Tropical Storm Colin is already bringing heavy rain to Florida and parts of the Southeast. The center of the storm is marked by the red X. (NOAA)

Tropical Storm Colin is maintaining intensity in the Gulf of Mexico and is expected to make landfall in Florida on Monday night. Colin’s main threats will be heavy rain and flooding, including the potential for a one- to three-foot storm surge at high tide in the Tampa area.

Despite its messy appearance, Tropical Depression Three was upgraded to Tropical Storm Colin on Sunday afternoon. Data from a hurricane hunter mission have found peak sustained winds of 50 mph. However, a hostile environment in the Gulf of Mexico is keeping Colin from becoming a significant threat. Strong vertical wind shear — which acts to tear tropical storms apart — is displacing the thunderstorm activity far from the center of circulation. This will prevent it from strengthening much as it approaches Florida.

Colin is the earliest third tropical storm of the season on record by a seven-day margin. The previous record-holder formed June 12, 1887.


Track forecast for Tropical Storm Colin. (Weather Underground)

Although the center of the storm was still 300 miles offshore Monday morning, heavy rainfall was already spreading across Florida and neighboring states. Rainfall will continue to increase through Tuesday.

The rainfall forecast remains high for the central and northern parts of Florida, but models have backed off on the higher amounts in the southern part of the peninsula. The map below shows an accumulated rainfall forecast from the National Weather Service through Wednesday morning.


(NOAA)

With any tropical cyclone, there is an elevated risk of tornadoes. The Storm Prediction Center indicates that northern and central Florida, as well as southeastern Georgia, should be alert for possible tornadoes today.

Although Colin is disorganized and not even a hurricane, it will still generate a storm surge to the south of the landfall point because of the onshore winds.

According to the National Hurricane Center, Indian Pass, Fla., down to Tampa Bay should expect a one- to three-foot storm surge. This means the water level will be one to three feet above the tide level. High tide will reach Cedar Key, Fla., and Tampa in the early afternoon hours, about 2 or 3 p.m., so that is likely when the threat of flooding would be greatest. The low tides are about three to four feet lower, so if the storm surge occurs then, the water level should not even exceed the normal high tide level.

A tropical storm warning has been issued for parts of northern Florida and the surrounding Gulf of Mexico and Atlantic marine areas. A flood watch is in effect for most of Florida and parts of southeast Georgia.


A tropical storm warning has been issued for the northern Florida peninsula and the surrounding water. (National Weather Service)

Interestingly, the last time Florida was hit by a tropical storm was June 6, 2013, when Tropical Storm Andrea made landfall. The sheared structure, track and landfall point were nearly identical to Colin’s.

Satellite image of Tropical Storm Andrea from the morning of June 6, 2013. The track is overlaid in red, with a yellow dot at the landfall point.

The next name on this season’s list is Danielle, and as of now, the long-range models do not show any indication of another storm in the next couple of weeks. The record for earliest fourth tropical storm formation date is July 5, and that was Dennis in 2005.