Tropical Wave 55 Still Being Monitored For Development

Tropical Wave 55 Key Messages:
– Tropical Wave 55 has low chances of development over the next 5 days as it moves west to west-northwest across the Central Atlantic Ocean.
– Impacts: For T&T, little to none. This tropical wave will move across the region on Thursday, with any active weather remaining to our north and east.
– Track: The wave itself will move across the Lesser Antilles by the end of the upcoming week, but any active weather will not affect T&T, based on the latest guidance.

Tropical Wave 55: Low Chances for Tropical Cyclone Formation

Tropical Weather Outlook as of 8:00 AM Sunday 11th October 2020
Tropical Weather Outlook as of 8:00 AM Sunday 11th October 2020

Over the last three days, we’ve been monitoring a tropical wave in the Atlantic, producing widely disorganized showers and thunderstorms.

The National Hurricane Center, in their 8 AM AST Tropical Weather Outlook, continue to monitor Tropical Wave 55 for tropical cyclone development. However, there is no model support for tropical cyclone formation at this time.

From the National Hurricane Center’s Tropical Weather Outlook, as of 8:00 AM EST, “A westward-moving tropical wave continues to produce disorganized showers and thunderstorms centered about 1200 miles east of the Windward Islands. Some development of this system is possible during the next few days while the system moves generally westward near 15 mph before upper-level winds are forecast to become unfavorable for further development by midweek.”

As of the 8:00 AM EST Tropical Weather Outlook, this system has a low chance, 10%, of tropical cyclone formation over the next 48 hours and a low chance, 20%, of tropical cyclone formation over the next 5 days.

What We Know

Tropical Wave 55 in the Atlantic, producing an area of scattered showers and thunderstorms. (Weathernerds)
Tropical Wave 55 in the Atlantic, producing an area of scattered showers and thunderstorms. (Weathernerds)

A tropical wave is along 46W from 18N southward moving west at (15 to 20 knots) 27 to 37 KM/H, is producing scattered moderate convection is from 09N-20N between 40W and 50W.

The approximate center of the broad cyclonic turning of this disturbance at 44W, 9.8N, making it just under kilometers east-southeast of Trinidad and Tobago. An SATSCAT pass at 11:01 UTC shows a very small area of winds between 20-30 knots near the approximate center.

As of Sunday morning, there is no well defined circulation of the system and it is still embedded within the Intertropical Convergence Zone, producing a natural area of vorticity (spin) for this disturbance to take advantage of.

Tropical Wave 55 is located in an area of very favorable upper-level divergence, low-level convergence and abundant moisture, but strong wind shear across the system presently, from the southwest.

By next week, wind shear is forecast to increase across the Atlantic and the Lesser Antilles, becoming very strong, up to 60 knots at times. This will limit development and limit thunderstorm and shower formation.

What We Forecast

Tropical Wave 55: Track

The tropical wave will generally progress westward, to west-northwestward, with active weather remaining to our north and east, but will be limited.

This tropical wave will move on the periphery of a deep-layered high-pressure system anchored over the subtropics. This high pressure system will gradually weaken this upcoming week, with a trough north of the Lesser Antilles by mid-week. This trough will coincide with the system when it is just east of the Lesser Antilles, allowing the steering flow to move the system poleward (northward). This will also allow for winds across the region to weaken, providing ample conditions for daytime heating and sea breeze convergence to trigger isolated heavy afternoon showers and thunderstorms.

When looking at the ensemble models, most of these outputs show that the system generally moves to the west-northwest, before taking a sharper turn northwest to the north just east of the Lesser Antilles.

Tropical Wave 55: Intensity

There is no model support, operational and ensemble, for this system. It is likely to remain a tropical wave.

Dynamical model guidance on systems that have not yet formed has a difficult time showing the eventual track or intensity of undeveloped systems.

Still, none of the operational models from top global models (EMCWF, GFS, UKMET) shows this system developing this upcoming week. Less than 5% of ensemble runs from the EPS (European EMCWF ensembles) bring a tropical depression east of the Lesser Antilles It also should be noted that this is a year where models have not performed well in detecting tropical cyclone genesis.

Thankfully, this system is still about 1,900 kilometers away as of Sunday morning so there is sufficient time to wait and watch.

The latest model runs of the EMCWF EPS runs showing the percent probability of tropical depression winds as of 0Z Sunday 11th October 2020. (weathermodels.com)
The latest model runs of the EMCWF EPS runs showing the percent probability of tropical depression winds as of 0Z Sunday 11th October 2020. (weathermodels.com)

But this model shows…

Individual model runs are just one possible outcome from a myriad of outcomes. Weather does not always follow what is modeled, and even what may be forecast. Beware of individual model runs being posted on social media.

Always check the National Hurricane Center for the latest information for tropical cyclones and your local meteorological offices for country-specific advisories.

What should I do?

Don’t panic. This system is several days and thousands of kilometers to our east-southeast so we quite a bit of time to wait and watch.

If you are a risk-averse person, now is a good time to check your inclement weather, flood, or hurricane season plan, ensuring your preparedness supplies are not expired, stocked, and in a safe location.

The Office of Disaster Preparedness and Management has put together a comprehensive guide for preparing for the Wet and Hurricane Season.

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