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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Good morning. And Good morning, Igor.
Member Since: Posts: Comments:
Quoting scott39:
Yea me too, with all this talk of a late busy season! Central/N Gulf Coast needs a break for about a decade. Its had its fair share for the last 15 years!


Well... The Gulf Coast might get a little bit of a break. It depends on the patterns.

However, if this next 10-15 years is similar to the 1950s, then the Gulf Coast will have a bit of a reprieve compared to the previous 10-15 years. It will still get hit, no doubt.

But, you look at the records for that decade. North Carolina got hit more than Texas, Mississippi, Alabama, and Louisiana combined. In fact, Maine had the same amount of hurricanes Louisiana did (NB: LA still had to deal with Audrey, a most vicious storm).

North Carolina got even more hurricane hits than Florida during the '50s.

Not to say all storms will love NC this next decade. History repeats itself, yes, but usually not in *exactly* the same way.

Plus, it's all based on a huge *if* - *if* these next few years are like the 50s.
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2171. scott39
Quoting traumaboyy:


LOL!!.....Hope northern GOMEX remains inhospitable till Christmas myself!!
Yea me too, with all this talk of a late busy season! Central/N Gulf Coast needs a break for about a decade. Its had its fair share for the last 15 years!
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Quoting scott39:
I think TD5 finally figured out that the N GOM is a brutal to TCs this season. So it is over Africa right now and going to try for it again Hoping for conditions to be in its favor this time! You know Mother Nature has to believe in recycling! LOL


LOL!!.....Hope northern GOMEX remains inhospitable till Christmas myself!!
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2169. scott39
Quoting traumaboyy:


They don't die....Former TD 5 still ready to move off into GOMEX and go after NOLA!!
I think TD5 finally figured out that the N GOM is a brutal to TCs this season. So it is over Africa right now and going to try for it again Hoping for conditions to be in its favor this time! You know Mother Nature has to believe in recycling! LOL
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Quoting Cotillion:


All spawn of Karen...


lol
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Quoting traumaboyy:


They don't die....Former TD 5 still ready to move off into GOMEX and go after NOLA!!


All spawn of Karen...
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Quoting scott39:
LOL, Yea I wonder if they ever "really" die!!


They don't die....Former TD 5 still ready to move off into GOMEX and go after NOLA!!
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2164. scott39
Quoting Cotillion:


Oh, Gaston's not dead. He's circling the globe to come back for a second try. Maybe by Hawaii now...

(I think he blew himself apart on Hispaniola, so around 70W or so. Not entirely sure, though).
LOL, Yea I wonder if they ever "really" die!!
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Quoting Cotillion:


It's looking like it might pass very close to Praia.



ok, thanks
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Quoting scott39:
What longitude did Gaston FINALLY die at?


Oh, Gaston's not dead. He's circling the globe to come back for a second try. Maybe by Hawaii now...

(I think he blew himself apart on Hispaniola, so around 70W or so. Not entirely sure, though).
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2161. scott39
Although 92L does look better than Gaston did at this same area.
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2160. scott39
Quoting Cotillion:
It wouldn't surprise me if it doesn't develop properly until past 75W. If it does actually develop.
What longitude did Gaston FINALLY die at?
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It wouldn't surprise me if it doesn't develop properly until past 75W. If it does actually develop.
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2157. scott39
Another pattern Ive noticed besides track, is that TCs really dont get going in developement unless they are in far Western Carribean/BOC-Alex, Hermine-BOC/SWestern GOM and the ones that have developed off of Africa. It looks like so far most of the Carribean is off limits and so is the SE GOM and N GOM for further developement if one enters these areas. In fact it finishes them off! I know things will probably change. We will see.
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2156. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15618
Quoting HurrikanEB:
coming out of lurking to ask a question
if 93L gets named/numbered today how close will it likely pass to CV? Closer than earl, to the south, west?


It's looking like it might pass very close to Praia.
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coming out of lurking to ask a question
if 93L gets named/numbered today how close will it likely pass to CV? Closer than earl, to the south, west?
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That area is known for suppressing development due to fast trade winds. I don't think any land interaction would be an issue. Bit of dry air on the fringes. Give it time, see what it does over the next couple of days.

Just because a storm can, doesn't mean that it will...
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2150. xcool
monsoonal good things
Member Since: September 26, 2009 Posts: 2 Comments: 15618
2148. scott39
I was thinking dry air is the fly in the ointment for some of these invests. They start out looking like thier going to do something and then fizzle out. I dont think 92L is going to do much if it doesnt develope in the next 48 hours.
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Quoting btwntx08:
???? again this is monsoonal type develop remember they take time and no the conditions are fine also it has a closed llc but needs to tighten up


is that the same junk that was happening to the early season storms/rainmakers??
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2146. xcool
come on now noo one down player 92l lol
Member Since: September 26, 2009 Posts: 2 Comments: 15618
Quoting Cotillion:
Good morning.

I see Igor has become a hurricane.


Morning Sir!
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2142. xcool
scott39 i'm not sure but need some more CONVECTION
Member Since: September 26, 2009 Posts: 2 Comments: 15618
2141. scott39
Xcool whats wrong with 92L? Looks like conditions are ripe for developement?
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2140. xcool
oh wow poor 92l
Member Since: September 26, 2009 Posts: 2 Comments: 15618
2138. xcool
cowboyz at 8pm lol
Member Since: September 26, 2009 Posts: 2 Comments: 15618
2137. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15618
5:00 AM AST Sun Sep 12
Location: 17.7°N 44.4°W
Max sustained: 80 mph
Moving: W at 18 mph
Min pressure: 988 mb
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2135. xcool
yeah cat 1 going too cat 3 ;)~!!!!1
Member Since: September 26, 2009 Posts: 2 Comments: 15618
2133. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15618
2132. xcool


going to positive
Member Since: September 26, 2009 Posts: 2 Comments: 15618
Good morning.

I see Igor has become a hurricane.
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Quoting AtHomeInTX:
Ok I started out tonight young but 92l finally done me in. Night you whipper snappers. SmileyCentral.com


good night young lady
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2129. xcool
AtHomeInTX lolol
Member Since: September 26, 2009 Posts: 2 Comments: 15618
within a degree if you add the lat/long key word"around"
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Ok I started out tonight young but 92l finally done me in. Night you whipper snappers. SmileyCentral.com
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2125. xcool

Member Since: September 26, 2009 Posts: 2 Comments: 15618
I think 92L finally has a closed low, possibly around 14.5N/70W
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2123. xcool

lol
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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.