A hurricane warning and a storm surge warning are up for the Florida Keys as Tropical Storm Eta gathers strength over the warm waters of the Florida Straits. Eta made landfall in south-central Cuba early Sunday morning with 65 mph winds, and emerged from its traverse of Cuba late on Sunday morning relatively intact, with a solid core of heavy thunderstorms. Eta’s spiral bands were spreading heavy rains over South Florida, the Bahamas, and Cuba. Eta is expected to pass through the Florida Keys on Sunday evening as a strong tropical storm or category 1 hurricane.

At 10 a.m. EST Sunday, November 8, Eta was a tropical storm with 65 mph winds and a central pressure of 993 mb, headed north at 14 mph. Tropical storm-force winds from Eta were already affecting the Florida Keys, with sustained winds of 46 mph, gusting to 53 mph, observed at Fowey Rocks. Wind shear was a high 20 – 30 knots over Eta, but the storm was over very warm waters of 29 degrees Celsius (84°F). Some dry air was wrapping toward the center of Eta from the southwest.

Forecast for Eta

The counterclockwise flow of air around a trough of low pressure to its west will steer Eta in a curving arc through the Florida Keys on Sunday, and then into the southeastern Gulf of Mexico on Monday. The southern end of the upper-level trough is detaching from the jet stream and forming a closed low over the southeastern Gulf, and this low is expected to merge with Eta on Monday. During this process, wind shear will fall from the high range to the moderate range, potentially allowing Eta to intensify into a category 1 hurricane as it passes through the Florida Keys on Sunday evening.

It’s more likely though that Eta would reach hurricane strength on Monday. However, there is also dry air associated with the trough, and that dry air will potentially wrap into the core of Eta and put the brakes on any rapid intensification.

Steering currents will be weak once Eta merges with the upper level trough, and it’s not yet clear whether Eta’s long-range path might end up closer to the west coast of Florida, as suggested by the GFS model; more to the north towards the Florida Panhandle, as predicted by the European model; or to the southwest towards Mexico’s Yucatan Peninsula, as predicted by the UKMET model. Eventually – maybe not until late in the week – the approach of a new upper-level trough may push Eta inland over the Florida Gulf Coast.

The main threats from Eta: Torrential rains and floods

Regardless of the exact track of Eta’s center, the storm will bring heavy rains, strong winds, and storm surge flooding well to the east of its center, resulting in several days of squally weather and locally torrential rain for South Florida and the Bahamas. One-day rainfall amounts of 1-3 inches, with a few areas of 3-5 inches, occurred in the 24 hours ending at 7 a.m. EST Sunday over South Florida (Figure 3). Storm-total rainfall amounts of 6-12″, with some isolated areas of up to 18″, could fall in the coastal cities of South Florida from Fort Myers and Naples to Miami and Fort Lauderdale, where soils are largely saturated from late-October rains. Tornadoes will also be possible in Eta’s rainbands.

Also see: Eta regains tropical storm status, heads for Florida after causing devastation in Central America

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Posted on November 8, 2020(12:55pm EST).