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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Newest microwave image.

Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:
This is a beautiful monster in the making, folks.


I'm afraid Rina is about to show us a well defined eye.
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Quoting HurricaneDean07:
Hey everyone,
Very scary, but unique situation in the caribbean right now.
Rina is sure beginning to live up to her to the lady she replaced. Thinking Category 1, 90 Mph, but won't be surprised to see a Strong Category 2/Category 3 Tomorrow morning. Once that convective burst organizes further into her core, this could become one of the 4 monster looking storms we've seen this season...

Irene,
Katia,
Ophelia,
RINA

And all of them are women names
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Quoting BahaHurican:
97L... still looks like it's got some gusto to it...



Yes, but VERY elongated(E-W)
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DAm the BAMD is all over the NHC track.
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Quoting TropicalAnalystwx13:
Here's a good example of Recon > Satellite Estimates

CI# /Pressure/ Vmax
3.7 / 994.1mb/ 59.0kt



thats no hurricane
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i new it i come home to a hurricane
Member Since: May 21, 2006 Posts: 5091 Comments: 114945
The models are a mess.. for now.
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Hey everyone,
Very scary, but unique situation in the caribbean right now.
Rina is sure beginning to live up to her to the lady she replaced. Thinking Category 1, 90 Mph, but won't be surprised to see a Strong Category 2/Category 3 Tomorrow morning. Once that convective burst organizes further into her core, this could become one of the 4 monster looking storms we've seen this season...

Irene,
Katia,
Ophelia,
RINA
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97L... still looks like it's got some gusto to it...

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storm for awhile this morning i thought it might head right for ya
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Quoting wunderkidcayman:
I think that the COC of H Rena is on the NE side of the CDO near 17.7N 83.1W


Hey bro, I just noticed that West Bay is kissing the cone!
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Quoting CybrTeddy:


Has that ''look''..

The look of death?
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Here's a good example of Recon > Satellite Estimates

CI# /Pressure/ Vmax
3.7 / 994.1mb/ 59.0kt
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thank God she did not bring heavy rain to Hoduras in la Ceiba just a few showers
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BAM is in very good agreement with the future track of Sean.....WOW
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Quoting CybrTeddy:


Has that ''look''..

Yeah, and I don't like the ''look''.
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Quoting GeoffreyWPB:
This is post 265... anybody else notice the line of clouds coming into view in the SE corner of the image???

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I've seen storms with the outflow restricted on one side do some weird things... There may be difficult to predict friction effects based on those thunderstorms hitting Cuba. This still seems pretty far out, but maybe that's one of many factors keeping the track forecast wide open.
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Quoting BahaHurican:


NHC isn't forecasting it to become a major until Wednesday, but I think this system looks like one that could reach cat three by this time tomorrow afternoon. This is probably the best looking cat 1 hurricane this season.




i hear ya still looks raged to me no eye or anything so...
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Quoting CybrTeddy:


Has that ''look''..

Agreed.
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how are the models looking
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Quoting FLWeatherFreak91:
Not really... Rina could leave a trough in her wake that would act to recurve and preceding tropical system earlier.



Yes Rina will leave a trough as i know but that was not the question. The question was could Sean sling Rina more North into Florida....and that answer would be NO Sean would not have much influence onto Rina into Florida, but as i said Rina could influence Sean into Florida...
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Quoting TropicalAnalystwx13:
This is a beautiful monster in the making, folks.



Has that ''look''..
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if i remember right when wilma was parked in the nw carribean the tracks were all over then suddenly pointed at so fl and was there fast. i believe late season storms in this area with the fairly fast moving fronts are really difficult to forecast.
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Quoting TropicalAnalystwx13:
This is a beautiful monster in the making, folks.



I agree , sure hope it doesn't make a direct hit on anyone! The banding looks carved on the NE quadrant !
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NHC isn't forecasting it to become a major until Wednesday, but I think this system looks like one that could reach cat three by this time tomorrow afternoon. This is probably the best looking cat 1 hurricane this season.
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Quoting stormstorm:
so glad to see a hurricane, after 2 days of naysayers and downcasters trashing it, had some model support saying it could rapidly intensify and it did. being a meterologist must be the only job where you can be wrong quite often and still not get fired!   good day to all.


That also applies to investment bankers these days.

Tropical cyclone intensity remains as difficult to forecast accurately today as it was ten years ago. There are so many variables to consider and even then storms will not behave as forecast about half of the time, when it comes to intensity.
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This is a beautiful monster in the making, folks.

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Quite a bit of difference in the last 24 hours!

24 hours ago:


Now:
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Still not able to get that deep convection around though, she's trying. Looking really intense tonight.
Member Since: August 19, 2005 Posts: 5 Comments: 5249
Quoting BahaHurican:


Very symmetrical at the centre...

and with outflow channel reaching N of Cuba... imagine if there wasn't any SEly shear to keep a southern outflow channel impeded...





Possible Dry Slot might hinder Intensification.
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I think that the COC of H Rena is on the NE side of the CDO near 17.7N 83.1W
Member Since: June 13, 2009 Posts: 2 Comments: 11761
Quoting FLWeatherFreak91:
Not really... Rina could leave a trough in her wake that would act to recurve and preceding tropical system earlier.


DIdn't Wilma do that to Tropical Storm Alpha?
Member Since: July 18, 2010 Posts: 50 Comments: 1860
Quoting FLWeatherFreak91:
Whoa... this is forecast to become a cat 3??? I missed something since I was in here at 6 am this morning lol.
Ayup.... Amazing amount of deepening in a very short time. If PPulse is right, it may go for a depression-to-major-in-the-shortest-time record as well....

Wonder which storm holds the ATL record for that?
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Quoting FLWeatherFreak91:
.PREVIOUS LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...MID/UPPER
LEVEL TROUGH WILL BE SETTING UP OVER THE EASTERN U.S. DURING THE
PERIOD WITH THE TROUGH AXIS FORECAST TO MOVE ACROSS FLORIDA FRIDAY
NIGHT AND SATURDAY. MEANWHILE AT THE SURFACE HIGH PRESSURE OVER
THE WESTERN ATLANTIC WILL RIDGE WESTWARD NORTH OF THE AREA ON
THURSDAY THEN A COLD FRONT ASSOCIATED WITH THE TROUGH WILL BE
MOVING THROUGH THE SOUTHEAST U.S. AND INTO FLORIDA. THE EXACT
TIMING OF THE FRONT CONTINUES TO VARY BETWEEN MODELS AND BETWEEN
MODEL RUNS...BUT APPEARS AT THIS TIME IT WILL MOVE ACROSS THE
REGION DURING FRIDAY NIGHT AND SATURDAY. THE OTHER FORECAST
UNCERTAINTY IS THE DEVELOPMENT AND EVENTUAL MOVEMENT OF RINA.
MODEL FORECASTS ARE HIGHLY VARIABLE...BUT MOST DO INDICATE SOME
DEEP MOISTURE MOVING NORTH AHEAD OF THE FRONT THURSDAY AND FRIDAY
BRINGING THE CHANCE OF SHOWERS TO THE AREA. BEHIND THE FRONT HIGH
PRESSURE WILL BUILD IN OVER THE UPCOMING WEEKEND BRINGING SOME
DRIER AND SLIGHTLY COOLER AIR INTO THE REGION ON BREEZY NORTHERLY
WINDS. TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL THURSDAY AND
FRIDAY THEN RETURN TO NEAR NORMAL OVER THE WEEKEND.



theres the front but, it does not sound like its a big one tho...
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Quoting BahaHurican:


Very symmetrical at the centre...

and with outflow channel reaching N of Cuba... imagine if there wasn't any SEly shear to keep a southern outflow channel impeded...




The outflow in that quadrant has really improved over the past few hours...Don't be surprised to see it have excellent outflow soon.
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Would not surprise me if Rina was a 100mph cat2 right now!The banding on the right side almost looks chiseled!
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Quoting TampaSpin:
NO Sean would have the opposite affect on Rina....actually Rina could spin Sean around to Florida would be the likely thing if they got close enough.
Not really... Rina could leave a trough in her wake that would act to recurve and preceding tropical system earlier.
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What if Rina and 97L merge on Saturday just before landfall on Cuba? Mainly a huge rain event or a perfect storm? Just a thought from looking at the forecast tracks of each ending on Saturday.
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Quoting Dakster:
Anyone else feeling like the NHC is gonna change the official forecast track at the next update?


yes
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Very symmetrical at the centre...

and with outflow channel reaching N of Cuba... imagine if there wasn't any SEly shear to keep a southern outflow channel impeded...



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Quoting TampaSpin:






I am really confused with this one.....there was suppose to be a weak cold front move into Florida about Friday or Saturday but, when you look at the Temperature forecast for Tampa, the NWS in Tampa is not showing much of a cold front.....


Below is the 8am temp forecast starting on Friday thru Sunday.







Below is from WU for Tampa.......

Friday, 28

85 | 65 °F
Chance of T-storms
Chance of
Precipitation40%
Saturday, 29

81 | 58 °F
Partly Cloudy
Chance of
Precipitation10%
Sunday, 30

81 | 61 °F
Partly Cloudy
Chance of
Precipitation


They made a big mistake. The trough is much to amplified to keep temps a broke even. At the very least, we should see an exact repeat of what happened behind the last front lol.:)
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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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