fredhopkinsiii
I'm a new member - I watched this tornado from a very good vantage point and remember it and the overall weather ...[very] vivedly. I'm not sure if I'm restricted from replying.
Thanks
I'm a new member - I watched this tornado from a very good vantage point and remember it and the overall weather ...[very] vivedly. I'm not sure if I'm restricted from replying.
Thanks
Bobby Prentice
Here is some information on these June 13, 1976 Iowa and Illinois tornadoes.
Jordan, IA F5 tornado, June 13, 1976
Lemont, Illinois F4 tornado, June 13, 1976
YouTube video clip- Jordan, IA F5 and F3 tornadoes; Lemont, IL F4 tornado from June 13, 1976 (from Tornado Video Classics by The Tornado Project (Tom Grazulis))
Storm Data severe weather reports map - June 13, 1976
Surface Analysis Chart - 19Z, June 13, 1976
500 Millibar Chart - 12Z, June 13, 1976
Omaha, NE Sounding (modified) - 12Z, June 13, 1976
YouTube video clip- Jordan, IA F5 and F3 tornadoes; Lemont, IL F4 tornado from June 13, 1976 (from Tornado Video Classics by The Tornado Project (Tom Grazulis))
Significant Tornadoes 1680-1989 by Thomas P. Grazulis said:
Storm Data severe weather reports map - June 13, 1976
Surface Analysis Chart - 19Z, June 13, 1976
500 Millibar Chart - 12Z, June 13, 1976
Omaha, NE Sounding (modified) - 12Z, June 13, 1976
fredhopkinsiii
Jordan Tornado Observations
Matthew I watched the "Jordan Tornado" from an interesting vantage point, from the roof of a 100' foot manufacturing/warehouse/office on the Skunk River bluffs just north of "Old US 30"/Lincoln Highway/Lincolnway just west of I-35, and just north of the CNW mainline.
Here, courtesy Mapquest, is a roadmap with rivers including the Skunk River and Squaw Creek.
Luther Ia is just south of Jordan, and Boone as well as what, the Racoon River are west of and to the left of this map. I used the Mapquest features to include Gilbert and Story City.
Here is the same Mapquest with Aerial view
Ames, Boone, and Jordan in between were on the C&NW mainline and when one of the first transcontinental highways was built that was the "Lincoln Highway" later named US30 and locally known across the country as "Lincolnway".
Iowa was plotted and surveyed before it was settled for the most part which is why the twentieth and twenty-first century road system as well as the layout of the counties on the state map is very much like a checkerboard.
In 1976 TV Stations were pretty much the only ones with and who could afford Video Cameras, The 'worldwideweb' was still only available to Darpa associates, and technologies and facilities we take for granted today were rare. There were cameras but no digital cameras for example.
I was working in the Engineering Dept and had worked previously for the head of plant maintenance - the group responsible for access to the roof.
What got us up to the roof that day and time was not "the tornado' so much as the sky and the weather:
Horizontal visibility was +15 miles, basically clear to the horizon but with both a very strong "bad feel to the air" and a very distinctive large weather feature.
The feature most pronounced for us was a nasty and windy cloud deck at what I gather to have been 5500 ft, at the time it was high enough that we had a clear view from west-southwest to north for a good 20 miles.
I expect everyone with any sort of weather interest has a handful of memories of a one of those seasick green cloud decks that looks more like an upside down very choppy sea than it does a cloud. What drew us to the roof was a sky like that way beyond normal Iowa summertime humidity. What was distinctive about it in the context of the Jordan Tornado discussion was that the "choppy sea" cloud deck was itself in a 20 mile diameter circular rotation.
We were not in any rain when we watched. When we were on the roof what we could see at a distance were what seemed to be locally heavy downpours at 5 to 10 miles.
We caught one very dark 'column' that appeared to be south of the residential area of west Ames. That particular column kicked up a debris V. One of the guys on the roof recognized it as a Tornado at that and with that we went back down to the office. That was the Jordan tornado maybe 5 miles west of where it appeared to be. Locally the tornado predated the public acceptance and usage of the Fujita scale, it appeared to us as a "Definite Tornado" and appeared to be on a course for the western residential areas of Ames.
On the maps Gilbert is next to US 69 north of Ames and Story City is east of US 69 north of our location and Ames on I-35. The "choppy sea rotating cloud deck' was west and north of us, bordered across the valley near Jordan, and also Gilbert north of Ames and mentioned in the archives.
In the immediate days after the Tornado we heard that a TV Channel 13 Cameraman resided or happened to be near Luther Ia at the start and managed to get footage that was very valuable as a research resource.
We heard at the time that they were able to get much better windspeed estimates from this tornado from what they had previously. My recollection is the news estimates at the time were 300+MPH - that may seem exaggerated given the weather radar technology today, but remember that technology wasn't around in '76.
It was in this post 'today' that I discovered that Professor Fujita included the Jordan Tornado in his research. That/he was the other thing that was 'not common knowledge' in 1976.
Very Interesting subject, brings back alot of memories - I'm just sorry I don't have any personal "JPG's" or "Videos" to post.
The Storm ended up dropping tropical amounts of rain just outside Story City - my recollection in the valley where the I-35 Scenic Overlook is on I-35.
On the maps Sioux City is west-northwest of the map maybe 100 miles distant - my recollection does not include anything about this storm heading towards Sioux City while Story City was at the North-northeast edge of the system when the Jordan tornado struck.
BTW the plant 'shelter points' were structures inside the facility and that was where we were after the observations.
Matthew I watched the "Jordan Tornado" from an interesting vantage point, from the roof of a 100' foot manufacturing/warehouse/office on the Skunk River bluffs just north of "Old US 30"/Lincoln Highway/Lincolnway just west of I-35, and just north of the CNW mainline.
Here, courtesy Mapquest, is a roadmap with rivers including the Skunk River and Squaw Creek.
Luther Ia is just south of Jordan, and Boone as well as what, the Racoon River are west of and to the left of this map. I used the Mapquest features to include Gilbert and Story City.
Here is the same Mapquest with Aerial view
Ames, Boone, and Jordan in between were on the C&NW mainline and when one of the first transcontinental highways was built that was the "Lincoln Highway" later named US30 and locally known across the country as "Lincolnway".
Iowa was plotted and surveyed before it was settled for the most part which is why the twentieth and twenty-first century road system as well as the layout of the counties on the state map is very much like a checkerboard.
In 1976 TV Stations were pretty much the only ones with and who could afford Video Cameras, The 'worldwideweb' was still only available to Darpa associates, and technologies and facilities we take for granted today were rare. There were cameras but no digital cameras for example.
I was working in the Engineering Dept and had worked previously for the head of plant maintenance - the group responsible for access to the roof.
What got us up to the roof that day and time was not "the tornado' so much as the sky and the weather:
Horizontal visibility was +15 miles, basically clear to the horizon but with both a very strong "bad feel to the air" and a very distinctive large weather feature.
The feature most pronounced for us was a nasty and windy cloud deck at what I gather to have been 5500 ft, at the time it was high enough that we had a clear view from west-southwest to north for a good 20 miles.
I expect everyone with any sort of weather interest has a handful of memories of a one of those seasick green cloud decks that looks more like an upside down very choppy sea than it does a cloud. What drew us to the roof was a sky like that way beyond normal Iowa summertime humidity. What was distinctive about it in the context of the Jordan Tornado discussion was that the "choppy sea" cloud deck was itself in a 20 mile diameter circular rotation.
We were not in any rain when we watched. When we were on the roof what we could see at a distance were what seemed to be locally heavy downpours at 5 to 10 miles.
We caught one very dark 'column' that appeared to be south of the residential area of west Ames. That particular column kicked up a debris V. One of the guys on the roof recognized it as a Tornado at that and with that we went back down to the office. That was the Jordan tornado maybe 5 miles west of where it appeared to be. Locally the tornado predated the public acceptance and usage of the Fujita scale, it appeared to us as a "Definite Tornado" and appeared to be on a course for the western residential areas of Ames.
On the maps Gilbert is next to US 69 north of Ames and Story City is east of US 69 north of our location and Ames on I-35. The "choppy sea rotating cloud deck' was west and north of us, bordered across the valley near Jordan, and also Gilbert north of Ames and mentioned in the archives.
In the immediate days after the Tornado we heard that a TV Channel 13 Cameraman resided or happened to be near Luther Ia at the start and managed to get footage that was very valuable as a research resource.
We heard at the time that they were able to get much better windspeed estimates from this tornado from what they had previously. My recollection is the news estimates at the time were 300+MPH - that may seem exaggerated given the weather radar technology today, but remember that technology wasn't around in '76.
It was in this post 'today' that I discovered that Professor Fujita included the Jordan Tornado in his research. That/he was the other thing that was 'not common knowledge' in 1976.
Very Interesting subject, brings back alot of memories - I'm just sorry I don't have any personal "JPG's" or "Videos" to post.
The Storm ended up dropping tropical amounts of rain just outside Story City - my recollection in the valley where the I-35 Scenic Overlook is on I-35.
On the maps Sioux City is west-northwest of the map maybe 100 miles distant - my recollection does not include anything about this storm heading towards Sioux City while Story City was at the North-northeast edge of the system when the Jordan tornado struck.
BTW the plant 'shelter points' were structures inside the facility and that was where we were after the observations.
Last edited by a moderator:
MatthewCarman
Thanks for that information Bobby. I just bought both significant tornado books recently for more information myself on events like this one.
Fred you must have an amazing sight being on the roof and watching the storm. Thanks for the story. I have enjoyed the discusion we have had on this event.
Ps. The tornado moved to Story City and not Souix City. That was a mistake from the weather site I was getting information from.
Fred you must have an amazing sight being on the roof and watching the storm. Thanks for the story. I have enjoyed the discusion we have had on this event.
Ps. The tornado moved to Story City and not Souix City. That was a mistake from the weather site I was getting information from.
James Hammett
EF4
Here's the event on the TornadoHistoryProject map:
http://tinyurl.com/yamulof
You can see the approximate paths that the satellite tornado(es) took. I know a guy who was camping at Ledges State Park just a few miles north of where the F5 touched down when this was unfolding. He experienced some hail at his location but it sure beat involuntarily experiencing the inflow on this beast
http://tinyurl.com/yamulof
You can see the approximate paths that the satellite tornado(es) took. I know a guy who was camping at Ledges State Park just a few miles north of where the F5 touched down when this was unfolding. He experienced some hail at his location but it sure beat involuntarily experiencing the inflow on this beast
I read the 1980 paper and from that have formed something of a personal theory as to the paths tornadoes take.
Everything in meteorology is part of a giant fractal of scales. Planetary scale motions contain synoptic scale motions which contain mesoscale motions which contain microscale motions, and smaller and smaller into the realm of atomic motions. While the large scale track of a tornado is directly related to the track of its parent thunderstorm, the track of the tornado on the smaller scale is directly related to the track of its parent mesocyclone and of the motions of the mesocyclone. Imagine a column of air 4 km in diameter rotating at say 10^-2 rad/s. These are typical values for mesocyclone properties. Then imgaine a 1 km diameter tornado doing its own thing somewhere below the mesocyclone. If the axis of the tornado coincides with the axis of the mesocyclone, the tornado will more or less directly follow the path of the mesocyclone. However, if the axis does not coincide, then the tornado will take a path that wobbles much like that of a cycloid. It will wobble farther around some center line the bigger the mesocyclone is and the farther from the center of the mesocyclone the tornado is. I'm pretty sure that's what the Jordan tornado did. When it took that sudden turn from NNW to ESE it probably reached a kink on the "cycloid" it was following.
This also explains why many tornadoes weave to the left near the ends of their lives. They revolve around a cyclonically rotating mesocyclone which would cause them to veer left gradually, but the veering would be more apparent the longer the tornado lives, and thus would be most apparent near the end of the tornado's life. The mirror image theory would lend itself to say that tornadoes spawned from anticyclonic supercells would tend to veer right.
Everything in meteorology is part of a giant fractal of scales. Planetary scale motions contain synoptic scale motions which contain mesoscale motions which contain microscale motions, and smaller and smaller into the realm of atomic motions. While the large scale track of a tornado is directly related to the track of its parent thunderstorm, the track of the tornado on the smaller scale is directly related to the track of its parent mesocyclone and of the motions of the mesocyclone. Imagine a column of air 4 km in diameter rotating at say 10^-2 rad/s. These are typical values for mesocyclone properties. Then imgaine a 1 km diameter tornado doing its own thing somewhere below the mesocyclone. If the axis of the tornado coincides with the axis of the mesocyclone, the tornado will more or less directly follow the path of the mesocyclone. However, if the axis does not coincide, then the tornado will take a path that wobbles much like that of a cycloid. It will wobble farther around some center line the bigger the mesocyclone is and the farther from the center of the mesocyclone the tornado is. I'm pretty sure that's what the Jordan tornado did. When it took that sudden turn from NNW to ESE it probably reached a kink on the "cycloid" it was following.
This also explains why many tornadoes weave to the left near the ends of their lives. They revolve around a cyclonically rotating mesocyclone which would cause them to veer left gradually, but the veering would be more apparent the longer the tornado lives, and thus would be most apparent near the end of the tornado's life. The mirror image theory would lend itself to say that tornadoes spawned from anticyclonic supercells would tend to veer right.
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