Tropical Storm Colin Becomes Earliest “C” Storm in Atlantic History

NOAA’s National Hurricane Center upgraded Tropical Depression 3 to Tropical Storm Colin in a special update at 5:30 PM EDT Sunday, June 5--making some history along the way. Never before have we been tracking the Atlantic’s third named storm of a calendar year this early in the year. As noted in a weather.com article, there have been two other “C” storms as early as June since current naming practices began in the 1950s: Hurricane Chris (which began as a named subtropical storm on June 18, 2012) and Tropical Storm Candy (June 23, 1968). Going all the way back to 1851, the previous earliest appearance of the season’s third storm was June 12, 1887, although some early-season storms were undoubtedly missed during the pre-satellite era.

As of 8 PM EDT Sunday, Tropical Storm Colin was located in the south central Gulf of Mexico at 23.4°N, 87.8°W, or about 460 miles southwest of Tampa, Florida. Colin is a minimal tropical storm, with top sustained winds of just 40 mph, and only modest further strengthening is expected before Colin approaches the northwest Gulf Coast of the Florida peninsula on Monday evening. The well-defined southwesterly flow steering Colin will take it into the Atlantic and on a track paralleling the southeast U.S. coast on Tuesday, where models suggest it will maintain or regain tropical storm strength, especially southeast of North Carolina. Update: At 11:00 PM EDT Sunday, NHC placed the southeast U.S. coast from Sebastian Inlet, FL, to Altamaha Sound, GA, under a tropical storm warning, with a tropical storm watch extending northward from the warning area to the South Santee River, SC. A tropical storm warning remains in effect on the Florida Gulf Coast from Indian Pass to Englewood.

As shown in Figure 1, the steering flow will keep Colin moving northeast rather than curving north or northwest toward the U.S. East Coast. The storm’s heaviest rains will likely remain just off the Southeast coast, although residents along the immediate coast should be prepared for tropical storm conditions and heed precautions as recommended by local authorities.


Figure 1. WU depiction of official forecast track of Tropical Storm Colin as of 8 PM EDT Sunday, June 6, 2016.


Figure 2. This enhanced infrared satellite image of Tropical Storm Colin from 8:37 PM EDT Sunday, June 6, 2016, shows convection blossoming (red and yellow colors) south of Colin’s center of circulation. Image credit: CSU/CIRA/RAMMB.


Colin has a quite elongated, asymmetric structure, with most of its showers and thunderstorms (convection) on its east flank, although very strong convection was beginning to bubble on Colin’s south side on Sunday evening (see Figure 2 above) as the circulation moves away from the Yucatan Peninsula. The nighttime burst in convection common to tropical storms will give Colin an opportunity to strengthen overnight over very warm waters of around 28°C (82-83°F). On Monday, wind shear will increase along Colin’s track toward the Florida coast (see Figure 4 below), which will limit the storm’s ability to strengthen further. The shear will also tend to favor a continuation of Colin’s asymmetric structure.


Figure 3. A plethora of watches, warnings, and advisories covered the central Florida peninsula and nearby waters on Sunday evening, June 5, 2016. Image credit: NWS.


Despite its modest strength, Colin may pack a noteworthy punch across Florida over the next day or so. Intense thunderstorms can be expected to race northward across the peninsula from Sunday night through Monday. Some of these may spawn tornadoes, as the vertical wind shear that limits Colin’s growth as a tropical system will also favor the development of rotating updrafts within thunderstorms. At high tide early Monday afternoon, a storm surge of 1 to 3 feet (perhaps higher in some areas) could affect the immediate coastline from Indian Pass south to Tampa Bay, with 1 to 2 feet possible south of Tampa Bay to Florida Bay. Very heavy rains are also on tap for much of the peninsula, with amounts easily topping 6” to 8” in localized areas.

We’ll have a full update on Colin by midday Monday. We are also keeping our eye on two areas of potential tropical development in the Northeast Pacific, although the odds are slim that either one will develop over the next two to three days.

Bob Henson


Figure 4. As it moves northward toward the west coast of Florida, Tropical Storm Colin will encounter increasing vertical wind shear (shown here in knots; multiply by 1.15 for mph). This wind shear will limit Colin’s ability to strengthen before it strikes the Florida coast. Image credit: University of Wisconsin/SSEC.