2:00 PM Tropical Weather Outlook: Invest 90L, First Tropical Wave of the Season, Subtropical Storm Jaguar in the South Atlantic

Overview:
— Invest 90L: High chance of development (70%) over the next 48 hours, short-lived tropical or sub-tropical cyclone possible.
— A rare occurrence, a subtropical storm has developed east of Brazil in the South Atlantic. No direct threat to land.
— The first “official” tropical wave of the 2019 Atlantic Hurricane Season has moved off the West African Coast. Forecast to move across T&T early next week.

Forecast Discussion

GOES-16 Natural Color Imagery of Invest 90L Southwest of Bermuda Credit: Tropical Tidbits
GOES-16 Natural Color Imagery of Invest 90L Southwest of Bermuda Credit: Tropical Tidbits

At 2:00 PM Monday 20th May 2019, the US NWS National Hurricane Center issued a Special Tropical Weather Outlook concerning a broad area of low-pressure southwest of Bermuda in the far western Atlantic. This low-pressure system as high chances of tropical development near 70%, through the next 48 hours, and high chances of development through the next 5 days, at 60%. This system is of no threat of Trinidad, Tobago and the remainder of the Eastern Caribbean.

From the National Hurricane Center’s 2 PM Outlook: “Showers and thunderstorms associated with a broad area of low pressure located several hundred miles southwest of Bermuda are showing signs of organization. Although recent satellite wind data suggest that the system currently lacks a well-defined center of circulation, environmental conditions are expected to be conducive for the formation of a short-lived subtropical or tropical cyclone later today or tonight. Conditions are forecast to become unfavorable for further development by late Tuesday, and the disturbance is expected to merge with a cold front on Wednesday. An Air Force Reserve reconnaissance aircraft is currently en route to investigate the disturbance. Interests in Bermuda should monitor the progress of this system.

Solid yellow contours indicate upper-level divergence. Solid light blue contours indicate low-level convergence across Invest 90L as of 2:00 PM Monday 20th May 2019. Image: (Cooperative Institute for Meteorological Satellite Studies/Space Science and Engineering Center/University of Wisconsin-Madison)

Favorable upper-level divergence and low-level convergence are present across Invest 90L. By Wednesday, however, conditions are forecast to become unfavorable for further development, and the system should be absorbed by a cold front.

As of the 0Z through 12Z runs of the top three models for forecasting tropical development, the UKMET, GFS, and EMCWF, Invest 90L has model support from all three. The EMCWF has 70% of its ensemble members showing the development of a subtropical/tropical cyclone. However, all models still indicate that this potential cyclone will only retain its tropical/subtropical characteristics Tuesday into early Wednesday.

Models show quick degeneration as a stronger non-tropical low-pressure system to the north will steer this weaker, potentially tropical or sub-tropical system northward to northeastward, by Wednesday into Thursday 23rd May. It is presented in an area with marginally favorable sea surface temperatures of 26-27 degrees Celcius, and moderate to strong upper-level wind shear of 25 knots.

Track-wise, models are generally in agreement that the low pressure to the north will steer this weaker, potentially tropical or sub-tropical system northward initially, to northeastward, by Wednesday into Thursday 23rd May.

Regardless of formation, interests in Bermuda should monitor the progress of this system, as there is the potential for a near miss or even a direct hit from a weak tropical cyclone by Wednesday.

The next Special Tropical Weather Outlook will be issued by 8 PM AST on Monday.

This system poses NO threat to the Eastern Caribbean, including Trinidad and Tobago.

If this system were to develop, the first name on the list of names for the 2019 Atlantic Hurricane Season is Andrea.

2019 Atlantic Hurricane Season List of Names
2019 Atlantic Hurricane Season List of Names

Subtropical Storm Jaguar East of Brazil, South Atlantic

A look at the South and Central Atlantic Ocean as of 12:00 PM Monday 20th May 2019, showing Subtropical Storm Jaguar and the first "official" Tropical Wave of the 2019 Atlantic Hurricane Season.
A look at the South and Central Atlantic Ocean as of 12:00 PM Monday 20th May 2019, showing Subtropical Storm Jaguar and the first “official” Tropical Wave of the 2019 Atlantic Hurricane Season.

At 11:00 AM Monday 20th May 2019, the Brazilian Navy upgraded a subtropical depression to Subtropical Storm Jaguar located at 24 degrees south, 38 degrees west, moving south to southwest at 15 knots. Gusty winds, up to 74 KM/H and rough seas with waves up to 5.0 meters possible in the immediate vicinity of heavy convection. This system is forecast to move out to sea with little direct land impacts beyond increased surf and swells.

Note that tropical cyclones in the South Atlantic Ocean are uncommon, but we’ve already had one for the year, Tropical Storm Iba at the end of March 2019.

This system poses NO threat to the Eastern Caribbean, including Trinidad and Tobago.

Tropical Weather Outlook Elsewhere Across the Atlantic Basin

No tropical development is forecast elsewhere across the North Atlantic Basin over the next 5 days according to the 2 PM Tropical Weather Outlook. The first tropical wave has moved off the Western African Coast into the Eastern Atlantic. Presently, as of 2:00 PM Monday 20th May 2019, this wave is located at 17 degrees west, between 10.5 degrees – 3 degrees north.

The National Hurricane Center has determined classical genesis from the African Easterly Jet and convection over North Africa for this feature.

Tropical waves typically take 5-7 days to travel across the Atlantic Ocean and move across Trinidad and Tobago. This wave is no different. As of the latest GFS, FV3, and EMCWF in their 12Z runs show the concentrated plume of tropical moisture arriving across Trinidad and Tobago Monday 27th May 2019 through Tuesday 28th May 2019. Note that this is still over a week away so impacts will be clearer closer to the dates mentioned. With tropical waves, locally heavy rainfall, thunderstorms, and gusty winds are generally possible.

The designation is significant to Trinidad and Tobago because the passage of the first Tropical Wave (or the first time the ITCZ modulates across T&T) signals the start of the wet season for the islands. Following the passage of the first true tropical wave, as designated by either the National Hurricane Center or by the discretion of the Trinidad and Tobago Meteorological Service, the wet season is declared. Hence, we’re looking towards early next week for the official start of the 2019 wet season.

May Tropical Cyclone Climatology

Tropical Cyclone Points of Origin for May (1851-2015). Credit: NWS/NOAA/NHC

While the official start to the Atlantic Hurricane Season isn’t until June 1st, early season tropical cyclones are not unheard of. 50 of the 89 out of season tropical cyclones in the Atlantic Basin have formed in the month of May, with the most recent being Tropical Storm Alberto on May 25th 2018. Thankfully, for Trinidad and Tobago, these early season systems tend to form in the Western Caribbean and Southwestern Atlantic, with no impact to the Eastern Caribbean and T&T.

However, it serves as a reminder that the 2019 Hurricane Season is rapidly approaching and it is important to become prepared for both the hurricane season and the rainy season ahead!

Facebook Comments