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Expect periods of heavy rain related to well-developed tropical disturbance

Tropical disturbance off Florida coast
Tropical disturbance off Florida coast (WPLG)

The Tropical Disturbance we have been following offshore of Central Florida has a well-defined circulation with strong thunderstorms on the south and east side. Upper-level winds blowing over the disturbance are not allowing the thunderstorms to wrap around the center, however. If the winds were to let up a bit allowing that to happen, the system would be designated a tropical depression.

The National Hurricane Center is giving the disturbance a decent chance of making the transition to a depression. There’s a slight chance it could jump to tropical storm if winds of 40 mph were found in the circulation, although that’s not currently expected. In any case, it wouldn’t make much difference to the weather across the Florida peninsula.

The flow around the circulation is pushing what amounts to a front down the peninsula. Air is drier to the north of the front, and very moist to the south. In fact, the moisture level in the atmosphere in South Florida is at or near record levels.

The combination of the front, the moisture, the upper-level components of the disturbance creating a flow from the northwest down the state, and strong July sun providing extra energy is expected to generate rounds of heavy rain over the next few days.

Tropical disturbance off Florida coast (WPLG)

The National Weather Service has issued a Flood Watch for all of South Florida through Monday given the forecast potential of two to four inches of rain with some areas getting more.

The disturbance is expected to meander off the Central Florida coast for the next day or so. On Sunday, the consensus of the computer forecast models is that the system, whether it organizes into a tropical depression or not, will drift across the central part of the state.

Once it reaches the Gulf, the counterclockwise circulation will be pulling additional moisture from the tropics over the peninsula, so that should keep the periods of heavy rain coming.

This evolving situation doesn’t lend itself to just one long-duration period of rain. Expect very steamy sunshine at times as well. But with so much moisture in the atmosphere, and upper-level winds supportive of strong thunderstorms, the ingredients are in place for excessively heavy downpours to develop.

When a circulation like this is involved, sometimes the thunderstorms form into lines, so one area gets one storm after the other. This is when flooding becomes a threat because the water doesn’t have time to drain off.

Be alert and stay aware over the next few days.

Saharan dust is forecast to reach Florida later next week, which should help dry out the atmosphere here. It should also keep the tropics under control.


About the Author:

Bryan Norcross is currently a hurricane specialist at Local 10 News, the station where he began his stretch on television in Miami in 1983.