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Saturday, July 16, 2005 |
| At 11 PM EDT, the center of Hurricane Emily was at 17.5 North 80.3 West, 140 miles south-southeast of Grand Cayman and moving to the west-northwest at 18 mph. Maximum sustained winds are 155 mph and minimum central pressure is 930 millibars (27.46"). Emily has essentially held her strength this evening. There is nothing present that would obviously weaken Emily, so structural changes (i.e. eyewall replacement cycles) should be the only thing that affects her intensity as she completes her Caribbean passage. Current track forecast is very similar to the previous one and is somewhat on the northern side of model guidance. It is too soon to tell if North America landfall will happen in northern Mexico or Texas. Evacuations have begun in the Yucatan Peninsula. Two planes flew 'surveillance missions' to collect upper-air observations to feed into the forecast models to help fill in the gaps that exist in observations over water. In recent years this has significantly helped the models in producing an accurate forecasts. The 00Z models will be closely watched for this reason. While the category five status is a big deal to weather enthusiasts, it doesn't mean that much in practical terms, when compared to the present state. While the extra 5 mph of winds would create additional damage (wind damage from winds at the higher end of the spectrum increases exponentially with increases in wind speed), 155 mile per hour winds create so much damage it is doubtful that the difference can be discerned. The situation is difficult for residents of southern Texas. The forecast currently keeps the hurricane just far enough away to be more of a rain maker than a destructive force to them. However, that forecast is predicated on events that have not ocurred yet and may be altered . The outcome may not be sealed until say, 24 hours before landfall. For this reason, residents of the area should be ready to take action quickly, whether it be evacuating from a low-lying area, preparing their residence for the storm, or purchasing supplies . 2005 Hurricane Season, Weather comment []11:28:25 PM  trackback []
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| The dropsonde that they released in the eyewall found 157 knot winds at the 925 milibar level , which suggests 161 miles per hour at the surface and 168 knots at 850 millibars, which suggests 155 mph at the surface (the reduction is 10% for the 925 and 700 millibar levels, 20% for 850 millibar level). 2005 Hurricane Season, Weather comment []8:28:14 PM trackback []
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| At 8 PM EDT, the center of Hurricane Emily was at 17.1 North 79.5 West, 195 miles southeast of Grand Cayman. Movement is to the west-northwest at 18 mph. Maximum sustained winds remain 155 mph but pressure has fallen to 929 millibars (27.43"). With a pressure one millibar lower than the lowest pressure found in Dennis, Emily is now officially the strongest hurricane ever known to exist in the month of July. It will be interesting to see how the rest of the mission goes. Pressure is nine millibars lower, but wind observations remain the same. Unless the pressure trend reverses itself, we could be in the situation of where the wind observation is behind the pressure observation (i.e. the winds are becoming stronger, but we haven't observed it yet). If the wind is indeed trailing pressure, then Emily will be observed as a category five this mission... we shall see... 2005 Hurricane Season, Weather comment []8:12:05 PM trackback []
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 This satellite image was taken at 6:25 PM EDT. White indicates extremely intense convection. That ring has been spreading around the eye since all afternoon and has almost formed a complete circle around it. This certainly looks like a category five hurricane. We will know for sure about one hour from now... 2005 Hurricane Season, Weather comment []6:43:32 PM trackback []
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| At 5 PM EDT the center of extremely dangerous Hurricane Emily was at 16.8 North 78.8 West, 130 miles south-southwest of Montego Bay, Jamaica and moving to the west-northwest at 18 mph. Maximum sustained winds are 155 mph and minimum central pressure is 937 millibars (27.67"). Emily has continued to strengthen this afternoon. Flight level winds recorded by the Hurricane Hunter supported 155 mph winds. Appearance on satellite has not changed enough to justify an increase. Any change in rated intensity will have to wait until recon goes back in this evening. Emily's heading remains 290 degrees. Forecast reasoning is unchanged. Track forecast remains solid through 48 hours and somewhat murky after that. Model guidance is pretty much unchanged, except for the UKMET model, which shifted its second landfall point to just south of the Rio Grande. The track forecast is an extension of the previous one in the short term, and is slightly south of the previous one after that. The intensity forecast is very problematic as one model indicates shear that doesn't seem to actually exist. A particular method of determing maximum possible intensity suggests that Emily has reached her peak. However, "it would not be a surprise if Emily became a category five hurricane for some part of the next 24 hr". Emily is expected to weaken when she passes over the Yucatan but still be a major hurricane afterwards. Emily is about to cross into that area that I've been discussing where the Sea Surface Temperatures are the warmest (west of 80 degrees longitude). The current forecast takes her south of the zone that I had been describing in previous posts. I have put up a map with a somewhat rough depiction of that 'danger zone', where Allen had 190 mph winds, Gilbert had a pressure of 888 millibars, and Ivan spent 30 hours as a category five. The forecast keeps Emily just a little bit south of that box. However, that area is by no means the only area where a storm can attain category five status, Ivan and Allen both did so in other parts of the Caribbean as well. Will Emily extend that box of records by becoming the first category five in the month of July? We shall see. The recon plane is on his way. At 5:15 or so, it was about 670 nautical miles away. It should not have much problem reaching the center of the storm by 7:30 PM EDT. I will be watching this mission closely and if I see something before the 8 PM advisory, I will post it here, otherwise I'll just post the 8 PM advisory... 2005 Hurricane Season, Weather comment []5:30:29 PM trackback []
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| At 2 PM EDT, the strongest hurricane ever(more accurately, the hurricane with the higest winds, see note below) in the month of July, the extremely dangerous Hurricane Emily, was at 16.4 North 78.0 West, 135 miles southwest of Kingston, Jamaica and moving to the west-northwest at 18 mph . Maximum sustained winds are 155 mph and minimum central pressure is down to 937 millibars (27.66") . The most recent (and unfortunately last one until tonight) observations from the northeast quadrant had flight level winds of 151 knots, which suggests a surface wind of 156 mph, which is category five strength. However, the practice is to round to the nearest multiple of five, so intensity was set at 155 mph winds; as close as you can get to category five. Also, the pressure is on the high side for a category five. However, with Emily being a smaller than normal storm you would expect pressure to be higher than usual for the corresponding wind strength (it is the gradient (the rate in decrease in pressure over a distance) that matters, a small storm at a given pressure has a greater gradient than a larger storm at the same pressure). The drop in pressure was 3 millibars in 2 hours, so 1.5 mb per hour. Unless an eyewall replacement cycle begins very soon, Emily will be a category five hurricane, but it will probably take actual observations for NHC to rate it as such; after all the last set of satellite estimates underrated her by 5 mph. The earliest a hurricane has ever gone Category five in the Atlantic is August 7, when Hurricane Allen did so in 1980. Allen's track was a little bit different different than the one Emily has taken and will take. However, as I've been saying, Emily will go through a similar earlier of warm deep water that could help her strengthen further. Right now there don't seem to be structural limitations to her ability to intensify. Only shear and eyewall replacement cycles will hold her down. NOTE: Premature in calling it the strongest of the month of July, my apologies, I got a bit excited.. NHC rates intensity by pressure, and Dennis' lowest recorded pressure was 930 millibars, so Emily is not there yet...if the pressure falls were to continue unabeted, she would be there by the time the next recon plane got there. However, it seems more likely that an eye-wall replacement cycle would occur between now and then, so it may be a while, (if it all) before Emily overtakes Dennis... 2005 Hurricane Season, Weather comment []2:12:54 PM trackback []
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| At 11 AM EDT the center of dangerous Hurricane Emily was at 16.2 North 77.3 West, 130 miles south-southeast of Kingston, Jamaica and moving to the west-northwest at 18 mph. Maximum sustained winds are up to 145 mph and pressure has fallen to 943 millibars (27.85"). UPDATE: Winds upgraded to 150 mph because pressure has fallen to 940 millibars Two disconcerting things: As I have mentioned in the past couple of days, Sea Surface Temperature Analyses the warmest waters are west of 80 degrees longitude. Relatively to the water she is about to enter, Emily is in cool water. Also, the waters are warmer deeper than they are in, say, the eastern Gulf of Mexico. The shallowness of the warm water is what kept Dennis' intensity at 145 mph and later caused him to weaken. The second thing worrisome thing is the shear analysis. It shows that upper level winds are becoming more favorable for Emily to maintain or increase her intensity. So, Emily is heading into the best spot of the Atlantic basin with favorable conditions. To repeat what I said yesterday: 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. The current forecast brings Emily into this box. Emily doesn't need to knock on the door of category five. As things appear now she can walk on in. While the near-term forecast is looking very strong, the uncertainty in the latter period justifies Texans continuning to monitor Emily's progress and be ready to take action quickly if the forecast shifts suddenly. 2005 Hurricane Season, Weather comment []12:39:42 PM 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 .
