22-years ago yesterday

[weatherwiz]

It was 22-years ago yesterday on July 10th, 1989 a major tornado outbreak affected portions of the Northeast. The states hit the hardest were NY/NJ/MA/CT with NY/CT being hit the most severe as two violent tornadoes struck these states. A total of 17 tornadoes were confirmed across the 4 states; with 3 being confirmed in NJ; 7 being confirmed in MA; 4 being confirmed in NY and 3 being confirmed in CT. While MA had the most confirmed tornadoes they were all fairly on the weak side with 5 of them being rated as F1 and the other two rated as F0's. The 3 in NJ were weak as well with 2 of the tornadoes rated as F0's and the other rated as an F1. It was NY/CT which saw the most damaging tornadoes. Of the 4 confirmed tornadoes in NY two of them were rated F2's, one was rated an F1 and the other was rated as an F4, the second highest rating on the Fujita scale. CT saw two tornadoes rated as F2's and the other rated a F4.

Tornado outbreaks in this part of the country are relatively rare but what made this one even more rare was the fact that there were two violent tornadoes within the outbreak, and one of them occurring in a state that really doesn't see this happen. In fact, since tornado records had been kept since 1950 this was only the second time a tornado was rated an F4 in the state of CT with the other time being nearly 10 years earlier; the famous Windsor Locks F4 which occurred on October 3rd, 1979.

In order for something some this caliber to occur you need a special weather pattern in place and you need all the right ingredients to come together and come together perfectly. In this part of the country this rarely every happens but on this day, July 10th, 1989 everything came together to produce a major severe weather/tornado outbreak.

Meteorological inside:

On the morning of Monday, July 10th, 1989 a warm front beginning lifting northward through the region from the southwest. The warm front was accompanied by some showers/t'storms with it's passage. As the front lifted through and the associated showers/t'storms exited the region a very warm, moist and unstable airmass quickly overspread the region. As the sun came out temperatures soared through the 80's...even near 90F in some locations and dewpoints rose through the 60's to even 70F. These two factors helped lead to an extremely unstable airmass across the region.

While conditions at the surface were ripe for severe weather something special was occurring up in the atmosphere that would not only help to increase the instability but also add fuel to the severe weather that would occur later on in the day. This something special was an elevated mixed layer (or EML). Elevated mixed layers are a crucial part to getting high end/large-scale severe weather and tornado outbreaks, especially here in the Northeast. In fact, nearly all of our major events have occurred when an EML has been in place. So what is an EML?

In the United States EML's originate across the intermountain west and the desert southwest. EML's are basically pockets of very warm and very dry air from about 6,5000 above ground level (AGL) to about 14,000ft AGL. This layer of the atmosphere is much warmer than the air just below it and just above it. This pocket of extremely warm air develops as air descending over the Rocky Mountains warms and dries plus, you have the desert southwest where it's very hot and very dry. This allows the EML to remain firm.

They will often propagate east and make it to the Plains and sometimes into portions of the Ohio Valley. However, once they usually work further east the EML tends to weaken as the airmass in this part of the country becomes much more moist and it's not as hot. There will be times though when the EML can survive all the way to the east coast, but it takes a very special synoptic setup for this to occur.

In order to get an EML to get into this part of the country one thing you'd like to see is a strong ridge that is setup across parts of the central and southern United States. You want the Northeast to be just on the crest of the ridge. This allows us to be in a more westerly/northwesterly flow in the mid levels of the atmosphere. With this setup the EML's will usually work from the SW and ride along the ridge, working northeastward through the central/northern Plains going into southern Canada, working east towards the Great Lakes and then finally into the Northeast. The kick about this is, having a pattern setup like this doesn't guarantee an EML getting into the region, there could be times where no EML breaks off from the southwest at all, or there could be times where the EML slowly washes out as it moves over the Great Lakes. This could occur from thunderstorms/showers moistening up and cooling the mid levels or just because the airmass is moving so slow it slowly moderated a bit.

Below is a 500mb map from July 10th, 1989. As you can see there is a strong ridge located across the central/southern US in which the Northeast is on the crest of the ridge allowing for the wind alignment in the mid levels to be from the west/northwest. The EML advected up over the ridge and survived the trip to the Northeast.

Elevated-mixed layers originate over the inter-mountain region and the desert southwest. They develop as air traversing over the Rocky Mountains dries significantly and then warms significantly when crossing over the desert areas. In EML's the temperatures from about 800mb to 600mb (~6500ft AGL-~14000ft AGL) will warm, sometimes significantly and the dewpoints in this layer will rapidly drop. The EML, as mentioned above, is an extremely crucial ingredient in high-end severe weather/tornado outbreaks.

EML's are associated with very steep mid-level lapse rates (change of temperature with height) and this can lead to extreme instability at the surface (depending on degree of solar heating at the surface and how high the dewpoints at the surface are). EML's can be visually seen by looking at a skew-t forecast sounding. Below is a skew-t sounding from Albany, NY at 8:00 AM EDT from July 10th, 1989. You can see the EML that is in place.

Besides providing the potential for extreme instability EML's are also important because they provide what is called a cap, this is why EML's can also be referred to as capping inversions. While EML's are important because they are associated with steep mid-level lapse rates which helps to enhance instability as mentioned above, the capping inversion is very important as well. Capping inversion prevent clouds/showers/thunderstorms from developing too early in the day. This is very important because it allows for more solar heating and allows the atmosphere to destabilize even further.

What makes the capping inversion from preventing clouds/showers/thunderstorms from forming? As mentioned earlier the capping inversion, or EML, is a layer within the atmosphere where the temperatures warm and the dewpoints drop. Water parcels which are in the atmosphere thanks to evaporation and transpiration will continue to rise only as long as they remain cooler than the surrounding air. Once the parcels reach this capping inversion they can no longer continue to rise, therefore, they will not reach the level of condensation and will not develop into clouds until this inversion is broken.

With the presence of the EML in place along with surface temperatures into the mid and upper 80's to near 90F and surface dewpoints into the upper 60's to near 70F the combination of everything helped to setup an extremely unstable airmass across the region and this was the fuel needed to feed the monster storms that developed later on that afternoon.

Besides the presence of extreme instability there was a great deal of wind shear aloft. There was a great deal of speed shear (change of wind speed with height) and a great deal of directional shear with height (change of wind direction with height). These two factors are highly critical in the development of supercells (rotating thunderstorms) and the development of tornadoes. If winds are increasing with height as well as changing direction with height this allows for the thunderstorms updraft to become tilted. This further separates the storms updraft from it's downdraft meaning the storm can keep fueling itself and last for a great deal of time. This also allows for the storms updraft to rotate and this can lead to the development of a funnel cloud and perhaps eventually a tornado or tornadogenesis.

Going back to the skew-t posted above if you look on the right hand side you will see a bunch of lines with more lines and even a triangle coming out if it. These are called wind barbs. Wind barbs tell you wind direction as well as wind speed. The way you tell the direction is just by looking at the configuration of the barb and where the lines coming out of it are coming from. For example, if the line is slanted from bottom left to upper right and the lines coming out are on the bottom left that indicates a southwest wind.

How you determine the speed is by looking at how many lines are coming out of the bard. The longer lines indicate 10 knots, the shorter lines indicate 5 knots and the triangles indicate 50 knots. For example, if you have a triangle, a long line and a short line that indicates 65 knots of wind present at that level of the atmosphere.

At 8:00 AM EDT the time the forecast balloon was launched from Albany and the data was recorded there was already a great deal of speed and directional shear present. Winds at the surface were out of the south/southeast and as you went up in the atmosphere they began turning to the southwest, then to the west, then to the northwest. This meant there was a great deal of helicity in place (measurement of directional shear) and suggested that any storms that developed could quickly turn into supercells and acquire strong rotation.

By late morning and especially mid to late afternoon thunderstorms had quickly exploded as the cap eroded and all that instability was unleashed. Given the presence of extreme instability and strong shear storms quickly turned into supercell storms and quickly began rotating. New York was the state first hit. In fact, the first tornado confirmed occurred right around 4:20 AM with thunderstorms associated with the warm front lifting northward. This tornado was rated as an F1 on the Fujita scale and affected the area just northeast of Ogdendensburg in St. Lawrence county.

The second tornado to be confirmed in NY was the granddaddy in NY that day and one of two F4's that would be confirmed that day. Just prior to 12:30 PM a supercell produced a tornado just east of Ames, NY. The tornado then continued moving southeast and as it neared Greenville, NY it really intensified, this was the town hit the hardest and where the F4 damage occurred. All in all this tornado was on the ground for 42 miles, although it did skip towards the end, meaning it lifted off the ground then reached back down. As one supercell neared CT in poroceded to produce a tornado in Putnam county which was rated an F2. As storms in CT moved into Long Island Sound they maintained their strength and ended up producing a tornado on Long Island in Suffolk county, this tornado was rated an F2 as well.

At this time storms were moving into NJ and developing across NJ. Supercells here went on to spawn a total of 3 tornadoes; all were fairly weak with two of the tornadoes rated as F0's and the other rated as an F1.

After a bit of a lull in some action storms quickly began developing in CT and moving into CT from NY. Here the storms really began taking off as the atmosphere was extremely unstable and there was a great deal of wind shear (both speed and directional) present. It was western CT that was hit the hardest; particularly Litchfield and New Haven counties. The first tornado touched down near Cornwall and traveled southeast tracking on the ground for about 10 miles. This tornado was rated as an F2. The second tornado touched down about 30 minutes later, this one just to the north of the Watertown area traveling on the ground for about 5 miles to near the Waterbury area.

The third and final tornado in CT that day was the big one, an F4 tornado that touched down in Hamden, CT and traveled on the ground for about only 3 miles, lifting just before getting into New Haven where serious issues could have occurred.

At the same time the CT action was ongoing a family of supercells in MA was busy spawning tornadoes as well, in fact a total of 7 confirmed tornadoes occurred in MA. However, all these tornadoes were very weak in nature, rated F0's and F1's.

All in all that day over 140 people were injured and unfortunately there was one fatality. Hundreds to thousands of buildings/structures were damaged or destroyed and it was estimated at least $130 million in damage was caused in total (measured in 1989 USD). Besides the tornadoes there were close to 50 reports of straight-line wind damage, with multiple measured wind gusts exceeding 80 mph and multiple reports of large hail, including a few reports greater than 2'' in diameter.

[Johnno]

Very good post Wiz. Yesterday we were at the g/f's family lake house on Bantam Lake for the tormado anniversary bbq. The tornado destroyed the original cottage and luckly her grandparents who were there at the time were smart and took her cousins into the basement and they all got through it uninjuried. Very interesting write up though, good work.

[weatherwiz]

Very good post Wiz. Yesterday we were at the g/f's family lake house on Bantam Lake for the tormado anniversary bbq. The tornado destroyed the original cottage and luckly her grandparents who were there at the time were smart and took her cousins into the basement and they all got through it uninjuried. Very interesting write up though, good work.

Thanks!

Glad to hear they were alright...must have been a pretty scary situation to be in.

[A-L-E-X]

Thanks!

Glad to hear they were alright...must have been a pretty scary situation to be in.

Wow, 1989 was a big year for severe weather up here, Paul. We also had the big November 1989 outbreak that resulted in the Coldenham tragedy! It was also a year where the leaves changed and fell a month early and we saw extreme temperature swings (probably what caused the late season severe weather.)

[weatherwiz]

Wow, 1989 was a big year for severe weather up here, Paul. We also had the big November 1989 outbreak that resulted in the Coldenham tragedy! It was also a year where the leaves changed and fell a month early and we saw extreme temperature swings (probably what caused the late season severe weather.)

Yeah that November outbreak was huge...November 16th I think...NY/NJ (especially NJ) hit very hard...I also think DE got into some of the action too.

[CoastalWx]

Had a weak EF1 in Brockton at the time. I remember the sky looking so crazy, but had no idea a tornado hit.

[AtticaFanatica]

The reason I study tornadoes was this day. Still the strongest rain I've ever seen (after the storm, our street was flooded with frogs from the sewers) and probably the loudest thunder I've ever heard and I've seen 30+ tornadoes. Truly terrifying, though I think we can all agree the F4 tornado was not an F4 tornado, probably an F2-F3. It hit about 5 miles away from my home.

Ironically, we hid in the upstairs hallway instead of the downstairs bathroom. Ooops.

[weatherwiz]

The reason I study tornadoes was this day. Still the strongest rain I've ever seen (after the storm, our street was flooded with frogs from the sewers) and probably the loudest thunder I've ever heard and I've seen 30+ tornadoes. Truly terrifying, though I think we can all agree the F4 tornado was not an F4 tornado, probably an F2-F3. It hit about 5 miles away from my home.

Ironically, we hid in the upstairs hallway instead of the downstairs bathroom. Ooops.

What about the F4 from NY? I read accounts that say some didn't believe that was a 4 either.

[AtticaFanatica]

What about the F4 from NY? I read accounts that say some didn't believe that was a 4 either.

Don't know honestly, I never saw that damage. To be fair, I was 8 when I saw the Hamden damage, but from what I remember about it and having seen F4 damage in person just 6 weeks ago, I feel pretty comfortable in saying it wasn't F4.

[weatherwiz]

Don't know honestly, I never saw that damage. To be fair, I was 8 when I saw the Hamden damage, but from what I remember about it and having seen F4 damage in person just 6 weeks ago, I feel pretty comfortable in saying it wasn't F4.

I wonder what the basis was for their conclusion in the rating...when I visited that area about 10 years ago looked like it was composed of lots of old buildings that probably weren't constructed all too well.

[AtticaFanatica]

I wonder what the basis was for their conclusion in the rating...when I visited that area about 10 years ago looked like it was composed of lots of old buildings that probably weren't constructed all too well.

IIRC, I think there was a gas station or a building near the gas station that was completely destroyed. I actually know where it is and it was destroyed, but all the houses in that area mostly had just moderate roof damage, though there was major tree damage. I don't know, I'm skeptical of basically all F scale ratings because I think we pretend to have precision that we just don't. There is actually a subtle underground movement starting in the community to just do "weak" "moderate" and "strong" ratings instead of the 6 categories we have now. Based on available science, I'd think strongly about supporting that.

[weatherwiz]

IIRC, I think there was a gas station or a building near the gas station that was completely destroyed. I actually know where it is and it was destroyed, but all the houses in that area mostly had just moderate roof damage, though there was major tree damage. I don't know, I'm skeptical of basically all F scale ratings because I think we pretend to have precision that we just don't. There is actually a subtle underground movement starting in the community to just do "weak" "moderate" and "strong" ratings instead of the 6 categories we have now. Based on available science, I'd think strongly about supporting that.

Wow...that sounds really interesting. Would be cool to see how far off the ground that movement goes.

[AtticaFanatica]

Wow...that sounds really interesting. Would be cool to see how far off the ground that movement goes.

There's a lot of people (especially on this forum) that go gaga over the climatology and I don't think they fully grasp that it's just not very accurate. Based on the most recent research, the accuracy of the (E)F-scale ratings are quite poor.

[New England Storm]

Had a weak EF1 in Brockton at the time. I remember the sky looking so crazy, but had no idea a tornado hit.

My dad was in brockton on that day, He said it was very dark and that the air felt "heavy". I dont know if that was befor or after the tornado hit but, he said it was the first time he affraid of a storm.

[weatherwiz]

There's a lot of people (especially on this forum) that go gaga over the climatology and I don't think they fully grasp that it's just not very accurate. Based on the most recent research, the accuracy of the (E)F-scale ratings are quite poor.

I really would think there would be alot of inaccuracies with tornado rating classifications...hopefully with the all the research going on right now sometime in the near future a new system can be developed which can be much more accurate. Doing the scale just on wind/damage alone can really be misleading.

[AtticaFanatica]

I really would think there would be alot of inaccuracies with tornado rating classifications...hopefully with the all the research going on right now sometime in the near future a new system can be developed which can be much more accurate. Doing the scale just on wind/damage alone can really be misleading.

Well, there's really no alternative, I think it's a matter of admitting maybe we're not as accurate we thought we were. That's a bitter pill for some to swallow though, so I'm skeptical anything will come of it.

[CoastalWx]

Vortex95 can write a book on this day. Maybe I can have him post, tomorrow.

[weatherwiz]

Well, there's really no alternative, I think it's a matter of admitting maybe we're not as accurate we thought we were. That's a bitter pill for some to swallow though, so I'm skeptical anything will come of it.

That's another issues as well, I just don't get why some people have trouble admitting certain things...I think it just sets things back rather than help with moving forward. It would be so much better if everyone had just a more open mind and not be so arrogant and think they know everything.

[AtticaFanatica]

That's another issues as well, I just don't get why some people have trouble admitting certain things...I think it just sets things back rather than help with moving forward. It would be so much better if everyone had just a more open mind and not be so arrogant and think they know everything.

Yeah, or the wind estimates that accompany surveys, which I strongly support doing away with. A survey crew that estimates the winds in the Joplin tornado as 200 vs. 210 vs. 220 mph, it just doesn't mean anything, I'm sorry. The error bars on that estimate completely obliterate any meaningful information that could be derived from it. But people like comparing things, even if the comparison is based on really crude estimates and, therefore, even if the comparison is not at all valid.

[AtticaFanatica]

You know, I've never tried to think about this scientifically.

The part of town that got hit by the tornado is NE of where I lived (I'll need to double-check that) and the storm was diving SSE. So I think where I was got RFDed, weird, I never considered that before, that I was in the RFD of the supercell. I guess I always assumed with the torrential rain that I was in the FF, but the storm was undoubtedly HP so that amount of rain was also possible in the RF.

[weatherwiz]

Yeah, or the wind estimates that accompany surveys, which I strongly support doing away with. A survey crew that estimates the winds in the Joplin tornado as 200 vs. 210 vs. 220 mph, it just doesn't mean anything, I'm sorry. The error bars on that estimate completely obliterate any meaningful information that could be derived from it. But people like comparing things, even if the comparison is based on really crude estimates and, therefore, even if the comparison is not at all valid.

Yeah I don't really understand the wind estimates either...for example, if the winds in the Springfield tornado had been estimated 10 mph higher going by the wind estimates of the EF scale it would have been classified as an EF4 rather than an EF3.

I understand how people like to compare things, nothing too wrong with that, however, you have to be extremely careful with what you're comparing and you have to be very open minded and you shouldn't really make a complete classification just based on if something, in this case damage looks similar.

As we go into the future as well and building structures are improved and codes are updated the wind criteria measurements are just going to become outdated and eventually it's just going to get to the point where these criteria measurements are only relevant for the present and a portion of the future and will mean nothing for past events. So it's basically getting to the point where past data and past records are just not really going to mean all that much.

[A-L-E-X]

That's another issues as well, I just don't get why some people have trouble admitting certain things...I think it just sets things back rather than help with moving forward. It would be so much better if everyone had just a more open mind and not be so arrogant and think they know everything.

This happens in all the sciences Paul and is the biggest hindrance to advance. You know that old Max Planck quote-- : "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."

With that said, I wonder if we will ever be able to accurately judge tornado intensity with radars-- maybe if we made them more precise they would one day be able to judge wind intensity within a decent margin of error?

[vortex95]

Vortex95 can right a book on this day. Maybe I can have him post, tomorrow.

I didn't know I could "right" a book...what's wrong w/ it???

Coastal Wx is now known as EML Man...that's all he talks about since the Dixie Super Outbreak this year!

[AtticaFanatica]

With that said, I wonder if we will ever be able to accurately judge tornado intensity with radars-- maybe if we made them more precise they would one day be able to judge wind intensity within a decent margin of error?

You'd need a dense network of radars so that all or most tornadoes could be sampled close to the surface, there's no way that's going to happen anytime soon though, it's just too costly.

[A-L-E-X]

You'd need a dense network of radars so that all or most tornadoes could be sampled close to the surface, there's no way that's going to happen anytime soon though, it's just too costly.

Yep, something like that would probably be a few decades away although something worth waiting for I think, because it should be more objective than our current means of estimating tornadic wind intensity

[vortex95]

The reason I study tornadoes was this day. Still the strongest rain I've ever seen (after the storm, our street was flooded with frogs from the sewers) and probably the loudest thunder I've ever heard and I've seen 30+ tornadoes. Truly terrifying, though I think we can all agree the F4 tornado was not an F4 tornado, probably an F2-F3. It hit about 5 miles away from my home.

Ironically, we hid in the upstairs hallway instead of the downstairs bathroom. Ooops.

The remark about the strongest rain...I believe it. Oxford CT had 4.4" of rain in just 30 minutes (from the BOS LSR) and

even though I failed to get to the monster HP in time, I hit some other cells N of it in the HFD area, and I have never seen

it rain so hard. Even though the cells were rather small, on the highway it looked like a very dark brown fog ahead from the

ground up. Little CC bolts where shooting all over the place from the upper part of the dark area. I have never seen anything

quite like that in terms of a storm darkness since, even in the chasing in the Plains.

I was told the skies were pitch black in HVN, and it was said since it so mean looking as that HP monster approached, a lot

of ppl took cover just b/c of that, whether or not they knew of the tornado warning.

[vortex95]

Here are all the svr reports I compiled for 7/10/89 for New England shortly after the outbreak. Most I got from LSRs. I can't remember

when I got the July 1989 issue of Storm Data months later if I went though and looked for more. I'll post more on this day soon.

JULY 10

-----------

WIND DAMAGE - SHAFTSBURY,VT

HAIL 1 3/4" - MONTPELIER,VT

WIND DAMAGE - MONTPELIER,VT

WIND DAMAGE - WILLIAMSTOWN,MA

HAIL 3/4" - HOLYOKE,MA

HAIL 3/4" - WESTFIELD,MA

HAIL 3/4" - NORTHFIELD,MA

CONVECTIVE GUST 50KTS - NORTHFIELD,MA

WIND DAMAGE - SOUTH RANDOLPH,VT

CONVECTIVE GUST 50KTS - PITTSFIELD,MA

WIND DAMAGE - TEMPELTON,MA

CONVECTIVE GUST 61KTS - STERLING,MA

WIND DAMAGE - STERLING,MA

HAIL 1" - MARLBORO,MA

WIND DAMAGE - SALISBURY,CT

WIND DAMAGE - SHARON,CT

WIND DAMAGE - LAKEVILLE,CT

HAIL 3/4" - WASHINGTON,MA

WIND DAMAGE - LENOX,MA

HAIL 3/4" - LENOX,MA

WIND DAMAGE - HARWICH,MA

TORNADO - HUBBARDSTON,PRINCETON,STERLING,WEST BOYLSTON,MA

TORNADO - ASHLAND,MA

TORNADO - BROCKTON,MA

TORNADO - HANOVER,MA

TORNADO - CANTON,MA

WIND DAMAGE - MILTON,VT

WIND DAMAGE - KENT,CT

WIND DAMAGE - CANAAN,CT

CONVECTIVE GUST 80KTS - MORRIS,CT

WIND DAMAGE - MORRIS,CT

WIND DAMAGE - WATERTOWN,CT

WIND DAMAGE - TORRINGTON,CT

WIND DAMAGE - WATERBURY,CT

HAIL 1 1/4" - WOODBURY,CT

TORNADO - CORNWALL,MILTON,BANTAM,CT

TORNADO - WATERTOWN,OAKVILLE,WATERBURY,CT

HAIL 1 1/2" - OXFORD,MA

HAIL 3/4" - LUDLOW,MA

HAIL 1" - WEST SPRINGFIELD,MA

WIND DAMAGE - WEST SPRINGFIELD,MA

CONVECTIVE GUST 70KTS - NEW HAVEN,CT

TORNADO - HAMDEN,CT

WIND DAMAGE - MIDDLETOWN,CT

WIND DAMAGE - SALISBURY,MA

WIND DAMAGE - NEWBURYPORT,MA

HAIL 3/4" - CHICOPEE,MA

HAIL 1 3/4" - HAMPDEN,MA

HAIL 3/4" - RICHMOND,MA

[weatherwiz]

Thanks for posting that! That's not a bad amount of reports considering it was still the late 80's and I'm sure the skywarn program and Ham program weren't completely established yet so I imagine back then it was more difficult to get reports. The convective gusts of 75 knots in New Haven is totally sick.