As we have been forecasting for the last 36 hours, aircraft reconnaissance this morning determined that the low off the Carolinas is in fact Subtropical Storm Andrea. The hurricane season does not officially start until June 1, but we are off to an early start this year.
AT 11 AM EDT...1500 UTC...A TROPICAL STORM WATCH HAS BEEN ISSUED ALONG THE SOUTHEAST COAST OF THE UNITED STATES FROM ALTAMAHA SOUND GEORGIA SOUTHWARD TO FLAGLER BEACH FLORIDA. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN THE NEXT 36 HOURS.
Aircraft recon reports that Andrea has a warm core at low levels from the surface up to 850mb and it cold core above that. This development of a warm core from the bottom up is consistent with a continuing wave of research into the tropical transition process. The continued strengthening of the low pressure system, despite having all frontal boundaries being cut off, is another clear indication that some subtropical processes must be in play within Andrea.
Andrea seems to have maximum sustained winds of about 45 mph over a large portion of the southeast side of the circulation. This would qualify Andrea as a Subtropical Storm. Fortunately for those of your near Jacksonville, the strongest winds are on the east side of the storm. Recon reported a central pressure of 1003 mb.
Andrea is a developing situation and more information will be coming very soon. Andrea is expected to continue on toward the Jacksonville area but stay out to sea. There is a great deal of spread between the models but the Southeast coast should continue to monitor the situation and check back in for updates.