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

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

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

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

that's a bold statement and you maybe right but there are many hours left to play in this game ...let's see what happens


Quoting barotropic:
With the new discussion out and the forecast track now not coming near the keys, I think we can put this one to rest. The TPC doesnt expect any strengthening at all, essentially weakening in about 24 hours and now is frcst to be a trop storm over NE tip of yuc. .......We really dont need the probs in fla anyway.
Quoting portcharlotte:
I am surprised by the further south track taken by NHC. I would have expected to at least continue with the previous track. I am not buying that but I could be wrong. If anything trends are looking for less shear and more moisture.


I agree, models seem confused. Rina is surely heading in the right direction and is picking up speed. No reason really why the trough wouldn't pick it up, except for the weakening cold front.
hey guys looking at the new forecast cone I don't think Rina will go that far N I think by early morn rina would start getting pulled NE-E
504. 996tt
Quoting reedzone:


Very good post and that's exactly why she weakened. Notice after she finally started to move, convection built up. I expect a 90-100 mph. storm before it winds down.


Haha, God love you. You stick to your guns and go out on a limb. What did you say Rina was going to do yesterday??? Maybe I am mixed up. If so, I apologize. Did you slam Cantorre who was down playing storm saying he was idiot or did you take up for Jim saying he had to be somewhat consistent with NHC. Someone was calling thus thing to be cat 4 or major, still string when gets to aflorida and calling Cantorre a kook.

I agree TWC people are all kooks who are 90 percent drama, 5 percent weather, and 5 percent general reporting. They over dramatize everything and like to insight fear and panic all in the name of increased ratings.

Haha, they were telling everyone in NYC to abandon high rise buildings for Irene or they were in serious peril and there would be many failures and injuries from flying glass and blown out windows. Then they accidentally interviewed a structural engineer who said mo worries, buildings were safe and you could see Cantorre's face was like oh crap, he just said opposite of the TWC's agenda and made them look like kooks. I used to love Weather Channel, but cannot watch it any more as it is so far from what it used to be.
Quoting 996tt:


Haha, God love you. You stick to your guns and go out on a limb. What did you say Rina was going to do yesterday??? Maybe I am mixed up. If so, I apologize. Did you slam Cantorre who was down playing storm saying he was idiot or did you take up for Jim saying he had to be somewhat consistent with NHC. Someone was calling thus thing to be cat 4 or major, still string when gets to aflorida and calling Cantorre a kook.

I agree TWC people are all kooks who are 90 percent drama, 5 percent weather, and 5 percent general reporting. They over dramatize everything and like to insight fear and panic all in the name of increased ratings.

Haha, they were telling everyone in NYC to abandon high rise buildings for Irene or they were in serious peril and there would be many failures and injuries from flying glass and blown out windows. Then they accidentally interviewed a structural engineer who said mo worries, buildings were safe and you could see Cantorre's face was like oh crap, he just said opposite of the TWC's agenda and made them look like kooks. I used to love Weather Channel, but cannot watch it any more as it is so far from what it used to be.


Thanks for the apology before hand...

I never really said anything about Rina until today. I just said anything is possible down there, and the impossible happened. It rapidly became a Hurricane.
Q: Will the 2011 Atlantic hurricane season end with Rina?

A. Yes
B. No
C. Undecided

==If you answered no to the above question, then ignore the below question==

Q: How many more named storms will the 2011 Atlantic hurricane season have?

A. 1
B. 2
C. 3
D. 4+

The NHC has a lot of deciding to do in post-season...From 96L in the Bay of Campeche in July, to 96L north of Bermuda in August (IIRC), to 93L off the Florida coast this month.
The outflow looks bad, the cirrus clouds are poor and the structure is bad, but those strong storms and cold cloud tops are persisting.

Quoting TropicalAnalystwx13:
Q: Will the 2011 Atlantic hurricane season end with Rina?

A. Yes
B. No
C. Undecided

==If you answered no to the above question, then ignore the below question==

Q: How many more named storms will the 2011 Atlantic hurricane season have?

A. 1
B. 2
C. 3
D. 4+

The NHC has a lot of deciding to do in post-season...From 96L in the Bay of Campeche in July, to 96L north of Bermuda in August (IIRC), to 93L off the Florida coast this month.


B
B or C
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5:00pm Advisory
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Good Afternoon.
NEW BLOG
Quoting robert88:
Hard to believe her eyewall is already gone.
000
URNT12 KNHC 261818
VORTEX DATA MESSAGE AL182011
A. 26/17:50:00Z
B. 18 deg 00 min N
085 deg 41 min W
C. 700 mb 2969 m
D. 63 kt
E. 063 deg 3 nm
F. 151 deg 72 kt
G. 062 deg 6 nm
H. EXTRAP 976 mb
I. 11 C / 3048 m
J. 22 C / 3045 m
K. 9 C / NA
L. NA
M. NA
N. 13 / 7
O. 0.02 / 2 nm
P. AF304 0818A RINA OB 06
MAX FL WIND 72 KT NE QUAD 17:48:00Z
SLP EXTRAP FROM 700 MB
SFC WINDS REPORTED ON EYE DROP WERE 31KTS
SFC PRESSURE REPORTED ON EYE DROP WAS 985MB
;


POOF go ahead egg the wishcasters on!! the games some people play
Quoting BenBIogger:


See that small tongue of dry air SE/E of Rina? Now watch what happens in 3-4 hours from now.


POOF I just don't like egging on people
Quoting alvarig1263:


Maybe you weren't paying attention to the recon data, but her winds have increased to 90 MPH and her pressure has fallen to 977 MB. That is not a TS to me. The reasonable explanation is that by sitting in the same area for a while it caused her to weaken, among other factors. but now that she has sped up and has made a turn to the NW, she is reintensifying.


+1000, robert says the same thing post after post
514. MahFL
Why is the cdo spreading south if there is southerly shear ?