Meteorologists often talk about the uncertainties in tropical cyclone track and intensity forecasts. We don’t often talk about the uncertainties associated with the size of the tropical cyclone circulation. Size is an important parameter in the case of Hurricane Sandy that will make a difference in how strong the winds get over South Florida.
There is the usual uncertainty associated with the track and intensity of Sandy, but the National Hurricane Center (NHC) has been very consistent in forecasting the center of Sandy to track across eastern Cuba and into the central and/or northwestern Bahamas. The strongest winds will be fairly close to the center and well away from South Florida. However, the computer models are indicating that the wind field is going to expand over the next few days. The extent of this expansion and timing will dictate, in large part, how strong the winds blow over us in South Florida.
NHC creates a probability graphic to help describe the likelihood of tropical storm force winds. This graphic takes into account the uncertainty in the track, the uncertainty in the intensity, and the variability of the size of the tropical cyclone. The current graphic, based on the forecast issued at 5:00 pm Wednesday, shows relatively low probabilities along portions of the Florida east coast but these probabilities have been increasing.
The National Weather Service forecasters thought there was a high enough chance of tropical storm force winds to post Tropical Storm Warnings from Ocean Reef to Sebastian Inlet which includes Miami-Dade, Broward and Palm Beach coastal areas.
Based on the current forecast, sustained tropical storm force winds (39 mph or greater) are likely somewhere in the warning area with the highest probability in Palm Beach County. And we could easily see gusts to 50 or 60 mph, most likely from late Thursday afternoon through Friday.
Regardless of precisely how high the winds get, we are in for a prolonged period of strong winds. these winds will likely be enough to produce some major beach erosion and possibly minor coastal flooding during high tides.