Karl hits the Yucatan; two simultaneous Cat 4s in the Atlantic for 2nd time in history

By: Dr. Jeff Masters , 2:37 PM GMT on September 15, 2010

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The Atlantic hurricane season of 2010 kicked into high gear this morning, with the landfall of Tropical Storm Karl in Mexico, and the simultaneous presence of two Category 4 hurricanes in the Atlantic, Igor and Julia. Tropical Storm Karl's formation yesterday marked the fifth earliest date that an eleventh named storm of the season has formed. The only years more active this early in the season were 2005, 1995, 1936 and 1933. This morning's unexpected intensification of Hurricane Julia into a Category 4 storm with 135 mph winds has set a new record--Julia is now the strongest hurricane on record so far east. When one considers that earlier this year, Hurricane Earl became the fourth strongest hurricane so far north, it appears that this year's record SSTs have significantly expanded the area over which major hurricanes can exist over the Atlantic. This morning is just the second time in recorded history that two simultaneous Category 4 or stronger storms have occurred in the Atlantic. The only other occurrence was on 06 UTC September 16, 1926, when the Great Miami Hurricane and Hurricane Four were both Category 4 storms for a six-hour period. The were also two years, 1999 and 1958, when we missed having two simultaneous Category 4 hurricanes by six hours. Julia's ascension to Category 4 status makes it the 4th Category 4 storm of the year. Only two other seasons have had as many as five Category 4 or stronger storms (2005 and 1999), so 2010 ranks in 3rd place in this statistic. This year is also the earliest a fourth Category 4 or stronger storm has formed (though the fourth Category 4 of 1999, Hurricane Gert, formed just 3 hours later on today's date in 1999.) We've also had four Cat 4+ storms in just twenty days, which beats the previous record for shortest time span for four Cat 4+ storms to appear. The previous record was 1999, 24 days (thanks to Phil Klozbach of CSU for this stat.)


Figure 1. A rare double feature: two simultaneous Category 4 hurricanes in the Atlantic, for only the second time in recorded history.

Karl
Tropical Storm Karl made landfall as a strong tropical storm with 65 mph winds and a central pressure of 991 mb at 8:45am EDT this morning on Mexico's Yucatan Peninsula, just north of the Belize border. Karl took advantage of nearly ideal conditions for intensification, and in just fifteen hours intensified from a tropical disturbance to a strong tropical storm with 65 mph winds. Had Karl managed to get its act together just one day earlier, it could have been a major hurricane at landfall this morning. Fortunately, Karl has a relatively small area of strong winds--tropical storm force winds extend out just 45 miles from the center of the storm, and wind damage is not the main concern. Heavy rains are the main concern, and Belize radar shows heavy rain bands from Karl spreading ashore over northern Belize near the border with Mexico. Cancun radar shows that heavy rains are relatively limited, though, near the tourist havens of Cancun and Cozumel.


Figure 2. Radar image of Karl at landfall this morning near the northern Belize/Mexican border. Image credit: Belize National Meteorological Service.

Forecast for Karl
Karl will traverse the Yucatan Peninsula today and emerge into the Gulf of Mexico's Bay of Campeche Thursday morning as a much weakened tropical storm, with perhaps 40 - 45 mph top winds. Once in the Gulf, conditions for intensification are ideal, with wind shear is expected to be low, 5 - 10 knots, SSTs will be warm, 29°C - 30°C, and the atmosphere very moist. These conditions, combined with the topography of the surrounding coast which tends to enhance counter-clockwise flow, should allow Karl to intensify into a strong tropical storm or a Category 1 hurricane before making landfall between Tampico and Vercruz, Mexico on Saturday morning. However, since Karl is a small storm, it is possible that passage over the Yucatan will disrupt the storm enough so that it will be much weaker. The ridge of high pressure steering Karl westwards is quite strong, and it is very unlikely that the storm will turn northwest and hit Texas. NHC is giving Brownsville, Texas, an 10% chance of receiving tropical storm force winds of 39+ mph.

Igor
Hurricane Igor put on a burst of intensification last night to put it at its strongest yet, a top-end Category 4 hurricane with 155 mph winds. Igor has weakened slightly this morning, but remains a formidable presence in the Central Atlantic with its 145 mph winds. Igor continues to show the classic appearance of a major hurricane on satellite imagery, with a well-formed eye, symmetrical cloud pattern, plenty of low-level spiral bands, and solid upper-level outflow on all sides.


Figure 3. Hurricane Igor as captured at 18 UTC Tuesday September 14, 2010, from the International Space Station. Image credit: Douglas Wheelock, NASA.

Intensity forecast for Igor
Wind shear is low, 5 - 10 knots, and is expected to remain low for the next 2 - 3 days. Waters are warm, 29°C, and will remain 29°C for the next 2 - 3 days. Igor is well armored against any intrusions of dry air for at least the next three days. These conditions should allow Igor to remain at major hurricane status for the next three days. The hurricane will probably undergo one of the usual eyewall replacement cycles intense hurricanes commonly have, where the eyewall collapses and a new eyewall forms from an outer spiral band. This will weaken the hurricane by 10 - 20 mph when it occurs, and may be responsible for the 10 mph weakening Igor experienced early this morning. Igor may regain its lost intensity over the next 36 hours. By Saturday morning, 36 hours before the core of Igor is expected to pass Bermuda's latitude, the trough of low pressure steering Igor northwestwards should bring moderate wind shear of 10 - 20 knots to the storm, weakening it. The SHIPS models predicts shear will rise to the high range, 20 - 30 knots, during the final 24 hours of the storm's approach to Bermuda. Igor will also be tracking over cooler 28°C waters during this period, and substantial weakening by perhaps 20 - 30 mph can be expected. Igor will still probably be at least a Category 2 hurricane on its closest pass by Bermuda on Sunday. NHC is giving Bermuda a 13% chance of experiencing hurricane force winds from Igor, but this probability is likely too low. The Bermuda Weather Service is calling for Category 1 or 2 hurricane conditions for the island on Sunday, with 20 - 25 foot waves in the offshore waters.

Track forecast for Igor
The track forecast for Igor remains unchanged. Igor has made its long-anticipated turn to the west-northwest, in response to the steering influence of a broad trough of low pressure moving across the Western Atlantic. This trough will steer Igor several hundred miles to the northeast of the Lesser Antilles, and high waves should be the only impact of Igor on the islands. Igor appears likely to be a threat to Bermuda, and that island can expect tropical storm force winds as early as Saturday. Igor will be moving at about 12 - 15 mph as it approaches Bermuda. Tropical storm force winds of 39+ mph will probably extend out about 250 miles to the north of Igor on Saturday, so Bermuda can expect 18 hours of tropical storm force winds before the core of Igor makes its closest pass. In all, Bermuda is likely to experience a very long pounding of 24 - 36 hours with winds in excess of tropical storm force.

The models have been in substantial agreement over multiple runs that Igor will miss the U.S. East Coast, and the danger to the U.S. will probably only come in the form of high waves. Large swells from Igor have arrived in the Northern Lesser Antilles Islands, and will spread westwards over the next few days, reaching the U.S. East Coast on Friday. By Saturday, much of the East Coast from northern Florida to Cape Cod Massachusetts can expect waves of 3 - 4 meters (10 - 13 feet), causing dangerous rip currents and significant beach erosion. These waves will continue through Sunday then gradually die down. The latest NOAA marine forecast for Cape Hatteras, North Carolina calls for 8 - 10 foot waves on Saturday, and 9 - 12 foot waves on Sunday.

Igor may pass very close to Newfoundland, Canada, but it is too early too assess the likelihood of this happening.

Julia
Hurricane Julia put on a remarkable and unexpected burst of intensification this morning to become the season's fourth Category 4 storm. Julia's 135 mph winds make it the strongest hurricane on record so far east; the previous record was held by the eighth storm of 1926 which was only a 120 mph Category 3 hurricane at Julia's current longitude. Julia's intensification was a surprise, since SSTs in the region are about 27.5°C, which is just 1°C above the threshold needed to sustain a Category 1 hurricane. Julia is headed northwest, out to sea, and it is unlikely that this storm will trouble any land areas. SSTs will steadily cool to 26.5°C today, and further intensification today is unlikely. Shear will be moderate, 10 - 20 knots, over Julia during the next two days, then rise sharply to 30 knots 3 - 5 days from now, as Julia moves within 1000 miles of Igor and begins to experience strong northwesterly winds from her big brother's upper level outflow. This should substantially weaken Julia.

Elsewhere in the tropics
The GFS and ECMWF models develop a new tropical depression a few hundred miles off the coast of Africa 3 - 6 days from now. The GFS also develops a tropical depression in the eastern Caribbean 6 - 7 days from now.

Portlight's 2-year anniversary
On September 14, 2008, the devastation wrought by Hurricane Ike on Texas and Louisiana moved members of the wunderground community to put into action their own impromptu relief effort. From this humble beginning has grown a disaster-relief charity I have been proud to support--Portlight.org. We've been blessed this hurricane season with relatively few landfalling storms, so Portlight's new disaster relief trailer (Figure 4), financed with a $21,500 grant from the Christopher and Dana Reeve Foundation, has yet to be deployed. With five weeks of peak hurricane season still to come, the new trailer may yet get a call to action. The mobile kitchen in the trailer will be able to feed several hundred people per day, and the trailer is equipped with portable ramps to help with shelter accessibility, as well as durable medical equipment to facilitate mobility and independence for survivors. The trailer is mobile, and Portlight is willing to load it up and fly it to Bermuda, if Igor ends up making a mess there!

The lack of landfalling storms has allowed Portlight to continue to concentrate their efforts on Haiti, where their assistance has been a tremendous boost for those most in need, the disabled. Portlight is working on constructing steel shelters out of shipping containers for homeless Haitians, as detailed in the Haitian Relief Recap blog post. Please visit the Portlight.org web site or the Portlight blog to learn more and donate. A few other items of note:

Portlight has been able to facilitate providing assistance to people with disabilities in Pakistan, where the worst natural disaster in their history has left 4 million homeless. While not directly involved in delivering relief, Portlight has been able to connect local Disabled People's Organizations with important sources of food, water, filtration systems, and medical equipment.

ABC News4 in Charleston broadcast a story about the Portlight relief trailer, and Portlight has also been featured on the Pacifica Radio Network.

Portlight launched a quarterly newsletter, The Portlight View, which can be seen on the newly redesigned website.


Figure 4. The new Portlight disaster relief trailer, funded by their $21,500 grant from the Christopher and Dana Reeve foundation.

I'll have an update Thursday morning.

Jeff Masters

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Quoting HurricaneGeek:
1158, 1559, 1160.
Thanks

3 in a row. THAT's a new record! =0


"1559" - wow - you have forecasting abilities.
lol.
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Quoting IKE:


Shows nothing in the Caribbean.
Only goes out to 120 hours. The system doesn't materialize until 144+ hours on the models that develop it.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting HurricaneGeek:


Yes. I mean let's say she was at 185 for 24 hrs, she'd make 10.24 ACE in 24 hrs?
Wow.


Correct. I think in a single day Dog has the lead in most ACE (6th September, 1950; 10.0825), though the most ACE in a 24 hour period by one storm alone was Camille in 1969.
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Quoting MiamiHurricanes09:
Yeah, I believe that the one you're speaking of that is off of the African coast is PGI45L.

The other one is located near 40W.


The one near 40W should be what develops in the Caribbean.
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1180. IKE
Quoting OctoberToRemember:
Evening, Ike! Hey, why did you write, ''pattern change'', a short while ago, on here, in quotation marks? Are not believing that it'll happen or what?


I don't know.
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Best Karl ever looked like a TS is over land.
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Quoting scott39:
Doom Doom Doom!!

do u have a link on that
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Quoting extreme236:
Lisa should form from the AEW off the African coast. Matthew would be the Caribbean system.
Yeah, I believe that the one you're speaking of that is off of the African coast is PGI45L.

The other one is located near 40W.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1175. IKE
Quoting xcool:


uk


Shows nothing in the Caribbean.
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Quoting weathermancer:


indeed.
Can you spell... hyper-active...
2 more months.



Yes.
h-y-p-e-r.. a-c-t-i-v-e =)
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I know you guys dont like to talk about this but i have to say Igor looks like it went anullar.

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Igor still on a wnw path. The NW turn remains to be seen.
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Lisa should form from the AEW off the African coast. Matthew would be the Caribbean system.
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LATITUDE EQ.
At the equator, both longitude and latitude measure approximately 60 nautical miles. This converts to 69.046767 statute miles.

Both latitude and longitude degree lengths change with respect to latitude; latitude however changes very minimally between the equator and the poles, the distance only changes by about 75 meters between 0 degrees (the equator) where the degree length is 110574 meters, and 90 degrees (the north pole) the degree length of latitude is 111694 meters (note: miles = meters/1609.344)

Longitude however changes quite a lot from the equator to the poles, at 90 degrees the degree length of longitude is 0, where as at the equator it is 111320m.


There are a number of ways of finding the degree length, for close enough approximations it is usually said that the degree length of latitude does not change, lets say it's=111132m (it's that around 45 degrees of latitude), and degree length of longitude is then computed as:

L - latitude in radians

Longitude = 111132*cos(L)


(note: here that since its a trig function you have to convert degrees to radians, which can be done with radians = degrees*pi/180)

A much more close approximations for arcdegree lengths, based on an ellipsoid earth are:


(Radii based on WGS-84 ellipsoid, used by all current GPS devices)
E - equatorial radius - 6378137
P - polar radius - 6356752.314
L = latitude in radians


Latitude = (pi/180)*((PE)2/((E*cos(L))2+(P*sin(L))2)3/2)
Longitude = (pi/180)*cos(L)*(P2/((E*cos(L))2+(P*sin(L))2)1/2)
Quoting Floodman:


Depends on where, on the globe, you are...chicklit provided a very nice equation the other day to determine the width and height of latitudinal areas based on location
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1158, 1559, 1160.
Thanks

3 in a row. THAT's a new record! =0
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1166. scott39
Quoting Jeff9641:


Thanks bud! Again sorry all for being a jerk on the blog yesterday.
I dont know what your sorry for, but if your big enough to say it hopefully its excepted.
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1165. xcool
Jeff9641.no problem
Member Since: September 26, 2009 Posts: 2 Comments: 15684
And ?
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1161. xcool


uk
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting HurricaneGeek:
Wow, is JULIA que strongest east hurricane o major hurricane ever in the ATL?
That would be a pository.
On line 6 of today's blog Dr. Masters wrote, "Julia is now the strongest hurricane on record so far east"
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Quoting HurricaneGeek:
Wow, is JULIA que strongest east hurricane o major hurricane ever in the ATL?


indeed.
Can you spell... hyper-active...
2 more months.

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Quoting HurricaneGeek:
Wow, is JULIA the strongest east hurricane o major hurricane ever in the ATL?
Yes. It is the strongest hurricane to form that far east in longitude.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Cotillion:


You mean if she was?

Her max was 185mph, which would be 2.5600 in ACE every 6 hours (I think in reality, it was only one advisory's worth).


Yes. I mean let's say she was at 185 for 24 hrs, she'd make 10.24 ACE in 24 hrs?
Wow.
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1156. Patrap
GOM IR Loop dee Loop

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1155. scott39
Quoting Jeff9641:


At the end of the 12Z GFS run another lows forms in the Caribbean and appears it may also follow the same path so stay tuned to see if this materializes later next week. We could very well have 2 majors move in the gulf over the next 3 weeks.
Doom Doom Doom!!
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Too mant oysters mess up the brain
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Quoting Midweststorm:


I do believe each latitude degree is approx 69 miles, tho not 100% sure.


Depends on where, on the globe, you are...chicklit provided a very nice equation the other day to determine the width and height of latitudinal areas based on location
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Wow, is JULIA the strongest east hurricane o major hurricane ever in the ATL?
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Quoting HurricaneGeek:


When Wilma was at peak intensity how much ACE was she producing every 6 hours?
Thanks.


You mean if she was?

Her max was 185mph, which would be 2.5600 in ACE every 6 hours (I think in reality, it was only one advisory's worth).
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Quoting scott39:
In Levis Video, I thought he said pressures in that area will be 1008mb
Yes. That would further support the development of a tropical cyclone in that region if environmental and thermodynamical conditions are favorable.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1147. Patrap
Quoting saltwaterconch:

As well I did not realize that this blog was on "autodelete" It explains alot. So If I were to create 5-8 fictitious accounts and swithed between them flagging posts I could basically shut this blog down ....... hmmmmmmm


No,,as its a Logic based algorithm.

If one constantly Flags when others do not,,the system recognizes that individual and disregards his/her input.
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another wave looking impressive coming off africa. whats the next name lisa? i believe
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Quoting twhcracker:
my husband has been telling me for thirty years that this is six inches!
lol.....if you've been married for 30 years then you're doing something right that can't be measured in inches.
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Been there
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Quoting StSimonsIslandGAGuy:


Was the wind blowing onshore or offshore?


From sea to land. Sorry is the way I can explain it.
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1141. xcool
Jeff9641 new 18z gfs come soon.
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting alfabob:


Yea the new wall structure looks pretty well defined, EWRC shouldn't take too much longer to finish. Wonder how much it will shrink though, it's about 1.2 degrees latitude in diameter right now; don't know what that would be in miles.



I do believe each latitude degree is approx 69 miles, tho not 100% sure.
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Quoting StSimonsIslandGAGuy:
ACE for today as of 5 pm:

Igor 4.2075
Julia 3.8550
Karl 0.7125

8.775

We'll probably have a total ace of over 11 today, but not 12 or 13. September 11, 1961's record ACE is safe.


When Wilma was at peak intensity how much ACE was she producing every 6 hours?
Thanks.
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Member Since: July 12, 2007 Posts: 0 Comments: 6065

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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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