Tropical Depression Sixteen will track over Nicaragua and Honduras today, then target Cancún Friday night, and will then pose a threat to parts of the U.S. Gulf Coast as a strong tropical storm or a low-end hurricane this weekend. The center of the tropical depression is about to move onshore in northeast Nicaragua, moving northwest at 5 to 10 mph.
Infrared satellite imagery indicates the thunderstorms nearest to the center of T.D. Sixteen are still mainly over the southwest Caribbean Sea, however, a broad gyre of low pressure called a Central American gyre (more on that feature below) has spawned numerous clusters of thunderstorms in Central America. A hurricane watch has been issued for Mexico’s Yucatan Peninsula from Punta Herrero to Rio Lagartos – including Cancún and Cozumel – meaning hurricane conditions are possible within the watch area within 48 hours.
Tropical storm warnings have also been issued for parts of the Caribbean coasts of Nicaragua and Honduras – from Sandy Bay Sirpi, Nicaragua, to Punta Castilla, Honduras – meaning tropical storm conditions are expected, in this case over the next 12 to 24 hours. Once the system reaches tropical storm status, it will be named Nate.
First Up: Central America/Mexico
The tropical depression will track through northeast Nicaragua and northeast Honduras through Thursday night, bringing clusters of heavy rain, gusty winds, and some elevated surf. After the center moves back over water Friday, environmental conditions are favorable for some additional strengthening. Western Caribbean Sea water temperatures are currently in the mid- to upper 80s, about 2 to 5 degrees above average, and wind shear may lessen a bit.
The future “Nate” will make its closest approach to Mexico’s Yucatan Peninsula – including Cancún and Cozumel – Friday night, as either a tropical storm or low-end hurricane. The main impacts there will include bands of locally heavy rain, which will pick up during the day Friday, elevated surf and tropical storm or hurricane-force winds. Areas of locally heavy rain from a larger-scale Central American gyre (again, more on this feature below) are likely to persist at least into part of the weekend from eastern Mexico into Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and, perhaps, parts of Panama.
Rainfall totals may reach 30 inches in a few locations in Nicaragua, 20 inches in Costa Rica and Panama, amd 12 inches in the eastern Yucatan Peninsula, according to the National Hurricane Center. This torrential rain may trigger dangerous flash flooding and mudslides, particularly over the mountainous terrain of Central America.
U.S. Threat This Weekend
This weekend, upper-level high pressure over the northern Gulf Coast is expected to weaken as a southward plunge in the jet stream carves into the central U.S. Therefore, future “Nate” is expected to be pulled north into the Gulf of Mexico, steered by the combination of upper-level high pressure centered near or east of the Bahamas and what is known as a Central American gyre. It is now likely the system will make landfall along the northern Gulf Coast, somewhere between Louisiana and Florida, Sunday. It remains too soon to tell where exactly this landfall will occur.
Most guidance also suggests this landfall will most likely be as a low-end hurricane. However, intensity forecasts are notoriously tricky this far out in time and may change. Speaking to that point, National Hurricane Center forecaster Eric Blake noted in the 5 p.m. Wednesday advisory that rapid intensification (at least 35-mph maximum wind increase in 24 hours or less) is a possibility with this system in the northwest Caribbean Sea or Gulf of Mexico thanks to the aforementioned deep, warm water and low wind shear environment.
However, too much land interaction with Central America or the Yucatan Peninsula would likely limit the amount of intensification despite the other favorable conditions. Here’s a general timeline of events with this system, regarding the U.S. Gulf Coast:
— Saturday: Last day to prepare; some outer rainbands, swells may arrive along the eastern Gulf Coast
— Sunday: Landfall, peak impact along the northern Gulf Coast somewhere from southeast Louisiana to Florida; heavy rain spreads inland into parts of the Southeast
— Monday: Nate inland, but heavy rain/flood threat spreads into the Appalachians, other parts of the Carolinas, East
For now, all interests along the U.S. Gulf Coast from Louisiana to Florida should monitor the progress of this system closely. We’ll have the latest forecast updates here at weather.com and will add details as they become clearer in the coming days.
Source : Weather.com