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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93L: 70%
Ex-99L: 10%
ABNT20 KNHC 112331
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT SAT SEP 11 2010
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM IGOR...LOCATED ABOUT 1140 MILES WEST OF THE CAPE VERDE
ISLANDS.
SHOWERS AND THUNDERSTORMS HAVE DECREASED IN ASSOCIATION WITH A
BROAD AREA OF LOW PRESSURE LOCATED OVER THE EAST-CENTRAL CARIBBEAN
SEA. HOWEVER...ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT OF THIS SYSTEM...AND A TROPICAL DEPRESSION COULD FORM
DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD INTO THE
CENTRAL AND WESTERN CARIBBEAN SEA. THERE IS A HIGH CHANCE...60
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL
IS POSSIBLE IN THE NORTHERN LEEWARD ISLANDS...PUERTO RICO...THE
VIRGIN ISLANDS...AND HISPANIOLA DURING THE NEXT DAY OR SO. THESE
RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD
SLIDES...ESPECIALLY IN MOUNTAINOUS TERRAIN.
SATELLITE IMAGERY INDICATES THAT SHOWER AND THUNDERSTORMS ASSOCIATED
WITH A VIGOROUS TROPICAL WAVE AND ASSOCIATED LOW PRESSURE ABOUT 400
MILES EAST-SOUTHEAST OF THE CAPE VERDE ISLANDS ARE GRADUALLY
BECOMING BETTER ORGANIZED. IF CURRENT TRENDS CONTINUE...A TROPICAL
DEPRESSION COULD FORM DURING THE NEXT DAY OR TWO AS THIS SYSTEM
MOVES TOWARD THE WEST-NORTHWEST AT 10 TO 15 MPH. THERE IS A HIGH
CHANCE...70 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS.
SHOWERS ACTIVITY HAS DEVELOPED IN ASSOCIATION WITH A WEAK LOW
PRESSURE SYSTEM LOCATED ABOUT 900 MILES EAST OF BERMUDA.
DEVELOPMENT OF THIS SYSTEM APPEARS UNLIKELY BEFORE IT IS ABSORBED
BY A FRONTAL SYSTEM. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER KIMBERLAIN/BEVEN
so....a bad turn to the west...soooo is this the one that hits sfla in a week
good cluster StormW
is this time..its going to make a left and then a sharp right...usa is in it target
B
Well, Canes lost, bleh. Out till' later.
Ophelia was the 15th named storm of the season, we're approaching our 12th. As you can see, we're not that far behind.
I remember Ophelia...Rain-maker.
Core has tightened up considerably.
new circle
Is negative favorable for development? what is this chart by the way?
60 70 and 10
The college football blog is around the corner..
yeah, that is a weird place for one...
This time in 2008, we were monitoring Hurricane Ike in the GOMEX. Josephine already died.
This time in 2007, Gabrielle. Today's the day that she weakened. Humberto would form tomorrow.
This time in 2006, we were monitoring Gordon, which would become a Category 2 hurricane.
This time in 2004, we were monitoring Ivan.
2008 is ahead of us by one, 2005 ahead of us by three. We'll beat 2004 tomorrow, which we are tied with, and tie with 2008.
If we were to get Karl and Julia tomorrow, we would only be behind by 1, & they're plenty more healthy looking waves coming off Africa.
They can't make up their minds.....kinda how it has been this year. Although they seem to have the locations down.
yea they say it may be absorbed by a frontal system
Yeah, I messed up the post some. 2008 is one ahead of us (At Josephine).
Who's on First?
Easy for you to say... But yeah, I get the point.
yeah, 92L is saying y'all just wait. I got the GOM (hot tub) ahead of me. patience.....:)
I know. Needed to do more research :D
The post is fixed. We should tie 2008 tomorrow, and beat 2004.
The new storm development of 92l looks to be just forming, there are tee tiny storms starting to fire what appears to be the center
Yeah blog is moving too fast. Typed my post up and clicked post and you had already figured it out XD
We'll be 5 behind 2005 tomorrow. That's considering that we get Julia from either 92L/93L tomorrow.
Yeah I was just about to post that as well lol. 2005 was at Ophelia at this time, their 15th named storm, 6 named storms ahead of us.
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