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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OK, where is Irene going to go? The models have shifted East this Morning to the East Coast of Florida with some while some hug the West Coast of Florida. Here is my thoughts to consider. Irene is moving at over 20mph. This is a strong indication of how strong this ridge of high pressure is currently. Irene must slow down to move in a different direction. A player that should be considered is Invest 98L which breaks the ridge down some but, in doing so will pump a ridge to its west very fast with very warm air spinning around. Depending upon the strength of 98L will depend upon how strong the ridge that will control Irene. I currently don't really have much of an idea except that the entire state of Florida and now i would have to put Georgia and South Carolina into the mix as the models have moved to the East overnite. Caution tho, as models shift back and forth this far out vey often.
That would be a worst case scenario for the SE.
Hati DM have a couple of 10,000 foot peeks.
Now, hopefully God forbid Irene won't become a category 5 hurricane. But, It may take on a path similar to David's back in 1979. David's structure was so impressive in that the land interaction he encountered only marginally weakened him.
So, if Irene can continue to get more impressive with a structure being very well stacked and strengthens into a formidable tropical cyclone, then it is very possible she can recover quite quickly after land interaction, similar to David.
What I'm saying is that I've begun disgrading the assumption that the islands will have a major impact. In the last several years I've seen Dennis, Ike, and Gustav all go through Cuba and remain dangerous.
Large storms lose a CAT or two but stay organized and remain large.
That's his disclaimer in case he is wrong. His forecast is landfall in NE FL to Georgia.
DEPRESSION CONTINUES TO MOVE RAPIDLY WESTWARD OR 270/18. THIS
GENERAL MOTION IS LIKELY TO CONTINUE DURING THE NEXT DAY OR TWO.
THEREAFTER...A WEAKNESS IN THE RIDGE OVER THE CENTRAL ATLANTIC
SHOULD CAUSE A GRADUAL TURN TOWARD THE WEST-NORTHWEST WITH A
REDUCTION IN FORWARD SPEED.
This is Dean. Notice that he was supposed to turn WNW after a day or two and he ended up tracking the whole way across the Caribbean to the Yucatan Peninsula. This is from the first advisory.
All are agreeing that it'll pass ~60-90 miles south of Puerto Rico. Should be cool to see it on radar.
here ya go
Link
Thanks! I only did a quick scan with mouse in Google Earth to come up with that 4-7k range. 10'000 foot up in to the airstream is a big friggin' wall.
Link Please
makes a friggin mess on the keyboard, though...
Good to go at mine, 2-$5
Thanks Mark, according to my Physical Terrorist, I'm ahead of schedule and getting around pretty well. Really hope Irene doesn't arrive in ECFL as a hurricane.
Presslord posted photos of tent city in Haiti yesterday. I cannot imagine anything worse than having this storm slam through there so wishcasting it north.
Doing the same today! Also looking forward to a fire sale on frozen goods if their power goes out!
Awe thanks. He is prepared to come home early if necessary. Hopefully it will just be a tropical storm and give us some much needed rain
"Ridge Pumping"
True but but any deviation might bring some effects to West Coast of FL.
I don't want to remember David. I went through David on a USCG High Endurance cutter on a search and rescue mission.
We had a saying.
YOU HAVE TO GO OUT, YOU DON'T HAVE TO COME BACK!.
David berrrr
They made a fuss about EMILY, and now we're under a hurricane watch from IRENE and they barely give a squat.
Irene is 09
SYNOPSIS FOR THE GULF OF MEXICO
430 AM CDT SUN AUG 21 2011
.SYNOPSIS...TROPICAL DEPRESSION HARVEY INLAND NEAR 16.0N 60.4W
AT 0900 UTC MOVING WNW OR 290 AT 19 KT. HARVEY WILL WEAKEN
FURTHER AND DISSIPATE TONIGHT. THE PATH OF HARVEY WILL ALLOW
WINDS TO INCREASE IN THE SOUTHERN BAY OF CAMPECHE TODAY. A WEAK
RIDGE ELSEWHERE THROUGH FORECAST PERIOD. TROPICAL STORM IRENE
WAS CENTERED NEAR 16.4N 61.3W AT 0900 UTC AND WAS MOVING W OR
280 DEG AT 18 KT. MAXIMUM SUSTAINED WINDS 45 KT GUSTS 55 KT.
IRENE IS FORECAST TO MOVE THROUGH CARIBBEAN TO THE STRAITS OF
FLORIDA NEAR 24.5N 80.5W BY THU. WINDS AND SEAS WILL INCREASE E
GULF THU.
THE UPPER LEVEL PATTERN WITH A SIGNIFICANT WEAKNESS EXPECTED IN THE
UPPER RIDGING OVER THE EASTERN UNITED STATES IS ONE THAT WILL HAVE
TO BE WATCHED LATE WEEK... FOR POTENTIAL TRACK/STEERING OF TROPICAL
CYCLONE IRENE. THE LATEST MODEL GUIDANCE IS IN GENERAL AGREEMENT
WITH THE NHC FORECASTS. THE EUROPEAN OPERATIONAL MODEL CONTINUES TO
THREATEN THE SE US COAST WITH IRENE BY LATE WEEK INTO THE WEEKEND.
THEREFORE... WE WILL MAINTAIN OUR CURRENT FORECAST WITH INCREASING
CHANCES OF SHOWERS FRI-SAT. EVERYONE ALONG THE EASTERN SEABOARD
ESPECIALLY IN THE SE US SHOULD KEEP UP TO DATE WITH THE LATEST
FORECASTS FROM THE NHC AND NWS.
Is school cancelled on Monday? lol
And they are now overloaded to the east due to the initial repositioning.
I suspect we see a shift back to the west albeit just slightly.
Viewing: 3201 - 3251
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