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Major changes with Ernesto's forecast

3PM UPDATE from Bryan: I haven't been posting for the last few days because I am at a mountain meteorology conference in Santa Fe. However, Adam has been doing an excellent job keeping up. Also, we have a new meteorologist, Carlos Szembek, joining us now. This morning I noticed that the computer model charts were not generating on time. I found the problem to be on the model server at Yale where I generate the charts. This morning I ran the scripts manually and contacted the ITS guy about the problem. I believe it has now been resolved and the model charts should be posting automatically again. Feel free to contact me at bryan@thestormtrack.com if you notice any more issues.


2PM UPDATE: The SFMR aboard the NOAA42 P-3 research aircraft has found surface winds of 55 kts to the east of the center of circulation. Ernesto is becoming much better organized by the hour.

While Ernesto has yet to develop a strong central core, with winds only at 40 kt (45 mph), there are major developments with the forecast. The satellite signature is indicating that Ernesto is starting to organize, with deep convection starting to develop over the estimated center of Ernesto (Figure 1). This will be important later in the discussion.

15Z_IR_29Aug.jpg
Figure 1. Infrared satellite picture of Ernesto. Thunderstorms have been developing near the center of low pressure this morning.

The current NHC track forecast has shifted to the west from last night's advisory (Figure 2). Interestingly, the official forecast track is at the extreme eastern side of the model guidance (Figure 3). The model forecasts are bimodal this morning. The global models (e.g. GFS, UKMET, Canadian, etc.) are forecasting a landfall early tomorrow morning in the Florida Keys. However, the statistical-dynamical (S-D) models (e.g. the BAMs, LBAR, etc.) are forecasting a landfall tomorrow night near or south of Tampa. Ordinarily, I would dismiss the S-D models as being out to lunch. Here, though, is where the S-D models shine. When a storm is poorly organized and not initialized well in the global models, as Ernesto is right now, the S-D models often have as good, if not better, forecasts for a tropical storm. Admittedly, this particular model run has me quite confused.

15Z_NHCTrack_29Aug.gif
Figure 2. Official NHC track forecast for Ernesto. I don't have a whole lot of confidence in the track forecast at the moment.

The intensity forecast is where things get really sticky. If the global models are right, Ernesto will not have much time to intensify and would come ashore on the Keys as a moderate to strong tropical storm, since Ernesto is just now starting to reorganize itself. However, if the S-D models are right about the track, Ernesto will have plenty of time to get its act together. That would be bad news for the Gulf coast of Florida. Should the S-D models be correct and Ernesto have 36 hours to spend over the open water, the dreaded rapid intensification would be back in the picture again. Currently, the SHIPS forecast has a probability of 32% for rapid intensification. While not high, it is also not insignificant. Should rapid intensification occur, Ernesto could easily be a Category 2 hurricane or higher at landfall on the Gulf coast. At the moment, the intensity models are all forecasting Ernesto to be a strong tropical storm as it makes landfall in the Keys (Figure 4). Obviously, in the models, the S-D solution has not been accounted for. Should the global models' track be correct, the intensity forecast is more or less correct. If not, Ernesto has the possibility of becoming a major event for the Gulf coast.

I haven't talked much about what happens to Ernesto after it moves across Florida. This was simply due to uncertainty in the forecast. The situation is starting to become a little clearer this morning, as most of the models are forecasting a second landfall near the South Carolina-North Carolina border. Folks in those areas should be monitoring this situation closely. The intensity at a second landfall of Ernesto is highly dependent on how much time Ernesto spends over Florida, so pegging a number at this time is not going to be anything but a shot in the dark. And for those of you who are sports fans, looking into the distant future (meteorologically speaking), college football games in the Ohio Valley, Mid-Atlantic, and Northeast could be affected by the remnants of Ernesto this weekend. Stay tuned to the StormTrack for more.


Posted by Adam Moyer | Permalink