Tropical Storm Harvey has changed little in organization since yesterday as it has dealt with moderate easterly wind shear, fast movement and dry mid-level air. The center of circulation is not particularly well defined, and significant strengthening is unlikely for the next day or two. However, conditions could become more favorable for strengthening as Harvey enters the western Caribbean Sea by early next week if it manages to avoid land interaction with the Honduras and Nicaragua.  The model guidance is beginning to indicate a possible northwestward turn by the time Harvey is expected to be in the Northwestern Caribbean, and if this occurs, it is possible Harvey could emerge over the Southwestern Gulf of Mexico. Aside from Harvey, Invest 92L over the tropical Atlantic is becoming less likely to develop, at least in the short term.

Harvey remains disorganized, long-term future uncertain

Tropical Storm Harvey has changed little in structure and intensity today, and is likely to maintain a similar intensity for the next couple of days. As of 11:00 p.m. EDT, Harvey was centered near 13.7°N 64.1°W, and was moving westward at about 18 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1005 mb. Harvey is a sheared tropical cyclone, and should continue to experience northeasterly shear of about 15-20 knots for the next 36-48 hours. Little to no strengthening will likely occur with Harvey during this time. The shear is expected to decrease significantly when Harvey enters the western Caribbean, but the storm’s fast movement could limit intensification. In addition, Harvey is expected to enter a much more moist mid-level environment when it reaches the Western Caribbean. Considerable uncertainty remains with Harvey during the next couple of days, as the ECMWF model continues to suggest the possibility that Harvey could degenerate into a tropical wave at any time, but it does indicate the possibility of regeneration in the Gulf of Honduras. The GFS and UKMET models keep Harvey intact as a tropical storm that eventually passes near the coast of Honduras. It is possible that Harvey could make landfall in Nicaragua or Honduras, but this seems slightly less likely than earlier today. Land interaction could limit Harvey’s potential to strengthen. The official National Hurricane Center (NHC) forecast for Harvey predicts it will strengthen into a strong tropical storm and make landfall in Belize by Tuesday. The SHIPS intensity guidance continues to bring Harvey to hurricane strength, and this is likely if Harvey manages to maintain itself as a tropical storm through the unfavorable conditions of the Eastern Caribbean.

After crossing the Yucatan Peninsula, it is unclear where Harvey will go if it does manage to maintain its status as a tropical cyclone through that time. It is possible that it could move further inland into Central America, and in this case, Harvey would likely dissipate. However, recent model guidance has begun to shift north, and it is possible that Harvey could emerge into the Bay of Campeche or perhaps even the Western Gulf of Mexico by the middle of next week. A Texas landfall cannot be ruled out, based on recent model trends. The future track and intensity of Harvey should become more clear in a day or two.

92L and the wave behind becoming less likely to develop

Invest 92L has changed little in organization today, and its circulation has not become better defined. As of 00:00 UTC Saturday, Invest 92L was centered near 19.3°N 55.2°W, and was moving west-northwestward at about 20 mph. Maximum sustained winds were 25 knots (30 mph) with an estimated minimum pressure of 1012 mb. Although it has been able to fire persistent deep convection, 92L has not been able to close off a well-defined circulation, and development is becoming less likely as it is expected to be in an unfavorable environment for the next couple of days. Wind shear is expected to be moderate to strong, and there is expected to be some dry mid-level air which will likely limit development. The National Hurricane Center (NHC) gives 92L a 50 percent chance of development, both within 48 hours and five days. Model support for the development of 92L has dropped significantly since yesterday, with only the 12z Friday UKMET model run developing 92L into a tropical cyclone near the Bahamas. The 18z Friday GFS and 12z Friday ECMWF model runs did not predict any development of 92L. Ensemble support was very limited as well. There is still a chance, however, that even if 92L fails to develop now, it could encounter more favorable conditions near the Bahamas if it manages to survive through the period of unfavorable conditions. This is where the 12z Friday UKMET develops 92L.

Behind 92L, another tropical wave has a low chance of development. The NHC gives this wave a 10 percent chance of development within 48 hours and a 30 percent chance within five days. This wave is becoming less likely to develop, as none of the latest ECMWF, GFS or UKMET model runs predicted development. It should not pose a threat to land.

The next two names on the Atlantic naming list are Irma and Jose.

Tropical Storm Kenneth forms in Eastern Pacific, no threat to land

A tropical disturbance developed into Tropical Depression Thirteen-E Friday morning over the Eastern Pacific. Late this evening, it strengthened into Tropical Storm Kenneth. As of 8:00 p.m. PDT (11:00 p.m. EDT), Tropical Storm Kenneth was centered near 15.0°N 119.1°W, and was moving westward at about 15 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1005 mb. Kenneth is gradually becoming better organized, and is likely to develop into a hurricane by Monday over the open waters of the Eastern Pacific. Kenneth is no threat to land, and should eventually spin down into a remnant low by the middle of next week as it moves over cooler waters.

I will be back tomorrow with another post.