Tropical weather analysis - June 1, 2010

The remnants of former Eastern Pacific Tropical Storm Agatha were recently designated an invest (91L), just around 150 miles east of the coast of Belize. I must say, this was quite a surprise, as I would not have expected the system to generate this much symmetrical convection, given how disrupted the structure was from passage over Central America.

Invest 91L

The overall organization of the system is quite poor at present, however. Visible satellite imagery depicts a broad circulation without any real surface reflection. I place the poorly-defined surface center near 19N 87W, though this is highly speculative, given the broad nature of the system, as well as the fact that deep convection is covering a portion of the alleged center. Interestingly enough, surface pressures are falling across several reporting stations in the area, including some from Belize, and some from the Yucatan Peninsula of Mexico. Given this, one could safely assume that a low pressure area is attempting to form with this area. CIMSS analysis depicts 20 kt of westerly shear blowing across where I estimate the center to be. Every model, save the NOGAPS, predict that this shear will continue. Obviously, this will make regeneration into a tropical cyclone unlikely (though not impossible). The NOGAPS is a notable exception, however, moving an anticyclone near the region in about 36 hours. I would be concerned about this, but none of the other models foresee this, and CIMSS observations contradict this.

As far as timing goes, I feel the GFS has the best handle on the system, with a very slow, less than 5 mph, motion to the NW or NNW for the next 12 hours. Thereafter, the system should gradually begin turning to the N with some acceleration as a shortwave trough approaches the system from the west. Steering currents will then briefly weaken again for about 12 hours or so, then strengthen significantly thereafter. This should bring the system near the west coast of Florida by around 48 hours. The NOGAPS and CMC keep the trough weaker, and further to the north, which would delay the turn to Florida by about a day or so. I'm inclined to agree with the GFS with regards to speed, due to the fast southwesterly flow currently present across the Gulf of Mexico. The system should be very near the western Florida peninsula by this time on June 3.

As far as intensity is concerned, as I mentioned earlier, models maintain the currently westerly shear. Additionally, shear becomes destructively unfavorable across the entire Gulf of Mexico, owing to the typical and persistent subtropical jet. Models do not foresee any real relaxation of this shear in the foreseeable future. Hence, I feel the chances of this system regenerating are rather low. I agree with the NHC, giving the remnants of Agatha a 10% chance of becoming a tropical cyclone in the next 48 hours. It could produce locally heavy rainfall across portions of central and southern Florida, however.

Elsewhere

The only other area of note in the basin today is a westward-moving tropical wave, currently evident from Panama northward into the southwest Caribbean. While this area is not currently displaying any significant organization, the NOGAPS has been persistent in developing this area into a tropical cyclone for the last several days. The GFS hints at development, but in the East Pacific. It is uncertain which model will win out, if any, but I prefer the GFS. Upper-level winds are quite favorable in this area, with an anticyclone evident at 250 mb upward, its axis centered just south of eastern Cuba. I will continue to monitor this area carefully over the coming days. This system should move W in the short-term.