Update 5:21 p.m.: Gusty showers along a cold front are moving offshore into Palm Beach coastal waters.
Winds are gusting upwards of 34 mph. National Weather Service is asking mariners to use caution.
Previous story: The Storm Prediction Center has increased the chances for thunderstorms this afternoon in South Florida as a cool front moves through the state.
Forecasters at the Norman, Okla.-based facility say areas from the tip of the peninsula to north of Lake Okeechobee are vulnerable to thunderstorms and lightning as the warming air interacts with the frontal boundary.
The storms are expected to be isolated, but National Weather Service forecasters in Miami said a results form a morning balloon launch found temperatures and moisture levels in the atmosphere primed for the kind of instability that can ignite storms.
The so-called “convective available potential energy” is above 2,500 joules per kilogram, which is considered large.
“Based on current forecasts in temperature and moisture, instability should be plenty sufficient,” forecasters wrote. “Limiting factors, however, will be abundant cloud cover, poor mid-level lapse rates and weak forcing ahead of the approaching weakening cold front boundary.”
Gusty winds to 40 mph, lightening and localized heavy rainfall are the biggest concerns for this afternoon into early evening.
National Weather Service forecasters in Miami are expecting another round of robust thunderstorms in South Florida today.
Tuesday’s storms recorded a 55 mph gust of wind at Palm Beach International Airport, which also ended up with 1.74 inches of rain.
The storms are being stirred up by a layer of deep tropical moisture lingering over the area along with frigid temperatures in the upper atmosphere of 19.4 degrees Fahrenheit.
The collision of the two air masses equals and eruption of thunderstorms, which can bring hail, lightning and gusty winds.
High temperatures today should reach near 90 degrees. There is a 50 percent chance of rain.
“The main driving mechanism for thunderstorm activity will be daytime heating and sea breeze boundaries,” forecasters wrote. “A few cells could become strong enough to produce damaging winds and small hail at times.”
Sea breezes help lift the warm surface air into the upper atmosphere.
Earlier, the Storm Prediction Center had issued a marginal risk of severe weather for South Florida today, noting cooler temperatures high in the atmosphere may spur robust thunderstorms.
National Weather Service forecasters in Miami said storms are expected to develop in the late morning to early afternoon along the coast, shifting to the interior and to the west coast through late afternoon early evening.
Concerns include nickel-size hail and wind gusts of up to 55 mph that could damage awnings, car ports, trees, and toss around light objects, such as lawn furniture.
A marginal risk is the lowest level on the center’s severe weather scale.
Temperatures at 18,000 feet are expected to reach a frigid 17 degrees this afternoon as a upper-level system moves the northeast Gulf of Mexico. That is expected to clash with the high pressure system that has been hanging over the southeast during the past week.
Miami forecasters have increased rain chances to 50 percent along the coast and 70 percent inland.
Complicating today’s forecast is a cluster of thunderstorms over the northeastern Gulf of Mexico and the Florida Panhandle combine with afternoon heating.
“Our atmosphere features plenty of moisture and available instability for diurnally induced convection to access,” Miami forecasters wrote.
Then there’s a gust front from a previous storm cluster that pushed through northern Florida earlier today. That will focus showers over inland South Florida moving east.
Previous story: The National Weather Service in Miami is expecting strong to severe thunderstorms throughout South Florida late this afternoon through evening.
While many of the storms will be focused inland and around Lake Okeechobee, forecasters said coastal areas should also be prepared for some of the stronger storms to bring wind gusts upwards of 60 mph, frequent lightning and localized street flooding.
The Storm Prediction Center has South Florida in a marginal risk for severe weather, with a 5 percent chance of damaging winds, mostly from thunderstorm downbursts. The chance of tornadoes is low, but Palm Beach County was put into the slight category for potential flooding. Slight is the second tier on a five-level weather threat scale.
Storms are expected to erupt as daytime highs near 90 degrees and sea breezes kick up. Showers may taper off after sunset, but forecasters note a cluster of thunderstorms moving east from the Gulf of Mexico could also affect South Florida through the evening.
Powerful thunderstorms and near record-high temperatures are forecast through Wednesday as the sprawling tail of a cold front whips into South Florida.
Small hail, wind gusts up to 60 mph and frequent lightning are the main concerns with the forecast, which puts Palm Beach County and the Treasure Coast in the marginal threat level for severe weather Tuesday and Wednesday.
While marginal is the lowest level on a five-tier scale, increasing moisture, and a dip in the jet stream that places South Florida under the swift-moving current of air, could make for potentially volatile 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 Storm Prediction Center in Norman, Okla., gave South Florida a 5 percent chance of severe weather as of Monday.
Tuesday’s temperature could hit 90-degrees, just one degree shy of the record set in 1986. Expected cloud cover could limit Wednesday’s high to 87 degrees.
Afternoon sea breezes are the expected trigger for Tuesday’s storms, which are forecast to mostly hug parts of the coast.
By Wednesday afternoon, the cold front associated with a low pressure system centered over the mid-Atlantic states will swing into South Florida. Speedy winds high in the atmosphere coupled with temperatures of just 14 degrees near 18,000 feet could mean robust updrafts, which are the makers of hail and lightning.
“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 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.”