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Friday, July 08, 2005 |
| At 11 PM EDT the center of Hurricane Dennis was at 23.0 North 82.1 West, 20 miles east of Havana, Cuba. Movement is to the northwest at 14 miles per hour. Maximum sustained winds are down to 100 miles per hour. Hurricane force winds extend up to 65 miles away from the center. Minimum central pressure is up to 962 millibars (28.41") Hurricane Dennis Advisory Number 18 (National Hurricane Center)
Key West radar
indicates that the eye structure of Dennis has degraded some, although
a tight inner core is still suggested. Wind speeds were based on
an estimate from doppler radar; not the method of choice, but it has to
do for now. Because of that, there could be a larger than normal
amount of error in the estimation of wind and pressure. Basic
reasoning behind the track forecast is unchanged; Dennis is expected to
travel around the periphery of an expanding ridge of high
pressure. Track model guidance is tightly clustered with their
spread ranging from southeastern Lousiana to the Florida
panhandle. Forecast track
is shifted ever so lightly to the left; it brings a category three
hurricane to Pensacola on Sunday afternoon. Intensity forecast
brings Dennis back up to category three strength, there remains a
possibility of getting up to category four before weakening prior to
landfall. The NHC has set a Tropical Storm warning from north of the Florida Keys to Tampa A Tropical Storm Watch extends north from there to the northeast corner of the Gulf of Mexico. A Hurricane Watch is set from there westward to Louisana. A Tropical Storm Watch is in place for southeast Louisana. This is pretty close to the unofficial watch earlier that I forecast earlier, with the only exception being that I had dropped the area east of St Mark's FL from my own; NHC is being a touch more conservative. I suspect they will also be a little bit more conservative than I am with my warning areas when they set the official warnings tomorrow (mine runs from Mobile east to Appalachicola). As noted in the forecast discussion, Dennis appears to have maintained his central organization; this is key to his potential for redevelopment. The area immediately north of Cuba features very warm temperatures and a low shear enviroment. Previously I had expected Dennis to get back up to strong category four strength; this was based on an assumption of Dennis leaving Cuba at 125 mile per hour strength. For now, I'll back down only slightly in my intensity forecast; expecting Dennis to get back up to minimal category four strength in the near term and landfalling as a strong category three (130 mile per hour winds). I bring Dennis down in landfall strength on the basis of the prospect of a less favorable upper air enviroment as he heads north. If you live between Mobile and Appalachicola and you haven't started preparing, turn to, immediately, especially if you live in the immediate vicinity of Pensacola. 2005 Hurricane Season, Weather comment []11:49:20 PM  trackback []
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URGENT - IMMEDIATE BROADCAST REQUESTED LATER: However, an hour before I noted this (9:18 PM EDT), there was a tornado warning posted for Miami-Dade County (based on Doppler radar); at the very least there was a severe thunderstorm; Hog On Ice in Coral Gables reported rough weather and losing power. It is a bit disconcerting that the Tornado Watch from the Storm Prediction Center in Oklahoma trailed the Warning from NWS Miami by half an hour. MUCH LATER: My apologies to the SPC... Tornado Watch 625 issued in the afternoon put up a watch for southern Florida, including Miami-Dade. The watch I posted to be here, (which I mistakenly thought to be brand new) was a northern extension of the previous one. They were on the ball. I, however, was behind the curve. 2005 Hurricane Season, Weather comment []10:21:28 PM trackback []
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| At 2 PM the center of Hurricane Dennis was at 22.1 North, 80.6 West, near Cienfuegos, Cuba and moving to the northwest at 17 miles per hour. Winds are down to 145 mph and pressure is up to 941 millibars (27.79") Hurricane Dennis Intermediate Advisory Number 16A
Well, the forecast models, while not in stellar agreement with each other, are reasonably close.Official Track forecast of National Hurricane Center 
Not shown here is the Canadian model. After making a dramatic shift this morning, moving its landfall prediction to Mississippi, it has shifted somewhat eastward bringing landfall to Alabama, instead. I have a significant gripe with its 12Z run. It placed Dennis about half a degree too far west at its initialization. That sort of error can yield a major error at the end of 72 hours. So based on the models and my own observations, I am narrowing my 'warning' area (assume that the hurricane is heading for you area) to cover Mobile, Alabama to Appalachicola , Florida. My 'watch' area (be on the lookout for a change that brings the storm your way) is from Mobile to New Orleans. Also, I would advise coastal residents from Fort Myers south to the Keys of a possibility of hurricane force winds if Dennis makes a tighter than expected curve when it enters the Gulf of Mexico. Intensity forecast is hopelessly tricky. One has to guess what the effects of land are going to be on Dennis directly as well as what effects it will have on its overall organization (which would affect Dennis' ability to restrengthen). A guess of Dennis' strength when it exits Cuba is 125 mph. There it will find exceptionally favorable Sea Surface Temperatures, which will help it recuperate. Those favorable temps cool down slightly the further Dennis gets away from the Gulf coast. In the upper atmosphere it appears that conditions will be slightly less favorable for Dennis then they were when he was in the Carribean. Not so unfavorable as to block development, but just enough to keep it from bombing out the way it did yesterday afternoon and this morning. I would expect landfall strength to be about 135 miles per hour. If people living in the 'warning' area I described have not started acquiring supplies for a hurricane, they should do so as soon as possible. Lines are going to be insane at the stores tomorrow with landfall imminent on Sunday morning. Everything I've written here after the link to the advisory is my personal thoughts and forecast, it is not affiliated with any organization, public or private. For official guidance please refer to the National Hurricane Center and your local National Weather Service Office. 2005 Hurricane Season, Weather comment []2:30:12 PM trackback []
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| At 11 AM EDT the center of Hurricane Dennis was at 21.4 North 79.9 West, 130 miles west of Camaguey Cuba. Movement is to the northwest at 15 mph with an occasional wobble to west--west-northwest. Winds are up to 150 miles per hour and pressure has fallen to 938 millibars (27.70"). Observations from the hurricane hunter were equivalent to 155 mph winds at the surface. However, theoretically, you can't have those kinds of winds with a pressure of 938 millibars. The value of 150 mph is a compromise between the wind observation and the wind speed that 'should' be observed with a 938 millibar pressure. Dennis has had some erratic wobbles in the past few hours, which is normal for intensifying major hurricanes. There is still a considerable spread in the model guidance after 36 hours. The forecast track is a bit to the right of the consensus, it favors the GFS models and NAM models because their analyses provide a better representaion of a particular upper air feature. Dennis is expected to weaken some over Cuba, nevertheless he is expected to make landfall as a major hurricane. The only good news is that it looks to be going ashore east of the more populated areas (east of Cienfuegos). At one point doing Dennis' wobbling last night, it was on a course that would have placed Havana in the strongest wind quadrant. The spot that it apppears to be headed into does have some mountains, which should help disrupt Dennis eye organization (similar to last night). Also the current trajectory maximizes the amount of time Dennis would spend over land (approximately six hours). Other than that, things are bleak. The areas that are in the right front quadrant of Dennis' path are going to be devestated enormously. For the time being I maintain my personal high probability landfall area from Mobile to St Mark's. For the time being I trim my watch area to the east to cover the area from St Mark's to the northeast corner of the Gulf of Mexico. I maintain my western watch area from Mobile to New Orleans. In the past several hours I have been entirely focused on the immediate nature of Dennis, and have not looked at the big picture. With the 12Z model runs coming out now, I am going to shift my focus and report back with my thoughts...  2005 Hurricane Season, Weather comment []11:45:32 AM trackback []
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| Recon just find minimum central pressure of 938 millibars in the center... an even bigger drop than I expected... unbelivable...shocking... wow For perspective, that is just under the minimum central pressure of Charley at landfall, meaning this storm is now at Charley strength at least.... WTNT64 KNHC 081225
Strongest. Hurricane. Before. August. EverTCUAT4 HURRICANE DENNIS TROPICAL CYCLONE UPDATE NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 825 PM EDT THU JUL 08 2005 ...AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INDICATES THAT MAJOR HURRICANE DENNIS HAS CONTINUED TO STRENGTHEN... JUST AFTER 8 AM EDT...1200Z...RECONNAISSANCE AIRCRAFT MEASURED A CENTRAL PRESSURE OF 938 MB...OR 27.70 INCHES...AND A FLIGHT-LEVEL WIND OF 136 KT IN THE SOUTHEAST QUADRANT...INDICATING A SURFACE WIND OF AROUND 140 MPH. THE AIRCRAFT IS STILL INVESTIGATING THE HURRICANE AND STRONGER WINDS MAY EXIST IN THE NORTHEAST QUADRANT. AN INTENSITY INCREASE WILL BE INDICATED IN THE NEXT ADVISORY ISSUED AT 11 AM EDT. FORECASTER STEWART 2005 Hurricane Season, Weather comment []8:26:49 AM trackback []
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| Hurricane Dennis kills five in Haiti (AP) Hurricane Dennis swept away a bridge and peeled tin roofs off homes in
Haiti, killing at least five people as it strengthened to a Category 4
storm and headed straight for Cuba... 2005 Hurricane Season, Weather comment []5:37:58 AM trackback []
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| At 5 AM EDT the center of Hurricane Dennis was at 20.7 North 79.1 West, 275 miles southeast of Havana, Cuba. Movement is to the northwest at 16 mph. Maximum sustained winds are 135 mph and pressure is down to 950 millibars (28.05") The eye was disrupted when it passed over land. However, since then Dennis has availed himself of the very warm waters off the coast of Cuba. Winds and pressure are based off hurricane hunter observations. Additional strengthening is possible. Some weakining may occur when Dennis passes over Cuba, but is forecast to be a category four hurricane in the Gulf of Mexico nonetheless. Official track forecast splits the difference between the extremes in the forecast models and follows the overall consensus. I don't remember ever seeing a comment like this, the final sentence of the discussion DENNIS IS EXPECTED TO BE A VERY POWERFUL HURRICANE WHILE CROSSING The additional data did have an effect on the models. It caused a dramatic shift in the Canadian model (which for a while was forecasting Dennis to run up the west coast of Florida). It changed its landfall prediction to Mississippi. Such a big shift should be viewed with great suspicion until it repeats itself at least once, so the 12Z run will be particularly interesting for that model. Its shift puts the GFS as having the easternmost track, with it showing Destin as its landfall (this was a modest shift to the west from the previous run). The western extreme continues to be the UKMET, which persists in forecasting a Louisana landfall. The scary thing at the moment is that the observations used for this observation were taken at 3:30 AM. The plane went off station shortly thereafter. When it left, the trend was very much an intensifying one. Dennis' appearance on satellite has become nothing less than outstanding since it recovered from its brief pass over land. I cannot think of an example of a hurricane gaining strength like this at the same time that as it is affecting a significant area of land. The thought of it is a bit horrifying. The lowest pressure ever recorded in a hurricane before August is 946 millibars. That record was set by Audrey in 1957. If Dennis at least holds on to what it has at this moment (I think the pressure has gotten lower since the 3:30 observation), then that record will fall. The schedule for the hurricane hunters that was drawn up yesterday scheduled an Air Force reserve WC-130 to be in the vicinity at 7 AM so that it could take observations for inclusion in the 8 AM advisory. I will be keeping a close eye on them and will post updates as appropriate... 2005 Hurricane Season, Weather comment []5:30:22 AM trackback []
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| At 2 AM EDT, the center of Hurricane Dennis was at 20.3 North 78.5 West, 80 miles west of Camaguey , Cuba and moving to the northwest at 15 miles per hour. Winds are estimated to be 135 miles per hour and minimum central pressure is 955 millibars. Hurricane Dennis Intermediate Advisory Number 14A
Dennis is the big winner in round one, taking a mere cut in the eye, as
it were. Of course, when the hurricane goes in as a category
four, it is pretty much guaranteed at least a draw. In this
round, the center of Dennis managed to slide around the higher
eleveations and stay overland for the briefest of time.
Nevertheless, the eyewall appeared to be opened up.Just after the advisory came out, the hurricane hunter collected an observation from the eyewall, which indicated winds of about 120 miles per hour. With Dennis regrouping, this ob may be a little bit under actual strength. 2005 Hurricane Season, Weather comment []2:38:28 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 .
