September 9, 2011

Tropical Weather Update


Katia remains a Category 1 hurricane with sustained winds of 85 mph. Katia will maintain is hurricane strength until Saturday morning as it will track over waters just warm enough to maintain tropical systems over the next 24 hours.

In addition, Katia is moving away from the stronger shear that was affecting the storm yesterday.

Beyond Saturday morning, Katia will then move northeastward into cooler waters and a zone of higher wind shear as it becomes more embedded in the westerlies. Katia will then transition to a powerful post-tropical storm over the weekend and will bring a round of heavy rain and gusty winds to the British Isles on Monday.

Tropical Storm Maria remains a tropical storm on Friday morning with sustained winds of 40 mph. Satellite imagery shows that although some deep thunderstorms have developed over the last 6-12 hours, they are nearly all to the north and northeast of the center of Maria.

The fast-forward motion of Maria combined with some strong southwesterly winds aloft are keeping Maria from becoming better organized at this time. However, Maria will have the opportunity to maintain its strength and perhaps slowly strengthen over the weekend as it moves into a zone of less wind shear.

However, if Maria does become a hurricane, it will likely not be until early next week.

In the meantime, Maria will bring gusty winds and squalls of heavy rain starting this morning to the Lesser Antilles. Eventually by Saturday night into Sunday, these squalls of wind and rain will spread all the way westward into Puerto Rico.

Maria is expected to eventually make a more northward turn later this weekend into early next week as forecast computer models show a weakening upper-level high pressure ridge to the north. However, there is also some concern the forecast models could be turning Maria too far north too quickly as the storm still has a considerable amount of westward momentum since it is moving nearly due west at around 20 mph.

Tropical Storm Nate remains nearly stationary over the Bay of Campeche with sustained winds of 70 mph. Computer forecast models have come into better agreement on Friday morning with respect to the track of Nate. The storm should remain nearly stationary over the next 12 hours or so and then a strengthening upper-level high pressure ridge building over the northern Gulf of Mexico will push Nate westward. This upper-level ridge should prevent Nate from moving northward into the Gulf and instead will force it westward into Mexico with a landfall likely between Tampico and Veracruz.

In fact, forecast models continue to trend southward so landfall near Veracruz may be more likely than near Tampico. The farther south Nate remains, the quicker landfall would be as there would be less distance across the Bay of Campeche for the storm to cover. A quicker landfall could also keep Nate from strengthening as much, but it is still likely to become a hurricane later today as it is over warm water with weak winds aloft. Several inches of rain will continue to affect the Mexican states of Campeche, Tabasco and Veracruz.

Elsewhere, there are no immediate threats for tropical development in the basin.

By Senior Meteorologist Dan Pydynowski

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