It would later be followed by a similar event on August 2, 2006 which was about the same, maybe larger in scale.
Radar Image:
More information on event: http://en.wikipedia.org/wiki/Great_Lake ... st_derecho
One year Anniversary of Southern-Ontario Derecho Event
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One year Anniversary of Southern-Ontario Derecho Event
On this date, one year ago a massive severe weather event hit not only southern-Ontario, but a large area of the Great Lakes and states around them. Earlier in the day, other smaller scale derechoes hit places like North Bay and caused quite a lot of damage with debris littering the streets. Tornado warnings were up for numerous places around there. Then in the evening, the large derecho set up for the rest of Ontario and around. I believe a few people were killed in the squall line from camping.
It would later be followed by a similar event on August 2, 2006 which was about the same, maybe larger in scale.
Radar Image:
More information on event: http://en.wikipedia.org/wiki/Great_Lake ... st_derecho
It would later be followed by a similar event on August 2, 2006 which was about the same, maybe larger in scale.
Radar Image:
More information on event: http://en.wikipedia.org/wiki/Great_Lake ... st_derecho
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CrazyC83
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Re: One year Anniversary of Southern-Ontario Derecho Event
Larger in scale on August 2nd? I don't think so. Maybe in Ontario yes, but not in the grand scope...
It was the start of a wild weather week. 4 of the 5 days in that work week (only Thursday the 20th did not) had significant to historic derecho events. That had to be almost unprecedented for so many to occur so fast.
Yet only one of those occured in even a MDT risk area...and one of them totally busted the forecast by going into an area with (at the time) no risk of severe weather!
The number of wind reports that week (in the US alone): 878 (795 if you took out the 20th)
181 on the 17th
212 on the 18th
151 on the 19th
83 on the 20th (scattered)
251 on the 21st
In addition, there were 11 tornado reports (most embedded in the derecho areas).
It was the start of a wild weather week. 4 of the 5 days in that work week (only Thursday the 20th did not) had significant to historic derecho events. That had to be almost unprecedented for so many to occur so fast.
Yet only one of those occured in even a MDT risk area...and one of them totally busted the forecast by going into an area with (at the time) no risk of severe weather!
The number of wind reports that week (in the US alone): 878 (795 if you took out the 20th)
181 on the 17th
212 on the 18th
151 on the 19th
83 on the 20th (scattered)
251 on the 21st
In addition, there were 11 tornado reports (most embedded in the derecho areas).
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Re: One year Anniversary of Southern-Ontario Derecho Event
CrazyC83 wrote:Larger in scale on August 2nd? I don't think so. Maybe in Ontario yes, but not in the grand scope...
In Ontario it was, but I remember on August 2nd the derecho squall line reached from southern Quebec to Illinois in the US. That was pretty huge, not the largest of the year maybe but it was huge. I don't remember the same with July 17, 2006 unless a radar image can show the whole thing (I saved a American radar map from Aug.2/06).
To this minute, there was a squall line coming from Lake Huron to southern Ontario...
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Re:
CrazyC83 wrote:Not just the 17th but the days following it...
Yeah, that's what I think you were talking about in the first place. I think you were thinking of the days of the overall event, and not the length of the single derecho on any one day.
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CrazyC83
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Re: One year Anniversary of Southern-Ontario Derecho Event
Cyclenall wrote:Radar Image:
There seems to be 4 lines there: the first one over Quebec (didn't do much), the second one over the Ottawa Valley (classic bow echo by then - the most destructive), the third one over southern Ontario (looks more like supercells) and the fourth one over Michigan and the Lake Michigan shores (also quite destructive) all going in different directions...
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Re: One year Anniversary of Southern-Ontario Derecho Event
CrazyC83 wrote:There seems to be 4 lines there: the first one over Quebec (didn't do much), the second one over the Ottawa Valley (classic bow echo by then - the most destructive), the third one over southern Ontario (looks more like supercells) and the fourth one over Michigan and the Lake Michigan shores (also quite destructive) all going in different directions...
I noticed that too. I don't know what that one over Michigan was, but it looked nasty.
If we think that is bad though, check out what's happening in northern Illinois and Indiana!
I saw a live lightning tracking on it and I have never seen that much lightning shown on it before. There is also many places within it with rotation. How scary would that be at night? It's also hitting the city of Chicago. Check out the radar!! It must be insane!
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tropicana
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Re: One year Anniversary of Southern-Ontario Derecho Event
yea, i was watching WGN TV news last night on cable from Chicago and the live video shots of downtown Chicago around 10:30pm ET ( 930pm CT) were just amazing, it was continuous and freqent lightning strikes. Here is the report:-
July 18, 2007
Flooding rains, dazzling lightning score direct hit on area
The Chicago area, which had escaped flooding rains during thunderstorm eruptions to the west and south Monday and Tuesday evenings, couldn’t escape Wednesday evening’s storms. Rains fell so heavily in parts of the area, motorists were forced to the shoulder. Lightning displays were dazzling. Nearly 20% of cloud-to-ground strokes were so-called “positively charged” lightning discharges, which are often of higher amperage (i.e. more energetic) and therefore more prone to setting fires and causing injuries. Police report a moving vehicle was struck by lightning in Riverwoods setting it on fire. Miraculously, there were no injuries.
The t-storms responsible tapped the most humid air of 2007 to date and towered to 59,000 ft. At peak intensity, 4,700 cloud to ground lightning discharges were measured in just 10 minutes Wed. evening.
Positive lightning
Positive lightning, also known colloquially as a "bolt from the blue" makes up less than 5% of all lightning.[citation needed] It occurs when the leader forms at the positively charged cloud tops, with the consequence that a negatively charged streamer issues from the ground. The overall effect is a discharge of positive charges to the ground. Research carried out after the discovery of positive lightning in the 1970s showed that positive lightning bolts are typically six to ten times more powerful than negative bolts, last around ten times longer, and can strike tens of kilometres/miles from the clouds.[19] The voltage difference for positive lightning must be considerably higher, due to the tens of thousands of additional metres/feet the strike must travel. During a positive lightning strike, huge quantities of ELF and VLF radio waves are generated.[citation needed]
As a result of their greater power, positive lightning strikes are considerably more dangerous. At the present time, aircraft are not designed to withstand such strikes, since their existence was unknown at the time standards were set, and the dangers unappreciated until the destruction of a glider in 1999.[20] Positive lightning is also now believed to have been responsible for the 1963 in-flight explosion and subsequent crash of Pan Am Flight 214, a Boeing 707[citation needed]. Subsequently, aircraft operating in U.S. airspace have been required to have lightning discharge wicks to reduce the chances of a similar occurrence.
Positive lightning has also been shown to trigger the occurrence of upper atmosphere lightning. It tends to occur more frequently in winter storms and at the end of a thunderstorm.[21]
An average bolt of positive lightning carries a current of up to 300 kA (kiloamperes) (about ten times as much current as a bolt of negative lightning), transfers a charge of up to 300 coulombs, has a potential difference up to 1 GV (gigavolts), and lasts for hundreds of milliseconds, with a discharge energy of up to 300 GJ (gigajoules).
-justin-
July 18, 2007
Flooding rains, dazzling lightning score direct hit on area
The Chicago area, which had escaped flooding rains during thunderstorm eruptions to the west and south Monday and Tuesday evenings, couldn’t escape Wednesday evening’s storms. Rains fell so heavily in parts of the area, motorists were forced to the shoulder. Lightning displays were dazzling. Nearly 20% of cloud-to-ground strokes were so-called “positively charged” lightning discharges, which are often of higher amperage (i.e. more energetic) and therefore more prone to setting fires and causing injuries. Police report a moving vehicle was struck by lightning in Riverwoods setting it on fire. Miraculously, there were no injuries.
The t-storms responsible tapped the most humid air of 2007 to date and towered to 59,000 ft. At peak intensity, 4,700 cloud to ground lightning discharges were measured in just 10 minutes Wed. evening.
Positive lightning
Positive lightning, also known colloquially as a "bolt from the blue" makes up less than 5% of all lightning.[citation needed] It occurs when the leader forms at the positively charged cloud tops, with the consequence that a negatively charged streamer issues from the ground. The overall effect is a discharge of positive charges to the ground. Research carried out after the discovery of positive lightning in the 1970s showed that positive lightning bolts are typically six to ten times more powerful than negative bolts, last around ten times longer, and can strike tens of kilometres/miles from the clouds.[19] The voltage difference for positive lightning must be considerably higher, due to the tens of thousands of additional metres/feet the strike must travel. During a positive lightning strike, huge quantities of ELF and VLF radio waves are generated.[citation needed]
As a result of their greater power, positive lightning strikes are considerably more dangerous. At the present time, aircraft are not designed to withstand such strikes, since their existence was unknown at the time standards were set, and the dangers unappreciated until the destruction of a glider in 1999.[20] Positive lightning is also now believed to have been responsible for the 1963 in-flight explosion and subsequent crash of Pan Am Flight 214, a Boeing 707[citation needed]. Subsequently, aircraft operating in U.S. airspace have been required to have lightning discharge wicks to reduce the chances of a similar occurrence.
Positive lightning has also been shown to trigger the occurrence of upper atmosphere lightning. It tends to occur more frequently in winter storms and at the end of a thunderstorm.[21]
An average bolt of positive lightning carries a current of up to 300 kA (kiloamperes) (about ten times as much current as a bolt of negative lightning), transfers a charge of up to 300 coulombs, has a potential difference up to 1 GV (gigavolts), and lasts for hundreds of milliseconds, with a discharge energy of up to 300 GJ (gigajoules).
-justin-
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