The 2011 Columbus Day Weekend Storm: Overcoming Challenges in Diagnosing a Rapidly Strengthening Maritime Low Pressure System and Communicating the Associated Warning Message

On 9-10 October 2011 (the Columbus Day weekend), an area of low pressure developed near the northwest Bahamas and moved north and west across the east central Florida Atlantic waters. The system intensified during the late afternoon (Sunday, 9 October) as it moved into the coastal waters of Brevard County. As the central pressure dropped below 1000 mb, sustained winds northwest of the circulation center, in the vicinity of the core convection, strengthened to tropical storm force accompanied by gusts to near hurricane force. The hybrid low made landfall near Cape Canaveral, Florida, during the late evening hours and maintained both inland and up-coast motion vector components during the overnight hours (early Monday, 10 October). Impacts were significant to both marine and coastal communities. As the storm rapidly intensified, ships traveling in/out of Port Canaveral were exposed to increased peril and area marinas were forced to quickly take additional precautions for maritime storm conditions (up from gale conditions). Along the Brevard and Volusia County coasts, residents and visitors experienced power outages and wind damage comparable to what typically occurs from landfalling (sub-)tropical storms. Adverse wind and seas conditions were announced well ahead of the arrival of the low pressure system, culminating in the issuance of a local Storm Warning for mariners and a local High Wind Warning for coastal land areas – both rare product issuances relative to the geography and time of year.

Of particular interest was the band of significant convection which developed northwest of the center. Its evolving mesoscale character signaled the increasing threat and subsequent impacts. The band was well-sampled by traditional observation platforms (such as the WSR-88D radar, cloud-to-ground lightning sensors, offshore buoys, etc.) and enhanced observation platforms unique to NASA/Kennedy Space Center and USAF/45th Weather Squadron (such as the 50 and 915 MHz profilers, mesonet tower winds, and total lightning information sensors). The enhanced data sets were essential to diagnosing the strengthening system and supported warning operations. Prior to landfall, the Lightning Detection and Ranging system showed increased (total) electrification of the core convection and inferred a rapid deepening of the low. Mesonet wind data across northern Brevard and southern Volusia counties helped to gage the extent of downward mixing of strong winds.

This presentation will explore the utility of the enhanced data sets as the low deepened and made landfall. The challenges of communicating the warning message to describe the evolving threat and potential impact will also be presented.