Tropical Storm Eta Slowly Weakening In The Gulf of Mexico

After briefly attaining hurricane strength in the Gulf of Mexico, the now Tropical Storm Eta is forecast to make landfall on Thursday, becoming the latest calendar year named storm to make landfall in Florida since Tropical Storm Gordon in 1994.

This tropical cyclone is not forecast to directly impact Trinidad, Tobago, or the Lesser Antilles. The tropical wave did produce floods, gusty winds, and landslides across parts of Barbados, St. Vincent, and St. Lucia.

List of names for the 2020 Atlantic Hurricane Season. The next named tropical cyclone will be called Iota.

At 5:00 PM AST, the center of Tropical Storm Eta was located by reconnaissance aircraft, Doppler radars, and satellites near latitude 27.3 North, longitude 83.6 West. Eta is moving toward the north near 12 mph (19 km/h), and this general motion is expected to continue overnight, followed by a turn toward the north-northeast and northeast Thursday morning. On the forecast track, the center of Eta will move closer to but just offshore of
the west-central coast of Florida tonight, and move inland over the northern portion of the Florida peninsula on Thursday. Eta is expected to move northeastward into the western Atlantic late Thursday and early Friday.

Data from the aircraft and NOAA Doppler weather radars indicate that maximum sustained winds are near 70 mph (110 km/h) with higher gusts. Slow weakening is expected as Eta approaches the west coast of Florida tonight, followed by rapid weakening after landfall occurs on Thursday.

Tropical-storm-force winds extend outward up to 115 miles (185 km) from the center. A wind gust to 60 mph (96 km/h) was reported this afternoon at Punta Gorda, Florida, while a gust to 55 mph (89 km/h) was reported St. Petersburg. The estimated minimum central pressure is 990 millibars.

Tropical Storm Eta Forecast Track as of 5:00 PM AST Wednesday 11th November 2020. (National Hurricane Center)
Tropical Storm Eta Forecast Track as of 5:00 PM AST Wednesday 11th November 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Eta Watches and Warnings as of 5:00 PM AST Wednesday 11th November 2020. (National Hurricane Center)
Tropical Storm Eta Watches and Warnings as of 5:00 PM AST Wednesday 11th November 2020. (National Hurricane Center)

A Storm Surge Warning is in effect for:

  • Bonita Beach to Suwanee River Florida, including Tampa Bay and Charlotte Harbor

A Tropical Storm Warning is in effect for:

  • Bonita Beach to Suwannee River Florida

A Storm Surge Watch is in effect for:

  • Steinhatchee River to Suwannee River Florida

A Tropical Storm Watch is in effect for:

  • North of the Suwannee River to Aucilla River Florida

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 6 to 12 hours.

A Storm Surge Warning means there is a danger of life-threatening inundation, from rising water moving inland from the coastline, in this case within 24 hours in the indicated locations. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Storm Surge Watch means there is a possibility of life-threatening inundation, from rising water moving inland from the coastline, in this case within 24 hours.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area.

Interests elsewhere along the Gulf Coast of Florida should monitor the progress of Eta.

Hazards Affecting Land

Tropical Storm Eta probabilities for tropical-storm-force winds as of 5:00 PM AST Wednesday 11th November 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Tropical Storm Eta probabilities for tropical-storm-force winds as of 5:00 PM AST Wednesday 11th November 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

WIND: Tropical storm conditions are expected in the Tropical Storm Warning area along the Florida west coast by this afternoon and evening. Tropical Storm conditions are possible in the watch area along the Florida Big Bend region by Thursday.

TORNADOES: A few tornadoes are possible through tonight over parts of western and central Florida.

SURF: Swells generated by Eta are expected to affect the north coast of Cuba, southern and western Florida, and the Florida Keys during the next day or so. These swells are likely to cause life-threatening surf and rip current conditions.

STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide:

  • Anclote River to Boca Grande, FL including Tampa Bay: 3-5 ft
  • Boca Grande, FL to Bonita Beach, FL including Charlotte Harbor: 2-4 ft
  • Steinhatchee River to Anclote River: 2-4 ft
  • Bonita Beach to Flamingo: 1-2 ft

The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and dangerous waves. Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

RAINFALL: Eta is expected to produce the following rainfall totals:

  • Western Cuba: an additional 1 to 3 inches (25 to 75 mm) through Wednesday, with isolated maximum storm total accumulations of 25 inches (765 mm).
  • West and central Florida, through Thursday: 2 to 4 inches, with maximum storm total accumulations of 6 inches.
  • North and South Florida, through Thursday: An additional 1 to 2 inches, with isolated maximum storm total accumulations of 4 inches in North Florida and 20 inches in South Florida.

Flash and river flooding will be possible in western Cuba through Wednesday, along with landslides in areas of higher terrain. Additional flash and urban flooding will be possible in South Florida through Thursday, especially across previously inundated areas. Flash, urban, and isolated minor river flooding are expected across portions of West and North Florida through Thursday.

This system is of no direct threat to the Windward Islands, including Trinidad and Tobago.

Tropical Storm Eta Forecast Discussion

Tropical Storm Eta (Weathernerds.org)

Almost as quickly as Eta regained hurricane status, it then lost it shortly thereafter. Dry air entrainment eroded most of the significant convection around the center this afternoon until a slight resurgence recently developed. However, the overall convective pattern has changed little with the bulk of the convection located primarily northeast through southeast of the center. The last recon pass through Eta showed that the central pressure had increased to 990 mb. Recent Doppler velocities of around 70 kt between 5000-6000 ft east of the center support surface winds of about 56-58 kt, so the 1800Z intensity of 60 kt will also be kept for the 21Z advisory intensity.

The initial motion estimate is northward, or 010/10 kt. Eta is expected to move between north and north-northeastward tonight as the cyclone rounds the western periphery of a deep-layer ridge to the east. The new NHC model guidance remains in excellent agreement on Eta turning northeastward after 12 hours, with the cyclone making landfall along the western coast of the northern Florida peninsula in the region from Cedar Key to Crystal River. Eta is then expected to accelerate northeastward across northern Florida as a weakening tropical cyclone and emerge over the western Atlantic by late Thursday morning or early afternoon. By 72 hours, if not sooner, Eta is forecast to merge with a frontal system off of the southeastern United States. The new official track forecast is similar to the previous advisory track and lies close to a blend of the consensus models TVCN, NOAA-HCCA, and FSSE.

Eta will be moving over progressively cooler waters during the next 12 hours, with SSTs decreasing to less than 25 deg C just before the cyclone makes landfall along the Florida coast. The cooler waters, in conjunction with continued dry air entrainment and increasing westerly vertical wind shear, should result in at least gradual weakening until landfall occurs, followed by more rapid weakening as Eta moves over the northern Florida peninsula. Although the official forecast calls for Eta to be a tropical storm as it nears the northeast coast of Florida, a Tropical Watch or Warning are not required at this time since any tropical-storm-force will likely be occurring over water and not inland or along the coast due to Eta’s poor convective structure that is expected at that time. Eta is forecast to degenerate into a remnant low by 60 hours due to even stronger wind shear, and dissipate by 72 hours due to frontal interaction.

Key Messages:

  1. There is a danger of life-threatening storm surge along portions of the Florida Gulf Coast from Bonita Beach to Suwannee River, including Tampa Bay and Charlotte Harbor. Residents in this area should follow any advice given by local officials.
  2. Tropical-storm-force winds are expected this evening and tonight along portions of the Florida Gulf Coast from Bonita Beach to Suwanee River, and are possible tonight and early Thursday from Suwannee River to Aucilla River. Interests elsewhere along the Florida Gulf Coast should monitor the progress of Eta.
  3. Heavy rainfall from Eta will continue to spread northward across west and central Florida through Thursday. Additional flash and urban flooding will be possible in south Florida through Thursday, especially across previously inundated areas. Flash, urban, and isolated minor river flooding are expected across portions of west and north Florida through Thursday.

Forecast discussion by NHC Forecaster Stewart.

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