NASA's GPM sees tropical storm Colin take aim at Florida

NASA and the Japan Aerospace Exploration Agency's Global Precipitation Measurement, or GPM, mission core satellite passed over Colin and measured rainfall rates within the storm as it has begun to affect Florida.

Colin formed Sunday, June 5, at 4:30 p.m. CDT (21:30 UTC) in the southern Gulf of Mexico about 120 miles north of the Yucatan Peninsula. Colin originated from a wave of low pressure that propagated across the tropical Atlantic and northern coast of South America and into the southern Caribbean. As thunderstorm activity picked up, the wave slowly organized into an area of low pressure as it turned northward and passed over the Yucatan, read the NASA website.

After entering the extreme southern Gulf of Mexico, the low became sufficiently developed to become a tropical depression (TD 3). However, the circulation was not very well organized as it was under the influence of moderate southwesterly wind shear, causing most of the thunderstorm activity to be located well east of the center.

The GPM core satellite passed over Colin at 3:53 am EDT (07:53 UTC) on June 6, 2016. The data was made into an image at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The image was created overlaying DPR (radar) rain rates in the center of the swath and GMI (microwave) rain rates in the outer swath overlaid on enhanced infrared data from NOAA's GOES-East satellite to provide a complete picture of the storm.

GPM showed two large areas of rain associated with two areas of deep convection. The northernmost area contains areas of heavy rain rates of up to ~75 mm/hr (~3 inches per hour, shown in magenta) and shows some evidence of banding (curvature), indicating the presence of a cyclonic circulation. However, the National Hurricane Center (NHC) reported that Colin is poorly organized with multiple small-scale circulation centers: one near this area of convection and the other well to the west-northwest.  At the time GPM passed overhead Colin was a minimal tropical storm with maximum sustained winds reported at 50 mph by NHC.

At 10 a.m. CDT (15:00 UTC) on Monday, June 6, the center of Tropical Storm Colin was estimated near 27.0 degrees north latitude and 87.0 degrees west longitude, about 285 miles (455 km) west-southwest of Tampa, Florida.

Colin was moving toward the north-northeast near 16 mph (26 kph). NHC forecasters said that a turn toward the northeast with an increase in forward speed is expected this afternoon. A rapid northeastward motion is expected tonight and Tuesday. Maximum sustained winds are near 50 mph (85 kph) with higher gusts. Little change in strength is forecast during the next couple of days.

A tropical storm warning is in effect on Florida's west coast from Indian Pass to Englewood and on the east coast from Sebastian Inlet, Florida to South Santee River, South Carolina.

Colin is expected to strike the Big Bend area of the Florida Gulf Coast sometime during the overnight hours this evening.  However, little change in intensity is forecast as Colin is still under the influence of moderate vertical wind shear and too disorganized to intensify significantly.

Image: NASA