September 24, 2007

The blob race is on

Filed under: Tropical — Erin @ 2:07 pm

Our three invests have been intensifying all day. All of them have developed banding features and notable rotation. The race is on to see which one is deemed TD 12 first.

96L is a massive system. The cyclonic rotation is very evident on it and I am surprised that it hasn’t been called a TD yet. The size of this storm’s rotation could be an impediment to rapid development, as well as its latitude.

97L has made quite the comeback today from the exposed swirl it was earlier. Models take this to a hurricane, and I wouldn’t be surprised to see it happen.

94L is sheared on the west side, but it too has put on a burst of convection today. It seems headed for Mexico and doesn’t appear likely to have the chance to develop into a powerful system.

September 23, 2007


Filed under: Tropical — Erin @ 11:32 am

Well, the Atlantic has awakened from dormancy once again. We have four features to track, three of which are a potential threat.

First, Subtropical Storm Jerry got named today. Its satellite photos show a classic subtropical storm. It is forecast to develop tropical features before merging with an extratropical system. I’m not sold on the tropical transition happening, but whether it does or not, it’ll provide extra energy to the system it is merging with and may prove to be a threat to shipping interests if it develops into a nasty high seas cold-core storm. Either way, it’s heading out.

Closer to home is 94L in the Gulf of Mexico, and the computer models are taking this one anywhere and everywhere, although it should be noted that none of them take it farther northeast than Texas. The SHIPS forecasts it to become a hurricane. I would disregard this if not for the inconvenient little fact of Humberto. Shear in the Western Gulf is forecast to be high, though, so SHIPS may indeed be out to lunch. At the moment the system doesn’t look like much; it would have to get organized soon to reach that intensity. On the whole, I’d deem this a rainmaker for Texas–which is unfortunate, as it does not need it.

Next is 96L, in my opinion, the most interesting. This one is looking good, with banding already showing up in the satellites. 96L is a potential Cape Verde system located in the Atlantic, and any interaction with land is many days away… however, SHIPS forecasts it to be a major hurricane by the time it reaches the Caribbean. I see nothing in the short term to prevent this from happening and expect this system to develop. Models are in agreement on a WNW track, with the global models forecasting a more NWly bend at the end, but the GFDL keeping it going WNW. At this point it’s tough to tell whether it will recurve at sea. For some reason, the HWRF and GFDL don’t develop this system beyond a tropical storm, but I think this is unrealistic, and am thus disinclined to put a lot of trust in their current solutions, including track, which at this time of year is very dependent on the strength of the system. The bottom line, keep an eye out. This one could be an East Coaster. Not saying it will, of course, but I want to point out the possibilities.

97L is in the Central Atlantic and is forecast by the models to enter the Caribbean. This one was recently declared and currently doesn’t look so hot, although better than 94L. If it wants to become anything, it needs to get its act together before it hits the infamous “dead zone” in the Caribbean. I’m unable to pull up model runs for this system yet. However, if it does develop, it seems that it is likely to go south of the big shear masses that are forecast to develop over the Caribbean.

August 15, 2007

Dean strengthening, TD5 in Gulf

Filed under: Tropical — Erin @ 4:32 am

Good morning!

TS Dean has maintained its intensity of 45 knots overnight. Satellites from around 0900Z indicate that Dean is trying to wrap convection around an “eye”-like structure, which may in time develop into a true eye. The system has taken on the classic recognizable “comma” shape of a tropical cyclone, and in the face of low shear, should develop into a symmetrical and photogenic hurricane. Dean is in very low shear now, having escaped the 20kt that limited its intensification previously. This is good for development. However, since it’s happening during the day, Dean’s ability to utilize this may be limited. We’ll have to see.

NHC’s forecast has taken a westward shift, in line with what the computers are indicating. As I said in my previous blogs, I am on board with a Caribbean –> Gulf storm and do not intend to change this prediction unless the ridge is eroded too much for it to happen.

The GFDL and HWRF, our two tropical cyclone-specific models, are both in unfortunate agreement in their 00Z runs of taking Dean to a borderline Cat 3/Cat 4 in the central Caribbean and sending it south of Hispaniola. If this pans out, there is a chance that he will enter the Gulf as a Cat 3 or Cat 4 without ever having hit a large landmass.

I’m not happy about this. In such a scenario, we’d have to hope for shear towards landfall, because the very hottest Gulf waters are right offshore.

Closer to home, TD5 has formed in the Gulf, although according to the NHC it seems to have some problems getting together. Well, it’s a new system. That’s what usually happens. Quite honestly, in my opinion, TD5 could landfall in Texas as anything from a depression to (if conditions are perfect and it takes advantage) a low-end Category 1 hurricane. The NHC is forecasting a 40kt landfall. I think that, if TD5 gets organized in time, it has the potential for rapid development, and this forecast could be too low. With the depression, everything comes down to the timing of its organizing.

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