NHC May Upgrade TD2 at 5PM; Code Orange Alert near Africa

The 18Z Tropical Model Suite initialized TD2 with maximum sustained winds of 35 knots; a good sign that the National Hurricane Center may upgrade the system to Ana 5PM EDT. Easterly shear is continuing to keep the circulation exposed to the east, and Saharan air coming in from the northeast is suppressing convection some. Overall, however, conditions appear marginal enough for very slow intensification over the next few days. Thereafter, the tropical cyclone will begin to encounter moderate westerly shear associated with the subtropical jet. The westerlies could induce weakening once the storm enters the western Atlantic. It should be noted that all guidance, with the exception of the UKMET, keeps the center north of the Virgin Islands. The biggest disagreement among the models is what happens thereafter.

The much anticipated tropical wave near the Cape Verde Islands is already getting a lot of attention by the National Hurricane Center. As of 2PM EDT, the NHC has highlighted that area as "code orange", meaning that there's at least a 30-50% chance of formation within the next 48 hours. The tropical wave is significantly larger than TD2/Ana thanks to an equally large and favorable anticyclone ventilating it aloft. Additionally, since the wave exited Africa at a lower latitude, water temperatures out ahead of it are much more favorable than TD2 has had to contend with. The 12Z GFS, ECMWF, and CMC are holding steady with their initial forecasts of a major hurricane threatening the northeast Caribbean next Thursday give or take a day or two. Even the UKMET, a notoriously conservative model over recent years, is now officially developing our wave into a tropical cyclone. The only dynamical model not indicating development is the NOGAPS, which has a very poor track record in this part of the world. The high intensity forecasts are dependent on the idea that the favorable upper high over the African coast will head west in tandem with the wave axis, thus protecting it from any unfavorable westerly wind shear. In fact, the models show the ridge pushing the subtropical jet (the same feature responsible for giving Ana some problems in a few days) north and away from the developing cyclone.

Interests in the northeast Caribbean shouldn't be be panic-stricken as we don't even have a tropical cyclone yet. But residents there should brace themselves for at least the threat of a hurricane in roughly 1 week. Several models take this system through the northern islands, but there is still time for those tracks to shift north into the Atlantic.

The African wave will not threaten the United States for at least another 10 days, if ever. Nevertheless, there is already rampant speculation among weather enthusiasts at to what may happen. The ECMWF, operational GFS, and the GFS ensembles members all agree on one thing at the moment: a broad trough will be anchored over the Northeast US and East Coast in 10 days. This is still very far out, but at least there's agreement. As long as the models have the general idea correct, then the big question would be whether the trough is deep enough to recurve the hypothetical hurricane just east of the eastern seaboard. We just don't know that answer right now. Then there's also the possibility that the timing is off. The hurricane could be slower, and the trough could begin to lift out by the time it enters the far western Atlantic.