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Hurricane Wilma: Category 1 and strengthening

By: Dr. Jeff Masters, 9:06 PM GMT on October 18, 2005

Wilma became a hurricane today, tying the record of 12 hurricanes in a season set in 1969. In that year, the last two hurricanes formed after October 30, so 2005 has a decent chance of breaking that record. I expect 2005 will also break the record of 21 total storms, which it now shares with the 1933 hurricane season.

Wilma continues to intensify as a modest pace. The Hurricane Hunters at 4 pm EDT found a central pressure of 970 mb and flight level winds on the weaker (north) side of the hurricane that correspond to winds of 70 - 75 mph at the surface. Stronger winds probably exist elsewhere in the storm, but all indications are that this is a medium strength Category 1 hurricane. An eye has popped in and out of visible satellite imagery this afternoon, but is not yet evident as a warm spot on infrared satellite imagery. Spiral banding and upper-level outflow continue to improve and cover a larger area.

The upper level environment looks excellent but not perfect for intensification, with low wind shear and two good outflow channels, one on the north side, and one on the southwest side. About five knots of wind shear is degrading the outflow pattern and symmetry on the northwest side, and there is still some dry air there for Wilma to contend with. Continued intensification into a Category 3 hurricane by Wednesday looks reasonable, and I'd give it a 40% chance Wilma makes it to Category 4 status by Friday. The GFDL is calling for a 922 mb Category 4 storm by Friday, but this forecast is probably overdone, as the GFDL has been consistently too aggressive with its intensity forecasts for Wilma. By Saturday, Wilma will be far enough north that wind shear from an upper-level trough of low pressure will reduce Wilma's winds by perhaps 20 mph.

Wilma is currently traversing an area of high oceanic heat content (see Figure 1), and this heat content will not significantly fall unless Wilma passes north of the Florida Keys. I would expect an additional 10 mph reduction in Wilma's winds if she makes landfall in Florida north of the Keys, due to the lower heat content of the water. So, expect landfall as a strong Category 2 hurricane if Wilma moves through the Keys, or as a weak Category 2 hurricane further north. Remember that hurricane intensity forecasts are poor, especially 3 - 5 days out, so Wilma's intensity could easily be a full Category higher or lower than this.

Figure 1. Total heat content of the ocean is high over the northwest Caribbean and the southern Gulf of Mexico south of 25 N latitude. Images credit: NOAA/AOML.

Jamaica continues to take a pounding from Wilma, but this should end tomorrow night as Wilma pulls away. The next area of concern is northern Honduras and Nicaragua, where rains of up to 12 inches are expected. However, the portions of these countries that will receive the heaviest rains are relatively flat, so I do not expect massive loss of life from flooding in the mountains.

Next on Wilma's list will be the Cayman Islands, but flooding is generally not life-threatening in that nation. Mexico and Cuba may escape serious damage if Wilma passes through the Yucatan Channel as forecast.

Figures 1. Computer model forecasts for Wilma.

Wilma started moving WNW at 8 mph today, as all the computer models predicted she would. The models are pretty unified, bringing Wilma through the Yucatan Channel or across the western tip of Cuba, and then northeastward into the Florida Keys or the west coast of Florida by the weekend. Two models (the UKMET and GFS) predict that Wilma will pass just south of the Keys. The furthest north model is the Canadian, which picks Sarasota for its landfall. The GFDL, NOGAPS, and the official NHC forecast are in the middle, with a landfall over the Everglades of Southwest Florida. The NOAA jet is scheduled to makes its first flight tonight, and tomorrow morning we should have a better idea of which part of Florida is at most risk. Climatology favors a more southern track, and I expect that we'll see the models converge on a more southerly track through the Keys in the runs we see Wednesday morning.

Elsewhere in the tropics, there is a large area of disturbed weather midway between Africa and the Leeward Islands. Upper level winds are not favorable for development of this area, which is also too close to the Equator. I'll be back with a update in the morning.

Jeff Masters

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

Some people are predicting a Cat 3 at lanfall........yuk!
It will be curious to see which way the computer models shift over the next two days. They seemed to have shifted to the south since this morning.
As the NHC points out in the most recent Wilma discussion "it is worth remembering that
there is little skill in long-range intensity forecasts."
It's possibly the worst possible track for a US landfalling hurricane - WILMA will have some juicy water to feed her - anywhere else and it would be a limiting factor for her.

In case anyone might be interested, here's what's happening in the Cayman Islands - and it is REALLY dark here!

Wilma Threatens: Schools Closed Tomorrow; Businesses Too
As of 2:00 p.m. 18 October 2005 Hurricane Wilma, currently a category one hurricane, has been maintaining its movement during the course of today.

Grand Cayman will begin to experience tropical storm force winds from the east- southeast after midnight tonight. These may last for 20 hours, until Wednesday night, with the strongest winds, 45 mph with gusts up to 55 mph, affecting the island mid-morning tomorrow (Wednesday).

Weather conditions tomorrow will not be suitable for persons to be moving and all residents are being urged to remain indoors until advised that conditions are suitable for normal travel. In turn, schools will be closed tomorrow (Wednesday, 19 October), including schools on the Sister Islands. Businesses should use the remainder of today to ensure that their own preparedness arrangements are completed. Employees should be allowed to leave work as soon as these arrangements have been completed in order for them to attend to their own personal property.

Employers should not expect employees to report to work tomorrow under the projected conditions. Emergency services, hotels and any other business which feel it essential to be open tomorrow are urged to make arrangements for staff to report to work tonight prior to the onset of these conditions and to be cared for until their services are needed.

Hurricane Wilmas winds will first affect the south coast of Grand Cayman, and then, as the storm passes, the south and southwest coasts will be affected. Storm surge is not expected with this storm. However, wave heights could reach eight to ten feet on the east, south and eventually west coasts.

Overnight there may be about 2.5 inches of rainfall. Grand Cayman residents living in areas prone to flooding should call 9-1-1 if they feel the need to evacuate their homes.

Cayman Brac and Little Cayman are not projected to experience tropical storm force winds but will experience gusty winds and heavy showers.

The interim report from Miamis National Hurricane Centre at 1:00 pm today (Tuesday, 18 October) put Hurricane Wilma about 180 miles south of Grand Cayman, moving west-northwest at 8 mph. A motion to the west-northwest or northwest is expected during the next 24 hours. With the barometric pressure now registering 975 MB and continuing to fall, additional strengthening is expected. Wilma is forecast eventually to become a Category 2 or 3 hurricane.

The National Hurricane Center in Miami is sending in a hurricane hunter aircraft into the centre of Wilma. This will provide much more definitive information for the 4 pm forecast.

Maximum sustained winds are now near 80 mph, with higher gusts. Hurricane force winds extend out up to 15 miles, with tropical storm force winds up to 120 miles from the centre.

We will of course continue to monitor the system closely. In particular, we will be updating our projected window of inclement weather conditions immediately following each of the substantive advisories from the National Hurricane Center at 4 and 6, said Chairman Donnie Ebanks. Were hoping to escape with just some strong wind and rain but with the way this system has performed, we have to be very cautious and prepare for somewhat worse than predicted.

NHC advice to local population The 5pm update will be more detailed. Everyone should continue to monitor local news reports but be patient in so doing because this system is extremely slow moving and vulnerable to change. Cayman Islands residents are advised to regularly monitor bulletins at www.gov.ky or www.caymanprepared.ky.

Details of Weather System at 1:00pm, Tuesday, 18 October:
Longitude -- 81.1W; Latitude -- 16.7N; proximity -- 180 miles south of Grand Cayman; minimal central pressure -- 957MB; speed of system and direction of movement -- maximum sustained winds have increased to near 80mph, with higher gusts. Hurricane Wilma is now moving west-northwest at 8 mph.

Why is it the worst possible track Wannabe? Because of Charley?
Does anyone have an updated windfield map?
Well Im headed to south florida early saturday morning....it only takes me about 4 hours to get there......just have to wait to make sure that wilma is still coming.....it might try and stay south.....wait and see
Little change in my prediction - just an increase in the strength. It hits Cuba as a Category 5, then slides just southeast of Florida as a Category 4 (after weakening to a Cat 2 over Cuba) en route to the Mid-Atlantic coast.

Current - 16.7/81.5 - 970mb - 80mph
6 hrs - 16.9/81.8 - 963mb - 100mph
12 hrs - 17.2/82.2 - 949mb - 125mph
24 hrs - 18.1/83.0 - 935mb - 145mph
36 hrs - 19.2/83.2 - 917mb - 165mph
48 hrs - 20.9/82.9 - 909mb - 175mph
60 hrs - 22.4/82.6 - 912mb - 165mph Near Isle of Youth
68 hrs - 23.2/82.2 - 916mb - 160mph Landfall
72 hrs - 23.5/82.0 - 927mb - 140mph Inland over Cuba
96 hrs - 26.7/79.6 - 937mb - 135mph Over Water near SE Florida
120 hrs - 32.4/77.5 - 935mb - 140mph
Maybe the wind shear and cooler SST will take some of the starch out of this thing.
CrazyC83 like that one there 175 mph cat 5 3 in a row i think that we nevere been done be LOL
i hav updated my blog with my updated wilma forecast.
CrazyC83 3 cat 5 in a row that a little cool i do not think that we had 3 cat 5 in a row in one hurricane year so this is new
Thanks CaymanGal for Update. Stay Safe.
Anyone with another prediction on windspeed at landfall?
If Wilma is a US landfalling hurricane, it's probably going to be retired...
Hiya from The Bahamas :)
Things are really not looking good for us and Freeport, Grand Bahama :(
They really took a pound from Frances and Jeanne last year :(

windnwaves , not bad. Of course when you are the boss you can take time off whenever you want, like when a hurricane forms. If you work really hard you might have the same chance someday.

Share you analysis with the blog - let's see what an expert like yourself has to say.
crazy, what exactly are you basing this forecast on, anyway?
windnwaves good luck with that.
This is my gut instinct based on the prevailing conditions - I'm predicting that the ridges will move east to open up the eastern route (which keeps most of Florida clear of the worst of the storm) but gives central Cuba a catastrophic pounding...

If Wilma is retired, that would be at least the sixth storm to be retired in 2005 (most likely) and who knows what will happen when we go Greek...
don't even stary with me. i will be monitoring your posts, and if you slip up with any of that "i'm a hardworking barrister bully!" i will mock you the likes of which the blogosphere has never seen. you have been condemned, did you know that?

OK - I will watch it.
If Wilma is a US landfalling hurricane, it's probably going to be retired...

I hope they don't. I am right in the bullseye, so if it does hit, I think the chances of another Wilma hitting the same place in 6,12,18 years or whatever their cycle is, would be low. But then again, I think I am going to win the Florida Lottery some day too, and I don't even play. :)
Anyone with another prediction on windspeed at landfall?
I'm headed to Orlando tomorrow for a national conference.
Scheduled to leave on Sunday am?

How's it look? Too early to tell?
cat3 115mph at landfall
windnwaves maybe you should think before you post?
lefty you are way off, at first landfall it will be cat 4.

Just stumbled upon this blog. Wondering if anyone has taken into account that it seems like most of the storms that have made US landfall this year has done so slightly to the right of the NHC Forecast track...even the tracks made just prior to landfall. Understanding there is always margin of error, no matter how close to landfall...seems like the models or NHC have been pretty close, but always just left of the final landfall. Anyone else notice this? And is this something to consider when thinking about Wilma? (Seems like it's predicted to take a pretty hard right turn already.)
URNT12 KNHC 182158
A. 18/21:42:20Z
B. 16 deg 36 min N
081 deg 32 min W
C. 850 mb 1112 m
D. 55 kt
E. 34 deg 051 nm
F. 111 deg 082 kt
G. 024 deg 009 nm
H. 963 mb
I. 17 C/ 1524 m
J. 20 C/ 1526 m
K. 20 C/ NA
M. C7
N. 12345/ 8
O. 0.02 / 1 nm
P. AF302 0524A WILMA OB 13
MAX FL WIND 82 KT NE QUAD 21:39:30 Z

The very latest sat shows a the first pic of a small eye.

I can't answer your question, but where are you in SWFLA? I am too, and I am very nervous about this one.
First landfall: 160mph - Cat 5 (Cuba)
Closest approach to FL: 135 mph - Cat 4 (about 60 miles SE of Miami)
Second landfall: 135 mph - Cat 4 (NC Outer Banks)
Final landfall: 115 mph - Cat 3 (Delaware Bay area)
963 wow!
In normal season this would be quite a feat, but in this season we've seen it so many times. A cat 4 is very possible!
pressure dropped 7mb from the last vortex?

is that possible?
82 knots and 963 mb? That would be a borderline Cat 1/2 storm (95 mph), although with a pressure more typical of a 110 mph storm...
wannabe, i am talking about florida penninsula landfall. cat3 115mph.

anyone want to stop by my blog tons of info and gopod links stop by


URNT12 KNHC 182009
A. 18/19:54:00Z
B. 16 deg 36 min N
081 deg 25 min W
C. 850 mb 1169 m
D. 55 kt
E. 335 deg 020 nm
F. 080 deg 075 kt
G. 348 deg 010 nm
H. 970 mb
I. 16 C/ 1526 m
J. 20 C/ 1526 m
K. 20 C/ NA
M. C10
N. 12345/ 8
O. 0.02 / 2 nm
P. AF302 0524A WILMA OB 06
MAX FL WIND 75 KT N QUAD 19:50:40 Z


URNT12 KNHC 182158
A. 18/21:42:20Z
B. 16 deg 36 min N
081 deg 32 min W
C. 850 mb 1112 m
D. 55 kt
E. 34 deg 051 nm
F. 111 deg 082 kt
G. 024 deg 009 nm
H. 963 mb
I. 17 C/ 1524 m
J. 20 C/ 1526 m
K. 20 C/ NA
M. C7
N. 12345/ 8
O. 0.02 / 1 nm
P. AF302 0524A WILMA OB 13
MAX FL WIND 82 KT NE QUAD 21:39:30 Z

Live in Bradenton, about 1/4 mile from Sarasota Bay. I'm not really concerned at this point...more just watching and waiting.
quick not. the temp diff inside and outside the eye is only 3 degrees c. so when that increases u will see ehr winds really pick up
2 hours, 7mb. That is some rapid intensification.

Lefty - OK you meant US landfall, that seems reasonable.

hey lefty lets be buddies - bury the hatchet you know
Because this is such a large cirulation field it will a longer time to spin up. In small hurricane can spin up faster and spin down just as fast. In Wilma's case because she is going to be unsualy large it will take quite some time to spin down later on. I read somewhere that this reminds them of a west Pacific typhoon.
wannabe thats on you. i have not said or done anything to you sicne i started my own blog. ur moe than welcome to pop in a add ur knowledge oir thoughts. its open to anyone all i ask is we keep it positive

lefty's blog
I agree lefty...if she makes it as far north as me(cape coral) she will be between 110- 120-- shear and water temps should knock her down a tad...however---I do not know what to think with some of her early behavoir problems---(pressure to wind) ( sw jog ) (quck nw jump) she seems to want to be one step ahead of our analysis. That being said---the models are in VERY good agreement. Chazz is a good example of how timing will be the key to where she goes If train "a" goes one way at 25 mph and train "b" goes in another direction at 20 mph when will A meet B? I was never good at those questions!

Live in Bradenton, about 1/4 mile from Sarasota Bay. I'm not really concerned at this point...more just watching and waiting.

Yeah, you seem to be good to go at this point. I am in Cape Coral. So we're not out of the woods. Charley sucked. Plywood and kit restock tomorrow. People aren't freaking out yet, but tomorrow is a different story.
Crazy, that's a pretty hard right turn you have there. i guess if wilma follows that path she could hit cat 4 or 5.

i think if Wilma gets caught up in the trough and races NE, which models are predicting, this will limit the strength when/if it hits Fla.
Wow. Wilma is beginning to remind me a lot of Rita. 7 mb in just a little over an hour... Wow.
Max Mayfield was with Bryan Norcross(CBS/MIAMI)...both seemed very concerned about the Keys. Talk of having enough time to prepare.

Norcross stated that "news isnt good: for south FL;dont be fooled because storm isnt coming in from the Atlantic.

ABC and NBC have backup weather crews. I do believe they will abdanon the "poo pooing/it could hit Mexico mode" to the "we go live to home depot/publix mode"

Stay classy.FURLEY OUT!
I think Wilma is containig her anger towards Fred. Sooner or later, she's going to explode.

Just so everyone knows, Fred will be used in 2009 as a replacement for Fabian.
When Wilma explodes, I just hope she doesn't go "Bam Bam" and leave lots of "Rubble". Sorry, I couldn't resist.
Jeff's got a new blog up. She's strenthin quick!
Oops, SWLA, I mean.
I've heard some talk in Miami of people saying that since it's coming in from the gulf, our affect will be minimal. NOT THE CASE. For one, it could be a Cat2 or maybe 3 at landfall and the forward speed will increase significantly, allowing for hurricane force winds to sweep easily across the peninsula (especially if the landfall is where it is projected to be as of the latest advisory. the everglades is nothing but warm water right now.) So Miami really needs to be concerned!
Yeah, if this is bad, only God knows what Fred will be like in 2009, especially considering that would more likely be an August or early September storm! (BTW, Frederic was the original name in that sequence in 1979, then Fabian in 1985, 1991, 1997 and 2003 and Fred in 2009).
Here we go again.....we are getting really good at this drill here in Key West. Nobody is going to evacuate this time because they don't have the time or the money with Fantasy Fest coming next week....between gas prices, hotel rooms, and lost wages, these stupid things are expensive to run from. If Wilma were to actually be the one to really clober us this season, she would have plenty of victims. We are getting really good at doing the Hurricane dance ......the shutters will go up in record time.

That's all from Key West......time to go visit the Grotto once again.
I am concerned here if storm goes through the Straits ... some of our islands still have damage from Floyd :(