Sub-tropical storm Nicole grows into broad-swath hit to US east coast

Subtropical storm Nicole is developing its powers while maintaining a track on the Bahamas and the Florida coast, with forecasters at the National Hurricane Center (NHC) still expecting the storm to be "near or at hurricane strength" when it hits the east coast.

"With Nicole's structure beginning to take on more tropical characteristics, strengthening is likely to commence later today," NHC forecasters wrote in in a warning at 04:00 a.m. eastern time.

Forecasters stand by their initial warning that Nicole should be "near or at hurricane strength" as it approaches the north-western Bahamas and the east coast of Florida.  Warm waters and upper-level air conditions are currently set to aid storm development.

Analysts at Guy Carpenter say look more at the breadth of impact than the severity, noting that a large circulation centre implies a broader regional impact.

"The duration of the event will be lengthy and noteworthy, more so than the severity of conditions," Guy Carp analysts said in a warning. They cite tropical storm force winds likely to extend to 400 miles from centre from the current 275-mile radius from the hybrid tropical/mid-latitude system

Hurricane conditions are likely in portions of the north-western Bahamas on Wednesday, where a Hurricane Warning is in effect. Hurricane conditions are possible across portions of the Florida coast beginning late Wednesday or Wednesday night, where a Hurricane Watch is in effect. A storm surge with "large and damaging waves" is expected along much of Florida and Georgia east coast. Heavy rainfall is likely Wednesday and Thursday across the Florida peninsula.

The NHC's current best-guess on storm course shows a path through Florida and Georgia before a run up the full eastern seaboard. Nicole should be extratropical by day 4 over the Mid-Atlantic US.

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