Tropical Storm Theta Maintains Intensity In The Atlantic

Theta, after transitioning into a fully tropical cyclone, maintains its intensity well away from landmasses. Tropical Storm Theta is forecast to weaken come this weekend as it moves between the Azores Islands and Portugal’s Madeira archipelago.

Theta pushed 2020 over 2005’s record for the most number of named tropical cyclones in Atlantic history.. This is the first time Theta has been operationally used in Atlantic history.

With Theta, 2020 has now recorded 29 tropical storm formations in the Atlantic, breaking the 2005 record of 28 tropical storms. 2005 still holds the record for the most number of systems at tropical depression strength at 31. 2020 is now at 30.

This tropical cyclone is not forecast to directly impact Trinidad, Tobago, or the Lesser Antilles as it moves generally eastward.

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 Theta was located near latitude 30.5 North, longitude 31.9 West. Theta is moving toward the east-northeast near 13 mph (20 km/h), and this general motion is expected to continue through Friday, followed by a turn to the east along with a slowing of the forward motion.

Maximum sustained winds are near 60 mph (95 km/h) with higher gusts. Only slight weakening is expected over the next couple of days. Faster weakening is forecast to occur this weekend. Tropical-storm-force winds extend outward up to 205 miles (335 km) from the center. The estimated minimum central pressure is 992 millibars.

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

Watches & Warnings

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

There are no coastal watches or warnings in effect.

Hazards Affecting Land

Tropical Storm Theta 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 Theta 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)

There are no hazards affecting land at this time.

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

Tropical Storm Theta Forecast Discussion

Tropical Storm Theta (Weathernerds.org)

The deep convection associated with Theta has been trying to wrap around the cyclone’s low-level center today, and the system consists of a large curved band feature with clouds tops as cold as -65 degrees C. There was no complete sampling of the cyclone’s circulation by the scatterometers today. However, a partial ASCAT-C overpass this morning showed that 40-45 kt winds were occurring in the eastern semicircle. This portion of the circulation has previously been the weaker portion of Theta, which suggests some higher winds could be occurring in the western semicircle. Therefore, the initial intensity is being kept at a somewhat uncertain 50 kt.

Theta appears to be holding its own in an environment of strong southwesterly shear and over relatively cool water temperatures of about 24 degrees C, within a favorable unstable atmosphere. The cyclone will be traversing over progressively cooler waters over the next couple of days, and the shear is expected to only abate slightly. These somewhat counteracting factors should either allow Theta to maintain its intensity or slowly weaken during that time. Over the weekend, the upper-level winds are expected to increase and shift out of the north and force more stable air across the cyclone. This should cause the convection to become displaced to the south of the center and gradually dissipate. The GFS/CMC/ECMWF simulated satellite imagery all indicate that the system should degenerate to a remnant low by 96 h. The latest NHC intensity forecast is similar to the previous one and remains near the various multi-model consensus aids.

The storm is moving east-northeastward at around 11 kt, steered by mid-latitude westerlies to the north of a mid-level ridge. This steering pattern is expected to remain in place for the next couple of days. Model guidance is trending slower over the weekend, as they are indicating that the ridge will weaken at around the same time that the shear vector becomes northerly. This would cause the cyclone to slow its forward motion and turn to the right, which is now indicated in the official forecast. However, the latest NHC track remains a little north of the consensus track guidance during that time frame. By the end of the forecast period, an approaching mid-latitude trough and associated front should pick up what remains of Theta and begin to accelerate it to the northeast.

Forecast discussion by NHC Forecaster Latto.

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