Rina rapidly intensifies into a hurricane

By: Dr. Jeff Masters , 7:59 PM GMT on October 24, 2011

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Rina is now a hurricane, just 21 hours after becoming a tropical depression. An Air Force Reserve hurricane hunter aircraft found winds of 75 mph--Category 1 hurricane strength--at 1:40 pm EDT in the north eyewall of Rina, using their SFMR surface wind instrument. Winds at flight level of 5,000 feet peaked at 78 mph, which typically translates to surface winds of 62 mph. On their second pass through the eye at 3:30 pm EDT, the winds were about 5 mph less, but the central pressure had fallen by two millibars, to 989 mb. Visible satellite loops show that Rina now has an eye, and the storm is steadily expanding in size and developing an impressive upper-level outflow channel to the north. Wind shear is a moderate 15 - 20 knots due to strong upper-level winds out of the southeast, and these winds are injecting dry air into Rina's southeast side, inhibiting heavy thunderstorm development there. Water temperatures are very warm, 29 - 30°C, and these warm waters extend to great depth.


Figure 1. Afternoon satellite image of Rina. An intense thunderstorm with a top that reaches into the stratosphere is visible on the southwest side of the eye. These "hot towers" are commonly seen in hurricanes undergoing rapid intensification.

Rina in historical context
Rina intensified into a hurricane just 21 hours after the first advisory was issued for it as a tropical depression. This is the second fastest such intensification since record keeping began in 1851. Hurricane Humberto of 2007 holds the Atlantic record for fastest intensification from first advisory issued to hurricane strength--18 hours. (Actually, Humberto did the feat in 14 1/4 hours, but this was rounded off to 18 hours in the final data base, which stores points every six hours). There have been six storms that accomplished the feat in 24 hours. Rina's formation brings this year's tally of hurricanes to six, which is average for an Atlantic hurricane season. The number of named storms this season is now seventeen, making it the 7th busiest Atlantic hurricane season since record keeping began in 1851. Only 2005, 1933, 1995, 1887, 2010, and 1969 had more named storms. However, 2011 has had an unusually low percentage of its named storms reach hurricane strength. Only 35% of this year's named storms have made it to hurricane strength, and normally 55 - 60% of all named storms intensify to hurricane strength in the Atlantic. The rare combination of near-record ocean temperatures but unusually dry, stable air over the Atlantic is no doubt at least partially responsible for this very unusual occurrence.


Figure 2. Microwave satellite image from 11:39 am EDT October 24, 2011, showing that Rina had a partially complete eyewall, which was open on the east side. Image credit: Navy Research Lab, Monterey.

Forecast for Rina
The hurricane hunters found an elliptical eyewall that had a gap in it during their 3:30 pm eye penetration. The aircraft measured a temperature difference of 6°C between the eye and the region outside the eye, which is difficult to get unless an eyewall is on its way to completion. Rina will need to complete its eyewall if it is to intensify into a major hurricane. Given the fact wind shear is not expected to increase until Wednesday, Rina has a 2-day period to close off an eyewall and intensify, and it will probably reach Category 3 or Category 4 strength by Wednesday. On Wednesday, Rina will encounter a dry airmass with high wind shear that lies over the extreme northwestern Caribbean. These conditions should weaken the hurricane, but Rina could still be a major hurricane if it makes landfall in the Yucatan Peninsula on Wednesday or Thursday.

A trough of low pressure is predicted to pass to the north of Rina late this week, and now that the hurricane is expected to be a Category 2 or stronger storm, the chances for Rina to make it farther north and affect the Florida Keys and Southwest Florida have increased. The latest 8 am EDT runs of the GFDL and HWRF models both predict that Rina will pass through the Yucatan Channel on Thursday and make landfall on Friday in the Florida Keys or extreme Southwest Florida, south of Naples. The NOGAPS and GFS models predict a weaker storm, and keep Rina trapped in the Caribbean. I think it is more likely that Rina will pass through the Keys. If Rina does make it to the Keys, it would likely be as a tropical storm, since wind shear, dry air, and possible land interaction with Western Cuba and Mexico would potentially knock down the storm's strength. Heavy rains from Rina should begin affecting Mexico's Yucatan Peninsula, northern Belize, and extreme Western Cuba on Wednesday. Rina's intensification into a hurricane over the Western Caribbean during the last half of October bring to mind Hurricane Wilma, which also performed such a feat in 2005. Wilma went on to become a Category 5 monster, the strongest Atlantic hurricane of all-time. I don't think Rina will be another Wilma, even though the ocean temperatures and total heat content are similar to what Wilma experienced. Wilma had nearly ideal upper-level atmospheric conditions with an anticyclone aloft and light wind shear, under 5 knots. Rina is experiencing 15 - 20 knots of wind shear and is also a smaller storm, and is thus more vulnerable to the effects of wind shear and dry air.

97L approaching ABC islands
A broad region of low pressure approaching the ABC islands of Aruba, Bonaire, and Curacao (Invest 97L), is moving west-northwest at 10 mph. Heavy thunderstorm activity has increased today, but the activity is not organized into spiral bands, as is apparent from Curacao radar. 97L is surrounded by a large region of dry air, and this dry air will retard development. 97L is under low wind shear less than 10 knots, and this shear is expected to remain low through Thursday. By the time 97L reaches the region between Jamaica and Nicaragua in the Central Caribbean on Thursday or Friday, the storm should find a moister environment, and could develop into a tropical depression. However, none of the reliable models are predicting that 97L will develop. NHC is giving 97L just a 10% chance of developing into a tropical depression by Wednesday. I put the odds higher, at 20%.

Jeff Masters

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Quoting TampaSpin:


Its certainly not a long term forecast but, out to 3-4 days this is a very good model......anyone that follows my site knows i always post the 3 BAM models separate from the other models just to see the spread difference in the storm strengths and track possibilities.
this is from NOAA HOWEVER...IT IS DIFFICULT TO TELL HOW
FAR SOUTH ITS INFLUENCE WILL EXTEND AT THIS POINT AND WHETHER A COLD
FRONT WILL MAKE IT THROUGH THE KEYS CLEANLY ON SATURDAY OR SUNDAY.
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Quoting ProgressivePulse:
The "Eye" to be, highly visible in this image. Appears to be taking on some shear ATM.


What? I thought it was ready to take off?
Member Since: July 6, 2010 Posts: 108 Comments: 30259
The rain has started up again from the band shown on the East side of the hurricane that is swiping across Grand Cayman.

Member Since: August 19, 2006 Posts: 0 Comments: 15671
Of note: Not much room for a very big eye.....
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Quoting klew136:

just want to ask you have you read the key west weather report, it says that nhc does not know if the front will clear keys saturday, if the front doesn't clear then what is going to happen? just asking because you know a lot more than i do.


I honestly think you should plan that party as is........but, keep an eye open for the next 2 days.....in 2 days a better idea will be forthcoming.
Member Since: September 2, 2007 Posts: 177 Comments: 20430
Quoting Mel1978:


Not to mention US1 is only two lanes, one going in and one coming out. It would be hard to get everyone out in time.
Well I hope everyone gets off.
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Just looking at the 5-day forecast for Rina, and speculating--has there ever been a hurricane that made a complete circle and came back through where it had been previously? Not that I think that might happen to Rina, but has it at some time?
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Quoting barotropic:


I thought even the deep layer was only good really for near term forecasting...not out 2 or three days. Isn't that the general rule?


Its certainly not a long term forecast but, out to 3-4 days this is a very good model......anyone that follows my site knows i always post the 3 BAM models separate from the other models just to see the spread difference in the storm strengths and track possibilities.
Member Since: September 2, 2007 Posts: 177 Comments: 20430
The "Eye" to be, highly visible in this image. Appears to be taking on some shear ATM.

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Impressive Satellite Presentation.
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Quoting TampaSpin:


Because the cold front which was once thought to be very strong and come very far south is not going to do so not it appears.....that is the reason....The HIGH is not going to break down as much as first thought. I may be wrong of course but, from everything that i have looked at all day with the cold front......this is what i have seen. The BAM models are very good models for direction. When the BAMD which is far a very strong storm goes that far WEST the rest of the models usually follow suit.....we will see. Just my opinion.

just want to ask you have you read the key west weather report, it says that nhc does not know if the front will clear keys saturday, if the front doesn't clear then what is going to happen? just asking because you know a lot more than i do.
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Quoting TampaSpin:
Ju

Because the cold front which was once thought to be very strong and come very far south is not going to do so not it appears.....that is the reason....The HIGH is not going to break down as much as first thought. I may be wrong of course but, from everything that i have looked at all day with the cold front......this is what i have seen. The BAM models are very good models for direction. When the BAMD which is far a very strong storm goes that far WEST the rest of the models usually follow suit.....we will see. Just my opinion.
I agree take a look at baynews 9 they are known to bring the temperatures down more than the other news channels and I see no 70's for highs and 50's for lows.



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Quoting TropicalAnalystwx13:

Still...



I agree that it would not happen quickly.
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Quoting kmanislander:
I was just watching the ADT loop for the center fix interpolation over the past several hours and at best there is a miniscule drift to the NW or NNW but more a stall than anything else. If this continues for too long upwelling could start to become a problem.



Quoting Dr. Masters "Water temperatures are very warm, 29 - 30°C, and these warm waters extend to great depth."
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699. MTWX
Quoting sunlinepr:
Interesting ULL in C. Atl.


Looks like Rina is already moistening its environment to its north and NW.
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Quoting TampaSpin:



MOst models are trending more West like the BAM models. The BAMD just moved to the direction i just spoke of as well.....the HIGH will force it more WEst and South.....the Navy model is also showing the same.



these models arent very reliable though.. i look at the HWRF GFDL GFS UKMET AND CMC. those are my favs :P
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Quoting kmanislander:


Its been over the same spot now for almost a day as it is.

Still...

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Then again, all them thar Fey Folk could just conjure up a decent weather spell.
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Interesting ULL in C. Atl.
Also it is a fact that 97L has more WV to feed that Rina...

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Quoting TropicalAnalystwx13:

There will be no upwelling with all that warm water that extends to a great depth. It would have to sit there for days and days, but it won't.


Its been over the same spot now for almost a day as it is.
Member Since: August 19, 2006 Posts: 0 Comments: 15671
Quoting TampaSpin:
Ju

Because the cold front which was once thought to be very strong and come very far south is not going to do so not it appears.....that is the reason....The HIGH is not going to break down as much as first thought. I may be wrong of course but, from everything that i have looked at all day with the cold front......this is what i have seen. The BAM models are very good models for direction. When the BAMD which is far a very strong storm goes that far WEST the rest of the models usually follow suit.....we will see. Just my opinion.


I thought even the deep layer was only good really for near term forecasting...not out 2 or three days. Isn't that the general rule?
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Quoting GTcooliebai:
Ok whatever, does it really matter if it's a gay couple? I'm sure they go to events like these all over the world. And I still see no mention of it being specifically for gay people only, since I see a good mix of men and women, in fact it looks like something I would go to and have a good time.


It is a good time. I have been, a few times, and it is a mix of gay and straight. It is a bunch of people having a great time regardless of their sexual preference.
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Quoting kmanislander:
I was just watching the ADT loop for the center fix interpolation over the past several hours and at best there is a miniscule drift to the NW or NNW but more a stall than anything else. If this continues for too long upwelling could start to become a problem.

There will be no upwelling with all that warm water that extends to a great depth. It would have to sit there for days and days, but it won't.
Member Since: July 6, 2010 Posts: 108 Comments: 30259
Quoting libertygirl:


You got that right, and add to it the possibility of an evacuation order, issued at the last minute, with 30,000 motorists (flights cancelled) up US1, 150 miles away from the mainland - nearest shelter.

For those South Florida peeps who don't understand - NHC evac orders are never issued in time...on a good day.

Pay attention. Our weather is going to start to deteriorate starting on Weds with 30mph winds and rains...throughout the week. If that's all we get, all the better.


Not to mention US1 is only two lanes, one going in and one coming out. It would be hard to get everyone out in time.
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Quoting barotropic:
''

Why do you put so much weight on the Bam models, especially so far out and especially with what may be a strong cat two or higher hurricane? Just curious.


Because the cold front which was once thought to be very strong and come very far south is not going to do so not it appears.....that is the reason....The HIGH is not going to break down as much as first thought. I may be wrong of course but, from everything that i have looked at all day with the cold front......this is what i have seen. The BAM models are very good models for direction. When the BAMD which is far a very strong storm goes that far WEST the rest of the models usually follow suit.....we will see. Just my opinion.
Member Since: September 2, 2007 Posts: 177 Comments: 20430
Quoting Mucinex:
No matter how one chooses to describe FantasyFest, the situation at hand would be equivalent to, or worse than, a hurricane showing up on Fat Tuesday during Mardi Gras in Nola.

I Agree
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Quoting Darryl7:
Fantasy Fest is a celebration of Gay People unlike Mardi Gras which is a celebration previous to the Lenten season.

IT IS NOT
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I was just watching the ADT loop for the center fix interpolation over the past several hours and at best there is a miniscule drift to the NW or NNW but more a stall than anything else. If this continues for too long upwelling could start to become a problem.
Member Since: August 19, 2006 Posts: 0 Comments: 15671
Quoting interstatelover7165:
666!


Especially this weekend, it is the height of the festivities. Many people come down for just for this weekend. Evacuating the Keys during this time will be a nightmare.
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Quoting TampaSpin:



MOst models are trending more West like the BAM models. The BAMD just moved to the direction i just spoke of as well.....the HIGH will force it more WEst and South.....the Navy model is also showing the same.




Its not going to go inland over the Yucatan and dissipate. A stronger system is more likely to go poleward, and with the trough, even if it is weak, coming down, Rina should turn northward. I'd be surprised if it actually even made landfall on the Yucatan Peninsula.
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Quoting Clearwater1:
What is fantasy fest all about?

it is a mardi gras only at halloween in the Keys, all of the keys are busy for fantasy fest, people stay in the upper keys because there is no hotels left in the lower keys. It is a crazy wild weekend
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Quoting Mucinex:
No matter how one chooses to describe FantasyFest, the situation at hand would be equivalent to, or worse than, a hurricane showing up on Fat Tuesday during Mardi Gras in Nola.


You got that right, and add to it the possibility of an evacuation order, issued at the last minute, with 30,000 motorists (flights cancelled) up US1, 150 miles away from the mainland - nearest shelter.

For those South Florida peeps who don't understand - NHC evac orders are never issued in time...on a good day.

Pay attention. Our weather is going to start to deteriorate starting on Weds with 30mph winds and rains...throughout the week. If that's all we get, all the better.
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Quoting TampaSpin:



MOst models are trending more West like the BAM models. The BAMD just moved to the direction i just spoke of as well.....the HIGH will force it more WEst and South.....the Navy model is also showing the same.



Yes and if it follows the BAMD...straight to Tampa Bay it goes!
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Here is the Navy Models which tend to be very conservative....

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Quoting TampaSpin:



MOst models are trending more West like the BAM models. The BAMD just moved to the direction i just spoke of as well.....the HIGH will force it more WEst and South.....the Navy model is also showing the same.

''

Why do you put so much weight on the Bam models, especially so far out and especially with what may be a strong cat two or higher hurricane? Just curious.
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I say Rena will pull a U turm near 19.5N 20.0N and head ENE-E passing inbetween Grand Cayman and Isle of Youth and make land fall in N-Central Cuba
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Quoting Mel1978:


That will be a disaster if Rina comes through the Keys. There are going to be so many people there, getting off that island will be very time consuming. I imagine a lot of people would stay. I know I am watching it closely since I am supposed to head down there on Thursday to celebrate my birthday.

The locals will not evacuate, why would the tourists,
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Quoting Mucinex:
No matter how one chooses to describe FantasyFest, the situation at hand would be equivalent to, or worse than, a hurricane showing up on Fat Tuesday during Mardi Gras in Nola.
666!
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Quoting wunderweatherman123:
disagree the most west rina will go is 10 to 20 miles inland as the high over the SE US immidiatly gets pushed about by a trough



MOst models are trending more West like the BAM models. The BAMD just moved to the direction i just spoke of as well.....the HIGH will force it more WEst and South.....the Navy model is also showing the same.



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Quoting dolphingalrules:


my house hit wilma..lost my patio..this time don't hit my house
Your house hit Wilma ? WOW. LOL, j/k
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No matter how one chooses to describe FantasyFest, the situation at hand would be equivalent to, or worse than, a hurricane showing up on Fat Tuesday during Mardi Gras in Nola.
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Quoting wunderweatherman123:
disagree the most west rina will go is 10 to 20 miles inland as the high over the SE US immidiatly gets pushed about by a trough


I think maybe 21 or 22 miles inland...but heck its still 2 days out...!!
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Quoting wunderkidcayman:
97L reminds me of Ivan somewhat
yes I know Ivan was furthe N when it passed Jamaica but generaly speeking

look at Ivans track when its in the Caribbean



now look at 97(PRE-Sean) models

IDK is it me or are the models for 97L acting like it's Aug. or Sept.?
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.