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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Quoting weatherman12345:

going back to negative

Is negative favorable for development? what is this chart by the way?
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1021. will40
Link

new circle
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Igor will probably be a hurricane at 11. Eye feature visible.



Core has tightened up considerably.
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This time in 2005, we we're monitoring Ophelia.

Ophelia was the 15th named storm of the season, we're approaching our 12th. As you can see, we're not that far behind.

I remember Ophelia...Rain-maker.
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1018. Dakster
Stormw - How's everything on the west coast (of Florida)?
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I see the NHC mentioned the area I was talking about a little earlier...likely that no development will come of it before it gets absorbed, but ya' never know.



Well, Canes lost, bleh. Out till' later.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting hurricanehunter27:
Poll Time:
When will Igor become a hurricane?

A: Tonight

B: Tommorow Morning

C: Tommorow afternoon

D: Moday

B
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1014. markot
storm have dynamic models turned more to the left......
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Quoting StormW:
18Z STATISTICAL MODELS


18Z DYNAMIC MODELS


is this time..its going to make a left and then a sharp right...usa is in it target
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1012. will40
Quoting StormW:
18Z STATISTICAL MODELS


18Z DYNAMIC MODELS


good cluster StormW
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1010. xcool
td 92l getting ready
Member Since: September 26, 2009 Posts: 2 Comments: 15618
Quoting blsealevel:
This takes Igor to Cat 4 for a couple days and then back to a Cat 2 with a bad turn to the West???



so....a bad turn to the west...soooo is this the one that hits sfla in a week
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92 seems to be a slow to form like Alex but when it does look out!!!
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000
ABNT20 KNHC 112331
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SAT SEP 11 2010

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM IGOR...LOCATED ABOUT 1140 MILES WEST OF THE CAPE VERDE
ISLANDS.

SHOWERS AND THUNDERSTORMS HAVE DECREASED IN ASSOCIATION WITH A
BROAD AREA OF LOW PRESSURE LOCATED OVER THE EAST-CENTRAL CARIBBEAN
SEA. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION COULD FORM
DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD INTO THE
CENTRAL AND WESTERN CARIBBEAN SEA. THERE IS A HIGH CHANCE...60
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL
IS POSSIBLE IN THE NORTHERN LEEWARD ISLANDS...PUERTO RICO...THE
VIRGIN ISLANDS...AND HISPANIOLA DURING THE NEXT DAY OR SO. THESE
RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD
SLIDES...ESPECIALLY IN MOUNTAINOUS TERRAIN.

SATELLITE IMAGERY INDICATES THAT SHOWER AND THUNDERSTORMS ASSOCIATED
WITH A VIGOROUS TROPICAL WAVE AND ASSOCIATED LOW PRESSURE ABOUT 400
MILES EAST-SOUTHEAST OF THE CAPE VERDE ISLANDS ARE GRADUALLY
BECOMING BETTER ORGANIZED. IF CURRENT TRENDS CONTINUE...A TROPICAL
DEPRESSION COULD FORM DURING THE NEXT DAY OR TWO AS THIS SYSTEM
MOVES TOWARD THE WEST-NORTHWEST AT 10 TO 15 MPH. THERE IS A HIGH
CHANCE...70 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS.

SHOWERS ACTIVITY HAS DEVELOPED IN ASSOCIATION WITH A WEAK LOW
PRESSURE SYSTEM LOCATED ABOUT 900 MILES EAST OF BERMUDA.
DEVELOPMENT OF THIS SYSTEM APPEARS UNLIKELY BEFORE IT IS ABSORBED
BY A FRONTAL SYSTEM. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

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

$$
FORECASTER KIMBERLAIN/BEVEN
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92L: 60%

93L: 70%

Ex-99L: 10%
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Quoting Tazmanian:
975. anyotherliestotell 4:13 PM PDT on September 11, 2010 Hide this comment.
looks like the pattern change emerged. now storms are going ever FURTHER east and out to sea away from land.
Action: Quote | Ignore User


poof


He forgot to say LOL!

Hey Taz!
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Quote..."The "ignore user" button is a wonderful thing. You should try it out on Jason. I did and it has improved my WU experience 100x!"


Amen to that!
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Quoting LoneStarWeather:
Quoting jason2010xxxx:
TROPICAL STORM IGOR big fish storm

The "ignore user" button is a wonderful thing. You should try it out on Jason. I did and it has improved my WU experience 100x!


Ha Ha-- I did not know he was even still around until someone quoted him. lol Does he still go on and on like he used to? I am so glad I put him on poof a month ago. :) Believe it or not, he is the only one on my ignore list. That is how big of an improvement it was. I can deal with everyone else.
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Quoting weatherman12345:
POLL TIME
93L off the coast of africa
8:00PM TWO

A. 50%
B. 60%
C. 70%
D. 80%
E. 90%


One of those two.
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stormpetrol, I agree surface circulation appears to be near there, maybe 14.7n and 68w.
Member Since: October 21, 2008 Posts: 243 Comments: 3608
Quoting blsealevel:
This takes Igor to Cat 4 for a couple days and then back to a Cat 2 with a bad turn to the West???




Say it isn't so .
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Quoting hydrus:
The 1935 Labor Day Storm(technically)probably holds that record. I Dunno.


You may very well be correct. Lol. Well the blog has been dining on my posts. So I guess I'll take a break and fix me dinner. :) BBL Y'all.
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This takes Igor to Cat 4 for a couple days and then back to a Cat 2 with a bad turn to the West???

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92L is struggling and does not look to become a depression for the next 24 hours. The 850mb vorticity is not impressive and shows no signs of a surface circulation. With the lack of surface convergence and strong upper level divergence this system will struggle with the normal convective DMIN and DMAX cycles. This system is simply being aided by the normal cycles of the DMIN and DMAX and no sustained signs of surface circulation. It appears south of Puerto Rico convection and the overall pattern appears to suggest a possible upswing to the development of a surface circulation, however I expect a depression to begin to form tonight and not become one until 5pm EDT tomorrow.
Member Since: October 21, 2008 Posts: 243 Comments: 3608
dont feed him Taz thats exactly what he is looking
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Quoting PELLSPROG:


Just like you would be if it happened to your team . Bangs fist on desk !!


I hear you... Disappointed myself.
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Quoting anyotherliestotell:


Hmm, let me try the ignore button out on you and see if your hypothesis is sound. Yep! Success.
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On the last few visible loops RGB i see a hint of possible circulation developing near 14.5N/67.5W.Anyway by tomorrow morning we should have a better idea, wouldn't be surprised to see 92L lowered to 40-50% and 93L upped to 60% JMO.
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Quoting largeeyes:


LOL. The only Hurricane that looks impressive is the one in the ocean.....


What Hurricane ?
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If 92l's mlc can work to the surface,we should see some quick development tomorrow night
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Quoting RufusBaker:
92 is retarded the carribean is HOT it the peak of the season but yet it is fizzing like a egg on hot pavement
...,because the blow up this morning was in the mid levels,aided by ridging aloft,give it time a closed surface low should form in the next 24hrs,patience young jedi....
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Quoting PELLSPROG:


shut up
lol..A little touchy are we...:)
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Quoting AtHomeInTX:


I think she was the strongest ever in the gulf pressure wise. Or I could be wrong. :)
The 1935 Labor Day Storm(technically)probably holds that record. I Dunno.
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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.