Rina still a Cat 2, and may have peaked in intensity

By: Dr. Jeff Masters , 1:48 PM GMT on October 26, 2011

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There is little change to Category 2 Hurricane Rina, which continues slowly west-northwest at 4 mph towards Mexico's Yucatan Peninsula. The most recent hurricane hunter mission was at 3:58 am EDT this morning, and the next aircraft is not due into the storm until this afternoon, so we'll have to rely on satellite estimates of the storm's strength until then. Recent satellite intensity estimates suggest Rina has peaked in intensity, and may have weakened slightly since the last hurricane hunter mission. The eye is no longer visible on visible satellite loops, and the storm has a distinctly lopsided appearance, which are both signs that Rina may be weakening. Recent microwave images (Figure 1) suggest that the southern portion of Rina's eyewall may have a gap in it. Wind shear is a moderate 10 - 20 knots due to upper-level winds out of the south. Water temperatures are very warm, 29 - 30°C, but Rina will be leaving a region of high oceanic heat content late tonight, and will not have as much high-energy fuel to sustain itself. Rina has brought sporadic heavy rain squalls to the Yucatan; Cozumel Island airport reported 9.10" of rain yesterday and another 3.25" as of 9 am EDT today. I'm not sure this is correct, since two personal weather stations on the island reported only 1 - 2" of rain over the past two days. The outer rain bands of Rina are visible on Cancun radar and the La Bajada, Cuba radar.

If Rina does make it to Category 3 strength, it would join a very short list of major hurricanes that have occurred this late in the year. Since record keeping began in 1851, there have been only twelve major hurricanes in Atlantic on October 26 or later. Rina is a medium-small hurricane, with hurricane-force winds that extend out 25 miles from the center. The latest estimates of Rina's Integrated Kinetic Energy (IKE) made yesterday afternoon by NOAA's Hurricane Research Division put the damage potential of Rina's storm surge at 2.5 on a scale of one to six. This is a relatively low number for a Category 2 hurricane, and means that storm surge damage will be confined to a relatively small area in the right front quadrant of Rina's eyewall. For comparison, the storm surge damage potential for Hurricane Irene when it was a strong tropical storm approaching Long Island, New York on August 28, 2011 was 4.1 on a scale of 1 to 6, since Irene was a huge storm that put vast areas of the ocean into motion.


Figure 1. Microwave satellite image of Hurricane Rina taken at 7:15 am EDT October 26, 2011. Rina appears to only have the northern half of its eyewall intact. Image credit: Navy Research Lab, Monterey.

Forecast for Rina
The hurricane hunters found that Rina had a large elliptical eye with a diameter of 23 - 34 miles with a gap in the south eyewall during their 3:58 am EDT eye penetration this morning. Rapid intensification usually requires a circular eye with no gap in it, and thus I expect only gradual intensification of Rina can occur today. Wind shear is not expected to increase to the high range until Thursday afternoon, so Rina still has a day and a half to potentially intensify. Given the storm's inability to close off its eyewall so far, I expect that a Category 3 storm is the strongest that we will see. It is more likely that Rina has peaked in strength, and will begin to weaken. On Thursday, Rina will encounter high wind shear associated with upper-level westerly winds associated with the jet stream and a trough of low pressure moving through the Gulf of Mexico. These conditions should weaken the hurricane, and turn Rina more to the northwest by Thursday and northeast on Friday. Cozumel Island off the coast of Mexico's Yucatan Peninsula appears at the highest risk of receiving a direct hit from Rina; the 5 am EDT Wind Probability Forecast from NHC gave the island a 27% chance of receiving hurricane force winds, the highest chance of any land area in the forecast. If Rina hits Mexico, it would most likely be at Category 1 strength, with Category 2 strength also quite possible. NHC is giving Rina a 21% chance of being a Category 3 or stronger hurricane on Thursday afternoon, and I don't expect the storm will be a major hurricane at landfall. The chief threat from Rina is probably its rains; the hurricane is moving slowly and has the capability of dumping 8 - 16 inches of rain over the coastal Yucatan. Western Cuba is also at risk of receiving heavy rains of 5 - 10 inches.

After Rina makes its closest pass by Cozumel, it is uncertain if the storm will be strong enough to fully "feel" the steering influence of the trough, and be swept to the east-northeast into Southwest Florida and the Florida Keys. If Rina makes landfall in the Yucatan Peninsula and weakens significantly, the storm will likely be too weak to get caught up by the trough and will remain trapped in the Western Caribbean. This is the solution of the latest runs of the ECMWF and HWRF models, with the usually reliable ECMWF model continuing to predict that Rina will dissipate over the Yucatan. However, if Rina grazes the Yucatan and remains strong through Friday, it is more likely to get caught up by the trough and drawn into the Florida Keys or Southwest Florida near Marco Island, as a weakening tropical storm. This is the solution of the latest 2 am EDT run of the GFDL model. The latest 2 am EDT runs of the GFS and NOGAPS models are in-between, predicting that Rina will get very close to the Keys on Saturday, but then weaken and sink southwards towards Cuba. There is high degree of uncertainty which set of model runs will be correct, and the threat to Florida depends strongly upon how much of a blow Mexico receives from the hurricane.

97L in the Central Caribbean not expected to develop
A broad region of low pressure in the Central Caribbean south of Haiti and the Dominican Republic, (Invest 97L), is moving west at 10 - 15 mph. Heavy thunderstorm activity has decreased since yesterday, and is disorganized. The storm is surrounded by a large region of dry air, and this dry air is the main impediment to development. Wind shear is a low 5 - 10 knots, and is expected to remain low through Thursday. None of the reliable models are predicting that 97L will develop, and NHC gave 97L just a 10% chance of developing into a tropical depression by Friday, in their 8 am EDT Tropical Weather Outlook. NHC is no longer interested enough in 97L to generate computer model forecasts of its track. Heavy rains from 97L should reach Jamaica on Thursday, and the Cayman Islands by early Friday morning.

There will be a new post on Rina late this afternoon.

Jeff Masters

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ok I say cause Rina is now making its Nward Movement early it very well make that NW-Eward earlier too may cause Rina to miss Fl, Fl Keys, and maybe even N Cuba
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Anticyclone heading west towards Rina at around 20 MPH, and wind shear weakening over the NW Caribbean and SE GOM. Shear has lessened too over Rina's south side to 10 knots. Things looking a little better for Rina.

Wind Shear @ 15Z:



Wind Shear Now @ 18Z:

Member Since: September 2, 2008 Posts: 0 Comments: 744
I'm thinking get ready for Rina's moisture to get picked up and thrown to FL. once that trough carves out.

North Atlantic - Water Vapor Loop
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311. Skyepony (Mod)
Quoting scottsvb:
BTW the pressure they sample is above the surface at the 850mb range.. pressure is about 981 right now from what report I recieved and I agree


There's a dropsonde that even though says it's dropped in the eye, doesn't look like it by coordinates. Also winds are kinda high for being the eye.

Extrapolated means they do the math to figure the difference for height.
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Quoting Seflhurricane:
convection really blowing up now


I agree P451 always use to tell me to use this infrared satellite to get an accurate view of how cold the cloud tops are.

RAMSDIS GOES-East 4 km IR4 Floater 2

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Well there still is a 30 degree F warming associated with the core, and a drop in pressure related to the most recent burst of deep convection.

There is a slight tilt from south at the surface to north aloft. One of the smallest core structures I've ever seen, which is susceptible to fairly rapid changes both up and down. (though the preponderance of factors suggest weakening late tonight into tomorrow)


The max surface wind they'll find is probably in the 75-85mph range.

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Quoting reedzone:


Don't argue with him, he's always right... :P

I agree, pressure drop is reasonable due to the convection burst and slight organization over the past 2 hours.


Reedzone, how you doing little buddy? They still haven't banned you for wishcasting every cloud to be a Cat 5 yet? Nice to see you still around :)
Member Since: January 22, 2006 Posts: 0 Comments: 1726
convection really blowing up now
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Good Afternoon...looks like the moisture is returning to the FL. Peninusula as Rina pushes the dry air towards the north. It will be interesting again to see the interaction between the front and Rina, just like 95L.

Gulf of Mexico - Water Vapor Loop
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Quoting reedzone:


Don't argue with him, he's always right... :P

I agree, pressure drop is reasonable due to the convection burst and slight organization over the past 2 hours.
hey reed how have you been. looks like the NW turn has begun
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Rina should hold her own tonight.. and probably organize like I said earlier. Winds expecting to be 90-100mph at landfall..pressure 966-973 at landfall
Member Since: January 22, 2006 Posts: 0 Comments: 1726
Quoting scottsvb:


Eddy the models have been showing a turn to the NW for days..even north then Northeast.. we know you know this already. Maybe your very young under 16years old, if so I'm sorry but if your older, I'm sure you know after asking same questions to peeps about going to S Florida that we don't know and right now, probably not. Wait till Friday morning to find out if it's going to S Florida.. cause right now..chances are only about 20% it will.


+++1 million!
Member Since: August 14, 2009 Posts: 0 Comments: 471
Quoting cchsweatherman:


I disagree. That is the extrapolated surface pressure reading the Hurricane Hunters found so no translation needed.


Don't argue with him, he's always right... :P

I agree, pressure drop is reasonable due to the convection burst and slight organization over the past 2 hours.
Member Since: July 1, 2008 Posts: 13 Comments: 7438
Quoting Seflhurricane:
i am calm but on here when someone makes those kinds of statements it becomes a rolling avalance , and i have seen it here for years. what i am saying is South florida and the Keys are by no ways out of the woods. it still looks like tropical storm conditions would affect the area
( hope not ) but its reality .


It looks like nothing right now cause your looking past 48hrs.. dont look past 36hrs right now.
Member Since: January 22, 2006 Posts: 0 Comments: 1726
Quoting Seflhurricane:
either way it appears she is stregthing again and even if they pass through and its a bit higher its still a drop in pressure from the current 982 MB
A burst of intense green near the center.
Member Since: September 27, 2007 Posts: 1 Comments: 23855
Quoting scottsvb:


Calm down.. no one said S Fla is in the clear.. just wait til Friday morning. Right now it's about if/where/when it makes landfall around Cozumel or west and how long it takes to get off the Yucitan and how strong she will be.
i am calm but on here when someone makes those kinds of statements it becomes a rolling avalance , and i have seen it here for years. what i am saying is South florida and the Keys are by no ways out of the woods. it still looks like tropical storm conditions would affect the area
( hope not ) but its reality .
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BTW the pressure they sample is above the surface at the 850mb range.. pressure is about 981 right now from what report I recieved and I agree
Member Since: January 22, 2006 Posts: 0 Comments: 1726
297. Skyepony (Mod)
Recon fix ~17.967N 85.700W, 976.8 mb (~ 28.84 inHg), they may find higher but on the way in highest flight was 73 knots
(~ 83.9 mph), surface 61 knots (~ 70.1 mph).
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Quoting scottsvb:


I bet they don't adjust it right now..at least till they get another fly thru
either way it appears she is stregthing again and even if they pass through and its a bit higher its still a drop in pressure from the current 982 MB
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Quoting Seflhurricane:
for anyone here to say that South Florida is in the Clear is absurd , yes the chances of a hurricane affecting the area are much lower but tropical storm force winds are still around 25-30% if there were no chances the NHC would not have the area in the cone. everyone needs to stick to the facts and not imagine things just to post a point !!


Calm down.. no one said S Fla is in the clear.. just wait til Friday morning. Right now it's about if/where/when it makes landfall around Cozumel or west and how long it takes to get off the Yucitan and how strong she will be.
Member Since: January 22, 2006 Posts: 0 Comments: 1726
Kat + Rina = Katrina
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Quoting cchsweatherman:


I disagree. That is the extrapolated surface pressure reading the Hurricane Hunters found so no translation needed.


I bet they don't adjust it right now..at least till they get another fly thru
Member Since: January 22, 2006 Posts: 0 Comments: 1726
for anyone here to say that South Florida is in the Clear is absurd , yes the chances of a hurricane affecting the area are much lower but tropical storm force winds are still around 25-30% if there were no chances the NHC would not have the area in the cone. everyone needs to stick to the facts and not imagine things just to post a point !!
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Quoting scottsvb:


translated down from where they do it.. its around 981mb


I disagree. That is the extrapolated surface pressure reading the Hurricane Hunters found so no translation needed.
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6 MB PRESSURE DROP! KNEW IT!

Time: 17:52:00Z
Coordinates: 17.9167N 85.75W
Acft. Static Air Press: 698.1 mb (~ 20.61 inHg)
Acft. Geopotential Hgt: 3,017 meters (~ 9,898 feet)
Extrap. Sfc. Press: 976.8 mb (~ 28.84 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 311 degrees at 45 knots (From the NW at ~ 51.7 mph)
Air Temp: 21.5C (~ 70.7F)
Dew Pt: 12.4C (~ 54.3F)
Peak (10s) Flt. Lvl. Wind: 49 knots (~ 56.3 mph)
SFMR Peak (10s) Sfc. Wind: 30 knots* (~ 34.5 mph*)
SFMR Rain Rate: 1 mm/hr* (~ 0.04 in/hr*)
(*) Denotes suspect data
Member Since: September 2, 2008 Posts: 0 Comments: 744
The overall structure looks weak, but the convection still continues to building strongly near the center.

Member Since: April 24, 2011 Posts: 1 Comments: 601
guys she is going through a very large patch of very hot TCHP just off the yucatan she could come back to the strength she had earlier
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Quoting eddye:
so south fla better get ready 7544


The chances for anything at all affecting any part of Florida is slowly but steadily diminishing.

Actually, nothing more than a tropical storm, and a weak one at that, has looked likely at all for Florida since at least yesterday.

Now there is a good chance that this system will completely miss Florida altogether,
as many models and as the NHC track has consistently indicated.

There really is not much point in wishcasting with this one. But wish cast if you wish, that is your right and you are certainly entitled to it.

Not to worry though. Someday, South Florida will surely get clobbered by a hurricane. It has happened over and over in the past and it will happen again and again.
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Quoting Seflhurricane:
cchs have the models had any changes in the 2pm run


The 2 PM models don't start coming in for another hour or so.
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Quoting cchsweatherman:
Interesting. Hurricane Rina may be strengthening again. Found a pressure of 976 mb which would be a 6 mb drop from the last update.


translated down from where they do it.. its around 981mb
Member Since: January 22, 2006 Posts: 0 Comments: 1726
This storm is a fighter. None of us really know what might happen intensity wise on this system. Sometimes they defy all odds and do what they want to do.
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Quoting cchsweatherman:


Exactly!
cchs have the models had any changes in the 2pm run
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Pressure is around 981mbs right now..she is holding her own.. we will see how she does in 4-12hrs at nightfall to see if she tightens up more before landfall.
Member Since: January 22, 2006 Posts: 0 Comments: 1726
976 mb.
Member Since: September 16, 2007 Posts: 0 Comments: 11052
Interesting. Hurricane Rina may be strengthening again. Found a pressure of 976 mb which would be a 6 mb drop from the last update.
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This is quite a blow up since the ll:45 bulletin about it weakening. Very strong storms near the center.

Member Since: April 24, 2011 Posts: 1 Comments: 601
looking at recon info looks to me Rina is a bit weaker maybe 80 Mph but the windfield has shrunk considerably
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Hey can some post the Belize radar
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Quoting scottsvb:
Rina is such a small system.. you can be 50 miles from the center and not have winds over TD status


Exactly!
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275. Skyepony (Mod)
Noticed Kermit left before completing the pattern Nrt posted earlier with the flight plan.

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Quoting alvarig1263:


Agreed. That new convection right over in core should drop the pressure about 5MB's or more IMO.


That's not how it works.
Member Since: January 22, 2006 Posts: 0 Comments: 1726
Quoting shawn26:
Any new Vortex data?


Not yet. Will post immediately when they are released.
Member Since: September 2, 2008 Posts: 0 Comments: 744
Rina is such a small system.. you can be 50 miles from the center and not have winds over TD status
Member Since: January 22, 2006 Posts: 0 Comments: 1726
Quoting Sfloridacat5:
991 mb at 18.050N 85.567W
So she's not weakening.


Agreed. That new convection right over in core should drop the pressure about 5MB's or more IMO.
Member Since: September 2, 2008 Posts: 0 Comments: 744
Any new Vortex data?
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have the new 2pm models come out yet and if they have any changes
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991 mb at 18.050N 85.567W
So she's not weakening.
Member Since: September 16, 2007 Posts: 0 Comments: 11052
267. Skyepony (Mod)
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Wilma at landfall in Mexico. If Rina looked like this, we'd be in trouble.
Member Since: September 16, 2007 Posts: 0 Comments: 11052
lets see if this new burst of convection gets her up and going again, but looking at the water temps she is going to go over a patch of very high TCHP
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Quoting eddye:
isnt northwest bad for south florida cchs


Eddy the models have been showing a turn to the NW for days..even north then Northeast.. we know you know this already. Maybe your very young under 16years old, if so I'm sorry but if your older, I'm sure you know after asking same questions to peeps about going to S Florida that we don't know and right now, probably not. Wait till Friday morning to find out if it's going to S Florida.. cause right now..chances are only about 20% it will.
Member Since: January 22, 2006 Posts: 0 Comments: 1726

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

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