Potentially dangerous 92L steadily developing; Igor nears hurricane strength

By: Dr. Jeff Masters , 3:04 PM GMT on September 11, 2010

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A tropical disturbance (92L) over the Eastern Caribbean, a few hundred miles south of Puerto Rico, is steadily organizing and appears likely to develop into a tropical depression by tonight or Sunday morning. Satellite loops show an impressive and expanding region of heavy thunderstorms, with good spiral banding and respectable upper-level outflow on all sides. Long range radar out of Puerto Rico shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. However, the rain bands are becoming more intense and more organized. San Juan, Puerto Rico reported a heavy rain squall at 8:44 am this morning, and radar estimates suggest two inches of rain fell in this squall just southeast of San Juan. Wind shear over 92L is low, 5 - 10 knots. The waters beneath are at near-record warmth, 30°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-northwest at 11 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 Mexico's Yucatan Peninsula on Wednesday. The HWRF model has a more northwesterly track, taking 92L over the Dominican Republic, Haiti, and Cuba, but this model has been trending too far north in its tracks. I expect 92L will follow a path south of the islands, bringing it near or just south of Jamaica on Monday, then into the Yucatan Peninsula on Wednesday. On this track, the southern Dominican Republic can expect heavy rains of 3 - 6 inches tonight through Monday morning; southern Haiti can expect similar rains Sunday through Monday, and Jamaica and the Cayman Islands can expect heavier rains of 4 - 8 inches Monday and Tuesday. Eastern Cuba will probably escape 92L's heaviest rains in this scenario (Figure 2.)

Intensity forecast for 92L
I can't find any reason to doubt this will be a tropical storm by Sunday or Monday, and potentially a Category 1 or 2 hurricane by Wednesday, if 92L avoids passage over Hispaniola and Cuba. The SHIPS model predicts wind shear will remain low, 5 - 10 knots, through the period, and makes 92L a Category 1 hurricane by Monday night. 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. The first Air Force Hurricane Hunter mission into 92L is scheduled for Sunday afternoon, but there will be a research mission by the National Center for Atmospheric Research G-V jet today that will give us valuable information on 92L's large scale environment and potential for development.


Figure 2. Forecast rain amounts from 92L from the 2am EDT Saturday run of the GFDL model. This model predicts most of 92L's heaviest rains will miss Haiti, but will affect Jamaica, the Cayman Islands, and the Yucatan Peninsula. Image credit: Morris Bender, NOAA/GFDL.

Igor
Tropical Storm Igor is very close to hurricane strength, and appears destined to become a large and powerful major hurricane over the Central Atlantic in the days to come. Wind shear is moderate, 15 - 20 knots, waters are warm, 28°C, and Igor has moistened its environment enough to keep the dry air of the Saharan Air Layer (SAL) at bay. Igor will track west under the influence of a strong ridge of high pressure for the next three days, then turn more to the west-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 has a slight chance of making landfall on the U.S. East Coast or Canada. Climatology shows that about 10% 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 5% for Canada. The forecast steering pattern for the coming two weeks from the GFS model 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. The odds of Igor hitting land in the U.S. or Canada are probably close to their climatological 10% and 5% probabilities, respectively.

Elsewhere in the tropics
A new tropical wave (Invest 93L) emerged from the coast of Africa yesterday, and is already showing signs of organization. Most of the models predict 93L will develop into a tropical depression 2 - 4 days from now, and NHC is giving 93L a 30% chance of developing by Monday.

Next post
This may be my only post today; I'll have a new post Sunday morning.

Jeff Masters

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2273. 1965
Quoting StormW:


Best I can make is, 15.0N;70.4W


I'd that is spot on. NOAA buoy at 15n/67.5w clearly shows the passage of the weak COC overnight.


°
09 12 6:50 am S 9.7 13.6 3.9 6 4.5 - 29.77 +0.01 83.5 86.4 76.1 - - -
09 12 5:50 am SSE 13.6 15.5 3.6 7 4.5 - 29.75 -0.02 84.2 86.4 76.6 - - -
09 12 4:50 am SE 11.7 13.6 3.3 6 4.7 - 29.75 -0.05 84.2 86.4 75.7 - - -
09 12 3:50 am SSE 9.7 13.6 3.3 6 4.9 - 29.76 -0.06 84.0 86.4 76.3 - - -
09 12 2:50 am SE 7.8 9.7 3.3 7 4.8 - 29.78 -0.05 83.8 86.5 76.1 - - -
09 12 1:50 am ESE 7.8 9.7 3.3 7 4.8 - 29.80 -0.01 84.0 86.5 75.4 - - -
09 12 12:50 am E 5.8 7.8 3.0 7 4.5 - 29.82 +0.03 84.0 86.5 75.4 - - -
09 11 11:50 pm E 9.7 11.7 3.6 7 4.6 - 29.83 +0.04 84.4 86.5 75.4 - - -
09 11 10:50 pm E 9.7 11.7 3.3 7 4.7 - 29.81 +0.02 84.4 86.5 75.4 - - -
09 11 9:50 pm ENE 11.7 13.6 3.3 7 4.3 - 29.79 +0.02 84.0 86.5 76.3 - - -
09 11 8:50 pm E 9.7 11.7 3.9 6 4.4 - 29.79 +0.01 84.0 86.5 75.6 - - -
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typical east-west flow acroos the atlantic basin. there are no indication just yet from the advancing clouds from Igor that a turn to the north is imminent. would be quite interesting if that turn before 50W does not verify
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2271. IKE
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN SEP 12 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE
IGOR...LOCATED ABOUT 1230 MILES EAST OF THE NORTHERN LEEWARD
ISLANDS.

SHOWERS AND THUNDERSTORMS REMAIN DISORGANIZED IN ASSOCIATION WITH A
BROAD AREA OF LOW PRESSURE LOCATED OVER THE EAST-CENTRAL CARIBBEAN
SEA. ENVIRONMENTAL CONDITIONS STILL APPEAR FAVORABLE FOR GRADUAL
DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION COULD FORM
DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 10 TO 15
MPH. THERE IS A MEDIUM CHANCE...50 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. REGARDLESS
OF DEVELOPMENT...LOCALLY HEAVY RAINFALL IS POSSIBLE IN THE VIRGIN
ISLANDS...PUERTO RICO...HISPANIOLA...JAMAICA AND CUBA DURING THE
NEXT DAY OR TWO. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH
FLOODS AND MUD SLIDES...ESPECIALLY IN MOUNTAINOUS TERRAIN.

SATELLITE DATA INDICATE THAT THE AREA OF LOW PRESSURE LOCATED ABOUT
315 MILES EAST-SOUTHEAST OF THE SOUTHERNMOST CAPE VERDE ISLANDS HAS
CONTINUED TO BECOME BETTER ORGANIZED...AND A TROPICAL DEPRESSION
APPEARS TO BE FORMING. IF CURRENT TRENDS CONTINUE...ADVISORIES
WILL BE INITIATED LATER THIS MORNING...AND WATCHES OR WARNINGS WILL
LIKELY BE REQUIRED FOR PORTIONS OF THE CAPE VERDE ISLANDS. THERE
IS A HIGH CHANCE...NEAR 100 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES GENERALLY
WESTWARD AT 10 TO 15 MPH.

A WEAK AREA OF LOW PRESSURE LOCATED ABOUT 900 MILES EAST-NORTHEAST
OF BERMUDA CONTINUES TO PRODUCE DISORGANIZED SHOWER ACTIVITY.
DEVELOPMENT OF THIS SYSTEM APPEARS UNLIKELY BEFORE IT IS ABSORBED
BY A FRONTAL SYSTEM IN THE NEXT DAY OR SO. THERE IS A LOW CHANCE
...10 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES NORTHWARD AT 20 TO 25 MPH.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BRENNAN
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2270. surfmom
Quoting scott39:
Looks like a big red Ant.
Hummm I thought an Acne pustule, reaches a head and then splat
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Early on Sunday morning, couple o' trivia questions:

Anyone wanna guess when the last time we had a season that had all of its storm above 1 in ACE?

Harder one: From 1875 (when storm records became a little bit more complete), when was the first time there was a storm below 0.5000 in ACE?
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Wow, looks like he has a nice eye and eyewall.
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2267. ackee
looks like 92L centre is comeing under the convection there are even warmer water south of Hait that where TD or karl could rapidly spin up we see
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2266. QMiami
igor trucking west and 92L pulsing up again

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Quoting tornadolarkin:
Is this something to be concerned about?


Hope not....does seem like one of the models last week was trying to develop something in BOC or off Yukatan though
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2264. scott39
Quoting clwstmchasr:


I was just looking at the IR Channel 2 loop and the circulation looks really good and it may have tucked under the SW corner of the convection to the NE.
It loos like 92L just might want to develope. I think the % will go up, if the convection keeps up.
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Is this something to be concerned about?
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2262. scott39
Quoting StormW:


Best I can make is, 15.0N;70.4W
Thanks
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Igor looks good this morning.
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Quoting traumaboyy:


morning Kori!


Good morning!
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2257. QMiami
morning Igor

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2256. scott39
StormW post 2247?
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Quoting KoritheMan:


Yep.


morning Kori!
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2254. scott39
Quoting StormW:



The higher height anomaly expanding over the Atlantic should keep things a little further south before they get a chance to re-curve

6-10 day forecast


1-5 day forecast
Thanks, Ive seen those maps before and wondered what they meant. That will help me understand in the future.
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Quoting BDADUDE:
Will Igor cause Bermuda any problems in the coming days?


Quite possibly. Watch it carefully.
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2252. BDADUDE
Will Igor cause Bermuda any problems in the coming days?
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Quoting barotropic:


It appears that the troughs continue to exit off the EC, providing a mechanism for recurvature. Home grown systems probably stand a better shot at conus strikes.


Yep.
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2250. WxLogic
Good morning...
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Quoting clwstmchasr:


I was just messing around. The thing about weather is that it is going to change. Climatology will be sure of that.


It appears that the troughs continue to exit off the EC, providing a mechanism for recurvature. Home grown systems probably stand a better shot at conus strikes.
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2247. scott39
Quoting clwstmchasr:


I was just messing around. The thing about weather is that it is going to change. Climatology will be sure of that.
I know you were. I wonder if the COC has slipped to the NE of 92L, under that big ball of convection?
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2246. teammc
Good morning StormW
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Off to do a radio show. TTYL...
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2243. scott39
Quoting clwstmchasr:


This will make it 1001 times.
Well maybe some other people missed it too.
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ah yai yai,its about to get crazy on here some people smoking whaco weed!!!! LOL
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Good Morning Chief!!
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2239. scott39
StormW, Iknow you have probably already explained this 1000 times but I missed it. What is going to make the current weather pattern change in reference to TCs current steering and direction?
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Quoting F4PHANTOM:
any particular seasons come to your mind?
2005 could be one.
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...or a wabbit.



back to the sack with coffee,homework and maybe a nap.
wonder if today will be its day. sure looks like it now.
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Quoting Cotillion:
The more I read this blog, the more I'm perplexed by the culture and passion of college football.


Sorry....my Alma mater is in Pain....did not mean to get off track!!
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Quoting Chicklit:
good morning, 92L fired up this morning.



He's just mad he couldn't develop yesterday. :)
Good Morning.
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Quoting Chicklit:
good morning, 92L fired up this morning.




Good morning. 92L looks like the Eye of Isis. lol
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2233. scott39
Quoting Chicklit:
good morning, 92L fired up this morning.


Looks like a big red Ant.
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Quoting Cotillion:


Opal? The African Wave is going to teleport into the GoM? That's some trick right there...

(I assume if you mean '95, you're thinking Felix or Luis?)


Aargh! I meant Noel, actually, and not Opal (I was checking on the former but became engrossed with the latter). Fixed. Thanks...
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good morning, 92L fired up this morning.


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Quoting Neapolitan:


You know, I don't think I've ever used the 'f' and the 'd' words here--other than in parody--so I don't think I'll start that now; I'll leave that to, uh, others. ;-) Anyway, 93L/Julia appears set to pull a '95 Opal kind of path, though even farther east than that storm. Igor looks to possibly follow Colin's path (while being much stronger, of course). 92L/Karl seems to be the biggest threat to land somewhere...

Yikes! Bermuda's gonna get whacked this year!
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The more I read this blog, the more I'm perplexed by the culture and passion of college football.
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.
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2227. scott39
Quoting DestinJeff:


what is this, Pin the Track on the Blogger?
The "Who" is 92Ls-7 Greats- Grandfather. OK-- thats all the hints you get. It is pretty tough to figure out though.
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Quoting Neapolitan:


You know, I don't think I've ever used the 'f' and the 'd' words here--other than in parody--so I don't think I'll start that now; I'll leave that to, uh, others. ;-) Anyway, 93L/Julia appears set to pull a '95 Opal kind of path, though even farther east than that storm. Igor looks to possibly follow Colin's path (while being much stronger, of course). 92L/Karl seems to be the biggest threat to land somewhere...


Opal? The African Wave is going to teleport into the GoM? That's some trick right there...

(I assume if you mean '95, you're thinking Felix or Luis?)

Edit: Or Noel, sure.
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2225. surfmom
2195 Neapolitan - nice review! much be great coffee
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Quoting scott39:
The TIDE will roll far inland, long after Hurricane Season is over!!


yes and wash my garnet and gold pain back into the GOMEX!!
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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.