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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StormW:
"If it's strong enough, and oriented in a certain way, it can, well, not really create it's own high pressure, but it can what we call "pump the ridge"...meaning, if there is a decent enough ridge to it's north, if the outflow of the hurricane is strong enough, the heat it pumps out, will reinforce the ridge to the North and NW of the hurricane enough, that it has a tendency to remain on a more of a WNW or even steady NW course, vice a more poleward motion. That is what we mean when we say the a strong hurricane can modify the environment around it."
Max Mayfield:
A large and strong hurricane can on occasion contribute to building a ridge to the north. Hurricane Gilbert in 1988 was such an example. Some of the models continued to indicate it would turn more toward the north in the Gulf of Mexico and it continued moving west-northwestward instead. Hopefully, the numerical models have improved enough to handle this much better. Examples like Isabel in 2003 and Bill in 2009 turning northward were handled well by the models.
With a tenth of a degree drop...if that continues then this will cause a change in the forecast path....that is all everyone is getting at....
Man today Im on point with my forecast... I guess I got lucky. I wonder if IGOR can strengthen the high pressure above it and continue on a more West Run?
Igor is a nasty little beast...
And since it still a ways out, here's a little westcasting humor...
OMG!!!! It's missing the turn! Look at the Xtrap model!
And as a note, for those of you that may want to post the SFWMD model graphic at some point. Copy the image location, but then make sure you change the https to http
In 1988, Galveston famously ordered an evacuation for Gilbert based on Accuweather's forecast of Gilbert turning north towards a trough.
The question is, can you really fault them for doing that?
In 1988, Galveston famously ordered an evacuation for Gilbert based on Accuweather's forecast of Gilbert turning north towards a trough.
The question is, can you really fault them for doing that?
XTRP goes through a Hebert Box!!!
that is no wobble...the hurricane is definitely heading wwsw....
on a straight line. Annular.
we have a player gentleman and ladies...
pucker. up...
Katrina, Camille...Andrew time....
I just saw one say that Igor was heading to the NE Caribbean moving straight west, not to be alarmed, but vigilant and he didn't even show the NHC cone. >:| WTH?
Evening Dart, good to see you around here.
While this may be true...And I agree there is still plenty of time with Igor. (I assume that's what we are referring to.) I think this is the same mentality of Mrs Lyda Ann Hunkerdown that cost lives on the Bolivar Peninsula. I also think some arguments could be made that this way of thinking may have also cost some lives during Katrina as well.
That is PERFECT for this blog! LOVE IT!!!!!! it should be the blogs mascot.
Its explosive development is also an indictment of the dynamical models' intensity predictions which haven't been particular good. Even the overambitious HWRF and GFDL grossly underestimated the RI just 12-18 hours ago.
I agree completely. Igor appears to be heading toward an EWRC in its near future. After that I believe we could see this powerful cyclone reach Cat 5. Not too concerned with 92L either. At least not until I see any real signs of development.
Just imagine if it were biannular!
That's HeRbert box to you :)
ty. will do.
They're fantastic ACE generators. Mayhap that's the source of said fascination with annulars?
Click image for loop.
we are currently 5 storms behind 2005, which was up to Ophelia at this point, Phillippe formed on the 17th
looking back at 6 of the busiest seasons so far and seeing where they were on this date
1933: 14 named storms, 7 Hurricanes, 4 Major Hurricanes, 15th storm formed on Sept 16th (21 storms total that season)
1969: 7 named storms, 5 Hurricanes, 4 Major Hurricanes, 8th storm formed on Sept 14th (18 storms total that season)
1995: 13 named storms, 6 Hurricanes, 2 Major Hurricanes, 14th storm formed on Sept 26th (19 storms total that season)
2004: 10 named storms, 6 Hurricanes, 4 Major Hurricanes, 11th storm formed on Sept 16th (15 storms total that season)
2005: 15 named storms, 8 Hurricanes, 4 Major Hurricanes, 16th storm formed on Sept 17th (28 storms total that season)
2008: 10 named storms, 5 Hurricanes, 3 Major Hurricanes, 11th storm formed on Sept 25th (16 storms total that season)
2010: 10 named storms, 4 Hurricanes, 3 Major Hurricanes,
No question. And they were supposed to learn from that experience. Mnay responders have now put in place protocols that allow for rapid deployment, but I personally feel this allows the NHC to be too conservative.
Season total ACE
01L (Alex): 6.7825
03L (Bonnie): 0.3675
04L (Colin): 1.9450
06L (Danielle): 21.7950
07L (Earl): 27.7750
08L (Fiona): 2.9400
09L (Gaston): 0.3675
10L (Hermine): 1.2725
11L (Igor): 7.1050
12L (Julia): 0.1225
--------------------------------------
Total: 70.4725
Bridge?
Don't you love how the room reacts to these storms a week before it gets close to anything!!...lol
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