Dr. Jeff Masters' WunderBlog

Hurricane Irene pounds Puerto Rico, heads for Hispaniola

Posted by: Dr. Jeff Masters, 2:40 PM GMT op 22 augustus 2011

+30

Hurricane Irene strengthened into the season's first Atlantic hurricane at 5am EDT this morning as the eye moved over San Juan, Puerto Rico, and crossed into the ocean just north of the island. Overnight, Irene held its own as the eye passed over the most mountainous portion of Puerto Rico, the El Yunque region. Winds in the higher mountains likely reached Category 2 strength, 96 - 110 mph, according to measurements from the San Juan Terminal Doppler Radar, and the hurricane pounded the island with damaging winds and flooding rains, resulting in widespread tree damage and power failures that hit 800,000 people. The San Juan Airport recorded top winds of 41 mph, gusting to 55 mph, and 2.87" of rain, as of 9am AST. Tropical storm conditions affected the Virgin Islands, with St. Thomas recording sustained winds of 40 mph, gusting to 67 mph, and 4.03" of rain as of 6am AST today. At 7am EDT, the ship Horizon Trader measured sustained northeast winds of 69 mph and wave heights of 11.5 feet at 19°N, in the northern eyewall of Irene. Latest observations from an Air Force hurricane hunter aircraft indicate that Irene is slowly intensifying, with a central pressure of 989 mb observed at 9:42am EDT. The eyewall is not fully formed yet, with a gap on the south side. This gap will need to close off before the hurricane can undergo rapid intensification.

Figure 1. A direct hit: the center of Hurricane Irene passed directly over the Terminal Doppler Radar at San Juan, Puerto Rico between 4am and 5am AST this morning.

Track forecast for Irene
The computer models show good agreement that Irene will pass along the north coast of Hispaniola today, but just a slight wobble in Irene's track to take it farther offshore--or push it onshore, over the mountains--will have major impacts on the ultimate path and strength of the hurricane. A trough of low pressure is expected to move across the Eastern U.S. on Wednesday and Thursday, turning Irene more to the northwest by Wednesday. The 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. Irene's strength will also matter--a stronger Irene is more likely to turn northward earlier. The most popular solution among the models is to take Irene to the northwest through the Bahamas on Wednesday and Thursday, then into the Southeast U.S. coast in South Carolina or North Carolina on Saturday. Irene would then travel up the mid-Atlantic coast, arriving near Long Island, New York on Monday morning as a strong tropical storm or Category 1 hurricane. One of the models proposing this solution is our best model, the ECMWF. However, we have two other of our very good models suggesting a landfall near Miami on Thursday night is likely (the GFDL and UKMET models.) NHC forecaster Stacy Stewart gave some good reasons in this morning's discussion to favor a track close to the east coast of Florida, but just offshore. Last years' worst performing major the model, the NOGAPS, predicts that Irene will pass out to sea, missing the Southeast U.S. coast. Keep in mind that the average error of a 4-day forecast from NHC is 200 miles, and just a small deviation in the path of a storm moving roughly parallel to the coast will make a huge difference in where it ultimately makes landfall. The NOAA jet will be flying its first dropsonde mission into Irene today, which should result in a more reliable set of model runs first thing Tuesday morning.

Intensity forecast for Irene
Irene is embedded in a large envelope of moisture now, and wind shear is expected to remain low, 5 - 10 knots, for the next five days. With water temperatures very warm, 29 - 30°C, these conditions should allow for intensification except when land is interfering. Satellite loops show that Irene is steadily growing in size, which will protect the storm against major disruption by its passage along the north shore of Hispaniola today. The storm is lacking much development on its southwest side, where dry air is interfering with development. This dry air may help keep southern portions of the Dominican Republic and Haiti from receiving more than 3 - 6 inches of rain. There is at least a 30% chance that passage of the eye over Hispaniola will reduce Irene to a tropical storm tonight and into Tuesday. Due to Hispaniola blocking inflow of moist air from the south, Irene will likely compensate by building an even larger region of heavy thunderstorms to the north, offshore. Thus, when Irene's center finally moves well away from the coast on Tuesday, it will be a bigger storm, with the potential to spread hurricane conditions over a wider area later in the week when it intensifies. One limiting factor for intensification may be in the upper-level outflow pattern. The hurricane is lifting a huge amount of air from the surface to the upper atmosphere, and all that mass has to be efficiently transported away in order for the hurricane to intensify. Right now, upper level outflow is only well-established to the north and east, and the forecast outflow pattern for the coming five days is only moderately favorable. Overall, I think the official NHC forecast of a Category 3 hurricane by Thursday is the right one, though Irene could easily be a Category 2 or Category 4 storm.

Irene's impact on the Dominican Republic
Heavy rains from Irene have already reached the eastern tip of the Dominican Republic, where Punta Cana has seen wind gusts up to 29 mph this morning. The northeast coast of the country near Samana will receive the worst of Irene's wrath, with sustained winds of 50 - 70 mph and gusts above hurricane force likely to cause widespread tree damage and power outages today. Passage along the coast of the island may weaken Irene to a tropical storm by Tuesday morning, and wind damage in Puerto Plata may be less severe than at Samana. The capital of Santo Domingo will see lesser winds, perhaps 30 - 50 mph, with gusts to 60 mph. The main danger to the Dominican Republic will be Irene's torrential rains, which are likely to reach 20 inches in some mountainous regions, causing dangerous flash floods and mudslides.

Irene's impact on Haiti
No nation in the Caribbean is more vulnerable to hurricanes than Haiti, whose northern reaches are expected to receive torrential rains of 5 - 10 inches from Irene. During the 2008 hurricane season, four storms--Fay, Gustav, Hanna, and Ike--dumped heavy rains on Haiti, leaving over 1,000 people dead or missing. The path and intensity of Hurricane Irene are very similar to that of Hurricane Jeanne of 2004, which dumped 13 inches of rains on the nation's northern mountains. The rugged hillsides, stripped bare of 98% of their forest cover thanks to deforestation, let flood waters rampage into large areas of the country, killing over 3000 people, mostly in the town of Gonaives, the nation's 4th largest city. Jeanne ranks as the 12th deadliest hurricane of all time on the list of the 30 most deadly Atlantic hurricanes, and Irene's rains are capable of causing a similar disaster. During 2004 and again this year, ocean temperatures off the coast of Haiti were 1 - 1.5°C above average, one of the top five values seen in the past 100 years. Since more water vapor evaporates into the air from record warm waters, the potential for devastating floods from hurricanes is much higher in these situations. However, satellite images of Jeanne show the storm had much more moisture on its south side when it hit Hispaniola than Irene currently has, so I am hopeful that Irene's rains will not be as intense as Jeanne's were.

Figure 2. Track of Hurricane Jeanne of 2004, which followed a path very similar to what is expected from Hurricane Irene along the north coast of Hispaniola. Irene is not going to do a big loop like Jeanne did, though.

As bad as the hurricanes of 2004 and 2008 were, the January 2010 earthquake was far worse. Up to 316,000 may have been killed, and the capital city of Port-Au-Prince was devastated, leaving over 1.5 million people living under tarps during the 2010 hurricane season. Fortunately, Hurricane Tomas missed making a direct hit on Haiti, and Haiti escaped major loss of life during the 2010 hurricane season. This year, approximately 595,000 Haitians still live underneath tarps outdoors thanks to the earthquake, and these unfortunate people will be at risk of being swept away by flash flooding from Irene's torrential rains. However, Port-Au-Prince lies to the south of where Irene's main rains will fall, and I doubt the earthquake refugee camps will suffer from a major flooding disaster.

Figure 3. Hospital admissions (black bars) and death rate in percent (red line) for Haiti's cholera epidemic of 2010 - 2011. The cholera epidemic surged out of control after Hurricane Tomas dumped heavy rains on Haiti on November 4, 2010, with hospitalizations increasing by a factor of three for over a month. Over 3% of all people who contracted cholera died after Tomas' rains. However, sanitation and medical care improved in the following months, and the death rate fell by a factor of five to 0.7% by the summer of 2011. Another surge in cholera cases occurred in June 2011, doubling after heavy rainy season rains occurred. Cholera deaths doubled during the surge, but the death rate remained constant at 0.7%. Image credit: Pan American Health Organization.

Another danger is that Irene's rains will worsen the cholera epidemic that surfaced after the earthquake. Cholera is a water-borne disease, and spreads readily after heavy rains. As of August 12, 2011, the 2010 - 2011 cholera epidemic had infected 419,000 Haitians, killing 5,968. After Hurricane Tomas passed on November 5, 2010, cholera cases exploded, with hospital admissions more than tripling for over a month. Similarly, heavy rains in June 2011 during the country's usual rainy season caused doubled cholera cases and deaths for several weeks. We can expect that Irene's rains will cause at least a doubling of cholera cases for a month or more. This will lead to several hundred additional cholera deaths, given the disease's 0.7% mortality rate this summer in Haiti (during June and July 2011, 95,212 cases were reported, with 626 deaths.) An increase in cholera deaths due to Irene's rains is also a concern in the Dominican Republic, where cholera has sickened 14,000 people and killed 92 as of the end of July.

Organizations Active in Haitian Relief Efforts:
Portlight disaster relief
Lambi Fund of Haiti
Haiti Hope Fund
Catholic Relief Services of Haiti

Links
For those of you wanting to know your odds of receiving hurricane force or tropical storm force winds, I recommend the NHC wind probability product.

Wunderground has detailed storm surge maps for the U.S. coast.

See my 2010 post, Haiti's tragic hurricane history.

An exceptionally active of hurricane season
Hurricane season is only one-third over, and we've already had almost a full years' activity already. Tropical Storm Irene is the 9th named storm this year, and an average season has just 10 - 11 named storms. Irene's formation date of August 20 ties 2011 with 1936 as the 2nd earliest date for formation of the season's 9th storm. Only 2005 was more active this early. However, the first eight storms of the year have done far less damage than is typical. All eight storms 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 4. 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.

Which model should you trust?
Wunderground provides a web page with computer model forecasts for many of the best-performing models used to predict hurricane tracks. So which is the best? Well, the best forecasts are made by combining the forecasts from three or more models into a "consensus" forecast. Over the past decade, NHC has greatly improved their forecasts by relying on consensus forecast models made using various combinations of the GFS, GFDL, NOGAPS, UKMET, HWRF, and ECMWF models. If you average together the track forecasts from these models, the NHC official forecast will rarely depart much from it, and the NHC forecast has been hard to beat over the past few years. The single best-performing model over the past two years has been the ECMWF (European Center model). This model out-performed the official NHC forecast in 2010 for 1-day, 2-day, 3-day and 4-day forecasts, and in 2009 for 4-day and 5-day forecasts. You can view ECMWF forecasts on our wundermap with the model layer turned on. The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on our computer model forecast page that plots positions from the other major models. As seen in Figure 5, over the past two years, the GFS and GFDL model have been the next best models, with the UKMET model not far behind. Last year, the NOGAPS model did very poorly, forcing NHC to come up with some new consensus models this year, the TCOA and TVCA, that do not include the NOGAPS model. For those interested in learning more about the models, NOAA has a great training video (updated for 2011.)

Figure 5. Skill of computer model forecasts of Atlantic named storms 2010. OFCL=Official NHC forecast; GFS=Global Forecast System model; GFDL=Geophysical Fluid Dynamic Laboratory model; HWRF=Hurricane Weather Research Forecasting model; NOGAPS=Navy Operational Global Prediction System model; UKMET=United Kingdom Met Office model; ECMWF=European Center for Medium Range Weather Forecasting model; TVCN=one of the consensus models that lends together all (or most) of the above models. Image credit: National Hurricane Center 2010 verification report.

Next post
There will be 2 - 3 posts per day in my blog this week during Irene, with Angela Fritz and Rob Carver doing some of the afternoon and evening posts.

Jeff Masters

Tropical Storm Irene hits Puerto Rico (lobdellJ)

Tropical Storm Irene hits the north coast of Puerto Rico

Tropical Storm Irene from Maunabo, PR (ronmil)

The first bands or Irene approaching Maunabo, Puerto Rico (SE corner)...

Irene (reefchild)

Irene @OPkB OceanParkBeach Puerto Rico 7pm

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1751. CCkid00 8:47 PM GMT op 22 augustus 2011
Quoting atmoaggie: Weather balloons launched from these locations at 18 Z: (This is unusual and was specifically requested by NHC). what does this mean? what are they looking for? thanks Member Since: 22 augustus 2008 Posts: 0 Comments: 266

1752. WxLogic 8:48 PM GMT op 22 augustus 2011
Quoting atmoaggie: Weather balloons launched from these locations at 18 Z: (This is unusual and was specifically requested by NHC). Do you believe the 18Z will be able to fully have this data ingested into them or 00Z? Given that they were sent out at 18Z I would assume they wouldn't be available until 00Z. Member Since: 14 augustus 2008 Posts: 4 Comments: 4666

1753. washingaway 8:48 PM GMT op 22 augustus 2011
Member Since: 14 juli 2006 Posts: 0 Comments: 1127

1755. Drakoen 8:48 PM GMT op 22 augustus 2011
Quoting scooster67: Sorry. I am at work and said that all wrong. The trough is pulling it north, so a stall means to me that the trough is not picking Her up. That trough isn't going to pull her out as it will be moving on out to the northeast. It's the series of shortwaves in the jet stream that will be opening up the weakness. Member Since: 28 oktober 2006 Posts: 57 Comments: 29010

1757. 900MB 8:48 PM GMT op 22 augustus 2011
Any recon out there? Convection looks pretty strong, especially considering that this time yesterday we were supposed to be over the DR, not skirting it. Member Since: 11 juni 2006 Posts: 0 Comments: 609

1758. TropicalAnalystwx13 8:49 PM GMT op 22 augustus 2011
Quoting treehuggingsister: Tosail Island, NC, Pre-Bertha 1996 Lovely LARGE dunes The beach is nice down here...That is where I go when I go to the beach. Lots of unwanted creatures in the water though (i.e. Sharks, Jellyfish, Stingrays). Member Since: 6 juli 2010 Posts: 89 Comments: 25142

1759. Tazmanian 8:49 PM GMT op 22 augustus 2011
Quoting KATRINABILOXIGIRL: So could this mean a more westward track? Thank you! well it could mean a more WNW track am not saying for sure the storm has stalled but it has been moveing vary slow the past few hrs and the more the storm moves slow the less of a ch that it will find that weak spot in the high for it too turn out too sea and the front could move out and the high too move back in Member Since: 21 mei 2006 Posts: 5088 Comments: 111312

1760. snow2fire 8:49 PM GMT op 22 augustus 2011
The join dates don't mean much. I've been on the Univ of Illinois and Michigan weather sites since early 1990's, and on weather underground since it was set up in 1990s. At one time, we thought it was great getting real time weather from both Champaign and Ann Arbor... just saying... Member Since: 5 juni 2006 Posts: 0 Comments: 158

1761. TomTaylor 8:49 PM GMT op 22 augustus 2011
Quoting atmoaggie: Weather balloons launched from these locations at 18 Z: (This is unusual and was specifically requested by NHC). hmm that's cool Quoting DookiePBC: Been a while since anyone posted the Rainbow image of DOOOOOOM!!! CDO looking better as cloud tops continent to cool Member Since: 24 augustus 2010 Posts: 18 Comments: 3886

1762. RitaEvac 8:49 PM GMT op 22 augustus 2011
Quoting cloudburst2011: i have news for you your models have no idea where irene is going...they are shifting to the east now because they have 3 short wave trofs coming down in the next 5 days...thats why the strong shift to the east..they have no idea how deep those trofs will be so they are playing it safe for now...if that a/b high starts to build further west and the high over texas pulls back to the nw in the 4 corners area ...then your models will start to shift back towards the west...the bottom line here is irene is not going anywhere anytime soon and its still open for anyone from brownsville to to maine could be affected ...so just because you are not in the cone do not let your guard down until a more certain path is established by irene... Brownsville? come on now.. Member Since: 14 juli 2008 Posts: 1 Comments: 8874

1764. Orcasystems 8:49 PM GMT op 22 augustus 2011
Quoting nrtiwlnvragn: I think that plane shown near Cuba is a glitch with Tropical Atlantic. The dropsonde data shown is from a mission for Emily on August 4th. Agreed.. thats explains the mission 13 number Ok, going to display 5 & 6 then Member Since: 1 oktober 2007 Posts: 77 Comments: 26077

1765. kylejourdan2006 8:49 PM GMT op 22 augustus 2011
Quoting KATRINABILOXIGIRL: So could this mean a more westward track? Thank you! Don't bet on it. While Irene may have slowed now, it is most likely very temporary and she should resume movement shortly. When storms undergo some structure organization, as Irene is currently doing, they tend to slow down and get themselves together (if you will) before they get moving again. Member Since: 18 juli 2006 Posts: 32 Comments: 1521

1766. yoboi 8:49 PM GMT op 22 augustus 2011
why do they have a plane in the GOM??? Member Since: 25 augustus 2010 Posts: 0 Comments: 2421

1768. Stormchaser2007 8:50 PM GMT op 22 augustus 2011
Member Since: 9 juni 2007 Posts: 4 Comments: 15243

1769. afwxguy86 8:50 PM GMT op 22 augustus 2011
Quoting WxLogic: Do you believe the 18Z will be able to fully have this data ingested into them or 00Z? Given that they were sent out at 18Z I would assume they wouldn't be available until 00Z. It won't be on the 18Z run. The 18Z run is already being completed, it will be in the 00Z run. Member Since: 1 augustus 2011 Posts: 0 Comments: 6

1770. Tazmanian 8:50 PM GMT op 22 augustus 2011
am not buying any mode runs at this time Member Since: 21 mei 2006 Posts: 5088 Comments: 111312

1771. CosmicEvents 8:50 PM GMT op 22 augustus 2011
Quoting atmoaggie: Weather balloons launched from these locations at 18 Z: (This is unusual and was specifically requested by NHC). Thanks Atmo. That's good info. I'd think they're sampling the upper air to see how strong the trough is. Member Since: 3 augustus 2005 Posts: 10 Comments: 5093

1772. WxLogic 8:50 PM GMT op 22 augustus 2011
Quoting CCkid00: what does this mean? what are they looking for? thanks They are sampling of the atmosphere at specific (strategic) points in order to get inputted into a computer model in order to increase their accuracy. Member Since: 14 augustus 2008 Posts: 4 Comments: 4666

1773. hurricanehunter27 8:50 PM GMT op 22 augustus 2011
So what the news with Irene, just got back from school and NHC is showing Hugo. Member Since: 22 juli 2010 Posts: 1 Comments: 3381

1774. treehuggingsister 8:50 PM GMT op 22 augustus 2011
Quoting cat5hurricane: Fran sure did do her share of roof eating. The way Fran came in chomping, we were really glad Bertha'd come through first and cleared out a lot of the flotsum and jetsam. Holy Christmas, there was 34 years of built up trees, weak roofs, all sorts of things that Bertha's landfall uncovered that were cleared up and secure when Fran came calling. Member Since: 18 augustus 2006 Posts: 0 Comments: 188

1775. charlottefl 8:51 PM GMT op 22 augustus 2011
This is interesting: Member Since: 18 december 2006 Posts: 7 Comments: 2672

1776. weatherlover94 8:51 PM GMT op 22 augustus 2011
i do see a chance this will recurve and just brush the outerbanks of NC Member Since: 8 september 2010 Posts: 0 Comments: 645

1778. 7544 8:51 PM GMT op 22 augustus 2011
Quoting Tazmanian: well it could mean a more WNW track am not saying for sure the storm has stalled but it has been moveing vary slow the past few hrs and the more the storm moves slow the less of a ch that it will find that weak spot in the high for it too turn out too sea and the front could move out and the high too move back in you getting good at this taz thru the years Member Since: 6 mei 2007 Posts: 0 Comments: 5922

1779. TropicalAnalystwx13 8:52 PM GMT op 22 augustus 2011
HURRICANE IRENE FORECAST/ADVISORY NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011 2100 UTC MON AUG 22 2011 CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY... THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A HURRICANE WARNING FOR THE CENTRAL BAHAMAS AND A HURRICANE WATCH FOR THE NORTHWESTERN BAHAMAS. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A HURRICANE WARNING IS IN EFFECT FOR... * NORTH COAST OF THE DOMINICAN REPUBLIC FROM THE HAITI BORDER EASTWARD TO CABO ENGANO * TURKS AND CAICOS ISLANDS...SOUTHEASTERN AND CENTRAL BAHAMAS A HURRICANE WATCH IS IN EFFECT FOR... * NORTH COAST OF HAITI FROM LE MOLE ST. NICHOLAS EASTWARD TO THE DOMINICAN REPUBLIC BORDER * NORTHWESTERN BAHAMAS A TROPICAL STORM WARNING IS IN EFFECT FOR... * SOUTH COAST OF THE DOMINICAN REPUBLIC FROM SANTO DOMINGO EASTWARD TO CABO ENGANO * ALL OF HAITI HURRICANE CENTER LOCATED NEAR 19.5N 68.6W AT 22/2100Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 11 KT ESTIMATED MINIMUM CENTRAL PRESSURE 988 MB MAX SUSTAINED WINDS 70 KT WITH GUSTS TO 85 KT. 64 KT....... 25NE 0SE 0SW 0NW. 50 KT....... 40NE 30SE 20SW 25NW. 34 KT.......160NE 60SE 40SW 90NW. 12 FT SEAS..180NE 60SE 30SW 120NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 19.5N 68.6W AT 22/2100Z AT 22/1800Z CENTER WAS LOCATED NEAR 19.3N 68.1W FORECAST VALID 23/0600Z 20.1N 70.2W MAX WIND 80 KT...GUSTS 100 KT. 64 KT... 15NE 0SE 0SW 15NW. 50 KT... 45NE 30SE 20SW 45NW. 34 KT...160NE 75SE 45SW 110NW. FORECAST VALID 23/1800Z 20.8N 72.5W MAX WIND 85 KT...GUSTS 105 KT. 64 KT... 15NE 0SE 0SW 15NW. 50 KT... 45NE 30SE 20SW 45NW. 34 KT...160NE 75SE 45SW 120NW. FORECAST VALID 24/0600Z 21.5N 74.0W MAX WIND 90 KT...GUSTS 110 KT. 64 KT... 15NE 0SE 0SW 15NW. 50 KT... 45NE 30SE 20SW 45NW. 34 KT...130NE 75SE 45SW 130NW. FORECAST VALID 24/1800Z 23.0N 75.5W MAX WIND 95 KT...GUSTS 115 KT. 50 KT... 60NE 40SE 25SW 45NW. 34 KT...160NE 75SE 45SW 130NW. FORECAST VALID 25/1800Z 26.0N 78.0W MAX WIND 100 KT...GUSTS 120 KT. 50 KT... 60NE 50SE 40SW 60NW. 34 KT...160NE 90SE 75SW 140NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 175 NM ON DAY 4 AND 225 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY OUTLOOK VALID 26/1800Z 29.5N 79.0W MAX WIND 100 KT...GUSTS 120 KT. OUTLOOK VALID 27/1800Z 34.0N 79.0W...INLAND MAX WIND 80 KT...GUSTS 100 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 19.5N 68.6W NEXT ADVISORY AT 23/0300Z $$ FORECASTER AVILA Member Since: 6 juli 2010 Posts: 89 Comments: 25142

1780. WxLogic 8:52 PM GMT op 22 augustus 2011
Quoting afwxguy86: It won't be on the 18Z run. The 18Z run is already being completed, it will be in the 00Z run. That's what I though... but got to check just in case they have a buffer window where they can still add additional data before the final product is generated. Member Since: 14 augustus 2008 Posts: 4 Comments: 4666

1781. interstatelover7165 8:52 PM GMT op 22 augustus 2011
10,970m (35,991 ft) -39.5°C (-39.1°F) Now look at that. It is a certain sign of a steadailiy strengthening system Member Since: 18 augustus 2011 Posts: 0 Comments: 871

1782. Titoxd 8:52 PM GMT op 22 augustus 2011
000 WTNT34 KNHC 222051 TCPAT4 BULLETIN HURRICANE IRENE ADVISORY NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011 500 PM AST MON AUG 22 2011 ...IRENE AIMS AT THE BAHAMAS...FORECAST TO BECOME A STRONG HURRICANE... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...19.5N 68.6W ABOUT 215 MI...340 KM SE OF GRAND TURK ISLAND ABOUT 65 MI...100 KM NNW OF PUNTA CANA DOMINICAN REPUBLIC MAXIMUM SUSTAINED WINDS...80 MPH...130 KM/H PRESENT MOVEMENT...WNW OR 295 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES WATCHES AND WARNINGS -------------------- CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY... THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A HURRICANE WARNING FOR THE CENTRAL BAHAMAS AND A HURRICANE WATCH FOR THE NORTHWESTERN BAHAMAS. SUMMARY OF WATCHES AND WARNINGS IN EFFECT... A HURRICANE WARNING IS IN EFFECT FOR... * NORTH COAST OF THE DOMINICAN REPUBLIC FROM THE HAITI BORDER EASTWARD TO CABO ENGANO * TURKS AND CAICOS ISLANDS...SOUTHEASTERN AND CENTRAL BAHAMAS A HURRICANE WATCH IS IN EFFECT FOR... * NORTH COAST OF HAITI FROM LE MOLE ST. NICHOLAS EASTWARD TO THE DOMINICAN REPUBLIC BORDER * NORTHWESTERN BAHAMAS A TROPICAL STORM WARNING IS IN EFFECT FOR... * SOUTH COAST OF THE DOMINICAN REPUBLIC FROM SANTO DOMINGO EASTWARD TO CABO ENGANO * ALL OF HAITI FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 500 PM AST...2100 UTC...THE CENTER OF HURRICANE IRENE WAS ESTIMATED TO BE NEAR LATITUDE 19.5 NORTH...LONGITUDE 68.6 WEST. IRENE IS MOVING TOWARD THE WEST-NORTHWEST NEAR 13 MPH...20 KM/H... AND THIS MOTION WITH A SMALL DECREASE IN FORWARD SPEED IS EXPECTED TONIGHT AND TUESDAY. ON THIS TRACK...THE CORE OF IRENE WILL BE MOVING JUST TO THE NORTH OF THE DOMINICAN REPUBLIC AND HAITI TONIGHT...NEAR OR OVER THE TURKS AND CAICOS ISLANDS AND THE SOUTHEASTERN BAHAMAS ON TUESDAY...AND NEAR THE CENTRAL BAHAMAS EARLY WEDNESDAY. MAXIMUM SUSTAINED WINDS REMAIN NEAR 80 MPH...130 KM/H...WITH HIGHER GUSTS. IRENE IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON SCALE. STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS AND IRENE COULD BE NEAR MAJOR HURRICANE STRENGTH AS IT MOVES OVER THE CENTRAL BAHAMAS. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES...45 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 185 MILES...295 KM TO THE NORTHEAST OF THE CENTER. ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB...29.18 INCHES. HAZARDS AFFECTING LAND ---------------------- WIND...TROPICAL STORM CONDITIONS WILL SPREAD OVER THE NORTHERN PORTIONS OF DOMINICAN REPUBLIC TONIGHT AND LOCALIZED HURRICANE CONDITIONS ARE EXPECTED OVER THE NORTHERN PORTIONS OF THE DOMINICAN REPUBLIC BY TONIGHT AND EARLY TUESDAY. THE HIGHEST WINDS ARE LIKELY TO OCCUR OVER AREAS OF ELEVATED TERRAIN. HURRICANE CONDITIONS ARE EXPECTED TO REACH THE SOUTHEASTERN BAHAMAS AND THE TURKS AND CAICOS ISLANDS TUESDAY...AND THE CENTRAL BAHAMAS BY LATE TUESDAY AND WEDNESDAY. RAINFALL...IRENE IS EXPECTED TO PRODUCE ADDITIONAL RAINFALL ACCUMULATIONS OF 1 TO 2 INCHES ACROSS PUERTO RICO AND THE VIRGIN ISLANDS. RAINFALL AMOUNTS OF 3 TO 6 INCHES ARE EXPECTED OVER NORTHERN HISPANIOLA...WITH ISOLATED AMOUNTS OF UP TO 10 INCHES POSSIBLE OVER HIGHER TERRAIN. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES IN AREAS OF STEEP TERRAIN. RAINFALL ACCUMULATIONS OF 5 TO 10 INCHES ARE POSSIBLE IN THE SOUTHEASTERN BAHAMAS...THE TURKS AND CAICOS ISLANDS AND THE CENTRAL BAHAMAS. STORM SURGE...A STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS ALONG THE ENTIRE COAST OF THE DOMINICAN REPUBLIC. STORM SURGE WILL ALSO RAISE WATER LEVELS BY AS MUCH AS 5 TO 8 FEET ABOVE NORMAL TIDE LEVELS OVER THE SOUTHEASTERN BAHAMAS...AND THE TURKS AND CAICOS...AND 7 TO 11 FEET OVER THE CENTRAL BAHAMAS. NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DANGEROUS WAVES. NEXT ADVISORY ------------- NEXT INTERMEDIATE ADVISORY...800 PM AST. NEXT COMPLETE ADVISORY...1100 PM AST. $$ FORECASTER AVILA Member Since: 28 juni 2010 Posts: 0 Comments: 241

1783. TropicalAnalystwx13 8:52 PM GMT op 22 augustus 2011
No change in strength. Member Since: 6 juli 2010 Posts: 89 Comments: 25142

1784. FranAteMyRoof96 8:52 PM GMT op 22 augustus 2011
Quoting cat5hurricane: Fran sure did do her share of roof eating. indeed Member Since: 3 juli 2008 Posts: 0 Comments: 189

1785. sarahjola 8:53 PM GMT op 22 augustus 2011
Quoting atmoaggie: Weather balloons launched from these locations at 18 Z: (This is unusual and was specifically requested by NHC). what do you think this means? Member Since: 10 september 2008 Posts: 0 Comments: 1291

1786. Tazmanian 8:53 PM GMT op 22 augustus 2011
Quoting 7544: you getting good at this taz thru the years thanks Member Since: 21 mei 2006 Posts: 5088 Comments: 111312

1787. OminousCloud 8:53 PM GMT op 22 augustus 2011
Quoting charlottefl: This is interesting: ~ Trof is lifting out?? Member Since: 16 juni 2010 Posts: 0 Comments: 73

1788. CybrTeddy 8:53 PM GMT op 22 augustus 2011
5pm out, no change. Member Since: 8 juli 2005 Posts: 253 Comments: 20179

1789. TropicalAnalystwx13 8:53 PM GMT op 22 augustus 2011
Member Since: 6 juli 2010 Posts: 89 Comments: 25142

1790. washingaway 8:53 PM GMT op 22 augustus 2011
78hrs. Member Since: 14 juli 2006 Posts: 0 Comments: 1127

1791. Titoxd 8:53 PM GMT op 22 augustus 2011
Disco out: 000 WTNT44 KNHC 222052 TCDAT4 HURRICANE IRENE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092011 500 PM AST MON AUG 22 2011 DATA FROM THE LAST AIR FORCE HURRICANE HUNTER AIRCRAFT AROUND 1700 UTC INDICATE THAT THE CENTRAL PRESSURE WAS STEADY AND THE WINDS HAVE NOT CHANGED DURING THE DAY. SINCE THEN...HIGH RESOLUTION SATELLITE IMAGES REVEAL SOME CONVECTIVE BANDS WRAPPING AROUND A CLUSTER OF DEEP CONVECTION NEAR THE CENTER...SUGGESTING THAT IRENE COULD BE SLOWLY INTENSIFYING. HOWEVER...DVORAK T-NUMBERS ARE 4.0 AND 4.5 WHICH SUPPORTS KEEPING THE INITIAL INTENSITY AT 70 KNOTS. ANOTHER PLANE WILL CHECK THE HURRICANE AROUND 0000 UTC TONIGHT. WITH THE EXCEPTION OF THE DISRUPTION OF THE OUTER CIRCULATION BY THE HIGH TERRAIN OF HISPANIOLA...WHICH PROBABLY WILL SLOW DOWN THE INTENSIFICATION PROCESS DURING THE NEXT 12 TO 24 HOURS...ALL OF THE INGREDIENTS ARE CONDUCIVE FOR IRENE TO INTENSIFY OVER THE NEXT FEW DAYS. THE OFFICIAL FORECAST CALLS FOR IRENE TO BECOME A STRONG CATEGORY 2 OR CATEGORY 3 HURRICANE ON THE SAFFIR-SIMPSON HURRICANE WIND SCALE AS IRENE MOVES ACROSS THE CENTRAL AND NORTHWESTERN BAHAMAS. IN FACT...BOTH THE GFS AND THE ECMWF GLOBAL MODELS INSIST ON MAKING IRENE A LARGE AND STRONG HURRICANE WITH MINIMUM PRESSURES AROUND 945 MB AND 952 MB...RESPECTIVELY. IRENE IS MOVING TOWARD THE WEST-NORTHWEST OR 295 DEGREES AT 11 KNOTS. CURRENTLY...THE MOTION OF THE HURRICANE IS BEING CONTROLLED BY A NARROW SUBTROPICAL RIDGE TO ITS NORTH. HOWEVER...THE FUTURE TRACK WILL DEPEND ON THE DEVELOPMENT OF A LARGE MID- TO UPPER-LEVEL TROUGH ALONG THE EAST COAST OF THE UNITED STATES. THIS PATTERN WILL INDUCE A GRADUAL NORTHWESTWARD AND THEN NORTHWARD TRACK THROUGH THE FORECAST PERIOD WITH A SLIGHT DECREASE IN FORWARD SPEED. THERE IS MORE CONFIDENCE IN THE FORECAST SINCE MOST OF THE TRACK MODELS... WITH THE EXCEPTION OF THE GFDL...HAVE NOW FOLLOWED THE LEAD OF THE ECMWF MODEL. THE GUIDANCE IS NOW IN BETTER AGREEMENT IN TURNING IRENE NORTHWARD ALONG 78 OR 79 DEGREES LONGITUDE. ALTHOUGH IT IS STILL TOO EARLY TO BE CERTAIN...THE GUIDANCE TREND CONTINUES TO LESSENS THE THREAT TO SOUTH FLORIDA BUT INCREASES THE THREAT TO THE CAROLINAS. DO NOT TO FOCUS ON THE EXACT FORECAST TRACK...ESPECIALLY AT DAYS 4 TO 5...SINCE THE MOST RECENT 5-YEAR AVERAGE ERRORS AT THOSE FORECAST TIMES ARE 200 AND 250 MILES...RESPECTIVELY. FORECAST POSITIONS AND MAX WINDS INIT 22/2100Z 19.5N 68.6W 70 KT 80 MPH 12H 23/0600Z 20.1N 70.2W 80 KT 90 MPH 24H 23/1800Z 20.8N 72.5W 85 KT 100 MPH 36H 24/0600Z 21.5N 74.0W 90 KT 105 MPH 48H 24/1800Z 23.0N 75.5W 95 KT 110 MPH 72H 25/1800Z 26.0N 78.0W 100 KT 115 MPH 96H 26/1800Z 29.5N 79.0W 100 KT 115 MPH 120H 27/1800Z 34.0N 79.0W 80 KT 90 MPH...INLAND $$ FORECASTER AVILA Member Since: 28 juni 2010 Posts: 0 Comments: 241

1792. cycleranger 8:53 PM GMT op 22 augustus 2011
18z Surface Wind Analysis Member Since: 1 juli 2008 Posts: 0 Comments: 111

1793. Grothar 8:53 PM GMT op 22 augustus 2011
The 5:00 is out start posting people Member Since: 17 juli 2009 Posts: 56 Comments: 19488

1794. drj27 8:53 PM GMT op 22 augustus 2011
im glad people stop asking if irene was going into the gulf jus saying Member Since: 25 augustus 2006 Posts: 0 Comments: 98

1795. ncstorm 8:53 PM GMT op 22 augustus 2011
track shifted to east.. Member Since: 19 augustus 2006 Posts: 7 Comments: 8324

1796. atmoaggie 8:53 PM GMT op 22 augustus 2011
Quoting WxLogic: Do you believe the 18Z will be able to fully have this data ingested into them or 00Z? Given that they were sent out at 18Z I would assume they wouldn't be available until 00Z. No, they surely are in 18 Z GFS (given it's 3 hour assimilation cycle). Quoting CCkid00: what does this mean? what are they looking for? thanks A better handle on mid and upper level conditions. Better tracking of the trough, etc. Will also give better, more thorough initial condition data to the 06 Z and 18 Z GFS model. (We usually only have this data at 0 and 12 UTC.) And, as GFDL and HWRF use GFS for synoptic initial and boundary conditions, hopefully a better handle on conditions in those, as well. Member Since: 16 augustus 2007 Posts: 6 Comments: 12461

1797. flasooner 8:54 PM GMT op 22 augustus 2011
Quoting atmoaggie: Weather balloons launched from these locations at 18 Z: (This is unusual and was specifically requested by NHC). Methinks the NHC folks have a real bad feeling about this one . . . Member Since: 11 september 2010 Posts: 0 Comments: 21

1798. StarnzMet 8:54 PM GMT op 22 augustus 2011
Drak and MississippiWx do you think the chances are increasing for a US recurve? Personally, I believe the current setup is favoring just that. I'm just waiting on the 00z runs before I give a final judgment. Member Since: 28 mei 2010 Posts: 0 Comments: 47

1799. afwxguy86 8:54 PM GMT op 22 augustus 2011
Is it just me or does it appear on IR/WV imagery that an eye is beginning to form? Member Since: 1 augustus 2011 Posts: 0 Comments: 6

1800. shadoclown45 8:54 PM GMT op 22 augustus 2011
Quoting sarahjola: what do you think this means? It means theres gonna be alot of ufo sitings tonight and better model data Member Since: 27 juli 2008 Posts: 0 Comments: 107

1801. ncstorm 8:54 PM GMT op 22 augustus 2011
Member Since: 19 augustus 2006 Posts: 7 Comments: 8324

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