Post mortem severe talk

[ineedsnow]

my friends mom in westfield had signifigant damage around the neighborhood it was blocked off but i saw pictures from there amazing!

Yeah and it may have cycled just east of Springfield before Monson/Brimfield too. Not sure. We'll have to wait and see.

[ORH_wxman]

The distance between the start point and stop point of the '53 tornado is about 40 or 41 miles, but since the tornado did not track in a direct straight line, the official length I believe is listed at 46 miles.

[adam038]

In that case even longer path, if it remained on the ground the entire length. I recall some question last night whether it cycled before Sturbridge and perhaps lifted? Guess we'll see.

As of right now it also stands tied as the second deadliest tornado in MA history with the EF4 in '73(?) out in Berkshire county.

The '73 one was either August 26th or 28th. I'll have to get the pictures around the Berkshire Farm home for boys from my parents (my mother worked there but had the day off when it took the roof off). That one blew the truck stop in West Stockbridge apart if I'm not mistaken.

[Amped]

This whole spring has been remarkably similar to 1953.

[Johnno]

Wow, just read in the Hartford Courant that one death was a pedestrian on the Memorial Bridge in Springfield, that must have been horrible

[DavisStraight]

Yeah that's impressive... the last official F-3 in this general geographic area would be from May 1998 in eastern NY when an F3 destroyed some Albany, NY suburbs. I remember from that one there were carried and flipped pick-up trucks and that was one of the criteria they used to rate F3.

Man my family's house on the MA/CT line in North Woodstock (just south of Sturbridge) just missed this one... in high school I worked at the Sturbridge Host Hotel right there by I-84/I-90 interchange. Know the area well and can't believe it got hit...spent many days in Sturbridge.

Can anyone tell me what streets exactly got hit in Sturbridge? I can't seem to find that information.

It came over Route 84 to the Hall Road, Route 131 intersection, thats where the Auto Body shop is that got nailed, then it went NE to Fiske Hill Road, I have some pics Ill try to get up later from Fiske Hill, then crossed McGilpin Road into Southbridge. Then over the Southbridge Airport to Route 169, hit an apartment complex there pretty hard, seems to have ended right around there as I didnt see any damage to the east of Route 169.

It looks like a 1/2 mile wide area was bombed.

[wxmanmitch]

I can't help but to think that the local terrain played a significant role in the event that transpired yesterday. The north-south orientation of the CT River valley acts to increase the low-level directional and speed wind shear. A low-level synoptic flow from the southwest will get forced ageostrophically from the south in the valley, acting to enhance the directional shear if the winds above are from the southwest or west. The valley can also act to funnel the air into greater velocities if the wind flow is parallel to the valley orientation, leading to a greater speed shear as well. Think of what happens when you walk between two large buildings on a windy day; the effect I'm speaking of here is pretty much the same. Greater wind shear in the CT River valley acted to locally increase the 0-1 km helicity values in the vicinity of where the tornado formed. The lower elevation of the valleys and the associated southerly flow also likely contributed to a pooling of more unstable air in these locations, allowing for greater temperature, dew point, and therefore CAPE values. These factors may have caused the cells to rapidly intensify and rotate as they moved through this area of greater instability and shear.

I also speculate that conservation of angular momentum may have played a role in this as well. As a rotating mesocyclone downslopes out of a more elevated area, the vortex may actually stretch vertically and contract horizontally. Stretching the vortex in this fashion will cause it to spin at greater speeds (think of what happens when a figure skater pulls his/her hands inward while spinning), and increase the amount of low-level rotation in the vortex that first spawned the tornado in Westfield. Of the above factors, I think the ones discussed previously are more likely to have played a role in what we observed than this. The last point is pure speculation on my part and is just about impossible to discern, but it is a subject worthy of researching.

While the general synoptic setup is critically important, I believe that the terrain impacts on events such as this are not to be overlooked. In fact, if one examines a climatology of tornadoes in western New England and eastern New York, a tendency for tornadoes to occur in the valley locations becomes apparent. The 1995 Great Barrington tornado occurred as the supercell traversed the Berkshire Valley, the 1979 Windsor Locks tornado occurred in the CT River Valley, and the 1998 Mechanicville, NY tornado occurred in the Hudson Valley. There are other examples, but these are the more notable cases. Yesterday's event strengthens the case that tornadogenesis is favored in the valley locales of eastern NY and western New England.

[CT Rain]

I can't help but to think that the local terrain played a significant role in the event that transpired yesterday. The north-south orientation of the CT River valley acts to increase the low-level directional and speed wind shear. A low-level synoptic flow from the southwest will get forced ageostrophically from the south in the valley, acting to enhance the directional shear if the winds above are from the southwest or west. The valley can also act to funnel the air into greater velocities if the wind flow is parallel to the valley orientation, leading to a greater speed shear as well. Think of what happens when you walk between two large buildings on a windy day; the effect I'm speaking of here is pretty much the same. Greater wind shear in the CT River valley acted to locally increase the 0-1 km helicity values in the vicinity of where the tornado formed. The lower elevation of the valleys and the associated southerly flow also likely contributed to a pooling of more unstable air in these locations, allowing for greater temperature, dew point, and therefore CAPE values. These factors may have caused the cells to rapidly intensify and rotate as they moved through this area of greater instability and shear.

I also speculate that conservation of angular momentum may have played a role in this as well. As a rotating mesocyclone downslopes out of a more elevated area, the vortex may actually stretch vertically and contract horizontally. Stretching the vortex in this fashion will cause it to spin at greater speeds (think of what happens when a figure skater pulls his/her hands inward while spinning), and increase the amount of low-level rotation in the vortex that first spawned the tornado in Westfield. Of the above factors, I think the ones discussed previously are more likely to have played a role in what we observed than this. The last point is pure speculation on my part and is just about impossible to discern, but it is a subject worthy of researching.

While the general synoptic setup is critically important, I believe that the terrain impacts on events such as this are not to be overlooked. In fact, if one examines a climatology of tornadoes in western New England and eastern New York, a tendency for tornadoes to occur in the valley locations becomes apparent. The 1995 Great Barrington tornado occurred as the supercell traversed the Berkshire Valley, the 1979 Windsor Locks tornado occurred in the CT River Valley, and the 1998 Mechanicville, NY tornado occurred in the Hudson Valley. There are other examples, but these are the more notable cases. Yesterday's event strengthens the case that tornadogenesis is favored in the valley locales of eastern NY and western New England.

Great post, Mitch. All great points and I was planning to blog about this sometime soon.

What we saw here was a second storm that formed on the Northampton supercells southwest flank that rapidly became tornadic from the parent mesocyclone when coming down off the Berkshires into the Valley. There was a very rich area of low level helicity in the valley thanks to backed surface winds and vortex stretching likely played a role as well with the tornadogenesis.

There are one of two good papers that talk about this occuring in the Mechanicville storm. The 1995 Great Barrington tornado likely had a similar process take place in the Housatonic River Valley coming off the Taconics.

As for the 1979 tornado I actually don't think topography was the main driver since the synoptic flow was out of the south and the sfc winds were backed from that.

[Tropopause_Fold]

I can't help but to think that the local terrain played a significant role in the event that transpired yesterday. The north-south orientation of the CT River valley acts to increase the low-level directional and speed wind shear. A low-level synoptic flow from the southwest will get forced ageostrophically from the south in the valley, acting to enhance the directional shear if the winds above are from the southwest or west. The valley can also act to funnel the air into greater velocities if the wind flow is parallel to the valley orientation, leading to a greater speed shear as well. Think of what happens when you walk between two large buildings on a windy day; the effect I'm speaking of here is pretty much the same. Greater wind shear in the CT River valley acted to locally increase the 0-1 km helicity values in the vicinity of where the tornado formed. The lower elevation of the valleys and the associated southerly flow also likely contributed to a pooling of more unstable air in these locations, allowing for greater temperature, dew point, and therefore CAPE values. These factors may have caused the cells to rapidly intensify and rotate as they moved through this area of greater instability and shear.

I also speculate that conservation of angular momentum may have played a role in this as well. As a rotating mesocyclone downslopes out of a more elevated area, the vortex may actually stretch vertically and contract horizontally. Stretching the vortex in this fashion will cause it to spin at greater speeds (think of what happens when a figure skater pulls his/her hands inward while spinning), and increase the amount of low-level rotation in the vortex that first spawned the tornado in Westfield. Of the above factors, I think the ones discussed previously are more likely to have played a role in what we observed than this. The last point is pure speculation on my part and is just about impossible to discern, but it is a subject worthy of researching.

While the general synoptic setup is critically important, I believe that the terrain impacts on events such as this are not to be overlooked. In fact, if one examines a climatology of tornadoes in western New England and eastern New York, a tendency for tornadoes to occur in the valley locations becomes apparent. The 1995 Great Barrington tornado occurred as the supercell traversed the Berkshire Valley, the 1979 Windsor Locks tornado occurred in the CT River Valley, and the 1998 Mechanicville, NY tornado occurred in the Hudson Valley. There are other examples, but these are the more notable cases. Yesterday's event strengthens the case that tornadogenesis is favored in the valley locales of eastern NY and western New England.

good post.

[Tropopause_Fold]

Great post, Mitch. All great points and I was planning to blog about this sometime soon.

What we saw here was a second storm that formed on the Northampton supercells southwest flank that rapidly became tornadic from the parent mesocyclone when coming down off the Berkshires into the Valley. There was a very rich area of low level helicity in the valley thanks to backed surface winds and vortex stretching likely played a role as well with the tornadogenesis.

There are one of two good papers that talk about this occuring in the Mechanicville storm. The 1995 Great Barrington tornado likely had a similar process take place in the Housatonic River Valley coming off the Taconics.

As for the 1979 tornado I actually don't think topography was the main driver since the synoptic flow was out of the south and the sfc winds were backed from that.

check your PM

[ORH_wxman]

Nice most Mitch.

The winds were backed more than models showed everywhere E of the prefrontal trough. The valley definitely enhanced it, but on the SPC mesoanalysis, a large swath of very high helicity existed to the E of prefrontal trough which was sitting pretty close to the E NY border with New England.

[adamrivers]

I can't help but to think that the local terrain played a significant role in the event that transpired yesterday. The north-south orientation of the CT River valley acts to increase the low-level directional and speed wind shear. A low-level synoptic flow from the southwest will get forced ageostrophically from the south in the valley, acting to enhance the directional shear if the winds above are from the southwest or west. The valley can also act to funnel the air into greater velocities if the wind flow is parallel to the valley orientation, leading to a greater speed shear as well. Think of what happens when you walk between two large buildings on a windy day; the effect I'm speaking of here is pretty much the same. Greater wind shear in the CT River valley acted to locally increase the 0-1 km helicity values in the vicinity of where the tornado formed. The lower elevation of the valleys and the associated southerly flow also likely contributed to a pooling of more unstable air in these locations, allowing for greater temperature, dew point, and therefore CAPE values. These factors may have caused the cells to rapidly intensify and rotate as they moved through this area of greater instability and shear.

I also speculate that conservation of angular momentum may have played a role in this as well. As a rotating mesocyclone downslopes out of a more elevated area, the vortex may actually stretch vertically and contract horizontally. Stretching the vortex in this fashion will cause it to spin at greater speeds (think of what happens when a figure skater pulls his/her hands inward while spinning), and increase the amount of low-level rotation in the vortex that first spawned the tornado in Westfield. Of the above factors, I think the ones discussed previously are more likely to have played a role in what we observed than this. The last point is pure speculation on my part and is just about impossible to discern, but it is a subject worthy of researching.

While the general synoptic setup is critically important, I believe that the terrain impacts on events such as this are not to be overlooked. In fact, if one examines a climatology of tornadoes in western New England and eastern New York, a tendency for tornadoes to occur in the valley locations becomes apparent. The 1995 Great Barrington tornado occurred as the supercell traversed the Berkshire Valley, the 1979 Windsor Locks tornado occurred in the CT River Valley, and the 1998 Mechanicville, NY tornado occurred in the Hudson Valley. There are other examples, but these are the more notable cases. Yesterday's event strengthens the case that tornadogenesis is favored in the valley locales of eastern NY and western New England.

WHAT A POST.... I don't know a ton about this type of stuff but learned a lot from this

[CoastalWx]

I think the local enhancement of backed winds in the CT valley was probably a significant contributor..good post Mitch. In fact...BDL had a 160 wind for a while! I mentioned earlier in the thread about the local enhancement, because we've seen it before. Those cells really started to rotate as they entered the valley. Could it be coincidence? Perhaps, but 3000+J of MLCAPE will surely allow any possible rotating column to stretch in the vertical and help generate rotation. I remember a few cases in the Hudson River valley where storms quickly started to rotate once they came off the mtns west and sw of ALY. I've heard Greg Forbes talk about this phenomenon as well. That stretching of the column is another good theory. I'm sure there have been studies done.

I think that's what strikes me with this event..is the MLCAPES generated with the EML. We had talk about possible dry air entrainment in the mid levels, but we also had K-Index values near 30 and very high 850TD's which is great to see on the soundings. EML layers are known for a pocket of dry air, but the key is very high TD's below 800mb or so. That helps generate the tremendous CAPE that causes those violent updrafts to finally punch through the cap. Lapse rates actually slightly improved in the aftn per RUC.

And look at the turning with height. 40-50kts at 925Mb and 850mb. 50kts at 500 from the west. This helped drive 0-3KM SRH to about 400 or so. Later on, as winds remained backed from a more southerly direction, we saw 0-1KM SRH soar to 450m2/s2!!. That's incredible. You combine that with 3000-4000MLCAPE, and boy does that spell something big. I think the NC outbreak on 4/27 had MLCAPES of 1,500 to 2,000J..but 0-1KM SRH was near 600m2/s2. Still, you need the good CAPE to generate violent rotating updrafts for strong tornadoes.

Supercell composite soared.

You can see the moist td's at 850 as well. Given that The SPC analysis is a little later than the sounding posted. but it still gives the idea.

[Tropopause_Fold]

great thread.

[CoastalWx]

I also wonder if some sort of boundary or storm interaction contributed like Ryan mentioned. Joplin sort of saw this as well. Just another reason for this to go nuts, gobbling up helicity like Pac-Man.

http://www.rap.ucar.edu/weather/radar/displayRad.php?icao=KBOX∏=bref1&bkgr=black&endDate=20110601&endTime=21&duration=2

[CT Rain]

I also wonder if some sort of boundary or storm interaction contributed like Ryan mentioned. Joplin sort of saw this as well. Just another reason for this to go nuts, gobbling up helicity like Pac-Man.

http://www.rap.ucar.edu/weather/radar/displayRad.php?icao=KBOX∏=bref1&bkgr=black&endDate=20110601&endTime=21&duration=2

It's possible an outflow boundary from the northern supercell enhanced low level horizontal vorticity and enhanced tornadogenesis. That may have happened in Joplin.

After the 1998 mechanicville, 1995 great barrington tor and now this one the last 3 violent tornadoes have occurred in river valleys on the other side of 1500-2000 ft hills. Local topography plays a huge role in storm scale conditions and is something that should be considered in real time warning decisions. There appears to be a relatively large risk for strong tors in north/south river valleys in new England and new York.

[OceanStWx]

A lot of good stuff mentioned so far in this thread. As Ekster stated earlier, the shear vectors were almost perfectly orthogonal to the initiating boundary, keeping storms discrete from Maine down to southeastern New York.

You can see shear vectors here (around the time the Springfield storm was approaching Sturbridge) are WNW or NW, versus the prefrontal trough being SW to NE oriented.

Toss in the added effects of vorticity stretching and locally backed flow and you have some classic, discrete supercells in southern New England. We saw multiple supercells rapidly develop mesos in the Westfield area, so there was definitely some kind of local effect going on there. I think the combination of the elevation change stretching the updraft such that the mid level mesos tightened up and the low level wind funneling up the valley providing enhanced helicity for the low level rotation helped in tornadogenesis.

In fact, taking a look at the hi-res terrain maps on AWIPS, there are three north-south "valleys" in the areas where the tornadic signatures seemed to cycle up.

The obvious being the Connecticut River Valley, but there are also two subtle changes in elevation south of Monson (and could argue for another near Brimfield), and again near Southbridge.

[polski]

There are one of two good papers that talk about this occuring in the Mechanicville storm. The 1995 Great Barrington tornado likely had a similar process take place in the Housatonic River Valley coming off the Taconics.

There's also a paper on terrain effects re Great Barrington. Conclusion:

"What data were available suggested that on a day when the mesoscale environment was supportive

of supercell thunderstorm development, according to conventional indicators of wind shear and atmospheric

stability, topographic configurations and the associated channeling of ambient low-level flows

conspired to create local orographic enhancements to tornadogenesis potential."

[Tropopause_Fold]

In fact, taking a look at the hi-res terrain maps on AWIPS, there are three north-south "valleys" in the areas where the tornadic signatures seemed to cycle up.

The obvious being the Connecticut River Valley, but there are also two subtle changes in elevation south of Monson (and could argue for another near Brimfield), and again near Southbridge.

With the above in mind...below is the evolution of this cell as it encounters the valley - as picked up from KENX. I'll post the BOX images from east of Springfield later on.

[weatherwiz]

Going to be rated an EF3 higher

..SOME PRELIMINARY TORNADO SURVEY INFORMATION

THE NATIONAL WEATHER SERVICE IN TAUNTON MASSACHUSETTS IS STILL IN

THE PROCESS OF CONDUCTING A STORM SURVEY. HOWEVER AT THIS TIME WE

ARE ABLE TO CONFIRM SOME INFORMATION REGARDING THE TORNADO THAT

PASSED FROM WESTFIELD THROUGH SPRINGFIELD AND EASTWARD TO MONSON AND

BEYOND.

SOME OF THE HARDEST HIT AREAS WILL BE CLASSIFIED WITH A RATING OF

EF-3 OR HIGHER ON THE ENHANCED FUJITA DAMAGE CLASSIFICATION SCALE.

WE ARE HOPING TO BE ABLE TO PROVIDE MORE COMPLETE INFORMATION ON

PATH LENGTH...PATH WIDTH...TIMING...AND EF SCALE RANKINGS...LATE

THIS EVENING.

[CT Rain]

Here are my tweets from the tornado. I love twitter... if you're not on it yet... get on it!

• Barnes AFB reports a funnel cloud. Strong storm with rotation heading toward Springfield.
• KBAF 012024Z 30005KT 1 1/4SM R20/4500VP6000FT FC +TSRA BKN024 BKN030 OVC065 26/22 A2984
• Springfield Mass take cover… . EXTREMELY violent storm moving in
• Have no idea why there’s no tornado warning on that cell
• Tornado warning technically now in effect for northern HFD, Tolland, and Windham Counties but I expect storm will stay north
• @WMassStormChsrs Did it touch down? BAF reported just a funnel cloud
• very strong rotation over downtown Sprinfield. No immediate threat to CT. Warning is out of an abundance of caution.
• Police report a tornado on the ground in Westfield Mass!!!
• Tornaod on the ground seemingly in SPRINGFIELD from WWLP
• INCREDIBLE LIVE VIDEO FROM WWLP OF TORNAOD ON THE GROUND IN SPRINGFIELD
• TORNADO HAS CROSSED CT RIVER…. SIGNIFICNAT DEBRIS IN THE AIR
• LIve stream from WWLP of large tornado on the ground
• Storm passing north of Stafford now… does not appear to be deviating in track. Will miss CT.
• WWLP showing live pics of houses without roofs in Springfield.
• Wibraham, Holland, and Sturbridge take cover. This is a very serious and life threatening situation.
• Areas south of the Mass Pike in Worcester County take shelter. If you are driving on 84 east toward Worcester delayer your plans
• Storm heading into Worcester County JUST north of Woodstock looks even stronger. Extremely dangerous and life threatening situation.
• HUGE debris ball on radar now JUST west of I-84 in Sturbridg
• I can’t express the seriousness of the storm heading toward Sturbridge just south of Mass Pike near 84. Tornado ON THE GROUND
• Wales, Holland, and Brimfield likely suffered serious damage with a huge debris ball on radar
• Debris ball on radar indicates tornado has picked up parts of trees and houses thousands of feet in the air. Heading straight to Sturbridge.
• Debris ball on Rt 20 in Brimfield and Fiskdale, MA.
• Closer to home… hail likely in 2 CT cells. One near Clinton and another heading to Willimantic.
• Tornado Warning still in effect for northern Windham County but tornado will miss to the north
• Reports are sketchy from Brimfield/Monson/Sturbridge but this could have been very large and violent
• Radar shows about as impressive of a debris ball as you can get
• Tornado about to cross I-395 north of Thompson. If you are traveling in NE CT on 395… DO NOT venture into Mass
• National Weather Service reports tornado touchdown on I-84 in Sturbridge.
• Damage in Springfield looks pretty bad but I am fearful the damage east toward Sturbridge is going to be much worse.
• Rotation finally appears to be weakening. This tornado could have been on the ground all the way from Westfield to Sturbridge
• Hearing uncomfirmed reports from Boston stations of “tremendous damage” and houses “gone” in Monson, MA

[Damage In Tolland]

Here are my tweets from the tornado. I love twitter... if you're not on it yet... get on it!

• Barnes AFB reports a funnel cloud. Strong storm with rotation heading toward Springfield.
• KBAF 012024Z 30005KT 1 1/4SM R20/4500VP6000FT FC +TSRA BKN024 BKN030 OVC065 26/22 A2984
• Springfield Mass take cover… . EXTREMELY violent storm moving in
• Have no idea why there’s no tornado warning on that cell
• Tornado warning technically now in effect for northern HFD, Tolland, and Windham Counties but I expect storm will stay north
• @WMassStormChsrs Did it touch down? BAF reported just a funnel cloud
• very strong rotation over downtown Sprinfield. No immediate threat to CT. Warning is out of an abundance of caution.
• Police report a tornado on the ground in Westfield Mass!!!
• Tornaod on the ground seemingly in SPRINGFIELD from WWLP
• INCREDIBLE LIVE VIDEO FROM WWLP OF TORNAOD ON THE GROUND IN SPRINGFIELD
• TORNADO HAS CROSSED CT RIVER…. SIGNIFICNAT DEBRIS IN THE AIR
• LIve stream from WWLP of large tornado on the ground
• Storm passing north of Stafford now… does not appear to be deviating in track. Will miss CT.
• WWLP showing live pics of houses without roofs in Springfield.
• Wibraham, Holland, and Sturbridge take cover. This is a very serious and life threatening situation.
• Areas south of the Mass Pike in Worcester County take shelter. If you are driving on 84 east toward Worcester delayer your plans
• Storm heading into Worcester County JUST north of Woodstock looks even stronger. Extremely dangerous and life threatening situation.
• HUGE debris ball on radar now JUST west of I-84 in Sturbridg
• I can’t express the seriousness of the storm heading toward Sturbridge just south of Mass Pike near 84. Tornado ON THE GROUND
• Wales, Holland, and Brimfield likely suffered serious damage with a huge debris ball on radar
• Debris ball on radar indicates tornado has picked up parts of trees and houses thousands of feet in the air. Heading straight to Sturbridge.
• Debris ball on Rt 20 in Brimfield and Fiskdale, MA.
• Closer to home… hail likely in 2 CT cells. One near Clinton and another heading to Willimantic.
• Tornado Warning still in effect for northern Windham County but tornado will miss to the north
• Reports are sketchy from Brimfield/Monson/Sturbridge but this could have been very large and violent
• Radar shows about as impressive of a debris ball as you can get
• Tornado about to cross I-395 north of Thompson. If you are traveling in NE CT on 395… DO NOT venture into Mass
• National Weather Service reports tornado touchdown on I-84 in Sturbridge.
• Damage in Springfield looks pretty bad but I am fearful the damage east toward Sturbridge is going to be much worse.
• Rotation finally appears to be weakening. This tornado could have been on the ground all the way from Westfield to Sturbridge
• Hearing uncomfirmed reports from Boston stations of “tremendous damage” and houses “gone” in Monson, MA

LOL.. I saw most of those that night when i got home.

Folks that join..I'd suggest following Ryan..and me

[CoastalWx]

LOL.. I saw most of those that night when i got home.

Folks that join..I'd suggest following Ryan..and me

LOL, you're on that??

[weatherwiz]

LOL.. I saw most of those that night when i got home.

Folks that join..I'd suggest following Ryan..and me

Who would want to follow you?

[Damage In Tolland]

LOL, you're on that??

Of course..Who isn't? It's real time data

[Damage In Tolland]

Who would want to follow you?

22 yr olds that have no drivers license or car

[CoastalWx]

Of course..Who isn't? It's real time data

I'm not. Maybe I should be.

I'm just picturing you sending weenie tweets about weather.

[Damage In Tolland]

I'm not. Maybe I should be.

I'm just picturing you sending weenie tweets about weather.

LOL..I do that and it's great

[Johnno]

twitter is in the words

[Johnno]

of the two chasers from Springfield in the youtube video "LEGIT" lol