Former Tropical Storm Michael strengthened into a hurricane on Monday morning and Watches were issued for portions of the Gulf Coast. At 11:00 a.m. EDT on Monday the center of Hurricane Michael was located at latitude 21.2°N and longitude 84.9°W which put it about 50 miles (80 km) south of the western end of Cuba. Michael was moving toward the north at 7 m.p.h. (11 km/h). The maximum sustained wind speed was 75 m.p.h. (120 km/h) and there were wind gusts to 90 m.p.h. (145 km/h). The minimum surface pressure was 982 mb.
A Hurricane Watch was in effect for the portion of the coast from the Alabama-Florida border to Suwanee River, Florida. Tropical Storm Watches were in effect for the portions of the coast from the Alabama-Florida border to the Alabama-Mississippi border and from Suwanee River to Anna Maria Island, Florida. A Hurricane Warning was in effect for the Cuban province of Pinar del Rio. Tropical Storm Warnings were in effect for the Cuban province of Isle of Youth and for the portion of the coast from Tulum to Cabo Catoche, Mexico.
Hurricane Michael continued to organize quickly. A circular eye with a diameter of about 30 miles (50 km) was forming at the center of Michael. A ring of strong thunderstorms was wrapping around the eye and the strongest winds were occurring in the ring of storms. Several bands of showers and thunderstorms were wrapping around the core of Hurricane Michael. Storms near the core were generating upper level divergence which was pumping mass away from the hurricane.
Winds to hurricane force extended out about 30 miles (50 km) primarily to the northeast of the center of Hurricane Michael. Winds to tropical storm force extended out about 175 miles (280 km) from the center of circulation. The Hurricane Intensity Index (HII) for Hurricane Michael was 10.4. The Hurricane Size Index (HSI) was 6.8 and the Hurricane Wind Intensity Size Index (HWISI) was 17.2.
Hurricane Michael will move into an environment that will become increasingly favorable for intensification. Michael will move over water where the Sea Surface Temperature is near 30°C. An upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation. Those winds were causing some vertical wind shear. However, the upper level trough will move westward away from Hurricane Michael and the wind shear will decrease. Hurricane Michael will continue to strengthen when it moves over the Gulf of Mexico and it could intensify rapidly once the eye and eyewall are fully formed. Hurricane Michael is likely to strengthen into a major hurricane.
Hurricane Michael will move around the western end of a subtropical high pressure system centered over the western Atlantic Ocean. The high will steer Michael in a northerly direction during the next several days. It will get bigger and stronger during the next 48 hours. On its anticipated track Hurricane Michael will approach the northeast coast of the Gulf of Mexico on Wednesday. It is likely to be a major hurricane at that time. Hurricane Michael has the potential to cause a storm surge of 10 to 15 feet (3 to 5 meters) at the coast. It will bring strong winds which could cause regional major damage and result in significant power outages. Locally heavy rain could cause flooding in some locations.
Tropical Storm Michael strengthened east of the Yucatan peninsula on Sunday. At 8:00 p.m. EDT on Sunday the center of Tropical Storm Michael was located at latitude 19.9°N and longitude 85.4°W which put it about 105 miles (170 km) east-southeast of Cozumel, Mexico. Michael was moving toward the north at 5 m.p.h. (8 km/h). The maximum sustained wind speed was 60 m.p.h. (95 km/h) and there were wind gusts to 75 m.p.h. (120 km/h). The minimum surface pressure was 997 mb.
A Tropical Storm Warning was in effect for the Cuban provinces of Pinar del Rio and the Isle of Youth. A Tropical Storm Warning is also in effect for the portion of the coast from Tulum to Cabo Catoche, Mexico.
The circulation around Tropical Storm Michael is still organizing and the distribution of thunderstorms is asymmetrical. Most of the thunderstorms are occurring in bands in the eastern half of the circulation. A new center of circulation formed on Sunday afternoon near those thunderstorms. Many of the rainbands in the western half of Tropical Storm Michael contain primarily showers and lower clouds. One outer rainband in the southwestern periphery of the circulation does contain numerous thunderstorms. The strongest winds are occurring in the rainbands on the eastern side of Tropical Storm Michael. The winds are weaker on the western side of the circulation. Storms on the eastern side of Michael are generating some upper level divergence which was pumping mass away from the tropical storm and was allowing the surface pressure to decrease.
An upper level trough over the Gulf of Mexico is producing westerly winds which are blowing across the top of Tropical Storm Michael. Those winds are causing moderate vertical wind shear which was slowing the rate of intensification, but the shear is not strong enough to prevent Michael from strengthening. The wind shear is probably the reason for the asymmetrical distribution of thunderstorms. The upper level trough will move westward during the next few days and the upper level winds will weaken. Michael will move over water where the Sea Surface Temperature is warmer than 30°C. Tropical Storm Michael will strengthen slowly during the next 24 hours. However, it will intensify more rapidly on Tuesday when the upper level winds weaken. Michael will strengthen into a hurricane when it moves over the Gulf of Mexico and it could intensify into a major hurricane.
Tropical Storm Michael has been moving slowly while the circulation organizes and the center reforms. Michael will move around the southwestern part of the subtropical high pressure system over the western North Atlantic Ocean. The high will steer Michael in a northward direction during the next two or three days. On its anticipated track the center of Tropical Storm Michael will pass between the western end of Cuba and the Yucatan peninsula on Monday. Michael could approach northern Florida by Wednesday. It will be a hurricane at that time and it could be a major hurricane. Michael could produce strong winds, a significant storm surge and drop heavy rain when it reaches the coast.
Subtropical Storm Alberto formed over the northwestern Caribbean Sea on Friday morning. The National Hurricane Center (NHC) designated an area of low pressure as Subtropical Storm Alberto on Friday morning based on data from buoys and ship reports. At 5:00 p.m. EDT on Friday the center of Subtropical Storm Alberto was located at latitude 19.4°N and longitude 86.3°W which put it about 85 miles (135 km) south-southeast of Cozumel, Mexico. Alberto was moving toward the east at 2 m.p.h. (3 km/h). The maximum sustained wind speed was 40 m.p.h. (65 km/h) and there were wind gusts to 50 m.p.h. (80 km/h). The minimum surface pressure was 1005 mb.
A Tropical Storm Watch has been issued for the portion of the U.S. coast from Indian Pass, Florida to Grand Isle, Louisiana including New Orleans. The government of Mexico issued a Tropical Storm Watch for the portion of the coast from Tulum to Cabo Catoche. The government of Cuba issued a Tropical Storm Watch for the province of Pinar del Rio.
The circulation around Subtropical Storm Alberto was asymmetrical. The low level center of circulation was located just to east of the Yucatan Peninsula. The strongest thunderstorms were occurring in a band located about 100 miles (160 km) east and north of the center. Flow around an upper level trough over the Gulf of Mexico was producing westerly winds which were blowing toward the top of the circulation. Those winds were causing strong vertical wind shear which was the reason why the thunderstorms were occurring well to the east of the center of circulation.
Subtropical Storm Alberto will move through an environment marginally favorable for intensification during the next 24 to 36 hours. Alberto will move over water where the Sea Surface Temperature is near 28°C. So, there is sufficient energy in the upper ocean to support intensification. However, the upper level trough will continue to cause moderate to strong vertical wind shear during the next day or so. The wind shear will inhibit intensification. Some gradual strengthening is possible. The winds are weaker near the axis of the upper level trough. If Alberto moves under the axis of the trough when it reaches the northern Gulf of Mexico, then the wind shear will decrease. Alberto could strengthen more quickly if that happens. There is a chance that Alberto could reach hurricane intensity. If more thunderstorms form closer to the center of circulation, then NHC could change the designation of Alberto to a tropical storm.
Subtropical Storm Alberto is moving around the western end of a large high pressure system over the Atlantic Ocean. The high is steering Alberto slowly toward the north-northeast. A general motion toward the north is forecast during the next day or so. When Alberto gets farther north, the upper level trough could steer it more toward the north-northwest. There is a chance that the steering currents could weaken when Alberto nears the Gulf Coast. Thus, there is much more uncertainty about the track forecast after that time.
The greatest risk with Subtropical Storm Alberto will be locally heavy rain and the potential for flooding. Most of the heavy rain is likely to fall north and east of the center. Much less rain is likely to fall from the western side of Alberto. The coast of the Gulf of Mexico is very susceptible to storm surges. The water level will rise along the eastern and northern coasts of the Gulf of Mexico where the winds blow the water toward the shoreline.