92L still a threat to develop; record SSTs continue in the tropical Atlantic
A tropical disturbance (92L) over the Lesser Antilles Islands lost most of its heavy thunderstorms last night, due to an infusion of dry air. However, 92L has redeveloped a moderate amount of heavy thunderstorm activity this morning, and remains a threat to the Caribbean--though not as great a threat as it appeared yesterday. Satellite loops show that 92L's heavy thunderstorms are slowly growing in areal coverage, and are becoming more organized. St. Lucia reported sustained winds of 33 mph this morning in a heavy rain squall, and heavy rain showers and gusty winds can be expected throughout the southern Lesser Antilles Islands today. Martinique radar shows that heavy rains are now affecting that island, but there is no rotation to the radar echoes evident. Surface observations indicate that pressures continue to fall at a number of stations in the Lesser Antilles, but no surface circulation is evident in the wind reports. A strong flow of upper level easterly winds is creating a moderate 10 - 20 knots of wind shear on the south side of 92L. The waters 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 over the northern Caribbean, and this dry air could interfere with development over the next few days.
Forecast for 92L
The disturbance is moving westward at 5 mph, but steering currents favor a more west-northwest motion Saturday. Lower shear lies over the Central Caribbean, away from the coast of South America, so any northward component of motion will allow for more significant development. There is drier air to the north, but 92L is steadily moistening the atmosphere in the Caribbean, so dry air may not be a problem for it. Model support for development is less than it was yesterday. The GFS and NOGAPS models do not develop 92L. The HWRF, GFDL, and UKMET models predict development, with a track taking 92L into the Dominican Republic on Sunday as Tropical Storm Julia. These models predict the storm will continue west-northwest, affecting Haiti, Eastern Cuba, Jamaica, and the Southeast Bahamas early next week. The ECMWF model foresees a more southerly track, taking 92L into Mexico's Yucatan Peninsula seven days from now.
Residents of the northern Lesser Antilles Islands and Puerto Rico should anticipate the possibility of heavy rains from 92L affecting their islands on Saturday and Sunday, though most of the action will probably stay south and west. The southern Dominican Republic should see heavy rains of 3 - 6 inches on Sunday and Monday from 92L, and Haiti, Jamaica, and eastern Cuba should anticipate similar rains on Monday and Tuesday. Should 92L make a direct hit on the Dominican Republic, it could destroy the storm, though. NHC is giving 92L a 40% chance of developing into a tropical depression by Sunday, which is a reasonable forecast. The first Air Force Hurricane Hunter mission into 92L is scheduled for Saturday morning, but there will be two research missions into the storm today that will give us valuable information on 92L's large scale environment and potential for development.
Figure 1. Morning satellite image of 92L.
Igor
Tropical Depression Igor has survived a bout with high wind shear, and is now in an environment of moderate 10 - 20 knots of shear that should allow for steady strengthening. Waters are warm, 28°C, and the Saharan Air Layer (SAL) is probably not close enough to Igor to prevent development. The models continue to predict development of Igor into a hurricane 2 - 4 days from now. Igor will track west to west-northwest over the next week, with long range forecasts from the GFS and ECMWF models putting the storm several hundred miles northeast of the Lesser Antilles Islands about 6 - 8 days from now. 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 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
The GFS and ECMWF models predict the development of a new tropical wave off the coast of Africa 3 - 6 days from now.
August SSTs in the tropical Atlantic set a new record
Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes had their warmest August on record, according to an analysis I did of historical SST data from the UK Hadley Center. SST data goes back to 1850, though there is much missing data before 1910 and during WWI and WWII. SSTs in the Main Development Region (10°N to 20°N and 20°W to 80°W) were 1.23°C above average during August, beating the previous record of 1.01°C set in August 2005. August 2010 was the 7th straight record warm month in the tropical Atlantic. The five warmest months in history for the tropical Atlantic have all occurred this year; June 2005 comes in sixth place, and August 2010 in seventh. As I explained in detail in a post on record February SSTs in the Atlantic, the Arctic Oscillation (AO) and its close cousin, the North Atlantic Oscillation (NAO), are in large part to blame for the record SSTs, though global warming and Atlantic Multidecadal Oscillation (AMO) also play a role.
The Bermuda-Azores High was weaker than average during August, which drove slower than usual trade winds over the tropical Atlantic. These lower trade wind speeds stirred up less cold waters from the depths than usual, and caused less evaporational cooling than usual, allowing August SSTs to remain at record warm levels. The Bermuda-Azores High and its associated trade winds are forecast to be at near-average strength during the next two weeks, according to the latest run of the GFS model. This means that Atlantic SST anomalies will continue to stay at record warm levels during September, significantly increasing the odds of major hurricanes in the Atlantic.
Figure 2. The departure of sea surface temperature (SST) from average for September 9, 2010. Note the area of cool anomalies off the U.S. East Coast, due to the passage of Hurricane Earl. Cool anomalies are also evident east of Bermuda, due to the passage of Hurricane Danielle. Image credit: NOAA/NESDIS.
Next post
I'll have an update Saturday morning.
Jeff Masters
Reader Comments
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That's the 'dog leg track' lol.
Now if you could just make it loop every 300-400 posts, we'd be good.
Why not? Although for me there is no such thing as good or bad forecaster.... just interesting and boring. :) JUNKY! GREAT POSTS ON DONNA vintage videos!!!
True
that is funny...roflmao...brilliant neo. thanks jeff for pointing it out... all of those letters confused me but once i focused it all started to make sense!
Very true.
It was in the first line.
Reminds me of Felix - same stuff, same general area, same sort of model dilemma.
Umm i know what it means in spanish thanks i do live on the island right next to Hispañola i am just telling you that in generall when you live in the antilles like i do you here it refered to as Hispañola pronounced ees-pa -ño-lA i am not saying your wrong or anything i am just saying i havent heard La Española since i studied Caribbean history in my geography class. My girl grew up on santo domingo side and she calls it Hispañola but she says the older folks call it still la española so tomato tomAto lol
92L definitely trying to get going now.
I see the remains of Hermine still have nice vorticity.
Precip Amt Day 1
Precip Amt Day 2
http://www.hpc.ncep.noaa.gov/medr/9lh.gif
Precip Amt Day 3
http://www.hpc.ncep.noaa.gov/medr/9mh.gif
Ex - Gastoon?
In depth blog update check it out.
I'm certainly not expecting a tame turn into the ATL right now.
81 °F
Light Showers Rain
Humidity: 94%
Dew Point: 79 °F
Wind: 7 mph from the NNE
Pressure: 29.80 in (Steady)
Heat Index: 88 °F
Visibility: 9999.0 miles
UV: 2 out of 16
Clouds: Scattered Clouds 1200 ft
Scattered Clouds 1400 ft
Mostly Cloudy 3200 ft
(Above Ground Level)
Elevation: 23 ft
92l is centered right between Grenada on the West, Trinidad and Tobago to the South and Barbados to the East by the look of the surface obs.
The Dreaded Squashed Spider
Looks like it's starting to roll.
It's starting to shake.
It's starting to shudder...
Para Espanol, marque dos.
Indeed. Surface pressures are now lower than they have been with this system to date. If it can hold on to the convection tonight this one could be on the way to TD status soon. Still a slow mover though which makes it potentially very dangerous with extra time over high TCHP
Best post of the week! +100
5:00 PM AST Fri Sep 10
Location: 16.7%uFFFDN 33.3%uFFFDW
Max sustained: 45 mph
Moving: W at 21 mph
Min pressure: 1002 mb
shake shake shake
shake shake shake
shake yo booty
shake yo booty
We need an advisory
SEVERAL DAYS HAS FINALLY STARTED TO ABATE AND CIRRUS OUTFLOW HAS
NOW BECOME PRONOUNCED IN ALL QUADRANTS. HOWEVER...SOME MID-LEVEL
SHEAR AND DRY AIR ENTRAINMENT IS STILL AFFECTING THE CYCLONE...
WHICH HAS RESULTED IN A VERY ASYMMETRIC CONVECTIVE CLOUD PATTERN
WITH THE LOW-LEVEL CENTER DISPLACED AT LEAST 30 NMI TO THE EAST OF
THE COLDEST CLOUD TOPS. INTENSITY ESTIMATES ARE 30 KT FROM SAB...55
KT FROM TAFB...AND UW-CIMSS 3-HR AVERAGE ADT VALUES OF 49 KT AND
AMSU ESTIMATES OF 53 KT. THE INITIAL INTENSITY HAS BEEN
CONSERVATIVELY INCREASED TO 40 KT...WHICH WILL BE TOO LOW IF THE
LOW-LEVEL CENTER IS ACTUALLY CLOSER TO THE DEEP CONVECTION.
120HR VT 15/1800Z 20.0N 55.0W 105 KT
OK, the discussion will be interesting since he looks stronger than that.
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