Tag Archives: Andrea

Tropical Storm Andrea forms in the Gulf of Mexico

The first named storm of the 2013 Atlantic Hurricane season has arrived! The area of disturbed weather in the Eastern Gulf of Mexico we have been following has acquired enough organization to be classified as a tropical storm. An aircraft reconnaissance mission was flown this afternoon and they determined that Andrea had formed a better defined low-level circulation center. Peak flight level winds were around 47 knots, which would normally mean about 40 knot surface winds, but the National Hurricane Center chose 35 knots at the time of the first advisory due to SFMR readings. At the time of the most recent advisory (10:00pm CDT) here is what the NHC had Andrea listed at:

SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...26.0N 86.3W
ABOUT 270 MI...430 KM WSW OF TAMPA FLORIDA
ABOUT 270 MI...430 KM SSW OF APALACHICOLA FLORIDA
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...N OR 10 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES

Tropical Storm watches and warnings have been issued for parts of Florida, Georgia, South Carolina and North Carolina:

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE WEST COAST OF FLORIDA FROM BOCA GRANDE TO OCHLOCKNEE RIVER

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* FLAGLER BEACH FLORIDA TO SURF CITY NORTH CAROLINA

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

Currently another hurricane hunter mission is investigating Andrea and should provide a more reliable reading of the storm’s intensity. On satellite imagery, Andrea exemplifies the typical June Gulf of Mexico tropical storm:

An enhanced infrared satellite image of Tropical Storm Andrea taken at 4:45Z. The center of the storm is along the western edge of the deep burst of convection (purples and white colors) west of Tampa, Florida.
An enhanced infrared satellite image of Tropical Storm Andrea taken at 4:45Z. The center of the storm is along the western edge of the deep burst of convection (purples and white colors) west-southwest of Tampa, Florida.

Andrea is currently experiencing about 20-30 knots of westerly shear which is keeping all of the heavy thunderstorm activity on the eastern half of the circulation. This sheared pattern is expected to continue until landfall on Thursday Night. As a result, Andrea is not expected to intensify significantly before landfall and should come ashore in the Big Bend region of the Florida peninsula with maximum sustained winds in the 45-50 mph range.

However, the impacts extend well away from the center. Heavy rains (3-6″ with isolated amounts of over 8″) and gusty winds will affect Florida over the next 24-36 hours. Furthermore, there will be a threat of tornadoes embedded within the bands of Andrea. Peak storm surge heights are expected to be between 2-4 feet from Tampa Bay northward to Apalachicola.

As Andrea approaches Florida she will begin to accelerate and move up the Eastern Seaboard. By 7am Friday, the storm is expected to be around coastal South Carolina according the latest NHC forecast track. By this time, the storm is expected to begin/have already lost tropical characteristics, but still will be capable of bringing heavy rains and gusty winds.

A couple of things to keep track of tonight:

  • The hurricane hunter mission currently investigating TS Andrea and has just found maximum flight level winds of 52 knots, so it appears Andrea is slowly intensifying.
  • This buoy, which has reported sustained winds of 31 knots, and a pressure of 1001.7mb. This means it is probable that the central pressure of TS Andrea is around 999mb or so.
  • I have read that satellite imagery provided by SSD is temporarily unavailable, and I can recommend this website, which has rapidly updating images over the Gulf of Mexico in the midst of this shortage. EDIT: it appears the SSD imagery has just returned.

Most importantly, stay tuned to the latest advisories provided by the National Hurricane Center and your local Weather Forecast Office.

I will update again once conditions warrant.

-Mike