Karl hits the Yucatan; two simultaneous Cat 4s in the Atlantic for 2nd time in history
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
Reader Comments
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Oh good only rich trolls can post...
+100
AOI
He was defending you through sarcasm... I'm pretty sure.
This also bears repeating, people. I'm in Dallas but am seriously contemplating a move to the northwest because of the criminal chemical slow kill that is being perpetuated in the Gulf. Any tropical cyclone that ventures through the Deepwater Horizon and surrounding area is going to have a field day with atmospheric disbursement of the toxic chemical soup.
It has little to do with peak wind speed. A lot to do with storm size.
I'm still rather impressed XD
Not as bad as other sites, where everyone who post is right!
STRENGTHEN...
SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...19.4N 90.7W
ABOUT 35 MI...60 KM SSW OF CAMPECHE MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/HR
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 15 MPH...24 KM/HR
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES
Discussion for Karl:
000
WTNT43 KNHC 160239
TCDAT3
TROPICAL STORM KARL DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL132010
1000 PM CDT WED SEP 15 2010
DESPITE KARL BEING OVER LAND FOR SEVERAL HOURS...THE CLOUD PATTERN
CONTINUES TO BE WELL ORGANIZED ON SATELLITE. THERE IS A RING OF
VERY DEEP CONVECTION SURROUNDING A CLEAR AREA WHICH RESEMBLES AN
EYE FEATURE...PROBABLY INDICATING THAT THE CYCLONE IS STILL
VIGOROUS AT THE MID-LEVELS. HOWEVER...SURFACE OBSERVATIONS OVER THE
YUCATAN PENINSULA SUGGEST THAT THE WINDS OF TROPICAL STORM FORCE
ARE PROBABLY CONFINED TO RAINBANDS MAINLY OVER WATER. THE INITIAL
INTENSITY IS KEPT AT 35 KNOTS. GIVEN THE OUTSTANDING STRUCTURE ON
SATELLITE AND THE FAVORABLE ENVIRONMENT FOR INTENSIFICATION WHICH
PREVAILS IN THE SOUTHERN GULF OF MEXICO...THE OFFICIAL FORECAST
CALLS FOR RE-STRENGTHENING ONCE THE CIRCULATION MOVES BACK OVER
WATER. KARL IS FORECAST TO REACH THE COAST OF THE STATE OF VERACRUZ
WITHIN THE WATCH AREA AS A HURRICANE. HOWEVER...NONE OF THE
GUIDANCE IS VERY AGGRESSIVE IN INTENSIFYING KARL.
KARL APPEARS TO BE MOVING TOWARD THE WEST-NORTHWEST OR 290 DEGREES
AT 13 KNOTS. THE CYCLONE IS TRAPPED ON THE SOUTH SIDE OF A NEARLY
STATIONARY AND STRONG HIGH PRESSURE SYSTEM OVER THE NORTHERN GULF
OF MEXICO. THIS STEERING PATTERN SHOULD FORCE KARL ON A GENERAL
WEST-NORTHWEST TO WEST TRACK WITH A DECREASE IN FORWARD SPEED. THE
FORECAST KEEPS KARL OVER THE EXTREME SOUTHERN GULF OF MEXICO FOR
THE NEXT DAY OR SO...AND BRINGS KARL TO THE COAST OF MEXICO AS A
HURRICANE WITHIN THE WATCH AREA IN ABOUT 48 HOURS. MOST OF THE
TRACK GUIDANCE HAS BEEN VERY CONSISTENT IN KEEPING KARL ANCHORED IN
THE SOUTHERN GULF SOUTH OF 22 DEGREES NORTH.
FORECAST POSITIONS AND MAX WINDS
INITIAL 16/0300Z 19.4N 90.7W 35 KT
12HR VT 16/1200Z 19.9N 92.0W 45 KT...OVER WATER
24HR VT 17/0000Z 20.7N 93.8W 50 KT
36HR VT 17/1200Z 21.0N 95.5W 55 KT
48HR VT 18/0000Z 21.5N 97.5W 65 KT
72HR VT 19/0000Z 21.5N 99.5W 25 KT...INLAND
96HR VT 20/0000Z 21.0N 102.0W 20 KT...INLAND
120HR VT 21/0000Z...DISSIPATED
$$
FORECASTER AVILA
Hey look, a cat5 that moved north!
Seriously, I think some people here are misinterpreting me. I have seen people comment here time and time again that as a storm gets stronger it *will* move north, and that is just simply not true. It may be more likely to do so, but there are plenty of examples to the contrary. I wrote a brief blog entry about this as Ike was churning through the Caribbean (after having moved in a SW direction for awhile!)
http://www.wunderground.com/blog/angiest/comment.html?entrynum=0
west would be worse that east. if he goes west of them they will be on the worse side. Other that a hit which would be worse case of course
Igor was only supposed to turn north at 47 in the first few track e that came out and we all know those are unreliable with a bogus center.
The forecast for the turn was fixed since Friday and at one point was 60W. And the ridge was not pumped it was the Azores high which has been pretty consistent all summer.
Great Idea... Let Them Pay
As strong as Igor is I am not sure that is really true. How much difference will there really be between the east and west sides?
RIP CURRENTS ALONG THE U.S. EAST COAST OVER THE WEEKEND...
SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.2N 56.5W
ABOUT 450 MI...730 KM ENE OF THE NORTHERN LEEWARD ISLANDS
ABOUT 980 MI...1580 KM SE OF BERMUDA
MAXIMUM SUSTAINED WINDS...135 MPH...215 KM/HR
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 9 MPH...15 KM/HR
MINIMUM CENTRAL PRESSURE...942 MB...27.82 INCHES
Discussion for Igor:
ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
HURRICANE IGOR DISCUSSION NUMBER 32
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
1100 PM AST WED SEP 15 2010
BASED ON RECENT MICROWAVE DATA...IGOR APPEARS TO BE COMPLETING AN
EYEWALL REPLACEMENT. IN ADDITION...INFRARED GEOSTATIONARY
SATELLITE IMAGERY SHOWS THE INNER CORE CONVECTION DIMINISHING WITH
AN OUTER RING OF CONVECTION BECOMING MORE PROMINENT. DVORAK
ESTIMATES FROM TAFB REMAIN AT T6.0/6.5 AND HAVE FALLEN TO T5.0/5.5
FROM SAB...AND THE LATEST ADT ESTIMATE IS T6.3. THE INITIAL
INTENSITY IS HELD AT 115 KT FOR THIS ADVISORY. IGOR IS EXPECTED TO
REMAIN IN AN ENVIRONMENT OF LOW SHEAR FOR THE NEXT 60 HOURS OR
SO...AND LITTLE CHANGE IN INTENSITY IS EXPECTED DURING THAT TIME.
FLUCTUATIONS IN INTENSITY ARE STILL POSSIBLE HOWEVER...ESPECIALLY
IF THE NEW OUTER EYEWALL CONTRACTS OVER THE NEXT COUPLE OF DAYS.
BY DAYS 3 THROUGH 5...SOUTHERLY SHEAR IS EXPECTED TO INCREASE AND
SHOULD INDUCE SOME WEAKENING. THE INTENSITY GUIDANCE IS IN FAIRLY
GOOD AGREEMENT DURING THAT TIME...AND THE OFFICIAL FORECAST WILL
SHOW WEAKENING TO CATEGORY 1 OR 2 STRENGTH BY DAYS 4 AND 5.
IGOR IS MOVING 295 DEGREES AT 8 KT. THE HURRICANE IS LOCATED NEAR
THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL RIDGE OVER THE CENTRAL
ATLANTIC AND IS BEING INCREASINGLY INFLUENCED BY A LARGE BUT FLAT
MID- TO UPPER-LEVEL TROUGH NEAR THE U.S. EAST COAST. SINCE THE
TROUGH IS NOT THAT SHARP...IGOR IS EXPECTED TO MAINTAIN ITS CURRENT
MOTION FOR THE NEXT 36 HOURS OR SO. IT SHOULD THEN BEGIN TO TURN
MORE SHARPLY ON DAYS 3 THROUGH 5...WITH ITS CENTER PASSING NEAR
BERMUDA IN ABOUT 96 HOURS. THE TRACK GUIDANCE IS TIGHTLY CLUSTERED
BUT DOES SHOW SOME SPEED DIFFERENCES BY DAY 5. THE OFFICIAL
FORECAST IS JUST A LITTLE TO THE WEST OF THE MODEL CONSENSUS TVCN
SINCE THE USUALLY-RELIABLE ECMWF LIES ON THE WESTERN SIDE OF THE
GUIDANCE ENVELOPE.
FORECAST POSITIONS AND MAX WINDS
INITIAL 16/0300Z 20.2N 56.5W 115 KT
12HR VT 16/1200Z 20.8N 57.6W 115 KT
24HR VT 17/0000Z 21.7N 59.2W 115 KT
36HR VT 17/1200Z 22.6N 60.8W 115 KT
48HR VT 18/0000Z 24.0N 62.6W 115 KT
72HR VT 19/0000Z 27.5N 65.0W 105 KT
96HR VT 20/0000Z 31.5N 65.0W 95 KT
120HR VT 21/0000Z 36.5N 60.5W 80 KT
$$
FORECASTER BERG
NNNN
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL132010
1000 PM CDT WED SEP 15 2010
...KARL ABOUT TO MOVE OVER THE BAY OF CAMPECHE...FORECAST TO
STRENGTHEN...
SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...19.4N 90.7W
ABOUT 35 MI...60 KM SSW OF CAMPECHE MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/HR
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 15 MPH...24 KM/HR
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...
THE GOVERNMENT OF MEXICO HAS ISSUED A HURRICANE WATCH FOR THE COAST
OF MEXICO FROM LA CRUZ SOUTHWARD TO BARRA DE NAUTLA.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT...
A HURRICANE WATCH IS IN EFFECT FOR...
* FOR THE COAST OF MEXICO FROM LA CRUZ SOUTHWARD TO BARRA DE NAUTLA
This place needs moderation. The irony is, my comment will probably be removed and the 20 pages of this blog that is troll garbage will stay.
People obviosly don't remember Ioki in the central Pacific a few years back. TC's don't need to be moving poleward to achieve maximum strength. In fact I would say it's the opposite. Storms moving moving poleward have felt the break in the ridge and more often than not the Shear created by a Trof that broke the ridging that brought the northern movement to begin with.
Sorry, I agree with Aussie... sarcasm does not reflect well in the written word... its an inflection... it was a stupid thing to say... period.
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