Irene roars into life; may become the season's first hurricane
Tropical Storm Irene roared into life this evening, transitioning from a tropical wave to a 50 mph tropical storm in just a few short hours. An Air Force hurricane hunter aircraft in the storm was finishing up its mission when it suddenly came across a region with intense thunderstorms and surface winds of 50 mph. The aircraft found that a center of circulation had barely closed off on the southwest edge of this region, though the plane found almost no winds from the west around the circulation center. The 6:10pm EDT center fix found a central pressure of 1007mb, which is quite high for the observed 50 mph winds. Dry air to the north and west is slowing development, as well as moderate wind shear of 10 - 20 knots, as analyzed by the University of Wisconsin CIMSS group. Infrared satellite loops and radar out of Martinique show the storm is poorly organized, with no evidence of spiral bands. The center of Irene is expected to cross over the Caribbean island of Dominica early Sunday morning, but the heaviest thunderstorms lie to the north of the center, and will affect Guadeloupe, Antigua, and St. Kitts and Nevis.
Figure 1. Evening satellite image of Irene.
The computer models have shifted southwards since yesterday, and now take Irene south of Puerto Rico on Monday, and along the south shore of the Dominican Republic on Tuesday. On Wednesday, Irene should pass near or over southern Haiti, Eastern Cuba, and Jamaica. On Wednesday and Thursday, the models agree that a trough of low pressure will dip down over the Eastern U.S., which is likely to turn Irene to the north. The exact timing and strength of this trough varies considerably from model to model, and will be critical in determining where and when Irene will turn to the north. We can expect that Irene will impact Central Cuba, the Bahamas, and the Florida Keys on Thursday, but it is uncertain whether Irene's turn to the north will take the storm into the Gulf of Mexico or not. Irene most reminds me of Tropical Storm Fay of 2008. Fay formed just off the coast of Puerto Rico, and was never quite able to get organized enough to become a hurricane, due to passage over Hispaniola and Cuba. Fay topped out as a strong tropical storm with 70 mph winds, and did over $500 million in damage in the U.S., mostly due to flooding rains in Florida that accumulated to over 25 inches in a few areas. Fay also dumped heavy rains on Hispaniola, triggering flooding that claimed eight lives.
Figure 2. Track of Tropical Storm Fay of 2008.
Irene will be battling dry air and moderate wind shear of 10 - 20 knots through Sunday, and it will take the storm 1 - 3 days to build up an eyewall and intensify into a hurricane. Irene is more of a threat than Tropical Storm Emily of early August was, since Irene has closed off a center farther east than Emily did and has more time to organize before encountering Hispaniola. I don't think passage over Hispaniola will destroy Irene, since it is a fairly large storm, and is likely to be a hurricane by then. However, if Irene follows the NHC forecast, it will have an extended encounter with Hispaniola and Cuba on Tuesday through Wednesday that will probably weaken the storm below hurricane force. Keep in mind that the average error for an official 5-day forecast from NHC for a developed storm is 200 - 250 miles. Irene could easily miss Florida and move up the East Coast and hit North or South Carolina, or pass through the Florida Keys and into Gulf of Mexico, ending up who knows where. Given the uncertainties, this weekend would be a good time to go over your hurricane preparedness if you live anywhere in the Caribbean, Bahamas, or U.S. coast, since Irene could well be paying you a visit as a tropical storm or hurricane sometime in the next week.
Harvey hits Belize
Tropical Storm Harvey made landfall at 2pm EDT on Saturday near Dangriga Town, Belize, as a tropical storm with 60 mph winds. Harvey continues to dump very heavy rains on northern Guatemala, Belize, and portions of Mexico's Yucatan Peninsula as the storm tracks westwards at 12 mph. Dissipation is expected Sunday as the storm pushes inland. Harvey was a small storm, and the strongest winds were confined to a short stretch of coast near where the center came ashore. Winds at Belize City, Belize on Saturday topped out at 15 mph.
Figure 3. Radar image of Harvey taken at 11:30am EDT on Saturday, August 20, 2011, a few hours before landfall in Belize. A small closed eye is visible just south of the offshore islands of Belize. Image credit: Belize National Meteorological Service.
An exceptionally active early part of hurricane season
It's been a strangely hyperactive season for weak storms in the Atlantic so far this year. Tropical Storm Irene is the 9th named storm this year, and its formation date of August 20 ties 2011 with 1936 as the 2nd earliest date for formation of the season's 9th storm. Only 2005 had an earlier date. The first eight storms this year have stayed below hurricane strength, making 2011 the first hurricane season since record keeping began in 1851 to have more than six consecutive tropical storms that did not reach hurricane strength. As I discussed in Friday's post, a major reason for this is the lack of vertical instability over the tropical Atlantic so far this year. We've had a large amount of dry, sinking air over the tropical Atlantic, and the usual amount of dry, dusty air from the Sahara, both helping to keep the atmosphere stable and stop this year's storms from intensifying into hurricanes. Hurricane activity typically ramps up big-time by August 20, with more than 80% of all the hurricanes and 65% of all the tropical storms occurring after that date. At our current pace, 2011 will become the second busiest Atlantic hurricane season on record, with 24 - 27 named storms. There are only 21 names in the list of names for a hurricane season, so we may have to break out the Greek alphabet again in late October this year, as occurred in 2005. Ironically, this was the last time the current set of names was used in the Atlantic, so 16 of this year's 21 names are repeats of 2005. I'm not too happy about seeing another hurricane season challenge the Hurricane Season of 2005 in any way, and let's hope we don't retire another five names this year, like occurred in 2005! With vertical instability much lower this year than in 2005, and that year having already seen one storm (Dennis) retired by this point in the season, I doubt that will happen, though.
Figure 2. The annual cycle of average hurricane frequency in the Atlantic. Historically, about 35% of all the tropical storms and 15% of all the hurricanes will have occurred by August 20.
Invest 98L near the Cape Verde Islands
A tropical wave near Cape Verde Islands off the coast of Africa, Invest 98L, is spreading heavy rains and strong gusty winds to those islands today. So far this morning, top sustained winds measured in the Cape Verde Islands were 23 mph at Mindelo. 98L has a long stretch of ocean to cross before it could affect any land areas. Approximately 70 - 80% of all tropical cyclones that pass this close to the Cape Verde Islands end up curving out to sea and not affecting any other land areas, according to Dr. Bob Hart's excellent historical probability of landfall charts. The latest set of long-range model runs go along with this idea, and I'd be surprised if 98L threatens any land areas.
Jeff Masters
Reader Comments
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Or Tampa Bay. :)
I see that overnight we had a center reformation with Irene.
This jump to 16N has resulted in the model runs shifting further N and E in the various runs. That was to be expected.
Looking at the steering ridge this morning and taking into account the fact that Irene has not deepened so far, I would expect to see Irene resume a more W than WNW heading for today. If this happens then the models will come to the left again.
Looking ahead I still believe Irene has a good chance to pass between Jamaica and Cuba before swinging to the NW but this is all dependent on how strong the system becomes. If it deepens significantly it will push its way towards the weakness around Wednesday. If it gets no stronger than CAT 1 then there would be a better chance IMO for it to push a little farther West than the present track forecast. Here is the current steering flow.
Thanks. I was at our beautiful beach yesterday (E. Central FL) just hoping we wouldn't have another storm come through and destroy it. One riding up the coast could be worse than a direct hit as far as that goes. SO the wait begins...we're all set here except for the need of one piece of plywood to replace some warped window coverings. We've had them since Floyd (Frances and Jeanne), so they've seen better days.
Tampa is covered in a protective shield..... :-)
I look at the models. I see the storm passing more north than predicted, and up the East Coast at some point, hitting Florida or not. Either way, the models in their current mode have a bad karma in it for New Jersey. If it's strong, and it hits on the west side, we have trouble. If it's strong on hits on the east side, we have trouble. Hurricane of 1878, 79's David hit on the west side. The '38 and the '44 and 60's Donna were to our east, and we were in a hot mess. Remember there are no fronts to speak of that will make it a quick extratropical transition. At upper latitudes, the storms move more quickly. I think this could be a major player for the least-prone hurricane state on the East Coast. If I'm wrong, I will eat my hat, and I possibly will have to. Nothing is set in stone, and no one can predict nature. I've just studied the past, and realize that so will go the future.
You can see in that model run that the high pressure ridge is blocking the trough.
No one should be counting chickens today, tomorrow, or Tuesday. 72 hours is a long time from now.
That could be a Texas drought buster... But where is the TX high located at?
Hell yes it is...........:)
TROPICAL STORM IRENE INTERMEDIATE ADVISORY NUMBER 3A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011
800 AM AST SUN AUG 21 2011
...IRENE MOVING INTO THE NORTHEASTERN CARIBBEAN SEA...
SUMMARY OF 800 AM AST...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...16.5N 62.0W
ABOUT 35 MI...55 KM WNW OF GUADELOUPE
ABOUT 45 MI...70 KM SSW OF ANTIGUA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...W OR 280 DEGREES AT 21 MPH...33 KM/H
MINIMUM CENTRAL PRESSURE...1005 MB...29.68 INCHES
Looks like the GFDL is still South........
Right. We just get slapped around a bit by storms cris-crossing the state, or on their way to the north Gulf Coast.
I agree, as long as it doesn't deepens too quickly which I have a feeling it won't, given the lingering dry air in the area (not much but is there still) and the land interaction.
72 hrs is a long time and 140+ even longer...Right now; I am primarily interested in where she is when it gets to DR/PR. Just S of or over; and those mountains should do a number on her. Just N of and all bets are off.
Just looked at steering flow........i see the same thing Kman..........wasn't a NOAA g-5......taking readings overnite also?
Pretty sure it will be close to its parent... GFS.
I totally agree. No certainty in track or intensity in the upcoming days exists right now.
Proves the point that no consensus exists at this time.
Not sure about the G-5 but no question that ridge is not shifting for now and irene is right up against the base.
We should be able to expect UKM also shifting and coming more in line with the other runs as consensus grows.
Latest runs show a path that would be awful for everyone on the east coast from florida to SE NC.
Does anyone know how strong GFS shows Irene when its hitting Georgia? (on the last run)
I liked it better when only one model had it heading towards the western part of the GOM. But if she can go east of Florida, that would be great.
I dont want bets to be off,,, I just put my house on the market last week and dont need this sh*t. :-)
Absolutely, a beautiful day here. T time @ 8:40 my time ( hour and a half from now ) so blogging time limited this morning Lol
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 21 2011
BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.
...SPECIAL FEATURE...
TROPICAL STORM IRENE IS CENTERED NEAR 16.5N 62.0W AT 21/1200 UTC
OR ABOUT 35 MI...55 KM WNW OF GUADELOUPE...OR ABOUT 45 MI...70
KM SSW OF ANTIGUA MOVING W AT 19 KT. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 45
KT WITH GUSTS TO 55 KT. PLEASE SEE THE LATEST INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT4/ WTNT34 KNHC
AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT4/
WTNT24 KNHC FOR MORE DETAILS. SCATTERED STRONG CONVECTION COVERS
A BROAD REGION OF THE ATLC AND EAST CARIBBEAN BASIN FROM 14N-21N
BETWEEN 57W-65W. IRENE IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 4 TO 7 INCHES IN THE LEEWARD ISLANDS...PUERTO
RICO AND THE VIRGIN ISLANDS...WITH ISOLATED MAXIMUM AMOUNTS OF
UP TO 10 INCHES. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH
FLOODS AND MUDSLIDES IN AREAS OF STEEP TERRAIN. TROPICAL STORM
CONDITIONS ARE EXPECTED TO BEGIN THIS AFTERNOON IN THE VIRGIN
ISLANDS AND PUERTO RICO. HURRICANE CONDITIONS ARE POSSIBLE OVER
THE DOMINICAN REPUBLIC BY LATE MONDAY WITH TROPICAL STORM
CONDITIONS POSSIBLE BY MONDAY AFTERNOON.
:) Tampa... is G-4.
Their next run is:
B. POSSIBLE G-IV SURVEILANCE MISSION FOR THE
SAME SYSTEM AT 22/0000Z.
Or basically tonight @ 8PM.
You ever seen a storm intensify over south Florida? It's happened. All the moisture from the Everglades, just one huge flat sea of hot, shallow water.
Correct. And it's important as always to not pay attention too closely to the center line; anywhere within the cone is still in the watch-and-wait mode. That five-day cone is roughly 500 miles in diameter; as such, Irene may miss Florida by a few hundred miles to the east or to the west, or she may wind up anywhere in between.
Current Weather Conditions:
Vc Bird International Airport Antigua, Antigua and Barbuda
Time
EDT (UTC) Temperature
F (C) Dew Point
F (C) Pressure
Inches (hPa) Wind
MPH Weather
Latest 7 AM (11) Aug 21 77 (25) 73 (23) 29.74 (1007) E 30 light rain
6 AM (10) Aug 21 77 (25) 75 (24) 29.74 (1007) ENE 25
5 AM (9) Aug 21 78 (26) 75 (24) 29.77 (1008) NE 24 light rain
4 AM (8) Aug 21 78 (26) 73 (23) 29.77 (1008) NE 18 light rain
3 AM (7) Aug 21 77 (25) 75 (24) 29.80 (1009) NE 22 light rain
2 AM (6) Aug 21 75 (24) 71 (22) 29.83 (1010) NE 10 light rain
1 AM (5) Aug 21 80 (27) 73 (23) 29.83 (1010) E 28 light rain showers
Current Weather Conditions:
Le Raizet, Guadeloupe, Guadeloupe
24 Hour Summary
Time
EDT (UTC) Temperature
F (C) Dew Point
F (C) Pressure
Inches (hPa) Wind
MPH Weather
Latest 7 AM (11) Aug 21 77 (25) 73 (23) 29.77 (1008) SSE 10 light rain
6 AM (10) Aug 21 75 (24) 73 (23) 29.74 (1007) S 9 light rain
5 AM (9) Aug 21 75 (24) 73 (23) 29.74 (1007) SSW 10 light rain
4 AM (8) Aug 21 75 (24) 73 (23) 29.74 (1007) SW 6 rain
3 AM (7) Aug 21 73 (23) 73 (23) 29.77 (1008) W 6 light rain
2 AM (6) Aug 21 73 (23) 73 (23) 29.77 (1008) WNW 3 light rain
1 AM (5) Aug 21 77 (25) 75 (24) 29.80 (1009) Variable 3 light rain
NOAA Caribbean Weather Observations
Good Morning. I agree Kman. As always we should watch closely and make no assumptions until it actually makes that turn. Of course, even afterwards we'll be watching closely as many of us have friends over in Florida - just won't have carry out the final stages of prep.
The next forecast point may be too far north in the 8 AM. Irene is up against the high pressure ridge at this hour.
Land interaction and Strength of the storm is the reason of the digestive disagreement currently. Will be interesting to see which model proves to be the best with this one.......
SkyPony usually post the models percentages.
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