Hurricane Irene pounds Puerto Rico, heads for Hispaniola

By: Dr. Jeff Masters , 2:40 PM GMT on August 22, 2011

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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 hits Puerto Rico
Tropical Storm Irene from Maunabo, PR (ronmil)
The first bands or Irene approaching Maunabo, Puerto Rico (SE corner)...
Tropical Storm Irene from Maunabo, PR
Irene (reefchild)
Irene @OPkB OceanParkBeach Puerto Rico 7pm
Irene

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NWS in Wilmington, NC has not updated their long term discussion since 3pm Sunday..thats comforting..
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What are the chances of Irene's eye skirting the north coast of Hispaniola?
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Irene and her anticyclone are starting to dance again.
Member Since: July 11, 2006 Posts: 14 Comments: 11288
Quoting NICycloneChaser:


Not sure why you think you see W movement when recon is in and finding the centre to be continuing to move WNW.


He said a jog west not a change in direction. Looks like a wobble.
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Quoting tiggeriffic:


hey ya press...so...whatcha think of this one eh? channel 5 says heading to Edisto...bad for us...


We're dead in the landfall crosshairs now. It'll change. Always does. Would not be surprised if this ends up being a OBX hit instead. Nevertheless, I am prepared.
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Quoting Orlando11:
p451 I agreed with you all day yesterday but the storm, not any features, clearly jogged to the WSW. It's just a jog, no big deal. take it easy man.

I agree with the SC landfall/NHC forcast btw.


It's just ridiculious...One day it's Florida next it's south carolina...the NHC really need's to fix there errors.
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Thnx Levi for the update. For a nonweather person, which I am, it's very easy to understand and follow along especially with all weather charts shown
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529. DFWjc
Quoting NICycloneChaser:


Not sure why you think you see W movement when recon is in and finding the centre to be continuing to move WNW.


Looking at the wobble on the radar, seems to me it's moved west for 2 frames...
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Quoting thedawnawakening3:
Crap, Sumter, SC is in the bullseye, not good, or good depending upon what it means to you. I actually may get to experience a category three hurricane for the first time in my life. I lived on Cape Cod, MA for 21 years, my first year in South Carolina, stationed at Shaw AFB.


live 5 news is saying Edisto Beach...that is worse for us in the Charleston area...would rather have the eye than it hit to the south like that
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Quoting Neapolitan:


Sorry, but no. Much as some might wish it were otherwise, unless Irene inexplicably dies or curves harmlessly out to sea, she will almost certainly become the nation's tenth weather disaster of 2011. In case you're wondering, here are the first nine:

1) Upper Midwest Flooding, Summer, 2011
2) Mississippi River flooding, Spring-Summer, 2011
3) Southern Plains/Southwest Drought, Heatwave, & Wildfires, Spring-Summer, 2011
4) Midwest/Southeast Tornadoes, May 22-27, 2011
5) Southeast/Ohio Valley/Midwest Tornadoes, April 25-30, 2011
6) Midwest/Southeast Tornadoes, April 14-16, 2011
7) Southeast/Midwest Tornadoes, April 8-11, 2011
8) Midwest/Southeast Tornadoes, April 4-5, 2011
9) Groundhog Day Blizzard, Jan 29-Feb 3, 2011



actually tornado season has been insane this spring/summer....i have been working wind/hail/tornado claims from massachusetts of all places......pounded from boston to springfield and back again north and south. i saw total losses in sturbridge and other places....it's been a crazy year for conus so far.


there have been tornadoes and straight line (microburst) damage all over the place....Chicago has been pounded hard too several times over the past few months.
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Quoting thedawnawakening3:
Crap, Sumter, SC is in the bullseye, not good, or good depending upon what it means to you. I actually may get to experience a category three hurricane for the first time in my life. I lived on Cape Cod, MA for 21 years, my first year in South Carolina, stationed at Shaw AFB.



oh man...I have tons of family around Sumter.....you should avoid them at all costs...
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Some of the most important words in NHC latest discussion on Irene


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.

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it still seems that the trough will be pretty strong; however, I remember Rob Lightbown from Crown Weather indicating a few days back (when all the tracks were for west florida) that he thinks the models are overdoing the strength of the troughs and not giving enough respect to the High pressure

anyhow, if the models have latched onto this correctly, Florida may have (again I say may have not has been) really dodged a major hurricane bullet

thank god
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i think someone state earlier hisanoilias a tc magnet,wouldnt b suprised if she hugs the coastline keeping her in check thru 24hrs
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What will the nhc do at 3?
A.85mph
B.100mph
C.110mph
D.TS
E.Higher/Lower
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Quoting JimboUSMC17:
I do agree its general motion is WNW, however that little jog to the West is plain as day to see. Can't deny that. I just don't understand why there are still 2 models insisting it hits S. FL. I live in S. FL and am really not too concerned. Can it change its course? Sure it can, but I think by tomorrow we will have a better idea obviously. I do also think we may get a Hurricane watch tonight at some point unless it starts its turn NW much earlier.


Not sure why you think you see W movement when recon is in and finding the centre to be continuing to move WNW.
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520. DFWjc
Quoting thedawnawakening3:
Crap, Sumter, SC is in the bullseye, not good, or good depending upon what it means to you. I actually may get to experience a category three hurricane for the first time in my life. I lived on Cape Cod, MA for 21 years, my first year in South Carolina, stationed at Shaw AFB.


Do you think the old Fort can hold up to Cat 3 winds? LOL
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No its dry air impacting the NW side of her circulation. Dry air is caused by subsidence associated with the trough of low pressure she is running up against.
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If Irene stays just off land several states will have hurricane conditions. That is possible.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
Anyone know why they dont initialze a storm at its current MB? they always seem to start off higher than they are. least for the gfs.
TIA
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goes floaters show her blowing up faster than a balloon on a helium tank at the circus......
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Crap, Sumter, SC is in the bullseye, not good, or good depending upon what it means to you. I actually may get to experience a category three hurricane for the first time in my life. I lived on Cape Cod, MA for 21 years, my first year in South Carolina, stationed at Shaw AFB.
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Quoting presslord:


hey ya press...so...whatcha think of this one eh? channel 5 says heading to Edisto...bad for us...
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Correct and I'm expecting further deterioration of the southern quadrant (specially) due to land proximity.



I totally agree. IMO I see the track shifting West with the 11pm update this evening.
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Quoting cat5hurricane:

I think you mean the globe's tenth billion-dollar disaster. The Earthquake and Tsamuni were in Japan.


Sorry, but no. Much as some might wish it were otherwise, unless Irene inexplicably dies or curves harmlessly out to sea, she will almost certainly become the nation's tenth weather disaster of 2011. In case you're wondering, here are the first nine:

1) Upper Midwest Flooding, Summer, 2011
2) Mississippi River flooding, Spring-Summer, 2011
3) Southern Plains/Southwest Drought, Heatwave, & Wildfires, Spring-Summer, 2011
4) Midwest/Southeast Tornadoes, May 22-27, 2011
5) Southeast/Ohio Valley/Midwest Tornadoes, April 25-30, 2011
6) Midwest/Southeast Tornadoes, April 14-16, 2011
7) Southeast/Midwest Tornadoes, April 8-11, 2011
8) Midwest/Southeast Tornadoes, April 4-5, 2011
9) Groundhog Day Blizzard, Jan 29-Feb 3, 2011
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Quoting thedawnawakening3:
Dry air is restricting her outflow to the northwest now, but the southern outflow channel is beginning to get started. Convection while isolated is beginning to develop again on the southern side of Irene's coc. You can see on IR that the cirrus outflow is beginning to ignite thunderstorms as storm relative wind shear begins to develop these isolated in nature convective cloud tops. Her convective core structure remains intact and latest 1615utc imagery suggests she is ready to intensify once again as she tries to dispell the dry air intrusions. Hispaniola will likely interfere with development of the southern outflow channel over the next 12 - 24 hours.


It's not really dry air preventing outflow to the northwest, it's pushing up against the trough somewhat. Certainly has some dry air problems around the core though. Shouldn't take too long to mix out.
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Quoting quakeman55:

I too wonder about the GFS's depiction of the strength of the trough. About mid last week, the GFS was showing a HUGE trough over the East that would certainly have brought a fall-like weather pattern with people breaking out light jackets in the Ohio valley and temps here in Nashville likely being in the 70s day/50s night. Just a couple days afterwards though, that trough retrograded back to the north and now isn't nearly as strong. So I'm thinking the strength of the trough shown on the GFS needs to be taken with a bit of a grain of salt.


Agree, It's not uncommon for some models to be too agressive with the depth of the troughs this time of year heading into Fall. We have seen cases all Summer of troughs lifting out flatter than forecast due to the Bermuda high.
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If ya rolled the gfs up even further we would be up to the M. storm grain of salt..
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Quoting KEEPEROFTHEGATE:
09L/H/I/C1
MARK
19.30N67.89W






ALWAYS FOLLOW NHC/TPC FORECASTS FOR ALL WARNINGS REGARDING THIS STORM


i'd much rather listen to a bunch of weather weenies on a blog
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Quoting Patrap:
San Juan
TDWR High Definition Radar


Southwest movement?? I've seen this before and I'm worried it might be happening again. One storm (forgot the name) moved almost exactly parallel to the north yucatan peninsula a number of years ago, and due to land friction on the south side was "dragged" onshore, weakened and stalled over land. It's like if one wheel of your car goes off the road into deep gravel or something... your whole car will go in. Have to hope this doesn't happen to haiti... even though that would mean a weaker storm or possibly even missing the SE coast (if it stalled over hispaniola). Just a possibility, not saying it WILL happen, and I might just be seeing things because it's moving out of radar range.
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Look at the cones; not the dots.


Updated regularly.
You can click on "Severe Weather" on the top of WU page, then click on Tropical and Hurricanes" and the projected path, models, storm plots come up.

You can get the NHC discussions and public advisories by going to this link.

LinkNHC
Member Since: July 11, 2006 Posts: 14 Comments: 11288
Quoting overwash12:
Look at the history of hurricanes in this position. There needs to be a big high to the northeast for this to go to Florida. We have none.
The Atlantic Basin high is the high pressure that will build behind the first trough.

It is east of bermuda.

Follow post 453 and watch the high build to the west.
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Thank you to all of those who continue to raise my level of knowledge year after year. I have been a paid member for only a few years, but I have been free and lurking for a long time. I continue to appreciate you sharing your knowledge. I am sure it gets frustrating at times.
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I do agree its general motion is WNW, however that little jog to the West is plain as day to see. Can't deny that. I just don't understand why there are still 2 models insisting it hits S. FL. I live in S. FL and am really not too concerned. Can it change its course? Sure it can, but I think by tomorrow we will have a better idea obviously. I do also think we may get a Hurricane watch tonight at some point unless it starts its turn NW much earlier.
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Dry air is restricting her outflow to the northwest now, but the southern outflow channel is beginning to get started. Convection while isolated is beginning to develop again on the southern side of Irene's coc. You can see on IR that the cirrus outflow is beginning to ignite thunderstorms as storm relative wind shear begins to develop these isolated in nature convective cloud tops. Her convective core structure remains intact and latest 1615utc imagery suggests she is ready to intensify once again as she tries to dispell the dry air intrusions. Hispaniola will likely interfere with development of the southern outflow channel over the next 12 - 24 hours.
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I expect Irene to struggle a little through this evening and into tonight due to proximity to Hispaniola, though I don't think she'll lose much strength, as her centre should remain offshore. I expect real strengthening to begin tomorrow morning.
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Irene looking a little rough, could result in a little less N in her travel if she stagnates or deteriorates a little while interacting with Hispaniola. Remember Emily was stubborn as hell about making her Northward turn, be interesting to see if that is going to become a trend.
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Quoting zoomiami:


If the Irene weakens as it comes across Hispaniola, will that affect the track much? Obviously the further west it goes, the worse for Florida.

But I guess the question is if the troughs that will lift Irene north will have the same affect if it weakens coming across the island?

Thanks! good to see you


Well it would have a tendency to go farther west but it would still want to move more poleward. This is a deep-layered weakness.
Member Since: October 28, 2006 Posts: 57 Comments: 30251
Quoting P451:


I hear ya.

As to what you see it doing right now that's not a course change it's in response to the blob of convection rotating around the system.

What is occurring will be short lived. You may even see the eye slow down in imagery. That's not the storm slowing down that's the force exerted by the blob.

Then you will see what would appear to be a momentary northward wobble followed by a resuming of the WNW motion.

In the end, the storm has continued, and will continue, on it's WNW motion.

When you look back several hours from now at a long duration satellite loop what you'll see is a steady WNW motion with a seemingly slightly displaced blob of convection rotating around the surface center.

This scenario has played out with Irene before she was even classified. It's just a part of her structure that has not changed. It is also being emphasized a bit more by land interaction.


Yet, through it all, the course has been and will continue to be WNW.

What IS the "Blob"?
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Quoting Drakoen:
Irene doesn't look to great on satellite imagery. Multiple outflow boundaries advecting off to the west. The northerly and northwesterly inflow is beginning to back up against the terrain of Hispaniola. The gap between her llc and the outer rainbands is primarily due to dry air.


Correct and I'm expecting further deterioration of the southern quadrant (specially) due to land proximity.
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Quoting InTheCone:
Gfs has Moe, Larry and Curly rolling along later in the run - LOL!




180 hrs - just for fun!
That is very interesting.
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Quoting Ryuujin:


That's what Levi was talking about in his tidbit. He also mentioned that as soon as she clears away from Hispaniola, then she'll start her true strengthening phase, which I tend to agree with.


Really? LOL
Member Since: October 28, 2006 Posts: 57 Comments: 30251

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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