92L still a threat to develop; Igor a hurricane; TD 12 forming near Africa
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
Reader Comments
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Mornin Scott....He is quite a monster!!
I can't wait for your take on 92 now :)
that turn by Igor might be delayed because the upper and mid level steering from CIMMS is still showing a strong ridge and a movement to west to continue, the weakness in the ridge seems to have levelled out and should delay that model turn. it is really dicey at the moment and the northern islands should monitor Igor very closely
Just a quick look in before I head to work...
I looked at the graphics archive, and I have to give NHC credit, as so far Igor has been on track, albeit a little faster than their forecast. At 8 a.m. this morning Igor was expected to have reached the point he passed around 11 a.m. yesterday [approximately 17N, 47W].
I'm still not buying an abrupt NW turn at 50W, which is what's been forecast pretty much since day 1, but I can understand why they'd be reluctant to change. I also am realizing that NHC has consistently been well LEFT of model consensus on this turn, so the tiny shifts to right have, I suppose, accommodated what they are likely seeing as strong model consistency. I'm watching today to see how much latitude Igor gains. IMO that'll be today's news, since by 11 a.m. we will see 50W crossed.....
Good Morning Cotillion!!
I could not have said it better!!
IMO the clouds to the west of Igor are moving generally towards the west. The two troughs to the north and northeast of Igor appear to be lifting towards the north...
I sure sure hope Igor does not go to Bermuda.
from its previous heading of (6.5degrees south of) dueWest
H.Igor's average speed moving between its last 2 reported positions was ~11mph(~17.7km/h)
12Sep . 09amGMT - - 17.7n44.4w - - - 80mph - - 988mb - - NHC.Adv.#16
12Sep . 03pmGMT - - 17.7n45.7w - - 105mph - - 970mb - - #17
7:30pmGMT H.Igor becomes 140mph-Cat.4
12Sep . 09pmGMT - - 17.7n46.9w - - 140mph - - 942mb - - #19
13Sep . 03amGMT - - 17.6n47.8w - - 150mph - - 935mb - - #20
13Sep . 09amGMT - - 17.7n48.8w - - 150mph - - 935mb - - #21
Copy&paste 17.7n44.4w-17.7n45.7w, 17.7n45.7w-17.7n46.9w, 17.7n46.9w-17.6n47.8w, 17.6n47.8w-17.7n48.8w, puj, pos, 17.7n48.8w-18.66n64.27w into the GreatCircleMapper for a look at the last 24*hours.
Using straightline projection upon the speed&heading averaged
over the 6hours spanning the last two reported positions:
~3days&19hours from now to Anegada
* The westernmost line-segment is the straightline projection.
I'm doubting any serious impact from these troughs right now...
I see the NHC expect a Cat 5 as well. I still stand firm with my prediction until it happens.
I see the intensity guidance doesn't bring him up to it. They seem to think he's reached his MPI. Be interesting to see if that is indeed the case.
Out for now. Will check in later this a.m. if time permits...
good morning Storm....will be anxious to see what you think 92L will do today and where it may head....have a great day
430 AM CDT MON SEP 13 2010
.SYNOPSIS...COLD FRONT WILL CLIP THE FAR NE GULF TODAY. LOW PRES
IN THE CENTRAL CARIBBEAN JUST SOUTH OF HAITI WILL MOVE INTO THE
NW CARIBBEAN WED...POSSIBLY AS A TROPICAL CYCLONE...INCREASING
WINDS AND SEAS IN THE FAR SOUTHERN GULF. THE LOW WILL MOVE INTO
THE SW GULF THU AND FRI...POSSIBLY AS A TROPICAL CYCLONE. THE
LOW WILL BE NEAR 21N93W THU AND NEAR 21N96W FRI.
...........................................
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 AM EDT MON SEP 13 2010
.SYNOPSIS...LOW PRESSURE NEAR 16N73W WILL MOVE TO NEAR 17N78W
TONIGHT AND NEAR 18N84W TUE NIGHT. THE LOW COULD POSSIBLY
DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
HURRICANE IGOR E OF THE AREA CENTERED NEAR 17.7N48.8W AT 0900
UTC. WILL MOVE TO 20.4N 54.9W TUE NIGHT AND NEAR 22.5N 57.7W WED
NIGHT THEN CONTINUE TO MOVE N OF THE AREA THU.
Ditto!!!
Everything this monster does will be interesting!!!
WEST!!??
Based on the current steering currents you have posted Igor will have 2 choices.... 1) Slow down further to turn NW to get out to sea or 2) Go further W underneath that High as it could potentially build N of it given that there's hardly a noticeable weakness to feel and continue further W... there might be another scenario but can't think of one just yet.
Holy Turnip Greens....that could change the forecast a bit!!!
I already made a mention of NHC in that comment.
I guess it is possible but I just don't see it happening.....
Cot. I trust you had a lovely Sunday : )?
24-Hours WV LOOP
First of all the CMC only develop it
Tropical Weather Discussion
now i'm no expert by any means, but it looks like the path west is a little clearer with the trof coming off the east coast and the other ones lifting north.....how long would that path stay clear?
- and so....,Igor not being -undertheinfluence
ain't a good thing - 'case that's a "go West young man" moment.......
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