We're getting pretty close to development out in the NW Caribbean this evening, with a broad area of low pressure becoming better defined and organized through time. The 0000UTC QuikSCAT over the region showed a well-defined circulation, but winds were fairly weak, generally only 15-20kt. A lot was rainflagged in the convection, but even then winds were generally on the order of 25-30kt. Low was centered near 18N/85W, currently on the southwest edge of the primary convection. That's likely going to be a standard appearance for this feature through it's lifetime, given the shearing environment, though if it and the mid-level circulation (currently just south of the Isle of Youth) can get oriented upright for some time, development could be temporarily enhanced.
Where the storm goes will likely determine it's intensity. If it travels NNW from here toward the central Gulf, it'll ride along a narrow tongue of very warm, deep waters toward the Loop Current. Further east (i.e. closer to Florida) and it'll be moreso in the shallower, cooler shelf waters. Ultimately, wherever it impacts, it's going to feel cooler, shallower waters before landfall, likely putting a brake on any intensification.
Question is, where is it going to go? Now that it looks pretty likely that we're going to get at least a TD out of this, it's time to start consider the "where" and the "when" questions. It's sort of trapped in a col region (area of light winds) at the end of the trough it's been interacting with for nearly a week now; thus, we don't see it moving a whole lot. A developing upper-low to its west should help provide a conduit for it to start northward, but how far north will it get? Still too early to tell. Anywhere from New Orleans over to Cape Hatteras needs to watch this one into the weekend for a potential impact. Likely landfall comes within 4-5 days, possibly into the late 3 day time frame as well. There's still enough uncertainty with the steering currents to not be able to specify a particular region, but the main model runs are suggesting somewhere along the Florida panhandle or west coast, focusing on the Big Bend region. It's not that unlikely climatologically; there are numerous instances of early-season tropical storms heading into the area near Perry-Cedar Key, FL. Needless to say though, still need to watch it over the weekend in case something changes; models tend to be fickle when the steering currents aren't all that well defined and the system is still in a formative stage.
Intensity? It's going to be in persistent westerly flow the entire time, but vertical shear analyses suggest that mid-level shear will be fairly weak while deep-layer shear will be more substantial in nature along that old boundary. The shallower it remains, the more likely it should remain coherent. While the narrow ridging environment present just east of the storm may build to the north some as it moves northward, it'll likely stay along its edge. Thus, I feel that the shear should be the ultimate throttle on intensity. Strengthening into a moderate tropical storm is possible, with weakening likely before landfall. I don't expect a hurricane at landfall at this point, with only a minimal shot at that intensity otherwise. Somewhere between last year and Bonnie in 2004 intensity-wise is what I think we're looking at here.
More tomorrow or as developments warrant.