube screenshot of twister in downtown Springfield MA

It has been 6 years since the devastating June 1, 2011, severe weather outbreak that left parts of the region in ruin.  The twister left a physical scar that can be seen in winter time, even years after the event.
NOAA GOES_East visible satellite 2/18/2015 (image Sean Breslin, The Weather Channel)
The emotional scars run deeper as business and homeowners in the path of the twister are still struggling to rebuild and recover.  Three people lost their lives, many more were injured, and millions of dollars of damage was done from Westfield to Sturbridge.  This post will not focus on any of that.  Instead, this will be an account of the storm from a meteorologist's perspective as it happened.   We will start on May 30, 2011, to see how well this event was forecast and we will end on the evening of June 1, 2011.

May 30, 2011

330 AM
The Storm Prediction Center (SPC) in Norman, OK first highlighted the potential for severe weather on June 1, 2011, two days ahead of time when they put most of the northeast in a "slight" risk in their 3-day convective outlook.  A wise and clever individual would say 6/1 is 2 days after 5/30, not 3.  You would be correct but the SPC Day 1 Outlook is valid from 8 AM that day until 8 AM the next.  So the 5/30/11 day 1 outlook is for 5/30/11 8 AM until 5/31/11 8 AM.  Day 2 is 5/31/11 8 AM until 6/1/11 8 AM etc.
SPC Day 3 convective outlook.  Issued 5/30/2011 for 6/1/2011
734 PM
The National Weather Service in Taunton (NWS BOX) issued its evening forecast discussion.  The forecaster's note the potential for severe weather thanks to an approaching cold front that is forecast to move through Southern New England (SNE) during the late afternoon.  This will pair the frontal passage with peak heating, thus elevating the potential for severe weather.  Despite some favorable parameter's such as wind shear, the forecaster's also noted the potential for high pressure offshore to limit thunderstorm growth and limit the overall severe weather threat.


130 PM
The Day 2 Convective Outlook continues to advertise the potential for severe thunderstorms in the northeast.
SPC Day 2 convective outlook issued 5/31/11 for 6/1/2011
450 PM
The NWS BOX forecast is still unsure about how widespread the severe weather threat will be on 6/1.  The forecaster notes the best dynamics will be in Northern New England closer to the parent cyclone.  However, it is also noted that the severe weather parameters are still high for SNE standards.  The forecast mentions the potential for strong winds and damaging hail Wednesday PM.

1001 PM
For the first time, the NWS BOX discussion mentions the potential for storms Wednesday AM.  The NAM model was forecasting the potential for storms in SNE as a warm front lifted into the region.  This warm front is the leading edge of the warm, humid air thunderstorms need for fuel.  While the forecaster seems to have doubts about this, it is mentioned.

1100 PM
Surface analysis at 11 PM on 5/31/11 shows a parent cyclone north of the Great Lakes with a trailing cold front through Michigan, Indiana, Illinois and back into Oklahoma.  A warm front was lifting through Central New England at the same time.
WPC Surface Analysis Tuesday, May 31, 2011, 11 PM

100 AM
Forecaster's still unconvinced of AM storms, but note the presence of the AM storms could impact the development of storms in the PM.

408 AM

Morning convection still not anticipated, but forecasters are now fairly certain Western Massachusetts will see severe thunderstorms.  A significant tornado outbreak is not anticipated.

8-1005 AM
Storm fire along the warm front.  Hail up to 1" diameter falls in NE MA and S NH.  Violent storms rip through Southern Worcester County, Northern RI, and SE MA.
NCEI radar archives 8 AM-10 AM 6/1/2011
The first severe thunderstorm warning of the day is issued at 830 AM for the thunderstorm near Lowell.
IEM Mesonet NWS STW Archive 6./1/11 830 AM
The skies clear after these storms move into the Atlantic.  Meanwhile, in Upstate New York, the sun emerges and thunderstorms begin to fire ahead of the cold front.  The SPC noted a growing damaging wind and hail threat around 930 AM.
The SPC issues the first watch of the day at 1005 AM.  This is a severe thunderstorm watch for PA. NY, Western and Northern New England.

1230 PM
The SPC issues its early PM Day 1 Convective Outlook.  It notes a 5% possibility of tornadoes across much of New England.
The SPC also issues an update to the severe thunderstorm watch.

100 PM
A Tornado Watch is issued until 8 PM

2-415 PM
A Tornado Watch is issued in Maine.
The first tornado warning of the event is issued for Berkshire, Franklin, and Hampshire counties in Massachusetts at 328 PM.
IEM Mesonet archive BOX tornado warnings 6/1/11
This cell was the first to get the attention of meteorologists as many TV stations broke into special live coverage.

At 415, a very strong supercell thunderstorm was entering Westfield, MA.  It was not yet tornadic, but the NWS noted rotation on radar.
IEM Mesonet archive BOX STW 6/1/11

Here is the radar loop from 200-415 PM.

NCEI Radar Archive 6/1/11

415-700 PM

The SPC issued an update to the Tornado Watch at 418 PM.

The severe thunderstorm in Hampden County that was showing signs of rotation has now produced a tornado. Law enforcement and media report damage in West Springfield.  The NWS issues a tornado warning at 430 PM.  This developed in the shaded area of MCD 1053 where the SPC believed a strong tornado was possible.
IEM Mesonet Archive Tornado Warnings 6/1/11

Viewers in Western Massachusetts watched the tornado cross the Connecticut River.  The threat shifted towards Worcester County around 5 PM.  The first tornado warning for Worcester County is issued at 501 PM.
IEM Mesonet Archive Tornado Warning 6/1/11
This cell did not end up producing a tornado.  The Springfield cell became a high-end EF-3 tornado.  It is my belief that atmosphere surrounding that supercell robbed this cell of the energy needed to produce a tornado.   Here is the radar loop from 430-800 PM.

NCEI radar archive 6/1/11

The Springfield tornado marched on towards Monson, Brimfield, and Sturbridge before lifting over Oxford, Sutton, and Northbridge.

Supercells continued to fire in Western MA.  Another tornado warning was posted at 607 PM.
IEM Mesonet Archive tornado warnings 6/1/11
Often overlooked, rightfully so, this supercell produced 3 tornadoes in Hampden and Worcester Counties.

700-1100 PM

The atmosphere was stilled primed as we entered the evening.
A tornado watch was issued for Eastern MA as supercells continued to fire in Western MA.

This is the radar from 8-10 PM.

The 3-day forecast verified from the Storm Prediction Center.   What no one predicted was that a high-end EF-3 tornado would cause major damage along a 37-mile path in South Central Massachusetts.
SPC Day 1 Outlook and verification 
The point of this post is to remind everyone that while major severe weather outbreaks are rare in Southern New England, they are extremely difficult to forecast.  This seemed like a run of the mill SNE severe weather event until the morning of.  I didn't expect the AM thunderstorms or tornadoes.   This event is the reason why I launched this weather blog.   Thank you for reading.

Works used
Radar Images

SPC Discussions, Watches, Outlooks

NWS Discussions

NWS Warnings

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