Potentially dangerous 92L steadily developing; Igor nears hurricane strength
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
Reader Comments
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Not much in My thinking from Yesterday update .....did you read on my Website. Also for you all i put up models like the one i posted on my blog if you all wanta view. I obviously have the same on my website as well.
)
You can drag it down to the northeast coast of florida - LONG time since we've had a direct hit. :)
...eventually.
Again, good stuff. I've enjoyed your atmospheric analyses. Sounds good for the CONUS, may be trouble for the Yucatan. And, agreed on Bermuda - got a target on it!
I'm done, y'all. Have a good sleep!
MLC <---------------------out for some shuteye!
I don't like the look of Igor at all.....i don't think its gonna hit that Trough. Its coming WEst i belive now. Hopefully another Trough gets there in time to make it turn North...Honestly anywhere from South Florida to the Carolinas need to watch this potential monster. Just my opinon as ussual!
It will be very interesting to see if what stormW has been talking about pans out next weekend - early next week.
Hey, atmo.
Thanks. Actually joined in 2006-started over with the current handle on 9/11/07.
By far, the lesser of the two evils for this day in our history.
(
Good to see you dropping in again.
Not sure Igor hits the weakness in the GFS either the way it looks before the High moves over head. This is gonna be all about timing now. If Igor speeds up that would be a good thing. If he slows down we might really be in trouble.
personal q which was none of his business really, don't you agree?
No... That's not it...
http://www.ssd.noaa.gov/goes/flt/t2/ir4-l.jpg
LOL....Good evening.....I wanted to say that one night last week looked at some of your photos and they are AMAZING!! +++
Thank you, I try my best. :D
A lot of peeps don't like the NOGAPS as it is a very conservative model but, i love it because it keeps one pretty honest.
I know you are worried about Igor. It's NOT coming here, don't worry. It will get picked at some point after 48W and towards 60W. That's an awful space to go up. It's already up to 17.7. We won't even feel rains from this one XD!
winter is upon us we might as well wait for next season.
:(
Looks like it completely dissipated then new flair up of convection........this season making me feel like a complete idiot (more than I usually feel I mean)
Aw, don't be down on yourself. :/
Its my favorite model as it is usually slow at show things but, when it does watch out as it is slower at showing things than other models i have always believed. Like i said it is my favorite model and when it shows the same as others i will always favor it when it has other models showing the same. Just my opinion.
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