Jack Beven
EF0
Hello, everyone!
May 8 is the anniversary of a significant severe weather event in my home town of Baton Rouge, Louisiana. On Ascension Thursday 1975 a line of severe thunderstorms swept through the city, apparently with an embedded tornado. I was in eighth grade at the time, and it was quite an event for me!
The convective system seems to have initiated over eastern Texas during the afternoon or evening of May 7 and moved southeastward. It cause several reports of wind damage, hail, and tornadoes across central and southern Louisiana before approaching the Baton Rouge area at about 2 AM.
In the early 1970's, several of south Louisiana's severe weather events, including tornadoes, occurred late at night. I tended to wake up during those events due to a fear of nighttime tornadoes, and sure enough I woke at at about 2:15 upon hearing the approaching thunder. I turned on my weather radio (Yes, I was a weather geek even at that age!) and was immediate hit with the sound of the old-fashion EBS tone alert, followed by a severe thunderstorm warning for East Baton Rouge Parish. I recall that since it wasn't a tornado warning I wasn't overly impressed at that point.
The storms came closer, then at 2:30 the wind started to blow - very hard! I saw a couple of flashes of blue-tinted lightning (power flashes as I now know), then my bedroom windows (facing northwest and southwest) were hit with heavy rain propelled by winds probably to hurricane force. I could see nothing out of them except the continued blue flashes. One of the flashes was the power going out at my house.
These winds were stronger than anything I had seen in a thunderstorm before, and as you might guess I thought I was getting hit by a tornado. It was one of the few times that I was honestly scared by the weather, and I was running around through my house in a rather agitated state. Everyone in my family woke up except for my brother, who managed to sleep through the storm even though his bedroom window was also getting blasted. The winds and rains continued for about 20 minutes and then stopped. After that, it was calm outside with just distant thunder to the east, some residual rain, and the sirens of emergency vehicles not far away.
It may sound strange, but school was not called off that morning, as my school (about 3 miles north of my house) had power. As you might guess, though, all of us there were a bit shocked and there was a lot of speculation about just what had happened. School ended that day in a rather strange fashion. One of the official came on the public address system saying that another line of thunderstorms was approaching and that classes would be dismissed immediately to let people get home before it hit. At the time that the storms were supposed to arrive, an overcast that had been present all day cleared and the sun came out. No second line of storms showed up that day!
To turn things to a more scientific note, I've never fully reconstructed what happened that night. The event was a squall line, one probably with embedded bow echoes, LEWPs, or HP supercells. Looking at the list of severe weather reports for Louisiana for that day in Storm Data and on the NCDC web site, I'm not sure it meets the criteria for a derecho. It may not have missed by much, though.
In the Baton Rouge area, the online tornado data base I've looked at shows a 6 mile long tornado track starting near the northern part of the LSU campus and passing about 1/2 mile north of my house. This tornado is rated an F2. All I can say is that I did not (and probably could not) see the tornado. However, if the track is right being that close to a tornadic circulation would certainly explain the ferocity of the winds. Two additional points: First, I crossed the damage track to get to school that morning and I don't recall seeing anything that leaped out to me as tornado damage. But then, I probably would not have recognized it in those days.
Second, a couple of miles east of my house there were some large trees that were blown down with the dirt balls pulled out of the ground along with the roots - almost to the point of being uprooted. Those trees were probably old enough that they survived Hurricanes Hilda and Betsy in 1964 and 1965 (the latter with 90 mph wind gusts), and their blowing down makes the F2 report more believeable.
The Baton Rouge airport (10 miles north of my house) had a peak gust of 59 mph, while another F2 tornado occured about 25-30 miles northeast of Baton Rouge. The storms caused $2 million in property damage in Baton Rouge, which was more than all the tropical cyclones that affected the area in the 1970's. The power was out at my house for two and a half days, and in other parts of town it was out for five days.
One thing I've never figured out is the report of the second line of storms. Most of that day there was mid-level gunge overcast with no surface heating to speak of. There were also no indications that I remember that would suggest a dynamically-forced squall line was approaching that would hit in spite of the gunge. I'm not sure whether there was something coming that dissipated when it hit the stable cold pool, whether there was rumor-mongering or false reports, or whether the administration just decided to let us off early.
I need to do more study on this , including looking at the available weather maps for the synoptic set up. Eventually, I'll probably need to look at the old radar films from NCDC to put together what happened on the mesoscale. In any case, I've got a lot to learn about this personal signature event.
Jack Beven
May 8 is the anniversary of a significant severe weather event in my home town of Baton Rouge, Louisiana. On Ascension Thursday 1975 a line of severe thunderstorms swept through the city, apparently with an embedded tornado. I was in eighth grade at the time, and it was quite an event for me!
The convective system seems to have initiated over eastern Texas during the afternoon or evening of May 7 and moved southeastward. It cause several reports of wind damage, hail, and tornadoes across central and southern Louisiana before approaching the Baton Rouge area at about 2 AM.
In the early 1970's, several of south Louisiana's severe weather events, including tornadoes, occurred late at night. I tended to wake up during those events due to a fear of nighttime tornadoes, and sure enough I woke at at about 2:15 upon hearing the approaching thunder. I turned on my weather radio (Yes, I was a weather geek even at that age!) and was immediate hit with the sound of the old-fashion EBS tone alert, followed by a severe thunderstorm warning for East Baton Rouge Parish. I recall that since it wasn't a tornado warning I wasn't overly impressed at that point.
The storms came closer, then at 2:30 the wind started to blow - very hard! I saw a couple of flashes of blue-tinted lightning (power flashes as I now know), then my bedroom windows (facing northwest and southwest) were hit with heavy rain propelled by winds probably to hurricane force. I could see nothing out of them except the continued blue flashes. One of the flashes was the power going out at my house.
These winds were stronger than anything I had seen in a thunderstorm before, and as you might guess I thought I was getting hit by a tornado. It was one of the few times that I was honestly scared by the weather, and I was running around through my house in a rather agitated state. Everyone in my family woke up except for my brother, who managed to sleep through the storm even though his bedroom window was also getting blasted. The winds and rains continued for about 20 minutes and then stopped. After that, it was calm outside with just distant thunder to the east, some residual rain, and the sirens of emergency vehicles not far away.
It may sound strange, but school was not called off that morning, as my school (about 3 miles north of my house) had power. As you might guess, though, all of us there were a bit shocked and there was a lot of speculation about just what had happened. School ended that day in a rather strange fashion. One of the official came on the public address system saying that another line of thunderstorms was approaching and that classes would be dismissed immediately to let people get home before it hit. At the time that the storms were supposed to arrive, an overcast that had been present all day cleared and the sun came out. No second line of storms showed up that day!
To turn things to a more scientific note, I've never fully reconstructed what happened that night. The event was a squall line, one probably with embedded bow echoes, LEWPs, or HP supercells. Looking at the list of severe weather reports for Louisiana for that day in Storm Data and on the NCDC web site, I'm not sure it meets the criteria for a derecho. It may not have missed by much, though.
In the Baton Rouge area, the online tornado data base I've looked at shows a 6 mile long tornado track starting near the northern part of the LSU campus and passing about 1/2 mile north of my house. This tornado is rated an F2. All I can say is that I did not (and probably could not) see the tornado. However, if the track is right being that close to a tornadic circulation would certainly explain the ferocity of the winds. Two additional points: First, I crossed the damage track to get to school that morning and I don't recall seeing anything that leaped out to me as tornado damage. But then, I probably would not have recognized it in those days.
Second, a couple of miles east of my house there were some large trees that were blown down with the dirt balls pulled out of the ground along with the roots - almost to the point of being uprooted. Those trees were probably old enough that they survived Hurricanes Hilda and Betsy in 1964 and 1965 (the latter with 90 mph wind gusts), and their blowing down makes the F2 report more believeable.The Baton Rouge airport (10 miles north of my house) had a peak gust of 59 mph, while another F2 tornado occured about 25-30 miles northeast of Baton Rouge. The storms caused $2 million in property damage in Baton Rouge, which was more than all the tropical cyclones that affected the area in the 1970's. The power was out at my house for two and a half days, and in other parts of town it was out for five days.
One thing I've never figured out is the report of the second line of storms. Most of that day there was mid-level gunge overcast with no surface heating to speak of. There were also no indications that I remember that would suggest a dynamically-forced squall line was approaching that would hit in spite of the gunge. I'm not sure whether there was something coming that dissipated when it hit the stable cold pool, whether there was rumor-mongering or false reports, or whether the administration just decided to let us off early.
I need to do more study on this , including looking at the available weather maps for the synoptic set up. Eventually, I'll probably need to look at the old radar films from NCDC to put together what happened on the mesoscale. In any case, I've got a lot to learn about this personal signature event.
Jack Beven
