Tropical weather analysis - July 3, 2010

Invest 95L

Invest 95L continues to struggle amidst unfavorable atmospheric and thermodynamic conditions. Although visible satellite animations indicate that the system has been able to actually generate convection today, this convection is not well organized, and not concentrated near the center. The shower activity associated with the system is displaced well to the south of the improving but still broad surface center, which, based on visible satellite animations and buoy observations, is located near 26N 88W. Upper-level winds are still not all that favorable, with 20 kt of northerly shear impinging upon the center. Additionally, analysis of water vapor animations suggests that the atmosphere in the vicinity of 95L is rather stable. This, along with the aforementioned vertical shear, will tend to limit any appreciable convective activity over the center of the system.

However, the 18z GFS forecasts the upper environment to gradually improve, particularly after 18 hours, and forecasts this to persist for the next several days. This could allow 95L to begin organizing by tomorrow morning, and we will need to keep a careful watch on this system. Currently, the NHC is giving this system a 20% chance of becoming a tropical cyclone within the next 48 hours. Based on the GFS forecast of an improving upper-level environment, however, I will go higher and say 30%. A reconnaissance flight is scheduled for the system tomorrow, if necessary, though it wouldn't surprise me to see it canceled, since even if shear abates by that time, dry air may still be a problem.

This system appears to be moving W at the moment, underneath the influence of a broad ridge to the north. The 12z loop of steering forecasts from PSU indicates that this system should soon come under the influence of a well-defined weakness in the ridge evident from 90W westward for several hundred miles. Hence, I expect 95L to soon turn to the WNW, then gradually bend to the NW and N as it feels this weakness. Based on my forecast track, this system should be inland somewhere along the northwestern Gulf Coast in no more than 48 hours. Right now, I am favoring a track toward extreme southeast Texas, though this could certainly come ashore farther east. Residents from central Texas to southeast Louisiana should carefully monitor the progress of this system over the next couple of days.

Caribbean disturbance

Of more pressing concern than Invest 95L is an area of disturbed weather in the Caribbean, associated with a tropical wave. This system has the potential to become the season's second named storm, and even the second hurricane. Upper-level winds appear favorable for gradual development of this system over the next several days as it moves WNW. The system could impact the Yucatan Peninsula in about three or four days, and subsequently enter the Gulf of Mexico. After that, the GFS and CMC (as per the 12z steering forecasts from PSU's e-wall) differ radically, with the GFS foreseeing a stronger ridge, keeping the system on a more westward path similar to Alex. The latter depicts more troughing in the upper westerlies, which would tend to force the system toward the northern Gulf Coast.

As I said, this system could become another dangerous hurricane in the Gulf of Mexico, and residents there, as well as long the Yucatan Peninsula, should carefully monitor the progress of this system over the next several days.