Igor turns west-northwest; Julia a hurricane; 92L growing more organized

By: Dr. Jeff Masters , 1:49 PM GMT on September 14, 2010

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Hurricane Igor remains an impressive Category 4 hurricane with 135 mph winds over the Central Atlantic. Though Igor's winds are 15 mph weaker than at its 150 mph peak yesterday, the hurricane continues to maintain the classic appearance of a major hurricane on satellite imagery, with a well-formed eye, plenty of low-level spiral bands, and solid upper-level outflow to the north and south.


Figure 1. Hurricane Igor as seen by the MODIS instrument on NASA's Aqua satellite at 12:40 pm EDT Monday, September 13, 2010. Image credit: NASA.

Intensity forecast for Igor
Wind shear is low, 5 - 10 knots, and is expected to remain low for the next 3 - 4 days. Waters are warm, 28.7°C, and will warm to 29°C by Wednesday. Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. These conditions should allow Igor to remain at major hurricane status for the next 3 - 4 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 15 mph weakening Igor experienced since yesterday. Igor will probably regain its lost intensity when the cycle completes in the 12 - 36 hours. By Saturday, when Igor should be nearing Bermuda, the trough of low pressure steering Igor northwestwards should bring moderate wind shear of 10 - 20 knots to the storm, weakening it. Igor will also be tracking over cooler 28°C waters then.

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. In the longer range, Igor appears likely to be a threat to Bermuda, and that island can expect tropical storm force winds as early as Friday. Igor does have a small chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 20% of all tropical cyclones that have existed at Igor's current position have gone on to hit the U.S. East Coast; these odds are about 5 - 10% for Bermuda and 15% for Canada. The forecast steering current pattern for the period 5 - 10 days from now from the ECMWF and GFS models shows several modest troughs of low pressure moving across the Western Atlantic. These troughs will probably be strong enough to recurve Igor out sea. However, 5 - 10 day forecasts are prone to large errors, and it is too early to be highly confident that Igor will miss hitting the U.S. or Canadian coasts.

Wave forecast for Igor
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 - 11 foot waves on Saturday.


Figure 3. Forecast wave heights for 2pm EDT Saturday September 18, 2010, as predicted by 00 UTC 9/14/2010 run of NOAA's Wavewatch III model.

Caribbean disturbance 92L
Tropical disturbance 92L over the Western Caribbean, between Jamaica and the Yucatan Peninsula, has become more organized this morning. The storm remains a threat to develop into a tropical depression, but time is running out for it to do so. There is no evidence of a surface circulation on satellite loops this morning, but the cloud pattern of 92L has become more circular, with low-level spiral bands developing on the west and north sides of the storm. 92L has a moderate but increasing area of intense thunderstorms; these are bringing heavy rains to Jamaica, the Cayman Islands, and western Cuba this morning.


Figure 3. Morning satellite image of 92L.

Forecast for 92L
Rains from 92L will spread over Belize, Northern Guatemala, and Mexico's Yucatan Peninsula tonight through Wednesday, bringing peak accumulations in the 4 - 8 inch range. Lesser peak amounts of 2 - 4 inches are possible over northern Honduras. Wind shear over 92L is low, 5 - 10 knots, and is expected to remain low for the next five days. The waters beneath are hot, 29.7°C, and these warm waters extend to great depth. Water vapor satellite loops show a large area of dry air lies to the north and west of 92L; this dry air has been interfering with development of 92L, and will continue to do so. NHC is putting the odds of 92L developing into a tropical depression by Thursday at 40%; I'll give it a 50% chance. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become any stronger than a tropical storm with 50 mph winds by Wednesday afternoon, when it will move over Belize and Mexico's Yucatan Peninsula. Once 92L crosses the Yucatan, the ridge of high pressure steering it is expected to remain in place, forcing 92L west or west-southwest to a second landfall in Mexico between Veracruz and Poza Rica early Saturday morning. The shape of Mexico's Bay of Campeche and the topography of the mountains surrounding the Bay help air spiral in a counterclockwise fashion, aiding tropical storm development, and 92L has its best chance of development once it crosses into the Bay of Campeche. With the shear there expected to be low and the waters warm, I give a high 70% chance that 92L will be a tropical depression or tropical storm in the Bay of Campeche. The GFDL model is predicting 92L could be a hurricane at landfall near Veracruz on Saturday morning; the other intensity models are much less aggressive. Given the rapid development of Hermine in a similar location last week, residents of the Mexican Gulf Coast should be wary of the possibility that 92L could intensify into at least a strong tropical storm before making landfall Friday night or Saturday morning. A Hurricane Hunter aircraft is scheduled to investigate 92L this afternoon.

Julia
Hurricane Julia is headed northwest, out to sea, and it is unlikely that this storm will trouble any land areas. The intensification of Julia into a hurricane brings our activity tally for the 2010 Atlantic hurricane season to 10 named storms, 5 hurricanes, and 3 intense hurricanes. An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes, so we've already had a full season's worth of activity, with about 45% of the season still to come.

Shear will be low to moderate, 5 - 20 knots, over Julia during the next two days. Shear will 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. Julia does have a window of opportunity today and Wednesday to intensify into a Category 2 hurricane before the shear rises.

Elsewhere in the tropics
The GFS and ECMWF models are suggesting the possibility of a new tropical depression forming a few hundred miles off the coast of Africa about seven days from now.

"Hurricane Haven" airing this afternoon
Tune in to my live Internet radio show, "Hurricane Haven", airing at 4pm EDT today. If you want to ask a question, the call in number is 415-983-2634, or you can email a question to broadcast@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line.

Today's show will be about 30 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Next post
I'll have a new post on Wednesday morning.

Jeff Masters

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869. srada



Seems to me west is coming into play..just saying..
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Igor still beautiful and terrifying:

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We shall see where they put it at but it is safe to say Karl is here.
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Quoting Hurricanes101:


not that soon, its still over 200 miles away


I was just estimating using the visible loops. In 7 hours Karl looks to have went 2 degrees west and .3 north.
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Good afternoon everyone!!!!!!!
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Quoting Max1023:
9-14 hours until landfall depending on track and any speed changes. Just my estimation.


not that soon, its still over 200 miles away
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9-14 hours until landfall depending on track and any speed changes. Just my estimation.
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which future storm are you talking about that the GFS shows Miami and St.Pete?
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Quoting TampaTom:


From the NHC:

What was the largest number of hurricanes in the Atlantic Ocean at the same time?

Contributed by Chris Landsea

Four hurricanes occurred simultaneously on two occasions. The first occasion was August 22, 1893, and one of these eventually killed 1,000- 2,000 people in Georgia and South Carolina. The second occurrence was September 25, 1998, when Georges, Ivan, Jeanne and Karl persisted into September 27, 1998 as hurricanes. Georges ended up taking the lives of thousands in Haiti. In 1971 from September 10 to 12, there were five tropical cyclones at the same time; however, while most of these ultimately achieved hurricane intensity, there were never more than two hurricanes at any one time.


I was almost positive that there had been 4 storms at once. I wasn't sure about 5 however. I kinda figured if there had ever been 5, that would be the max.
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Quoting StSimonsIslandGAGuy:


Cool, I'm here a lot---look at my comment count ;)

Nahunta musta been nice and cool last night, was 68.9 at my house.

Ya i remember your posts from the last several years. yes it was pretty cool last night (thank god a little relief) I work in brunswick @ night I think it was a little warmer there. But just wanted to say hey we are in pretty close proximity. I visit SSI quite often love fishing from the pier.
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karl feels that really warm water looking for a weakness
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Judging by the vortex message of 64mph, I think the NHC will go no less than 50mph on the first advisory.
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Quoting StSimonsIslandGAGuy:


Yes my forecast was 13/7/3 Hasn't gone wrong yet ;)


I was thinking 15, but the way things are going, the pre-season numbers may not be too far from the actual truth.
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Quoting shauntanner:
Dr. Masters is on the Hurricane Haven here at 4 p.m. ET, 1 p.m. PT. Questions for Dr. Masters can be emailed to broadcast@wunderground.com or called in to 415-983-2634

http://www.wunderground.com/wxradio/wubroadcast.html


Tell the Doc that he forgot about Gustav when proclaiming Igor as the strongest storm since Felix. (Gustav got revised to 155mph max speed in the TCF - Tropical Cyclone Report)
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Quoting 1900hurricane:

That's impressive. I imagine that they'll go a little below that for the initial advisory, but I wonder how strong they will put it at.

They often like to go for the nearest multiple of 5 in MPH below the SFMR reading. In this case, that would set the initial intensity at 60 MPH.
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NEO, you should send that Sept. Oct. thing(Post 784) to DR. M for his tropical discussion.
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Quoting CybrTeddy:


Hey storm, we all did. There wasn't a post for like 20 minutes. They must have done that to add to the suspense, now that we've got TS Karl.


I thought we were going through an Ignore List Replacement Cycle (ILRC).

There was a little bout of Intense Poofing going on there..
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850. shauntanner (Admin)
Dr. Masters is on the Hurricane Haven here at 4 p.m. ET, 1 p.m. PT. Questions for Dr. Masters can be emailed to broadcast@wunderground.com or called in to 415-983-2634

http://www.wunderground.com/wxradio/wubroadcast.html
Quoting Max1023:


Shouldn't be, we would see an erosion of the outer bands before an erosion of the core.

I'm not quite sure what it is, but it's from the GOES-15, so it's the most recent stuff we have. Here is the loop

Maybe it's an eyewall break?
Member Since: August 2, 2006 Posts: 47 Comments: 11759
Karl's pressure is up to 1004, that first reading must have been sketchy due to the altitude change. However, the plane has sent back a 56 knot surface wind while no flight winds above 40 knots have been found. Since flight level is 500 feet, something must be up. Either the sfmr or the planes anemometer is off.
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Quoting oakland:


I did check it out and don't like it. I lived in Ft. Lauderdale for a long time and still have many friends there. I now live just south of St. Pete. So that scenario, if it comes to fruition, is not good for me.


I totally understand. Its an area to watch for now and pray / rebuke the storm back to go away
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What's eatin' Igor's NW eyewall?
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Quoting Tazmanian:
D. Estimated (by SFMR or visually) Maximum Surface Wind: 56kts (~ 64.4mph)

That's hugely impressive - from an area of interest with no defined circulation to a top-end tropical storm, in a single afternoon. I strongly suspect that by the 11PM update we're going to be looking at Hurricane Karl.

And here's what's worrisome. If Karl spins up quickly enough on this side of the Yucatan, it has a decent chance of maintaining some circulation during its passage, and restrengthening on the other side.
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Quoting Jeff9641:
What wave is the GFS developing that slaps FL with a major hurricane? Is it the wave that is about to emerge? GFS has had this since Saturday in the gulf come the end of next weekend. GFS also shows what looks like a series of storms coming up at us from the Caribbean. I can't believe the strenght of this system even far inland in GA.


No it is not that wave

seems the area comes from the ITCZ, kind of similar to how Karl has formed
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Huh...11 named storms now. Only two more storms needed to reach Ike's prediction of 13 total. With the last half of September, October and November, I think we'll easily reach thirteen. :-)
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Quoting Grothar:
Looks healthy enough



I noticed that the white close to the center disapears While convection deepens and the west,northwest,and southwest part form some dark blue,If this trend continues for the next 12-15 hours,we could see a cat-5.Just my observations.(P.S. That is probaly the smartest thing I have ever said on here:)
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Quoting MercForHire:
Here's one for all of you Hurri-History fanatics out there .... and I say that respectfully, as I'm a historian also .... just military, not weather.

What is the greatest number of well developed tropical storms/hurricanes ever to be active at one time in the Atlantic? Tropical depressions will work too I suppose, as long as they are somewhat well developed.

Basically what I'm wanting to see is one of those images of the Atlantic, all the way from Mexico to Africa, that just makes you go, "Wow!! Look at all that activity!"

Of course we'll never be able to get any worse than that terrible week day way back on February 30th of 1735 that we all remember:



But except for that time, when have we had the most storms active at once? Just curious.


From the NHC:

What was the largest number of hurricanes in the Atlantic Ocean at the same time?

Contributed by Chris Landsea

Four hurricanes occurred simultaneously on two occasions. The first occasion was August 22, 1893, and one of these eventually killed 1,000- 2,000 people in Georgia and South Carolina. The second occurrence was September 25, 1998, when Georges, Ivan, Jeanne and Karl persisted into September 27, 1998 as hurricanes. Georges ended up taking the lives of thousands in Haiti. In 1971 from September 10 to 12, there were five tropical cyclones at the same time; however, while most of these ultimately achieved hurricane intensity, there were never more than two hurricanes at any one time.
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Quoting Tazmanian:
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 14th day of the month at 19:45Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 305)
Mission Purpose: Investigate fourth suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 10
A. Time of Center Fix: 14th day of the month at 19:24:50Z
B. Center Fix Coordinates: 18°10'N 83°55'W (18.1667N 83.9167W)
B. Center Fix Location: 183 miles (295 km) to the WSW (245°) from George Town, Cayman Islands (GBR).
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 56kts (~ 64.4mph)
E. Location of the Estimated Maximum Surface Wind: 10 nautical miles (12 statute miles) to the S (176°) of center fix
F. Maximum Flight Level Wind Inbound: From 255° at 27kts (From the WSW at ~ 31.1mph)
G. Location of Maximum Flight Level Wind Inbound: 13 nautical miles (15 statute miles) to the S (176°) of center fix
H. Minimum Sea Level Pressure: 1004mb (29.65 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 214m (702ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 25°C (77°F) at a pressure alt. of 212m (696ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 24°C (75°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 1,500 feet
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind Outbound: 34kts (~ 39.1mph) in the northeast quadrant at 19:32:00Z
Sea Level Pressure Extrapolation From: Below 1,500 feet

That's impressive. I imagine that they'll go a little below that for the initial advisory, but I wonder how strong they will put it at.
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Quoting wayfaringstranger:


Several friends living down in the St Pete Miami area...seriously and I am sure IKE would agree that this system could cause some major damage and that being prepared, evac plan, etc - now is the time...your looking at 14 days out and this GFS model has been "accurate" even in the longer range.

Where do your friends live? I too reside in the greater St. Petersburg - Miami metroplex area. Maybe I know them!
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Quoting xcool:
AtHomeInTX .sorry.justing getting ready.pattern change come..sorry ;(*


Lol. I know. Just playing. Not gonna say we dodged another season til November anyway. September is usually our worst but October happens. :)
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Although the 10/6/2 climatology figure is weighted down due to technology and limited sampling, the true figure is likely to be something like 13/7/2.

As said before, Landsea believes the figure to be closer to 13 (remember: The last season to have all storms above 1 in ACE was back in 1997; there were also no storms below 0.49 ACE between 1875 and 1969 as far as I can tell, nearly a 100 years. Shows well how the little storms got missed for a long time.)

Even with that realistic adjustment/estimate, we're *still* coming up to be in line with it in the middle of September.
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Judging by recon vortex, Karl might be a 60 mph TS at 5.
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Quoting wayfaringstranger:
Yes...Tampa.

The iso bars showing though covers the eastern tip of FL which would include Miami. Seriously check out the GFS run.


And from the looks of the "run" it intensifies REALLY fast. Not suprising considering the location it's coming from. Everything that's come across that area so far hasn't had a chance to "stir-the-pot" as it were. Looking at the water vapor at that time, the conditions appear about as good as it gets for development...all relative to what's been being passed around recently that leans toward the pattern shift.
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Quoting Cotillion:


Dry air?


Shouldn't be, we would see an erosion of the outer bands before an erosion of the core.
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Quoting StSimonsIslandGAGuy:


what does ATCF say about the Caribbean storm?

I heard someone say there were 11 storms this season---has that been upgraded?


Yes, ATCF says 92L has become Tropical Storm Karl.
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14/1745 UTC 18.6N 52.7W T6.5/6.5 IGOR
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 14th day of the month at 19:45Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 305)
Mission Purpose: Investigate fourth suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 10
A. Time of Center Fix: 14th day of the month at 19:24:50Z
B. Center Fix Coordinates: 18°10'N 83°55'W (18.1667N 83.9167W)
B. Center Fix Location: 183 miles (295 km) to the WSW (245°) from George Town, Cayman Islands (GBR).
C. Minimum Height at Standard Level: Not Available
D. Estimated (by SFMR or visually) Maximum Surface Wind: 56kts (~ 64.4mph)
E. Location of the Estimated Maximum Surface Wind: 10 nautical miles (12 statute miles) to the S (176°) of center fix
F. Maximum Flight Level Wind Inbound: From 255° at 27kts (From the WSW at ~ 31.1mph)
G. Location of Maximum Flight Level Wind Inbound: 13 nautical miles (15 statute miles) to the S (176°) of center fix
H. Minimum Sea Level Pressure: 1004mb (29.65 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 20°C (68°F) at a pressure alt. of 214m (702ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 25°C (77°F) at a pressure alt. of 212m (696ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 24°C (75°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 1,500 feet
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind Outbound: 34kts (~ 39.1mph) in the northeast quadrant at 19:32:00Z
Sea Level Pressure Extrapolation From: Below 1,500 feet
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Yeah, 14 days is a long way out, these models can drop a system that far out, just like that.
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Link
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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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