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Subtropical Storm Ana Forms Near South Carolina

The area of disturbed weather (90L) off the Southeast U.S. coast finally gained a well-defined circulation center and enough heavy thunderstorms near its core to be designated Subtropical Storm Ana at 11 pm EDT Thursday. Ana's formation date of May 7 is the earliest appearance of a named storm in the Atlantic since a previous incarnation of Subtropical Storm Ana was recognized on April 20, 2003.

Long-range radar out of Charleston Thursday evening showed only a modest amount of heavy rains associated with the storm, and satellite loops showed a large circulation with most of the heavy thunderstorms more than 100 miles away from the center. This is a typical appearance for a subtropical cyclone. As explained in wunderground's subtropical storm tutorial, a subtropical cyclone has characteristics of both tropical and extratropical cyclones. The difference between a subtropical storm and a tropical storm is not that important as far as the winds they can generate, but tropical storms generate more rain, and tropical storms have the potential to rapidly intensify into hurricanes, while subtropical storms do not. Wind shear over Ana was a moderate 20 knots late Thursday night, and water vapor satellite loops showed a large area of dry air to the west over the Southeast United States. This dry air is retarding development, thanks to strong upper-level winds out of the west driving the dry air into the storm's core. Ocean temperatures were near 25 - 26°C (77 - 79°F), which is just at the limit of where a tropical storm can form. Given these relatively cool ocean temperatures and the fact Ana will need at least a day to transition to a fully tropical storm, I expect that the worst Ana will be able to do is intensify to a 65-mph tropical storm that brings 4 - 6" of rain to the coasts of South Carolina and North Carolina on Saturday and Sunday. The 11 pm EDT Thursday forecast from NHC, which calls for a 50-mph storm bringing 2 - 4" of rain to the coast, is more likely.

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2978

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So, we have another early Ana! In 2003, a previous incarnation of Ana became a tropical storm in April.

Convection is rather sparse in association with the 40kt subtropical Ana today, as dry air wraps into the circulation from the south. Sea temps are around 25C. If Ana manages to increase it's convection near the LLCC, then it could become fully tropical, but significant strengthening is unlikely. Ana is expected to drift northwestwards towards the Carolinas, where landfall is expected. Cooler water near the coast should weaken Ana before this occurs.

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Ana is now classified as tropical, and has intensified to 50kts. The wind field has contracted, and although convection is not very deep, it is located over the LLCC now. Ana is not expected to strengthen any further, and should weaken before landfall.

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Convection has increased quite a bit over Ana this evening, definitely looking like a proper tropical storm now:

post-1820-0-69505400-1431197825_thumb.jp

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Ana made landfall this morning in South Carolina. The storm is now weakening and will continue to do so as shear also rises and Ana or it's remnants emerge back over waters too cool for tropical development.

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Ana made landfall this morning in South Carolina. The storm is now weakening and will continue to do so as shear also rises and Ana or it's remnants emerge back over waters too cool for tropical development.

attachicon.gif20150510.1730.goes13.x.vis1km_high.01LANA.35kts-1002mb-339N-789W.100pc.jpg

 

How strong did she get? Looks great.

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