Update 5:40 p.m.: Storms are developing over coastal areas of Palm Beach County, including West Palm Beach, but appear to be limited.
The worst of the thunderstorms are in Miami-Dade County where forecasters said a waterspout was spotted on radar off shore.
As recent as 5 p.m., meteorologists said the ingredients still existed for a few strong thunderstorms to develop into tonight.
“Small hail and a few funnel clouds/waterspouts may be possible along the eastern peninsula,” forecasters wrote in their 4:58 p.m. discussion.
The Storm Prediction Center has Palm beach County in its marginal threat level for severe weather today, noting that supercell thunderstorms are possible along the coast.
Forecasters said the highest chance for storms will be this afternoon as the sea breeze kicks up with daytime highs nearing 90 degrees.
Supercell thunderstorms are characterized by a rotating mesocyclone and strong updrafts that often produce hail and frequent lightning.
But the worst of the weather may be Wednesday as a cold front sweeps through South Florida.
Thunderstorms, some severe, may bubble up on the leading edge of that front. The storms may be amplified by a dipping jet stream that will have winds whipping high in the atmosphere at more than 100 mph.
Daytime temperatures Wednesday are expected to reach in to the high 80s. That buoyant air will soar into the atmosphere, running into sub-freezing temperatures. The energy created by the difference in those air columns is what contributes to the strength of storms.
“With the warm humid air building, all we need is for the cold air aloft and strong winds aloft to interact with that to cause severe weather,” said Dan Kottlowski, a senior meteorologist with the Pennsylvania-based AccuWeather. “That’s why we believe that Florida is looking to be primed for that potential.”
The National Weather Service is warning of the possibility of small hail, frequent lightning and strong wind gusts. Flash flooding in poorly drained areas is also a concern.
“We’ll assess as we go,” said Robert Molleda, warning coordination meteorologist with the National Weather Service in Miami. “Wind and hail appear to be the two biggest threats, but we can’t rule out anything else.”
The ingredients are similar to what South Florida experienced two weeks ago when hail as big as golf balls pummeled the coast. One person was also struck and killed by lightning.
The cold front will bring in drier air and force temperatures down a little. Thursday’s high is expected to reach 83 degrees, which is about normal for this time of year. Friday’s daytime temperature will climb only to 80 degrees, four degrees shy of normal.
Some rain will likely be welcomed by parts of parched Palm Beach County, which ended April below normal for rainfall.
An average of just one inch of rain fell last month in coastal areas of Palm Beach County, according to the South Florida Water Management District. That’s two inches below normal for April.
Rain chances Tuesday stand at about 50 percent, increasing to 70 percent Wednesday.
“The timing for this couldn’t be worse for the Palm Beaches,” Kottlowski said about Wednesday’s storm forecast. “It looks like all the ingredients are coming together during the mid to late afternoon hours.”