92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa

By: Dr. Jeff Masters , 2:18 PM GMT on September 12, 2010

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Tropical disturbance (92L) over the Central Caribbean, a few hundred miles south of the Dominican Republic, remains a threat to develop into a tropical depression. Satellite loops this morning show 92L may be starting to form a surface circulation, and an Air Force Hurricane Hunter aircraft will investigate 92L this afternoon to see if a tropical depression is forming.

The storm has only a modest area of heavy thunderstorm with limited low-level spiral banding and upper-level outflow, thanks to an infusion of dry air last night that disrupted the storm. Long range radar out of Puerto Rico shows that heavy rains are affecting that island, but there is no rotation to the radar echoes evident. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are hot, 29.5°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, and this dry air could interfere with development at times over the next few days.


Figure 1. Morning satellite image of 92L.

Track forecast for 92L
The disturbance is moving west to west-northwest at 15 mph, and steering currents favor a continuation of this motion for the next three days. Model support for development is scattered. The GFS and NOGAPS models do not develop 92L. The GFDL and ECMWF models predict development, with a track taking 92L into Belize or Mexico's Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches today through Monday morning; southern Haiti can expect similar rains tonight through Monday night, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba can expect rains in the 2 - 4 inch range. Once 92L crosses the Yucatan, the ridge of high pressure steering it is expected to remain in place, forcing 92L to a second landfall in Mexico south of the Texas border.

Intensity forecast for 92L
NHC is putting the odds of 92L developing into a tropical depression by Tuesday at 50%; I'd put them higher, at 70%. However, time is running out for 92L to become a hurricane before hitting the Yucatan Peninsula on Wednesday. Given the current disorganized state of 92L, it would be difficult for it to intensify quickly enough to become a hurricane by then. The storm may also suffer another of its mysterious evening collapses, where it loses most of its heavy thunderstorm activity. However, the SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and water temperatures are certainly warm enough to support development. The main detriment to intensification is likely to be dry air, and 92L could wrap in some of the dry air to its northwest at times, slowing down development. There are a number of research flights being made into 92L this afternoon that should help long-term efforts to make better predictions in the future on whether or not disturbances like this will develop or not.


Figure 2. Morning satellite image of Igor.

Igor
Hurricane Igor appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is low, 5 - 10 knots, and is expected to drop below 5 knots for the next five days. Waters are warm, 28°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. Igor is undergoing a period of rapid intensification today, and will probably be a Category 3 or 4 hurricane by Monday.

The track forecast for Igor remains unchanged. Igor will move west under the influence of a strong ridge of high pressure for the next 2 - 3 days, then turn more to the west-northwest then northwest in response to the steering influence of a broad trough of low pressure moving across the Western Atlantic on Tuesday and Wednesday. This should allow Igor to pass several hundred miles to the northeast of the Lesser Antilles. In the longer range, Igor may be a threat to Bermuda, and does have a small chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 15% 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 10% for Bermuda and 10% for Canada. The forecast steering pattern for the period 5 - 12 days from now from the ECMWF and GFS models shows a continuation of the pattern we've seen all hurricane season, with regular strong troughs of low pressure moving off the U.S. East Coast. This pattern favors Igor eventually recurving out to sea without affecting any land areas. Recent runs of the ECMWF model indicate that these troughs may not be as intense as previously thought, so it is possible Igor has a higher chance than usual to hit land than climatology suggests. One wild card may be the possible development of TD 12 behind Igor. If TD 12 develops into a hurricane, and moves close to Igor, as some of the models are suggesting, the two hurricanes could rotate around a common center, forcing Igor more towards the coast of the U.S. The long term fate of Igor is difficult to predict at this point.

Tropical Depression Twelve forms
Tropical Depression Twelve formed between the Cape Verdes Islands and coast of Africa this morning, and is already affecting the Cape Verdes with winds near tropical storm strength; sustained winds of 35 mph were recorded in the northwest Cape Verdes this morning. You can follow the progress of TD 12 through the Cape Verdes today using our wundermap.

Next post
I'll have a new post Monday morning, and perhaps late this afternoon if events warrant.

Jeff Masters

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Quoting StormW:


Levi,
you wasn't sposed to let our secret out!

Ok Dont mean to sound like a newbie but where exactly is the SW Atlantic?
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There's certainly enough heat in the water.

At what point do the westerlies start kicking in in the GOM - like where they shot Wilma east off the Yucatan Pen.? Is that in Oct?
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1444. MZT
Quoting Max1023:


White donut of doom usually means a 135-140 knot system. The eye just needs to clear out a little more on IR. If I see a grey donut of doom I will probably s**t my pants, that means a 155 knot system in most cases.
Have to admit I've always had trouble making sense of the Dvorak images. This boils it down to it's essentials. Heh
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Convective burst in the SE eyewall:



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Quoting doorman79:


Yes, I must say Levi is one intelligent young man.
+1
Plus well-spoken and well-mannered.
You've got a bright future Levi.
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1441. xcool
MiamiHurrican .1964 years too
Member Since: September 26, 2009 Posts: 2 Comments: 15603
No-name hurricane
Quoting KanKunKid:
First it was cheesecake, now donuts.

I'll be back. Tracking Igor is gonna be hard on my diet!
well kid, hate to admit it,but you made and old man laugh...
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Quoting Max1023:


White donut of doom usually means a 135-140 knot system. The eye just needs to clear out a little more on IR. If I see a grey donut of doom I will probably s**t my pants, that means a 155 knot system in most cases.
Huh? What are these donuts you're speaking about? Lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Brownsville NWS Afternoon Forecast Discussion

THE REST OF THE FORECAST PERIOD WILL DEPEND ON THE STRENGTH OF THE
RIDGE AND THE AREA OF DISTURBED WEATHER OVER THE CENTRAL CARIBBEAN
SEA MOVING INTO THE WESTERN CARIBBEAN SEA TUESDAY. WHETHER THE
BROAD AREA OF LOW PRESSURE DEVELOPS INTO A TROPICAL
CYCLONE...ABUNDANT TROPICAL MOISTURE SHOULD MOVE WESTWARD ACROSS
THE YUCATAN PENINSULA WEDNESDAY INTO THE BAY OF CAMECHE AND
SOUTHWEST GULF OF MEXICO THURSDAY. WILL CONTINUE TO MENTION A
SLIGHT CHANCE TO CHANCE OF SHOWERS AND THUNDERSTORMS TUESDAY INTO
WEDNESDAY MAINLY FOR SEABREEZE CONVECTION IN THE AFTERNOON. WILL
NOT MENTION RAIN CHANCES THURSDAY AS SOME SUBSIDENCE SHOULD
DEVELOP ACROSS THE NORTHWEST GULF OF MEXICO BEFORE A POSSIBLE
TROPICAL DEPRESSION OR STORM MOVES TOWARDS THE MEXICAN COAST
FRIDAY. ALL INTERESTS IN THE WESTERN GULF OF MEXICO SHOULD REMAIN
VIGILANT OF A TROPICAL SYSTEM DEVELOPING THE NEXT COUPLE OF DAYS AND
MOVING WESTWARD INTO THE AREA TOWARDS THE END OF THE WEEK. WILL GO
AHEAD AND MENTION AT LEAST A CHANCE OF RAIN FRIDAY INTO THE
WEEKEND WITH LOW TO MID LEVEL MOISTURE INCREASING ACROSS NORTHEAST
MEXICO AND DEEP SOUTH TX LATE THURSDAY INTO EARLY FRIDAY.

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1437. Max1023
Quoting RecordSeason:
White donut of doom complete.

Gray donut of doom forming...



Yeah...




Definitely at least 5 to 10mph stronger than the advisory. I might even say 15mph stronger...


White donut of doom usually means a 135-140 knot system. The eye just needs to clear out a little more on IR. If I see a grey donut of doom I will probably s**t my pants, that means a 155 knot system in most cases.
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Quoting MiamiHurricanes09:

Looking at the crossed eyed eye I might dare sat he is annular, and sorry to bring this up but another famous storm was around this position around this time frame and became annular, she became VA's costliest natural disaster ever
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On the models and accuracy:

Seems to me nobody's arguing the 72hrs out... pple are basically ignoring that in their discussions of model accuracy. Does this mean we are taking that level of accuracy for granted these days? With a storm like Igor that 3 day forecast seems almost a "given".

The big argument here is always nowadays about the 4 - 7 [or even 6 - 10] day forecast. The big divergence with Igor is coming AFTER we enter the 4-day forecast range. Since not even NHC reposes much faith in their track errors at that point [500 miles is the difference between Mayaguana and Abaco, almost the entire length of the Bahamas, in fact] I dunno why we are even arguing about it. I agree with StormW and others like him who are looking at the WV for the last 12 hrs and observing realtime trends. I think we get a better idea of what could happen past that 3-day forecast period. For example, what's to see on the WV loop for the CONUS today? Anything out there to add oomph to the trough which will likely turn Igor NW, but may not be enough to recurve it fully before 70W?

And for those of u who think we "don't need to worry" and that because Earl paralleled the Bahamas far enough east to minimize effects here we should not pay attention to Igor, get this: every, EVERY system is different. The storm itself is different. The synoptic pattern is different, and even small differences in either can result in track differences that currently allow for potential impacts to locations from the NE Antilles/PR to Nova Scotia. WE ARE TOO FAR OUT FROM A RELIABLE FORECAST RIGHT NOW for anybody to be "ruling out" potentialities beyond that.
Member Since: October 25, 2005 Posts: 19 Comments: 20686
Quoting xcool:
storms going start developing in Caribbean & gom.Cape Verde season come to end jmo
Yup, that's when systems similar to Wilma and Rita start to develop. Unfortunately, a system similar to Wilma could very well happen in the western Caribbean if upper level conditions are perfect.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting BenBIogger:


This was yesterdays 12z CMC Ensemble RUN. It had it knocking on your door.

264hrs (Long-Range)



I realize this is extremely long range, I cant find a loop on the web, where is that system over Tampa coming from?
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Quoting RecordSeason:
White donut of doom complete.

Gray donut of doom forming...



Yeah...




Definitely at least 5 to 10mph stronger than the advisory. I might even say 15mph stronger...


Whaat? You mean 145 to 150 mph by 5 PM? Igor is nuts I tell you! This is an awesome storm, and will stay awesome as long as it doesn't bother land or shipping interests.
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Quoting NCHurricane2009:


LOL, I tell you what, Levi is pretty good at pointing out the trends ahead. Back when things were quiet (before Danielle), Levi talked about the switch over to a pattern favoring a Cape Verde outbreak, and here we are, Danielle, Earl, Fiona, Gaston, Igor, TD 12...

Good job Levi!


Yes, I must say Levi is one intelligent young man.
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1428. xcool
storms going start developing in Caribbean & gom.Cape Verde season come to end jmo
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting Cantu5977:
Corpus Christi NWS Afternoon Forecast Discussion

ATTENTION THEN
SHIFTS TO THE BAY OF CAMPECHE AS A DISTURBANCE CURRENTLY OVER THE
CENTRAL CARIBBEAN MOVES WEST NORTHWEST. THE LONG TERM FORECAST RIDES
HEAVILY ON THE EVENTUAL EVOLUTION OF THE DISTURBANCE. THE MODELS ARE
HINTING NOW THAT THE RIDGE MAY WEAKEN ACROSS THE WESTERN GULF OF
MEXICO BRIEFLY AND ALLOW THE DISTURBANCE TO GAIN A LITTLE BIT OF
LATITUDE. THE GFS KEEPS THE DISTURBANCE AS AN OPEN WAVE WHILE THE
ECMWF DEVELOPS IT INTO A TROPICAL CYCLONE. THEY BOTH MOVE THE
DISTURBANCE TOWARDS CENTRAL/NORTHERN MEXICO. THEREFORE...BUMPED UP
POPS TO CHANCE FOR THE WEEKEND ACROSS THE COASTAL PLAINS AND
SOUTHERN CWA AND HAVE SLIGHT CHANCE POPS ELSEWHERE. TEMPS WILL
REMAIN AT OR ABOVE AVERAGE FOR THE EXTENDED.



Ugghh! Enough already, the Bay of Campeche, Texas/Mexico have had enough this year! Alex, TD 2, Hermine. Yuck.
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I don't see why Igor would stop intensifying now I think 150mph by 5 and 160 by 11 he already looks like Celia from the E-pac
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Igor

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Quoting StormW:


Levi,
you wasn't sposed to let our secret out!


LOL, I tell you what, Levi is pretty good at pointing out the trends ahead. Back when things were quiet (before Danielle), Levi talked about the switch over to a pattern favoring a Cape Verde outbreak, and here we are, Danielle, Earl, Fiona, Gaston, Igor, TD 12...

Good job Levi!
Member Since: Posts: Comments:
Corpus Christi NWS Afternoon Forecast Discussion

ATTENTION THEN
SHIFTS TO THE BAY OF CAMPECHE AS A DISTURBANCE CURRENTLY OVER THE
CENTRAL CARIBBEAN MOVES WEST NORTHWEST. THE LONG TERM FORECAST RIDES
HEAVILY ON THE EVENTUAL EVOLUTION OF THE DISTURBANCE. THE MODELS ARE
HINTING NOW THAT THE RIDGE MAY WEAKEN ACROSS THE WESTERN GULF OF
MEXICO BRIEFLY AND ALLOW THE DISTURBANCE TO GAIN A LITTLE BIT OF
LATITUDE. THE GFS KEEPS THE DISTURBANCE AS AN OPEN WAVE WHILE THE
ECMWF DEVELOPS IT INTO A TROPICAL CYCLONE. THEY BOTH MOVE THE
DISTURBANCE TOWARDS CENTRAL/NORTHERN MEXICO. THEREFORE...BUMPED UP
POPS TO CHANCE FOR THE WEEKEND ACROSS THE COASTAL PLAINS AND
SOUTHERN CWA AND HAVE SLIGHT CHANCE POPS ELSEWHERE. TEMPS WILL
REMAIN AT OR ABOVE AVERAGE FOR THE EXTENDED.

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Quoting Cantu5977:


But then he will become more mad lol

Then he might crash the mash!!!
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If the NHC goes with the ADT again it is possible they will raise it to 145 mph.

CI# /Pressure/ Vmax
6.4 / 939.6mb/124.6kt


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92L

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Quoting StormW:
Back in a while.

Someone tell Igor, he's not invited to the Monster Mash.


But then he will become more mad lol
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Quoting Max1023:


He needs to get above 18N, he is still at 17.7.


Yep, Igor's been chugging along straight west at 17.7N for the last few advisories. I think Igor won't start to gain latitude until it gets just west of 50W.
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Quoting angiest:
Sincve becoming a tropical storm again on the 10th, Igor has been pretty well on that forecast track with only minor deviations.
Quoting Stormchaser2007:


Quoting Levi32:
I still believe recurvature east of the US is more likely than a landfall, but I am going to point out all of the possibilities that could lead to a landfall so that people are aware of them in case they actually do happen. The JMA isn't completely wacko in that it makes meteorological sense, but so do the other models (not the GFS though lol).

Reasonable possibilities are fine..
The GFS has done well.
Excellent job with Colin, Danille
Earl was not so hot until after it passed by the islands
Ecellent job with not redeveloping Gaston and no while 92L has possibilities it's not developed yet either..

Lets see where Igor crosses 20N GFS is now saying about 56W
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1412. Max1023
On IR there are 2 meso-vortices in the eyewall.
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An intensity of 120kt (140mph) is what I'm expecting at 5pm EDT.

Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting kimoskee:


IGOR!!! Go to your room!!!
And don't take all the cookies with you!
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1405. Levi32
While Igor is stealing the show, the pattern will be turning towards one that is favorable for the SW Atlantic Basin to light up during the end of September, and we're starting to see results and hints from some of the models. The CMC is consistently showing very low pressures in the Caribbean and GOM in 15 days, and the GFS operational and ensemble mean has been saying there should be a hurricane hitting the US in 2 weeks or so.

Just hints of things to come, and support for the idea that the SW Atlantic will start picking up the slack and take the torch as the Cape Verde season winds down.

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1404. MZT
TD12, followed by another large storm about to roll off from Africa:
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Quoting stormpetrol:
If I was in the Bahamas , I'd watch Igor very closely, jmo.
I am in the Bahamas, and I am most certainly watching. Still not nixing the idea of a NW turn before 65, but not seeing it as automatically happening either.

Member Since: October 25, 2005 Posts: 19 Comments: 20686
1402. Max1023
Igor already looks better overall than earl did as a 928mb cyclone. If I were the NHC I would get a G4 in front of it right away, something this strong NEEDS to have the best data possible, as anything it hits is pretty much toast.
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1401. xcool
btwntx08 lol
Member Since: September 26, 2009 Posts: 2 Comments: 15603
Quoting cknltl:
Pimples... A rapid growth spurt... Why won't Igor just go to his room and slam the door like every other growing boy with a temper?


IGOR!!! Go to your room!!!
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Quoting muddertracker:
For the first time since 92l was named, I am actually seeing some visible rotation. Let's hope that high in the gulf holds. Some parts of Texas do not need anymore rain...

Yeah. I'm also seeing a nice rotation.
Member Since: August 9, 2009 Posts: 10 Comments: 4498
1397. WxLogic
Quoting StormW:


Just sayin?


LOL just saying... nothing to add unless I'm wrong on an observation.
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12 hr out



24 hr out



36 hr out



48 hr out

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About JeffMasters

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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