The “Little Wave that Could” is now a Tropical Depression in the open Atlantic Ocean. The system is well away from the mainland of the United States and isn’t anticipated to impact the US during the next five days – if ever.
As we get closer to the peak of Hurricane Season, seeing systems develop in the Atlantic basin is expected. Right now there are a handful of tropical waves to track. The only other one that shows signs of ‘life’ is Invest 98L off the coast of Florida.
Model guidance on Tropical Depression 5
The model guidance does not, necessarily, support what the National Hurricane Center has forecast. That isn’t to say the NHC is wrong. That is just a nugget of information to remember when looking over the data. If you read some of the maps and charts and think, “wait, what?” you aren’t missing something.
Most of the model guidance suggests that T.D. 5 will still be a tropical depression or a tropical storm during the next five days. In fact, there are two clusters of potential strengths between all of the guidance. It is almost like the models got together and picked one or the other: It will either be a tropical depression or a strong tropical storm.
Of course, that doesn’t actually happen. But it is interesting to see how specific – and close together – some of the model guidance is.
The model guidance for the track of T.D. 5 is much more consistent.
Nearly every model puts the storm near Puerto Rico by Thursday morning, next week. Beyond that, ensemble data takes T.D. 5 scraping across the Caribbean Islands during the next eight days. Ensemble guidance keeps T.D. 5 as a weak system throughout, likely due to the interaction with land.
NHC Discussion
Tropical Depression Five Advisory Number 1
NWS National Hurricane Center Miami FL AL052019
1100 AM AST Sat Aug 24 2019
…NEW TROPICAL DEPRESSION FORMS EAST-SOUTHEAST OF THE LESSER ANTILLES…
The small low pressure system that the NHC has been tracking the past several days across the tropical Atlantic Ocean has acquired enough deep convection to be classified as a tropical depression, the fifth tropical cyclone of the 2019 hurricane season. Two ASCAT passes between 1200-1300Z this morning indicated that the system had a closed circulation and surface winds of at least 30 kt, and that is the intensity set for this advisory. Upper-level outflow is fair to the northwest and restricted to the southeast due to moderate easterly vertical wind shear.
The initial motion estimate is 280/10 kt. The NHC model guidance is in very good agreement that the cyclone will move in a general west-northwestward direction along the southern periphery of a deep-layer ridge for the next 5 days, bring the system through the central or northern Lesser Antilles on Tuesday, and into the northeastern Caribbean Sea on Wednesday and Thursday. The official forecast track is close to the consensus model TVCN, which is a little north of the NOAA HCCA corrected-consensus model.
The small cyclone is currently experiencing easterly to southeasterly shear of about 15 kt. The shear is forecast to
steadily decrease over the next 24 h and be around 5 kt in the 24-to-72-hour time period. Although the depression is expected to remain embedded in a fairly dry mid-level environment, the small overall circulation, small radius of maximum winds, low shear regime, and warm SSTs of 28.0-28.5 deg C should allow for slow but steady intensification through the 5-day period despite occasional intrusions of dry air. The NHC intensity forecast is a blend of the
statistical-dynamical SHIPS and LGEM models, and the more robust HWRF model.
At 1100 AM AST (1500 UTC), the center of newly formed Tropical Depression Five was located near latitude 10.4 North, longitude 7.9 West. The depression is moving toward the west near 12 mph (19 km/h) and this general motion is expected to continue today. A turn toward the west-northwest is forecast on Sunday, and that motion is expected to continue through Tuesday. On the forecast track, the tropical cyclone is expected to be near the central Lesser Antilles on Tuesday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.Gradual strengthening is forecast during the next few days, and the depression is forecast to become a tropical storm later tonight or on Sunday.
The estimated minimum central pressure is 1010 mb (29.83 inches).
