Hurricane Frances Question
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- Blown Away
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Hurricane Frances Question
It was clear that Frances encountered dry air as she approached the Bahamas knocking her down from a Cat 4 to a Cat 2. But she stalled over the Gulf Stream for hours w/o any significant strengthening. Is the Gulf Stream providing energy for rapid development hype?
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Frances was also under 25KT of shear when it weakened.
I showed in my M.S. Thesis that vertical shear is required for dry air to cause weakening. Once the shear affected the storm, the dry air was able to penetrate the core and cause weakening. However, the environmental air was drier in Frances a few days earlier, when the shear was weak. My thesis also shows what dry air can do in low shear environments (the case study I used was Rita)
I showed in my M.S. Thesis that vertical shear is required for dry air to cause weakening. Once the shear affected the storm, the dry air was able to penetrate the core and cause weakening. However, the environmental air was drier in Frances a few days earlier, when the shear was weak. My thesis also shows what dry air can do in low shear environments (the case study I used was Rita)
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Re: Hurricane Frances Question
I thought it was because the shear/dry air had disrupted the core of Frances. Thus, Frances was unable to strengthen despite the warm waters.
I think a disrupted core was also why Georges did not strengthen over the Gulf despite very favorable conditions.
I think a disrupted core was also why Georges did not strengthen over the Gulf despite very favorable conditions.
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- brunota2003
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Re: Hurricane Frances Question
Blown_away wrote:It was clear that Frances encountered dry air as she approached the Bahamas knocking her down from a Cat 4 to a Cat 2. But she stalled over the Gulf Stream for hours w/o any significant strengthening. Is the Gulf Stream providing energy for rapid development hype?
I think the GS does both. Come live in the Carolina's, and I'm sure you will find your answers.
Isabel held her own after being severely disrupted because of...the GS and had she of had a few more hours over water, it is likely she would of tried to restrengthen.
Alex in 2004, do I even need to go there?
Charley in 2004, held on as a Cat 1 to make landfall in NC after crossing Florida.
Gaston in 2004 went from a 30 mph Tropical Depression to a 75 mph Category 1 Hurricane in 48 hours before making landfall in SC.
Hurricane Dennis in 1999 jumped from a 75 mph Hurricane to a 105 in 24 hours.
Perhaps the better known one though, is Bertha in 1996. Hurricane Bertha experienced a weakening trend coming up the GS (shear or dry air or both, dunno which)...but in the 12 hours prior to her making landfall, she jumped from 80 mph to 105. 25 mph in 12 hours before making landfall.
Hurricane Ione in 1955, after making landfall in NC, strengthened dramatically as she emerged off the coast, going from 70 mph to 105 in a matter of 12 hours. 35 mph in the 12 hours after emerging from land.
http://www.wunderground.com/hurricane/at19559.asp
And of course, to keep the Florida people happy

http://www.wunderground.com/hurricane/at19922.asp
For some reason, though, weatherunderground has not updated that to show Andrew as a Cat 5 at landfall.
And of course, you have the daily thunderstorms and the Nor' Easters that like to bomb off the coast. The reason why hurricanes typically do not "rapidly intensify" over the gulf stream, is because obviously, most times they are already strong or something is weakening them as they move into the area. However, this area is not hyped for rapid development, in fact, I think it is overlooked more times than not. Anyone who lives right on the coast from Florida to Virginia should be very wary when a storm is poised to move over the Gulf Stream, because you never know...
Just an example of the Gulf Stream's power:

http://www.wunderground.com/hurricane/at20041.asp
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- HalloweenGale
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Re: Hurricane Frances Question
brunota2003 wrote:Blown_away wrote:It was clear that Frances encountered dry air as she approached the Bahamas knocking her down from a Cat 4 to a Cat 2. But she stalled over the Gulf Stream for hours w/o any significant strengthening. Is the Gulf Stream providing energy for rapid development hype?
I think the GS does both. Come live in the Carolina's, and I'm sure you will find your answers.
Isabel held her own after being severely disrupted because of...the GS and had she of had a few more hours over water, it is likely she would of tried to restrengthen.
Alex in 2004, do I even need to go there?
Charley in 2004, held on as a Cat 1 to make landfall in NC after crossing Florida.
Gaston in 2004 went from a 30 mph Tropical Depression to a 75 mph Category 1 Hurricane in 48 hours before making landfall in SC.
Hurricane Dennis in 1999 jumped from a 75 mph Hurricane to a 105 in 24 hours.
Perhaps the better known one though, is Bertha in 1996. Hurricane Bertha experienced a weakening trend coming up the GS (shear or dry air or both, dunno which)...but in the 12 hours prior to her making landfall, she jumped from 80 mph to 105. 25 mph in 12 hours before making landfall.
Hurricane Ione in 1955, after making landfall in NC, strengthened dramatically as she emerged off the coast, going from 70 mph to 105 in a matter of 12 hours. 35 mph in the 12 hours after emerging from land.
http://www.wunderground.com/hurricane/at19559.asp
And of course, to keep the Florida people happy
http://www.wunderground.com/hurricane/at19922.asp
For some reason, though, weatherunderground has not updated that to show Andrew as a Cat 5 at landfall.
And of course, you have the daily thunderstorms and the Nor' Easters that like to bomb off the coast. The reason why hurricanes typically do not "rapidly intensify" over the gulf stream, is because obviously, most times they are already strong or something is weakening them as they move into the area. However, this area is not hyped for rapid development, in fact, I think it is overlooked more times than not. Anyone who lives right on the coast from Florida to Virginia should be very wary when a storm is poised to move over the Gulf Stream, because you never know...
Just an example of the Gulf Stream's power:
http://www.wunderground.com/hurricane/at20041.asp
What do you mean thunderstorms bomb off of the coast?
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- brunota2003
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Re: Hurricane Frances Question
HalloweenGale wrote:What do you mean thunderstorms bomb off of the coast?
I didnt say thunderstorms bomb off the coast...there are the daily thunderstorms over the GS, and then the Nor' Easters that like to bomb off the coast (i.e. the major snow producers ^^).
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Re:
Derek Ortt wrote:Frances was also under 25KT of shear when it weakened.
I showed in my M.S. Thesis that vertical shear is required for dry air to cause weakening. Once the shear affected the storm, the dry air was able to penetrate the core and cause weakening. However, the environmental air was drier in Frances a few days earlier, when the shear was weak. My thesis also shows what dry air can do in low shear environments (the case study I used was Rita)
Since Frances stalled with so much of the storm over land, did frictional effects play a significant role in keeping the storm from getting stronger?
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- Blown Away
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Re: Hurricane Frances Question
I think coastal N PB County and Martin County received similiar wind gusts as Broward due to Wilma strenghtening over the GS as the E eye wall moved offshore and roated that energy back onto the coast.
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Re: Hurricane Frances Question
No doubt that PB County received higher winds from Wilma than from Frances & Jeanne. Wilma's E eye wall seemed to strengthed as soon as it started moving offshore and rotated winds near what was reported down S. The area I was referring to was my area from Jupiter through Stuart where 90-116kt gusts were reported, not sure how credible the 116kt gust was but I rely on the Hobe Sound Annex readings of 94kt winds.
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