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Friday, July 15, 2005 |
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...MAJOR HURRICANE EMILY AGAIN STRENGTHENS TO CATEGORY 4...
A HURRICANE WARNING REMAINS IN EFFECT FOR JAMAICA AND FOR ALL OF THE
CAYMAN ISLANDS. At 11 PM EDT the center of Hurricane Emily was at 15.1 North 74.2 West, 265 miles south of Kingston, Jamaica. Movement is to the west-northwest at 18 mph. Maximum sustained winds are 135 mph and minimum central pressure is 954 millibars (28.17"). "Emily has abruptly changed strength again". Observations from the Hurricane Hunter shows that pressure has fallen 15 millibars since 2 PM this afternoon. An Eyewall Replacement Cycle might be set to take place, which would cause a fluctuation in intensity. The forecast, as usual does not try to do the impossible by accounting for these fluctuations. It keeps Emily at 135 mph winds across the Carribean. Heading is set at 285 degrees (west-northwest). The forecast track is adjusted slightly south of the previous one. As model guidance has shifted south, the forecast is now on the northern side of the envelope. Incredible resilience shown by Emily. I had ruled out the possibility of a full come-back entirely. While NHC's forecasters probably weren't quite as absolute, they didn't forecast this come-back either. Oh, the joys of intensity forecasting. Between the satellite outage and what may be a bit more wobbling than usual, it has been hard to discern Emily's course and compare it to forecasts. Right now it does not appear to bust my track expectations. The limited area models shifted their landfall forecast to south of the Rio Grand on their 00Z run, and spread out. As they have been very sensitive to changes in course, they will probably move back north some in the 06Z run No telling whether they will recluster. While the forecast appears to be solid, it is by no means bullet-proof, especially for what would appear to be the second landfall. While the current forecast keeps the worst of the storm south of Texas, it would only take a subtle alteration in course to change that scenario completely. Residents of the Texas coast should be sure to check up on Emily's progress during the weekend. 2005 Hurricane Season, Weather comment []11:49:00 PM  trackback []
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| At 8 PM EDT the center of Hurricane Emily was at 14.9 North 73.4 West, 305 miles southeast of Kingston Jamaica. Movement is to the west-northwest at 18 mph, with this general motion expected to continue for the next 24 hours. Maximum sustained winds are 115 mph and minimum central pressure is 958 millibars (28.29 "). Once again, Emily has outfoxed the forecasters. Just when her chances for intensification are written off, she comes roaring back. The ground station for the GOES 12 satellite (the one that covers the Eastern US and Atlantic)took a lightning strike at about 3:30 this afternoon. For this reason, satellite images from the NHC site are either blank or dated. The problem has been fixed in the past half hour, and people with direct feeds are seeing current data now. It should hit the public feeds soon. Infrared satellite images that can be zoomed in are available from another satellite. 2005 Hurricane Season, Weather comment []8:13:47 PM trackback []
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AT 5 PM AST...2100 UTC...THE GOVERNMENT OF THE CAYMAN ISLANDS HAS
At 5 PM EDT the center of Hurricane Emily was at 14.7 North 72.8 West,
350 miles southeast of Kingston, Jamaica and moving west at 20 mph with
a gradual turn to the west-northwest expected during the next 24
hours. On this path, Emily will pass not far south of Jamaica
within the next 24 hours. Winds are down to 105 mph and pressure
is 969 millibars (28.61").
ISSUED A HURRICANE WARNING FOR ALL OF THE CAYMAN ISLANDS.
A HURRICANE WARNING REMAINS IN EFFECT FOR ALL OF JAMAICA. Based on the last reports of the hurricane hunter and a detoriating image on satellite, Emily's intensity is reduced, and is perhaps generous at the moment. Models are weakening the shear that has been affecting Emily, but there are not indications of that starting to happen. Emily is heading for the part of the Carribean where storms historically intensify and the models insist that upper-level conditions will become more favorable. The intensity forecast is a bit of a compromise between observed action and predicted action; modest strengthening is forecast after 12 hours. Emily's average motion has been slightly north of due west and there have been no signs of a turn to the west-northwest. A gradual turn to the west-northwest, as predicted by the models (but yet to actually materialize) is forecast. Official forecast follows model guidance, but is on the southern side of the envelope. Sigh. After having nice things to say about the forecast this morning, I am back to grumpiness. Pretty much for the same reason I was unhappy on Tuesday... they are going with the model consensus when most of the models have had a bias to the north. A better solution, in my opinion, would have been to favor the NOGAPS and European forecasts, which are a little bit further to the south (and are probably headed further south given Emily's motion today). People in south Texas will want to keep an eye on Emily and be prepared to start taking action if it appears that Emily is turning more solidly in their direction. Also, as I have been harping all week, if you are headed to Cancun/Cozumel this weekend or the beginning of next, you might want to reconsider. 2005 Hurricane Season, Weather comment []5:35:27 PM trackback []
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A HURRICANE WARNING REMAINS IN EFFECT FOR ALL OF JAMAICA.AT 2 PM EDT the center of Hurricane Emily was at 14.5 North 72.0 West, 395 miles southeast of Kingston, Jamaica and moving west at 20 mph with a bend to the west-northwest expected in 24 hours. On this track, Emily will pass near or just south of Jamaica on Saturday. Winds are down to 115 mph and pressure is up to 969 millibars (28.41"). No significant changes are expected today. The coincident timing of the shear and the eyewall replacement cycle have hurt Emily. The last observations from the recon plane before this advisory indicated that her appearance on radar had started to improve and that she had hit a bottom for now as far as weakening goes. Judging by satellite imagery, it appears that the shear from the upper level low to the north of Emily has abated somewhat. However, its damage may be lasting in that Emily has lost the tight organization that it had before this morning. Storms tend not to fully recover from such a change. While Emily may strengthen some, it will probably be gradual, and she may not make it back to category four anytime soon, if at all. I have looked at the forecasts of the global models from Tuesday morning for this morning (i.e. their 72 hour track forecast for Emily). It's a close call, but it looks like NOGAPS offered the best, with the European not far behind. The GFS was a bit off to the north. The UKMET did not do so well, off to the north signficantly. The worst performer, far and away was the Canadian, which forecast Emily to be over the Dominican Republic this morning. Besides being accurate, the European and NOGAPS have also been commendable in that their forecasts have been consistent; they haven't jumped around left and right wildly. Until last night, the European model had been offering a very similar forecast since Monday night, and the NOGAPS was more or less unchanged since Tuesday morning...both had been calling for a landfall between Belize and Cozumel, Mexico. Last night, both models shifted to the north, the European depicted a landfall near Cancun, and NOGAPS kept the center of Emily off the Peninsula. Both had a second landfall in northern Mexico. This morning, their forecasts shifted back towards their early ones. Keeping in mind that past performance, while it may indicate future performance, does not guarantee it, here are the latest outputs from the global models. Southern most is the European model, it has Emily making landfall north of Cozumel on Sunday, with a second landfall in northern Mexico (somewhat away from the border) on Tuesday. Moving north, NOGAPS shows a northern Yucatan landfall on Sunday afternoon/evening with a northern Mexico landfall on Tuesday. UKMET and Canadian are similar with regards to track: Cancun on Saturday, Rio Grande vicinity on Tuesday morning. Finally, the northern outlier at this time, the GFS keeps Emily just off the Yucatan and has landfall in the vicinity of Corpus Cristi on Tuesday morning. Wunderground's model summary shows all of these models, except the European (and at time of posting, the NOGAPS depiction was 12 hours old). So, a landfall on the Yucatan Peninsula is looking increasingly likely. People looking to travel there this weekend will probably want to cancel or reschedule their trip unless they enjoy travelling to a place about to be hit by a hurricane. Further on, people in southern coastal Texas should continue to watch this storm closely and think about preparations if the forecast edges north and has the storm heading their way. Points north and east should check up on her to ensure that something unexpected does not happen. 2005 Hurricane Season, Weather comment []3:31:49 PM trackback []
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| At 11 AM EDT the center of Hurricane Emily was at 14.4 North 70.9 West, 465 miles east-southeast of Kingston, Jamaica and moving to the west-northwest at 20 mph. Winds have fluctuated down to 125 mph and pressure has similarly gone up to 968 millibars (26.59") On its most recent pass through the eye (at 9:30 EDT or so), the recon plane found concentric eyewalls. That is an indication that an eyewall replacement cycle is ocurring at this time. As this causes a (temporary) weakening and the storm and the recon plane hadn't seen category four winds since earlier in the morning, Emily is downgraded to a category three storm. The shear forecasts have reversed themselves and are now showing an unfavorable upper-air enviroment in front of Emily's path. However, Emily is expected to remain a major hurricane as it approaches the Yucatan, however, no re-intensification is expected after she crosses the peninsula. Forecast track is on the southern side of the model consensus because overall, the models to this point have been too far north in their forecasts. Judging by satellite, it appeared an eyewall replacement cycle started at around 6 or 7 this morning (EDT). It has been pretty neat to see the recon observations come in and show the changes that occur with this. While the replacement cycle may be entirely to blame for the weakening, it is possible that Emily is being affected by shear. As mentioned in the discussion and somewhat visible in the water vapor loop , and somewhat apparent in the GFS 200 millibar analysis this morning, there is an upper level low centered north of Cuba. That is putting 15-20 knots of wind in the face of Emily. That is not favorable for strengthening. In earlier posts, I have mentioned the perils of shear forecasting. The reversal of a favorable shear forecast to unfavorable really nails the point home. I had mentioned that if shear were low west of 80 degrees longitude, then Emily could be off to the races as far as intensity goes. That was based on SST and heat content analysis. This morning I found that the historical record supports that idea as well. The box southwest and west of Cuba with boundaries 19.4 North and 20.4 North and 82 West and 87.9 west is home to three of the greatest moments in Atlantic hurricane history. In 1980, Hurricane Allen attained a wind strength of 190 mph. In 1988, Hurricane Gilbert had the lowest pressure ever recorded in the Atlantic basin, 888 millibars. Finally, in 2004, Hurricane Ivan had his record-setting 30 hour stint as a category five. At the moment, it appears that upper level winds will not let Emily do something to join the exalted ranks of that trio of hurricanes. I was really happy when I read the 5 AM discussion. A few days ago I was fuming over how the NHC kept falling for models that were turning the storm prematurely. Right now the forecasters are staying with what the storm is actually doing, moving west/west-northwest as it has for days now, instead of buying into a more northwesterly turn. This is somewhat in defiance of the models, at the latter part of the forecast window, there is only one model west of the NHC's forecast (the ECMWF/"European") and even then it is only slightly to the west. The relevant paragraph: THE INITIAL MOTION ESTIMATE REMAINS 285/17...AS IT HAS BEEN FOR MORE In the time it took me to write this, a recon plane has found that pressure is now 969 millibars and that the eye is yet to become closed again... 2005 Hurricane Season, Weather comment []11:37:08 AM trackback []
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A HURRICANE WATCH IS IN EFFECT FOR JAMAICA AND FOR ALL OF THEAt 2 AM EDT the center of Hurricane Emily was at 13.7 North 68.3 West, 635 miles east-southeast of Kingston, Jamaica and moving to the west-northwest at 20 mph. Maximum sustained winds are up to 135 mph and pressure is down to 952 millibars (28.11"). We haven't seen a truly sharp pressure fall.. just 1-2 millibars per hour, which would be modest. However, when that rate is sustained for hours on end the way it has for Emily, it really amounts to something. The models have shuffled themselves somewhat and have moveded their consensus track to the north. The furthest south of them continues to be the European model, which has Emily hitting the tip of the Yucatan in 3 days and then coming in just south of the Rio Grande in 5 days. NOGAPS has shifted off of the Yucatan track that it had been forecasting consistently since Tuesday morning. It now brings Emily across Jamaica in 36 hours and then around the Yucatan Peninsula and towards Texas, but like the European model, a sharp left turn keeps it south of the Rio Grande. For the first part of the run, the UKMET model is further south than NOGAPS; it keeps Emily south of Jamaica , but after that turns her northwest through the Yucatan channel and has her making a hard left into Corpus Cristi. The GFS brings Emily very close to Jamaica in 36 hours, but keeps her offshore. After turning the storm northwest and moving it over the western part of Cuba, the GFS then turns it to the west for a Corpus Cristi landfall in just less than 6 days (for some reason the GFS has been consistently slower than the other models). http://www.wunderground.com/tropical/tracking/at200505_model.html gives a visual depiction of most of what I have described (it doesn't show the European model ). At this point people in southern Texas should be considering their hurricane preparedness. It has been a while since a significant hurricane has hit the area (Alicia in 1983), so unlike Florida, the area is a bit out of practice. They may want to check out the National Hurricane Center's hurricane preparedness site) to remind themselves (or educate themselves if they are fairly young or new to the hurricane zone) of what steps they should be taking when. 2005 Hurricane Season, Weather comment []2:44:03 AM trackback []
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© Copyright
2005
Charles Fenwick
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Last update: 8/2/2005; 2:00:40 PM .
Last update: 8/2/2005; 2:00:40 PM .
