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Thursday, July 07, 2005 |
A HURRICANE WARNING REMAINS IN EFFECT FOR THE LOWER FLORIDA KEYS At 11 PM EDT the center of Hurricane Dennis was located at 19.9 North 77.6 West, near Cabo Cruz, Cuba and moving to the northwest at 15 miles per hour. Winds are up to 135 miles per hour and pressure is estimated to be 950 millibars (28.05"). This makes Dennis a category four hurricane. Wind and pressure estimate is based on a combination of a hurricane hunter observation from early this evening and the hurricane's appearance on satellite. Forecast track is essentially the same through the first 36 hours, after that it is shifted slightly to the left (west). Intensity forecast is very troublesome because of the number of variables in play such as how Dennis will come out from Cuba. Their guidance on whether Dennis intensifies is split in two extremes; their forecast, which brings Dennis back up to category three strength before landfall is a compromise. The game of the day was to stare at the water vapor loop and try to divine how the ridge was shifting, if it was at all (the ridge takes an appearance of clockwise spinning. This afternoon and evening it was apparent as kind of an oval across Florida from southwest to northeast.) If the ridge were weakening or moving offshore to the northeast, then it would leave Dennis free to travel more or less due north. If the ridge were steady, then Dennis would get turned to the west soon and then travel northwest once it reached its outside edge. If the ridge were strengthening then the prospect of landfall in Louisana would increase. Today, National Weather Service offices in the southeast took soundings every six hours (i.e. twice as frequently as they usually do) to help forecasters gauge what was going on in the upper atmosphere. Also NOAA had one plane in the Gulf of Mexico and another in the Atlantic/Carribean taking numerous observations to help draw a complete picture. As indicated in the discussion, they found the ridge to be more or less steady. This makes the prospect of the up-the-coast scenario offered by the Canadian model just about impossible, short of something fairly dramatic happening to the ridge. It will be interesting to see if and how the forecast models change in reaction to this copious amount of data that they are being fed tonight. 2005 Hurricane Season, Weather comment []11:34:37 PM  trackback []
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A TROPICAL STORM WATCH IS IN EFFECT FOR ALL OF THE SOUTHERN FLORIDA The pause in strenghening lasted for about an hour; the next hour featured modest strengthening. This past hour featured another round of explosive intensification as the pressure fell four millibars. It appears that it is going to go west of the highest mountains on the peninsula that I mentioned earlier. After that, it is a relatively flat area along Dennis' path. At current course and speed, Dennis will be overland for about six hours, which should get winds back down to category two or so. 2005 Hurricane Season, Weather comment []8:02:43 PM trackback []
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| At 5 PM EDT the center of major Hurricane Dennis was at 19.0 North 76.6 West, 90 miles southeast of Cabo Cruz, Cuba. Movement is to the northwest at 15 mph. Winds are up to 115 mph and pressure has fallen to 957 millibars. Hurricane force winds extend up to 45 miles away from the center and tropical storm force winds extend up to 140 miles away. Pressure has been falling at an average rate of 1 mb per hour since this morning. Eye is 9 miles in diameter and the eyewall is now closed. Dennis is expected to weaken as it passes over Cuba, but is forecast to regain its strength despite what may be less hospitable upper air conditions. The key to the track forecast is the positioning of the edge of a subtropical high pressure ridge. The models are disagreeing on how it weakens or strengthens, therefore they are in disagreement with the track of Dennis. Forecast track is shifted ever so slightly to the right Strengthening may have taken a break as the pressure increased 1 millibar between hurricane hunter fixes this afternoon (it can be argued though, that the hurricane may have missed the precise spot of lowest pressure). The key question in the short term is how passing over Cuba will affect Dennis. At the moment, it appears that he is headed for a fairly rugged part of Cuba, with mountains reaching up to 3000 feet. (See http://www.posolstvo-cuba.ru/cuba/cuba-map-relief-big.jpg . I am refering to the area marked Granma, that is west of Guantanmo ) . However, if Dennis were to bounce off that peninsula to the west and proceed northwest, he would have a fairly short overland trek over low lying land (say, west of Camaguey). To the west of that is more rugged terrain. Mountains would weakn Dennis significantly as would significant time overland (which could happen if Dennis took an oblique approach to the island, nearly paralleing the coast's south-east to northwest orientation). A quick look at some media reports: Key Tourists ordered to evacuate; residents may be told to leave (Miami Herald) Visitors to the Florida Keys were ordered to leave immediately this afternoon as Monroe County emergency management officials debated whether to urge residents to leave the Lower Keys if Hurricane Dennis continues to strengthen. No decision was expected on a possible resident evacuation until late today or early Friday...
Evacuation orders could come Friday (Pensacola News Journal) Do it now: Decide where you want to be if Hurricane Dennis strikes the Panhandle within the next week, and be ready to leave as early as Friday if you reside in an evacuation area. That's the advice given by emergency management officials in Santa Rosa and Escambia counties if Hurricane Dennis continues to track toward the Pensacola area. Forecasters expect Dennis to develop into a strong Category 2 hurricane, and perhaps a Category 3 (major) hurricane in the Gulf of Mexico by the weekend. Pensacola-area officials said they would waste no time issuing early evacuation orders to compensate for several road construction projects and limited routes out of the area. "We're going to be very conservative with our evacuations because of the time it's going to take because of roadway construction," said Escambia County Public Safety Director Janice Kilgore. "If evacuation orders are issued, people need to be ready to act."... Officials: Prepare now for Hurricane Dennis (Tallahassee Democrat) State emergency-preparedness officials urged Panhandle residents to get hurricane supplies and make evacuation plans now for Hurricane Dennis, the season's first hurricane. State meteorologist Ben Nelson and Craig Fugate, director of the Division of Emergency Management, said voluntary evacuation plans were implemented at noon for the Florida Keys. They said the Federal Emergency Management Agency is positioning supplies and search-and-rescue teams along Florida's east coast and in Alabama, ready to move in when they know where the storm is likely to hit... 2005 Hurricane Season, Weather comment []5:24:42 PM trackback []
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| Hurricane hunter recently found a minimum central pressure of 956 millibars. That was only one hour after they had found the pressure to be 962 millibars. That is a staggering drop in one hour. That combined with the 118 mph hour flight level winds found on the last pass means that Dennis almost certainly will get classified as a category three storm in the 5 PM advisory. 2005 Hurricane Season, Weather comment []3:23:15 PM trackback []
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| At 2 PM EDT the center of Hurricane Dennis was at 18.6 North 76.1 West, 65 miles northeast of Kingston, Jamaica. Movement is to the northwest at 15 mph. Winds are up to 110 miles per hour and pressure has fallen to 962 millibars (28.41"). Wind speed and pressure are based on very recent observations from a hurricane hunter. The spread between forecast models at this point in time is mildly disconcerting. On the western edge are the UKMET and ECMWF models, which bring Dennis to Louisana on Monday. On the eastern edge is the Canadian model, which brings Dennis to the Keys on Friday night. In between, NOGAPS puts Dennis in Pensacola on Sunday, while the GFS opts for Appalachicola on that day. At this time, I have not seen anything to change my thinking on the probable landfall area of Dennis. Again, I am considering the highest probability to be from Mobile to St Mark's (Wakulla County), FL. My expanded area of watch extends west to New Orleans and east/southeast to Tampa. I continue to think that the scenario offered by the Canadian model is unlikely, but I am not prepared to offer a definitive argument as to why that is the case. Of course, everyone's ultimate source for forecasts for planning purposes should be the National Hurricane Center and their local National Weather Service office. 2005 Hurricane Season, Weather comment []2:25:48 PM trackback []
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| Given the title of this blog,I would be remiss to not post one of the first images of Dennis with a distinct eye 
2005 Hurricane Season, Weather comment []12:28:01 PM trackback []
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AT 11 AM EDT...A HURRICANE WATCH IS ISSUED FOR ALL OF THE FLORIDA At 11AM EDT the center of Hurricane Dennis was at 18.0 North 75.6 West, 80 miles east of Kingston, Jamaica and moving northwest at 13 mph. Maximum sustained winds 105 mph and pressure is 968 millibars (28.59") Satellite data and fixes from reconnaisance aircraft indicate that Dennis is moving to the northwest, a rightward turn from his previous west-northwest motion. It appears that some forecast models forecast to strong of a ridge north of the storm in their earlier runs. Last night they were fed data from the enviroment collected by a NOAA Gulfstream-IV jet. This has caused them to reevaluate the ridge in a more accurate fashion. As a result those models have shifted their track to the right (east). The official forecast track is shifted accordingly. Intensity forecast is more or less unchanged, conditions remain favorable for development with the only wildcard being how Dennis handles his trip over Cuba. Note that the hurricane hunter returned to base after the 8 AM advisory. Next plane is scheduled to be on station at 1 PM and should be able to provide data for the 2 PM advisory. Having just woken up (after going to bed after seeing the results of the 06Z GFS model run, which wasn't out until after 6 AM), I haven't seen much of the storm in the past few hour, nor what the situation is weather-wise over land in the U.S. With that caveat, my basic idea on where Dennis is unchanged. In my 11 AM updated yesterday I set my unofficial watch points to be from New Orleans to Tampa and my warning points from Mobile, Alabama to Wakulla, FL. When I was doing this, I was thinking in terms of landfall managed to overlook the thought in my head that Dennis could brush the Gulf coast of Florida closely. Because of that possibily, I now extend my watch area south to the Florida Keys. Again, with the caveat that I have not looked at the most recent data, I think the forecast track of the National Hurricane Center has the potential to shift to the right some more; after all they have to maintain continutity with their forecast, that is, they can only shift it so much from one advisory to the other. While I am personally not expecting it at this time, residents of southwest Florida should be prepared for the possibility of Dennis running up the coast, putting hurricane force winds onto land. Those preparations should be made today. It should be supply and provision shopping day for residents of the Gulf coast from Mobile to the Big Bend of Florida. With landfall forecast for Sunday, people living in that area should have tomorrow reserved for getting their homes ready, etc; not standing in gargantuan lines at Wal-Mart and Home Depot. People living west of Mobile should maintain close watch on this storm as it is not yet certain that those areas are in the clear. 2005 Hurricane Season, Weather comment []11:51:38 AM trackback []
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| At 5 AM EDT the center of Hurricane Dennis was 17.0 North 74.6 West, 160 miles east-southeast of Kingston, Jamaica. Movement is to the west-northwest at 15 mph. Winds are up to 90 mph and pressure is down to 970 millibars (28.64") Organization continues to improve. An eye is seen intermittently on satellite images. Wind intensity was based on a flight level wind observation of 87 knots from the hurricane hunter. Forecast track follows model consensus and FSU superensemble. Intensity forecast is unchanged. Minutes after completing its first pass through the hurricane and fixing the center, the plane found winds at the 850 millibar level to be 96 knots (that observation was just minutes too late to get into the advisory package). To approximate surface winds, we deduct 10%, which gives us 87 knots. Multiply by 1.14 and we get 99 miles per hour. Based on that, it wouldn't be surprising to see a significant jump in wind speed at the 8 AM intermediate advisory. 2005 Hurricane Season, Weather comment []5:03:00 AM trackback []
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© Copyright
2005
Charles Fenwick
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Last update: 8/2/2005; 2:00:34 PM .
Last update: 8/2/2005; 2:00:34 PM .
