11:45 AM | Tropical storm threat for Florida by early next week and “Bonnie” re-develops near the Outer Banks

GOES visible image of "Bonnie" which has re-developed into tropical depression status; image courtesy Penn State eWall, NOAA

Overview
The official Atlantic Basin hurricane season has just begun and it may be more active than normal and more active than recent years as El Nino fades in the tropical Pacific Ocean and La Nina conditions develop (see tropical outlook). Tropical Storm "Bonnie" formed this past weekend and lasted as a minimal tropical storm for little more than 14-15 hours before making landfall Sunday morning near Charleston, SC.  “Bonnie” has actually re-developed this morning into a tropical depression and is likely to produce additional heavy rainfall over coastal eastern North Carolina during the next 6-12 hours.  In addition, signs indicate a new tropical storm is likely to form in the eastern Gulf of Mexico by early next week and then cut across Florida potentially producing several inches of rain for a good portion of the state.  If this next system were to become a named tropical storm, it would be called “Colin” and be the third of the 2016 Atlantic Basin season (“Alex” formed in January).

The 00Z European model forecast map for Sunday night with low pressure headed into the Gulf of Mexico; map courtesy tropicaltidbits.com

“Bonnie”
“Bonnie” became the second named tropical system of 2016 in the Atlantic Basin and reached tropical storm status over the holiday weekend before making landfall near Charleston, SC on Sunday.  After landfall, Bonnie weakened and spun around for the next few days, but it did not completely disappear and this raised the possibility for some re-development.  Indeed, the system has now returned to tropical depression status with winds near 30 mph and slight strengthening is possible during the next 24 hours as it slowly moves away from the NC coast. The current estimated central pressure is 29.80 inches.

The 00Z European model forecast map for Monday night with potential tropical storm "Colin" in the eastern Gulf of Mexico; map courtesy tropicaltidbits.com

“Colin”
Looking ahead, signs point to the formation of a tropical storm in the eastern Gulf of Mexico by early next week and this system would likely then cut a general west-to-east path right across the state of Florida.  If “Colin” does form and take this path, it could produce several inches of rain over a good portion of Florida in the Monday/Tuesday time period.  For now, as is typical early in the Atlantic hurricane season, there is strong wind shear (strong W-NW winds at upper-levels, easterly winds at low-levels) over the Gulf of Mexico and Caribbean Sea which is inhibiting tropical activity.  By this weekend, an area of disturbed weather is likely to form near the Yucatan Peninsula as a broad trough of surface low pressure arrives in that region.  With upper-level high pressure centered to the east from the Bahamas to the central Caribbean Sea and broad low pressure aloft near South Texas, this area of disturbed weather should be steered into the Gulf of Mexico by Sunday or Monday and then possibly become the third named tropical system of the year.  

Any storm that does form in the eastern Gulf of Mexico is likely to cut across Florida in a general west-to-east fashion and then head E-NE into the western Atlantic - rather than turn northward up the east coast. The reason for this is that deep upper-level low pressure will be setting up early next week over the NE US and its steering currents would quite likely prevent any northward movement of “Colin” up along the east coast.  The European computer forecast model has had a good handle on the unfolding situation in the Gulf of Mexico and its most recent forecast maps are shown (above) with low pressure headed towards Florida by early next week.

Meteorologist Paul Dorian
Vencore, Inc.