Tropical Update: Tropical Wave Brings Cloudiness, Showers to T&T Today. Heavy Rainfall Likely Early Next Week.

Tropical Weather Update:
Tropical Wave 07: The axis of this wave has moved across Trinidad and Tobago as of the 12:00 PM tropical update, based on satellite imagery and model guidance. As expected, increased cloudiness and isolated to scattered showers are occurring across Trinidad and Tobago, forecast to persist into the night. No significant rainfall accumulations forecast. There is the chance for a thunderstorm, particularly this (Saturday) afternoon.
Tropical Wave 08: The axis of the tropical wave is forecast to move across Trinidad and Tobago on Sunday night through early Monday. Model guidance continues to trend towards scattered to widespread heavy rainfall across both islands, indicating the first heavy rainfall event for 2019. Much of the heavy rainfall is forecast on Monday leading into Tuesday. Street/Flash flooding, gusty winds, and landslides are all possible as isolated to scattered thunderstorms possible. Medium confidence of severe weather, with high rainfall accumulations.
Tropical Wave 09: On the heels of TW08, the axis of this tropical wave is forecast to move across Trinidad and Tobago on Tuesday into Wednesday, though there is some model guidance disagreement on when the “active” weather associated with this wave will occur. Regardless, isolated to scattered thunderstorms, with heavy rainfall, street/flash flooding, gusty winds, and landslides are possible. Medium confidence of severe weather, with high rainfall accumulations.
Tropical Wave 10: This tropical wave is just moving off the West African coast with deep tropical moisture, but also a dense plume of Saharan dust to its north. Regardless, this wave is forecast to move across T&T next Wednesday into Thursday. Saharan dust is forecast to limit shower and/or thunderstorm development. No significant rainfall accumulation forecast.
No Tropical Development forecast elsewhere across the Atlantic basin over the next 5 days as of the latest tropical update.

Tropical Wave 07

The axis of this weak tropical wave moved across Trinidad, Tobago and the Southern Windwards overnight through early this morning. There has been an increase in showers and cloudiness, with a notable decrease in Saharan Dust across the islands.

As with most tropical waves, favorable low-level convergence and upper-level divergence follow the wave axis. This, in combination with a surge in low-level moisture, is presently supporting some isolated to scattered showers east of Trinidad and southeast of Tobago. Wind shear remains highly unfavorable for the present convection to persist as it moves westward. Much of the blue, green and yellow colors on the above-infrared satellite image indicate mid to upper-level clouds, not necessarily precipitation producing clouds.

However, additional convection is forecast to develop across mainly Trinidad later this morning through the evening.

11:45 AM Radar Update: Isolated light to moderate showers are approaching Eastern Trinidad as the “active” weather of this tropical wave approaches Trinidad. Light to moderate showers is also nearing across parts of Tobago. Showers to continue through the evening. Radar Image: Trinidad and Tobago Meteorological Service

This wave is not forecast to produce widespread or scattered severe weather, nor is it forecast to produce widespread heavy rainfall. However, locally heavy rainfall is possible in heavy showers and/or thunderstorms. This “active” weather is forecast to persist overnight and mostly subside by tomorrow morning.

Little rainfall accumulation is forecast, with 24-hour totals forecast to be less than 5 millimeters across Tobago. Across Trinidad, generally, less than 10 millimeters are forecast, with isolated areas across Southern and Eastern Trinidad recording 10-15 millimeters. Gusty winds may occur in the vicinity of heavy showers and/or thunderstorms, though thunderstorm chances are fairly low at this time.

Following the passage of this tropical wave, another surge of Saharan Dust is forecast to move across T&T overnight, though this surge is forecast to be short-lived and subside by Sunday afternoon.

Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.
Tropical waves typically have fair weather ahead of the wave axis, though other features in the area such as surface troughs, increased atmospheric moisture, and local climatic effects, to name a few, may trigger showers and the odd thunderstorm. Following the passage of the wave, much of the active weather typically associated with a tropical wave occurs.

Why did I not experience rainfall?

A frequent complaint is the forecast is wrong because I didn’t experience any rainfall. Scattered showers mean that you, individually, may experience some showers intermittently throughout the day and there is a higher chance for this activity than isolated activity. Generally, because of winds associated with weak tropical waves, showers and thunderstorms tend to follow a west-northwest track, generally missing areas across Southwestern Trinidad and even Northwestern Trinidad – though activity due to local climatic effects such as daytime heating may trigger shower and thunderstorm development across these areas. See the below graphic for a simple explanation.

Tropical Wave 08

Satellite Image of Tropical Wave 08 as of the 12:00 PM Saturday 15th June 2019 Tropical Update.
Satellite Image of Tropical Wave 08 as of the 12:00 PM Saturday 15th June 2019 Tropical Update.

This tropical wave’s axis extends along 48W from 04N to 14N, moving west at 15 knots. Widely scattered moderate convection is ongoing near the wave axis presently.

Based on present model guidance, this wave axis is forecast to move across Trinidad and Tobago Sunday night into Monday. Both the GFS and EMCWF are indicating widespread showers of varying intensities and scattered thunderstorms beginning on Sunday and particularly on Monday. Increased atmospheric moisture will be present across nearly all levels of the atmosphere, and generally favorable conditions will be present for the development of moderate to strong convection.

This wave is not forecast to produce widespread severe weather based on the latest model guidance. However, isolated to scattered heavy rainfall is possible and we may see isolated to scattered severe weather mainly across Trinidad.

On Sunday (2:00 AM Sunday – 2:00 AM Monday), 24-hour rainfall accumulation is forecast to be less than 10 millimeters across Tobago and less than 15 millimeters across Trinidad. However, isolated areas across Eastern and Southern Trinidad may see up to 20 millimeters.

On Monday (2:00 AM Monday – 2:00 AM Tuesday), 24-hour rainfall accumulation is forecast to be less than 20 millimeters across both Trinidad and Tobago. Isolated areas may see between 20-40 millimeters in areas of locally heavy showers/thunderstorms or in areas with prolonged rainfall, particularly Eastern areas of Trinidad and Tobago. Note that across Southeastern Trinidad, a few models are also indicating accumulations upwards of 50 millimeters in the 24 hour period.

Based on the latest model guidance, these scattered to widespread showers, with isolated to scattered heavy showers and thunderstorms may produce severe weather across Trinidad and Tobago. Street flooding, flash flooding, and if these rainfall accumulation totals above 50 millimeters verify, even riverine flooding may be possible. Gusty winds are possible in the vicinity and during heavy showers or thunderstorms. These gusty winds and heavy rainfall will be capable of triggering landslides in landslide-prone areas, as well as downing trees and utility poles.

We’ll be keeping an eye out for any adverse weather or riverine flood alerts, watches or warnings from the Trinidad and Tobago Meteorological Service in the coming days. While this rainfall may produce some disruption to the public, it is most welcome across both islands as reservoirs are at concerningly low levels across Trinidad and Tobago.

Tropical Wave 09

Satellite Image of Tropical Wave 09 as of the 12:00 PM Saturday 15th June 2019 Tropical Update.
Satellite Image of Tropical Wave 09 as of the 12:00 PM Saturday 15th June 2019 Tropical Update.

This tropical wave’s axis extends along 37W from 02N to 13N, moving west at 20 knots. Widely scattered moderate to strong convection is ongoing near the wave axis presently.

Based on present model guidance, this wave axis is forecast to move across Trinidad and Tobago Tuesday night into Wednesday. Both the GFS and EMCWF are indicating widespread showers of varying intensities and scattered thunderstorms through this period, continuing from Monday’s activity. Increased atmospheric moisture will be present across nearly all levels of the atmosphere, and generally favorable conditions will be present for the development of moderate to strong convection.

This wave is not forecast to produce widespread severe weather based on the latest model guidance. However, isolated to scattered heavy rainfall is possible and we may see isolated to scattered severe weather mainly across Trinidad.

On Tuesday (2:00 AM Tuesday – 2:00 AM Wednesday), 24-hour rainfall accumulation is forecast to be less than 20 millimeters across both Trinidad and Tobago. Isolated areas may see up to 50 millimeters in areas of locally heavy showers/thunderstorms or in areas with prolonged rainfall, particularly Eastern areas of Trinidad and Tobago.

On Wednesday (2:00 AM Wednesday – 2:00 AM Thursday), 24-hour rainfall accumulation is forecast to be less than 15 millimeters across both islands, with isolated totals up to 25 millimeters across Eastern parts of Trinidad and Tobago.

There seems to be continuing discrepancy between the GFS and EMCWF on the timing of the heaviest precipitation, with the GFS favoring heavier showers and thunderstorms on Tuesday while the EMCWF favoring on Wednesday. Based on present analysis of data, it is increasingly likely that the heaviest activity may occur on Tuesday, with lingering showers and possible thunderstorms through Wednesday afternoon. Saharan dust is forecast to return by Wednesday evening, which is likely to inhibit heavy shower and thunderstorm development due to a dry mid-level environment.

Based on the latest model guidance, these scattered to widespread showers, with isolated to scattered heavy showers and thunderstorms may produce severe weather across Trinidad and Tobago. Street flooding, flash flooding, and if these rainfall accumulation totals above 50 millimeters verify, even riverine flooding may be possible, adding to possible flooding on Monday. Gusty winds are possible in the vicinity and during heavy showers or thunderstorms. These gusty winds and heavy rainfall will be capable of triggering landslides in landslide-prone areas, as well as downing trees and utility poles.

As mentioned above, we’ll be keeping an eye out for any adverse weather or riverine flood alerts, watches or warnings from the Trinidad and Tobago Meteorological Service in the coming days.

Tropical Wave 10

Satellite Image of Tropical Wave 10 as of the 12:00 PM Saturday 15th June 2019 Tropical Update.
Satellite Image of Tropical Wave 10 as of the 12:00 PM Saturday 15th June 2019 Tropical Update.

This tropical wave’s axis extends along 17W from 02N to 13N, moving west at 20 knots. Scattered moderate to strong convection is ongoing near the wave axis presently.

Based on present model guidance, this wave axis is forecast to move across Trinidad and Tobago on Thursday. This wave is not forecast to produce heavy rainfall as it will be affected by significant concentrations of Saharan Dust, though a few isolated showers and increased cloudiness can’t be ruled out.

What this wave will bring is a dense plume of Saharan dust following the passage, reducing air quality across the Eastern Caribbean to moderate and at times unhealthy for sensitive groups levels.

This wave is not forecast to produce any severe weather based on the latest model guidance with minimal rainfall accumulations.

On Thursday (2:00 AM Thursday – 2:00 AM Friday), 24-hour rainfall accumulation is forecast to be less than 10 millimeters across both Trinidad and Tobago. Very isolated areas may see up to 20 millimeters in areas of locally heavy showers, particularly Eastern areas of Trinidad and Tobago.

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the month of June. Though attention is usually placed on the Western Caribbean, Gulf of Mexico and the Western Atlantic, a few storms have developed east of Trinidad and Tobago during the month of June, most recently and notably – Tropical Storm Bret in 2017.

In June, we turn our eyes to the Western Caribbean and the Gulf of Mexico for the formation of tropical cyclones in the Atlantic Basin, historically. However, tropical cyclones can form in the Atlantic Basin, without regard for the location once conditions support development.

There are NO tropical cyclone threats to the Eastern Caribbean, including Trinidad and Tobago at this time in the latest Tropical Update.

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