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Thursday, July 14, 2005 |
| At 11 PM EDT the center of major Hurricane Emily was at 13.6 North 67.5 West, 375 miles south-southeast of Santo Domingo, Dominican Republic. Movement is to the west-northwest at 20 mph. Maximum sustained winds are up to 125 mph and pressure is down to 957 millibars (28.26 "; both observations from recent recon observations). First part of the discussion talks about the reconnaisance observations that I noted in my previous post. Forecaster states that there isn't much to prevent her from maintaining major hurricane status or possibly reaching category four status. The GFDL intensity model suggests a near category four status the rest of the way across the Carribean. Emily took a slight jog south during the last few hours but seems to have resumed a west-northwest heading. Forecast is adjusted to the right slightly, but is still to the left (south and west) of the overall model consensus. The forecaster took off a bit more than is the norm for a flight level observation and didn't really explain why. Perhaps it was because of the clipped appearance that the storm has in its northwest quadrant, maybe he didn't like the pressure wind relationship... I don't know... 18Z NOGAPS run shifted off its predicted landfall location and now kept it off the Yucatan Peninsula. With the runs of NOGAPS being so consistent, that is significant news. If the 00Z run shows that this was not an aberration then this storm will be much more of a worry for Texas then it was previously. As there is still a recon plane in the air and I am following it closely, I will cut off my post here for now. I'll post back with how the 00Z model runs forecast Emily... 2005 Hurricane Season, Weather comment []11:18:19 PM  trackback []
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| Recon plane started the mission by finding a pressure of 962 millibars, a drop of 12 mb since the last observation, with the average drop rate between observations of slightly less than 2 millibars ... they just reported 958 millibars (observed at 9:30 EDT); that implies pressure is currently falling at a rate bit quicker than 2 millibars per hour... they also found 125 knot winds (in the northeast quadrant) at flight level, which implies surface winds at or just below category four level (135 mph)... note that the 8 PM advisory maintained 115 mph winds because the recon plane made its approach to the eye through the weaker northwest quadrant. 2005 Hurricane Season, Weather comment []10:04:42 PM trackback []
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| At 5 PM EDT the center of major Hurricane Emily was at 13.3 North 65.9 West, 445 miles southeast of Santo Doming, DR. Movement is to the west-northwest at 21 mph. Estimated Winds are up to 115 mph and estimated pressure is down to 968 millibars (28.59"). Strenghening is expected during the next 24 hours. The eye has become much more distinct on satellite. Satellite analysis indicates Emily has strengthened since the last observations were taken by the recon plane. Becuase of that, Emily is upgraded to a category three storm, the second major hurricane of the season. Forecast reasoning is unchanged. The global models form a tighter cluster now, with their only significant differences in the mid term (3-4 days) being exactly when Emily makes landfall. Global models suggest that shear will be low along Emily's path as she makes her way west, however, there presently is shear to her west. If it doesn't clear as forecast, her ability to intensify further will be limited. Unpredictable things such as eyewall replacement cycles could cause intensity fluctuations; the intensity forecast does not attempt to account for them. Current intensity forecast brings Emily up to 130 mph winds and keeps intensity there for landfall. Right at the time I threw up my note about a significant change being necessary for NHC to up their estimates, the change started to occur. Emily has featured a distinct eye since 1:45 PM EDT. As mentioned in the discussion, the current shear analysis shows significant shear (20 knots) south of Jamaica and in the area immediately around the Yucatan. The discussion also mentions how that shear is forecast to push off, and not affect Emily. The caveat to this is that the shear forecast isn't always known for its reliability. It is derived from two forecasts: winds at a specified upper level and winds at a specified lower level. The shear forecast is potentially only as good as the worse of the two forecasts that it is derived from. It is one of the things that makes intensity forecasting such a difficult challenge. With that in mind, if the shear forecast does hold out and Emily enjoys low shear the whole way across, then it could be off to the races as far as her intensity goes, especially west of 80 degrees longitude. Sea Surface temperatures there are warmer than they were off of Florida when Dennis made his run to 145 mph. That, combined with the fact that warm water is found significantly deeper than it is in the part of the Gulf that Dennis passed over argues that with regards to heat potential from the ocean, Emily is in a better situation than Dennis was. One other thing to consider, that I'll mention briefly and in a somewhat squishy way is central organization. We really don't have a good handle on why some storms can take off in intensity under seemingly adverse situations, while others get fed perfect conditions and don't do much with it. The answer seems to be how the storm is organized. Ivan during his runs to category five had exemplary organization; at his peak Dennis did his best Ivan impersonation. Right now, Emily looks to following the same pattern. (This is qualitiative, not quantitative, that's why I call this squishy). The fact that she managed to hang together at the lower latitude, near South America until conditions got more favorable as she moved west-northwest argues that her organization is a bit better than average (that area is historically a graveyard for tropical systems; Ivan was the exception of all exceptions). The immediate landfall forecast (Yucatan Peninsula) is looking pretty solid. At the moment, all of the global forecast models are pointing to that area as the point of landfall. As I have been suggesting, anyone with vacation plans for Cozumel/Cancun for the end of this weekend and later probably should be rescheduling/cancelling. The differences in the global models emerge after landfall. There are a couple of models suggesting that Emily will proceed northwest from there towards the Rio Grande. Obviously, this would be of concern to people in southern Texas. Just enough of a concern for people in that area to warrant them paying attention to Emily's movement, but not enough at this time to advise anything further. 2005 Hurricane Season, Weather comment []5:34:39 PM trackback []
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| At 11 AM EDT the center of Hurricane Emily was a 12.7 North 64.0 West, 650 miles southeast of Santo Domingo, Dominican Republic. Movement is to the west northwest at 18 mph and that movement is expected to continue for the next 24 hours. Winds are now 100 mph and pressure has fallen to 976 millibars (28.82"). Reports from the Hurricane Hunter, (which entered Emily at around 7:30 this morning) indicate that Emily has started another round of strengthening. Pressure fell 13 millibars in eight hours. The highest flight level winds observed by the plane thus far suggested surface winds of 90 mph; the forecaster assumed that winds have not reacted to the pressure fall yet and therfore set winds at 100 mph. The track reasoning is unchanged. High pressure north Emily is expected to expand west-ward to keep her on a west-northwest track. The official forecast is supported by the GFS, GFDL, NOGAPS, and FSU Superensemble models. The Canadian and UKMET models have tracks to the north of the forecast. Intensity models still bring Emily to major hurricane strength. Some upper level westerly winds, (which would provide unfavorable shear) are present ahead of Emily, but they are expected to "get out of the way". Emily is expected to pass over waters with a high amount of heat content (not just warmer, but warmer at deeper depths). This is expected to help strengthen Emily further. The intensity forecast brings Emily to 125 mph strength before landfall on the Yucatan Peninsula. It is going to be interesting to see what kind of winds the recon plane finds during the second half of his mission. Will they find winds to justify the 100 mph estimate? Last night they found the 90 mph low level winds in the early part of the mission when convection was firing up like crazy, but didn't find anything like that again for the rest of the flight. It makes me wonder if the true sustained winds aren't 5-10 miles per hour lower. I'll keep an eye on what they find during the rest of the mission and tack on an update to this post. The global models are divided among the good, the not-so good, and the ugly. Good (to this point)have been NOGAPS and the Europan models, both have had consistent tracks over several runs and indicate landfall in the Yucatan Peninsula. Not so good has been the UKMET. Yesterday's morning run jumped to further east than its previous three forecasts (which had been shifting west) and forecast landfall in south-eastern Louisana. The type of turn it was showing Emily making to do that was quite implausible. The evening run jerked the track back to the west and had Emily going across Jamaica before making landfall near the Rio Grande, a scenario not so far-fetched. Ugly are the GFS and the Canadian for different reasons. The GFS has been horrible at depicting Emily on its forecasts. More often than not it fails to draw any closed isobars around the low. Unacceptable. That said, it has offered a reasonably consistent track forecast, it has been indicating a Yucatan landfall. Finally, the Canadian has been awful. There's no guessing where the next forecast track is going to be, nor whether it will actually depict Emily the whole way across the Carribean. Not good at all. AT 1:25 EDT... Flight level winds are vindicating the forecaster (100 mph winds at the surface) ...in fact, a recent dropsonde observation suggests category three winds (120 mph winds at the surface)... it will be interesting to see what the forecaster goes with for the 2 PM intermediate advisory... AT 1:45 PM EDT... They split the difference and went with 110 mph, which is just under category three...with the next plane not scheduled to fly through the center until this evening (around 8 PM EDT), it would take a significant improvement in Emily's appearance on satellite (such as a well defined eye appearing) for the 5 PM advisory to change anything. 2005 Hurricane Season, Weather comment []11:52:11 AM trackback []
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© Copyright
2005
Charles Fenwick
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Last update: 8/2/2005; 2:00:39 PM .
Last update: 8/2/2005; 2:00:39 PM .
