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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Hey Patrap....WHO DAT!
Love the avatar with your answer.
We Dat of course my friend. Saints Vs Frisco,,Sept 20 at Frisco,,Sept 20th.
Monday Night Football
Road Trip to Game and Wunderground Headquarters maybe?
There is no NW turn that was suppose to happen.
Igor is a threat to Bermuda and maybe eastern Canada.
From the latest discussion....
THE HURRICANE CONTINUES TO MOVE WESTWARD AT 11 KT...AND IS ON THE
PREVIOUS FORECAST TRACK. IGOR IS EXPECTED TO TURN WEST-
NORTHWESTWARD IN ABOUT 24 HOURS AND THEN NORTHWESTWARD IN A
COUPLE OF DAYS AS IT APPROACHES A BROAD TROUGH OVER THE CENTRAL AND
WESTERN ATLANTIC.
I went to sleep last night remembering Ike. Hadn't realized it was 'the' night he did come in.
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112010
0900 UTC MON SEP 13 2010
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
HURRICANE CENTER LOCATED NEAR 17.7N 48.8W AT 13/0900Z
POSITION ACCURATE WITHIN 10 NM
PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT 11 KT
lucky s0b
thats a real good shot
Also note the ridging over the GOM and SE.
300mb winds (jet stream)
Off to work.
Right but if a storm was to get to 160+ knts that would be the surface or the winds would actually be higher at the surface because the 900 mb level would be underground with a sub 900 mb storm
Good morning, Skincarediva. I am intrigued by his comments, as well.
Storm:
I can understand why it is hard for folks to see the potential turn but am not a pro. Can you outline for us how the turn is made in the current set up?
It isn't obvious and folks might learn something....
That is an amazing picture of an amazing part of nature.
Same question I have more or less...
Also last night on local news 13 houston said we needed to watch 92L but only as a rain maker.
Have you used the forgot my password page?
I just checked my local weather here in Tampa and rain chances are very low for the rest of the week into next week a sure sign of a strong high pressure system plus were gonna have winds out of the E to NE!
You posted here ..so whats the problem.
I told my hubby last night.. We were evacuating right now!
I made a new log-on
Storm- at this time (and it is early) it is not looking great for Nova Scotia? We are still cleaning up from Earl.
Suggesting a trend of plateauing.
1. There appears to be a small anti-cyclone ~200miles to the WNW
2. There is a large high pressure system over the US
3. There is a 1005mb low pressure system off the NE US coast
If Igor continues W it will have to dip down and under the Anti-Cyclone... unlikely.
For Igor to move W, the High over the US will have to move pretty quickly over the Atlantic to block a turn to the NW... unlikely
The path of least resistance (based on 500mb steering) it to make a turn to the NW soon and follow the Low off the NE coast.
Thoughts?
The question is did the ridge retreat or did the environment Igor's created around himself push it right out of the way?
Morning everyone. Wow. Igor is one of the most beautiful TCs I've seen in years.
Under the log in is forgot my password. I have tried a few times. You put your email address in and they send the password.. Anyway guess its not that big of a deal i just have to start over. lol.
Its within the realm of possiblity. I won't speculate on odds tho.
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