Hurricane Irma strengthened into a rare category 5 hurricane Tuesday morning just east of the Leeward Islands, and has since intensified further to become the strongest Atlantic hurricane in wind speed since Wilma in 2005. Irma is an extremely dangerous hurricane with a well-defined, large eye surrounded by a ring of very deep convection. Irma is likely near its peak intensity and will likely begin to weaken by tomorrow if an eyewall replacement cycle occurs, but Irma is likely to remain a very powerful hurricane through the weekend as it tracks west-northwestward.

Irma: An extremely dangerous category 5 storm for the record books

As of 2:00 p.m. EDT Tuesday, Hurricane Irma was centered near 16.9°N 59.1°W, and was moving westward at about 14 mph. Maximum sustained winds were 160 knots (185 mph) with an estimated minimum pressure of 926 mb, based on data from a reconnaissance aircraft. This makes Irma the strongest Atlantic hurricane since Wilma in 2005 by wind speed, and the strongest Atlantic hurricane on record by wind speed outside of the Caribbean or Gulf of Mexico. Irma is also Earth’s strongest tropical cyclone so far in 2017 by wind speed – a rare event for the Atlantic, as this title usually belongs to a storm in the Western Pacific.

Irma is likely to begin to turn to the west-northwest very shortly, passing through the Leeward Islands Wednesday morning. Irma should then pass north of Puerto Rico Wednesday evening, and then pass just north of Hispaniola on Thursday. Although the center of Irma should remain far enough north to avoid land interaction, hurricane conditions are still possible in these areas. By Friday, Irma should continue heading west-northwestward towards the Turks and Caicos Islands and the Southeastern Bahamas. Irma’s forecast track is of fairly high confidence through this time. Irma should be very near or just north of the Cuba coast by Saturday. If Irma does make landfall in Cuba (as suggested by the ECMWF model), land interaction will likely weaken the cyclone, but Irma would still likely be a hurricane if it pulls northward towards Florida as expected. Residents of these areas should rush their preparations to completion. After the weekend, the track forecast becomes uncertain. Computer models continue to suggest that Irma may make a sharp turn to the north, although it is not clear when this turn will occur. There is still a chance it could turn to the north without making landfall in Florida, and in this case, the eastern coast of Florida, Georgia, and the Carolinas would be the most at risk for direct impacts from Irma. There is also a chance that Irma turns north right over the Florida peninsula, and weakens inland without much impact in other states. A third possibility is that Irma emerges into the eastern Gulf of Mexico and makes landfall in the Florida Panhandle or Big Bend region. Regardless of the exact track of Irma, significant impacts in Florida are likely, and residents of the entire state should have a hurricane plan ready. Unfortunately, it does not appear likely that Irma will be able to turn out to sea without impacting the United States at this time. It is very possible that Irma could be the second major hurricane to make landfall in the United States this season after none for 12 years.

The official National Hurricane Center (NHC) forecast predicts that Irma will maintain its current intensity before slowly weakening throughout the next five days. The intensity forecast of Irma is hard to predict, considering the possibility of eyewall replacement cycles. I think we will likely see Irma weaken, perhaps to a category 4 hurricane, tomorrow before some restrengthening is possible later in the week. Regardless of the exact intensity, Irma is an extremely dangerous hurricane and catastrophic damage is possible. It should be stressed for those in the path of Irma to have a hurricane plan ready and be prepared!

A Hurricane Warning is currently in effect for: Antigua, Barbuda, Anguilla, Montserrat, St. Kitts, and Nevis; Saba, St. Eustatius, and Saint Maarten; Saint Martin and Saint Barthelemy; the British Virgin Islands; the U.S. Virgin Islands; Puerto Rico, Vieques, and Culebra. A Hurricane Watch is currently in effect for: Guadeloupe; Dominican Republic from Cabo Engano to the northern border with Haiti; Haiti from the northern border with the Dominican Republic to Le Mole St. Nicholas; the Turks and Caicos Islands; and the Southeastern Bahamas. A Tropical Storm Warning is currently in effect for Guadeloupe and Dominica. A Tropical Storm Watch is currently in effect for: the Dominican Republic from south of Cabo Engao to Isla Saona; and Haiti from south of Le Mole St. Nicholas to Port-Au-Prince. No watches or warnings have been issued yet for Irma in the United States.

Tropical Storm Jose forms in the central tropical Atlantic, no imminent threat to land

A tropical wave (Invest 94L) developed an elongated, but well-defined, center of circulation Tuesday morning, and acquired sufficient convective organization to be designated Tropical Storm Jose. Jose is likely to strengthen into a hurricane, and it is not out of the question tat the Atlantic could have simultaneous major hurricanes by the weekend for the first time since 2010.

As of 11:00 a.m. EDT, Tropical Storm Jose was centered near 12.3°N 39.1°W, and was moving west-northwestward at about 13 mph. Maximum sustained winds were 35 knots (40 mph), with an estimated minimum pressure of 1008 mb. Jose is the tenth named storm of this unusually active 2017 Atlantic hurricane season. The average tenth named storm in an Atlantic season forms, on average, around October 19, meaning that Jose is over six weeks ahead of schedule. Jose is likely to strengthen into a hurricane due to favorable conditions for the next three days, including low wind shear of less than 10 knots, warm sea surface temperatures of near 29°C (84.2°F), and a moist atmosphere with mid-level relative humidity values of over 70 percent. The official NHC forecast predicts that Jose will strengthen into a category 2 hurricane by Friday, while not predicting any strengthening thereafter due to an expected increase in shear from Hurricane Irma’s outflow. It is not out of the question that Jose could become a major hurricane if rapid intensification occurs. Jose is likely to remain active for at least a week, and is no imminent threat to land. Regardless, the Leeward Islands should closely monitor Jose, especially after Irma passing through the Islands as a category 5 hurricane.

95L in Bay of Campeche likely to develop

A well-defined area of low pressure (designated Invest 95L) is producing disorganized showers and thunderstorms over the western Bay of Campeche, and is likely to develop into a tropical cyclone during the next day or two. As of 12:00 UTC Tuesday, Invest 95L was centered near 22.0°N 97.0°W, and was nearly stationary. Maximum sustained winds were 25 knots (30 mph), with an estimated minimum pressure of 1010 mb. The NHC gives 95L a 70 percent chance of development within 48 hours, and an 80 percent chance within five days. Residents of Veracruz, Mexico should closely monitor the progress of this system, as it is likely to move very little for the next few days as it is expected to consolidate. Significant development of 95L appears unlikely due to moderate wind shear. If 95L becomes a tropical storm, it will be named Katia.

I will be back with another blog post later tonight or tomorrow.