— An Adverse Weather Alert Yellow Level in effect until 2:00 AM Friday for Tobago. Much of the Adverse Weather has subsided as of 8:30 PM.
— Through Sunday, an additional 1 to 2.5 inches (25 to 62.5 millimeters) are possible across Trinidad and Tobago with heavier totals across Northern and Western halves of Trinidad, as well as Tobago. There is an elevated threat of street flooding and flash flooding, particularly across Tobago and Western Trinidad.
— Seas will remain slight to moderate, with waves up to 1.5 meters are possible in open waters and less than 1.0 meter but choppy in sheltered areas.
— Gusty winds in excess of 65 KM/H possible, particularly on Tuesday. Winds of this strength will produce wind damage including downed trees, utility poles and roof damage. Localized power outages possible.
— Landslides possible in elevated areas.
The Adverse Weather Alert
The Trinidad and Tobago Meteorological Service has issued an Adverse Weather Alert (Yellow Level) at 6:22 PM Thursday as Tropical Wave 55 continues to affect Tobago. The alert went into effect from 6:22 PM Thursday 17th October 2019 through 2:00 AM Friday 18th October 2019. Tropical Wave 55 and its moisture is forecast to affect the region through Saturday, dragging the ITCZ across the region.
The timing of the adverse weather alert is curious, as much of the inclement weather subsided prior to the issuance of the alert, much like one of those reactionary adverse weather alerts we wrote about of earlier this year.
Trinidad and Tobago is NOT under any tropical storm watch or warning AT THIS TIME.
Based on the latest model guidance and analysis, much of the severe weather across Tobago has subsided, with light rain and isolated showers possible through the night.
Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for October 17th-18th, 2019.
“Activity associated with the passage of a Tropical Wave is expected to affect Tobago over the next 6 to 8 hours. During this period Tobago can expect periods of heavy showers and thunderstorms which may result in some flooding and landslide/landslips mainly along hilly areas. Gusts of up to 65km/h are likely near heavy downpours. These strong winds can also result in choppy sea conditions. A gradual improvement in conditions can be expected after midnight.” according to the Trinidad and Tobago Meteorological Service. This “alert” status takes into account the possibility of the event occurring. This adverse weather event is observed.
The color of the alert indicates the severity of the event and the probability of the event occurring. Currently, the alert level is at Yellow. This means that the hazard is possible to be aware of the impacts of Street/Flash Flooding and Gusty Winds in your area. Areas prone to landslides should also be aware of the hazard and impacts.
What We Know
The axis of Tropical Wave 55 is moving across Trinidad and Tobago, affecting much of the Lesser Antilles, north of Trinidad.
T&T is located in an area of favorable upper-level divergence and low-level convergence. Moisture remains abundant throughout all levels of the atmosphere.
An upper-level diffluent pattern spawning most of the island chain will continue to provide favorable upper-level conditions across Trinidad, Tobago, and the region. As a result, scattered showers, rain and thunderstorms will remain likely across the region.
Thursday (until midnight): Tropical Wave 55. Lingering showers are likely into the night mainly across Tobago, though it is not expected to be severe, as well as Northern and Eastern areas of Trinidad.
Friday (until midnight): Tail End of Tropical Wave 55. Similar conditions to Thursday are forecast. After an initially hot and sunny early and mid-morning, isolated to scattered showers and thunderstorms are likely across both islands, with heavier showers and thunderstorms favoring the Western and Northern halves of Trinidad, as well as Tobago. Conditions are forecast to become settled into the night.
Saturday (until midnight): Lingering moisture & localized climatic effects and the ITCZ. Essentially the same forecast as the two previous days. After an initially hot and sunny early and mid-morning, isolated to scattered showers and thunderstorms are likely across both islands, with heavier showers and thunderstorms favoring the Western and Northern halves of Trinidad, as well as Tobago. Conditions are forecast to become settled into the night.
Sunday (until midnight): Surface to Mid-level Ridge. Much drier conditions are forecast, with isolated late morning through afternoon showers and thunderstorms across Western Trinidad, interrupting hot and sunny skies.
Peak sustained surface winds of 25 KM/H to 45 KM/H with gusts in excess of 55 KM/H are possible in heavy showers or thunderstorms across Trinidad and Tobago, particularly on Thursday and Friday during heavy shower or thunderstorm activity.
With wind gusts in excess of 55 KM/H, whole trees are expected to be in motion and there may be some inconvenience when walking against the wind gusts. Light outdoor objects may topple or become airborne such as garbage cans, potted plants, loose galvanize or construction material and other outdoor furniture. Tents may jump. Older/weaker trees may fall, bringing down utility poles and lines.
Through Sunday, an additional 1 to 2.5 inches (25 to 62.5 millimeters) are possible across Trinidad and Tobago with heavier totals across Northern and Western halves of Trinidad, as well as Tobago.
Thunderstorms and Lightning
With thunderstorms, locally severe wind (in excess of 55 KM/H), violent rainfall rates (in excess of 50 millimeters per hour) and lightning are all possible.
Gusty winds and lightning pose a threat to our power grid, causing localized power outages. Lightning may also strike trees, homes or utility poles causing damage to property. Lightning can also be deadly to persons outside during a thunderstorm.
Seas and Surf
Seas are forecast to be moderate in open waters with waves between 1.5 to 2.0 meters. In sheltered areas, seas are near 1.0 meters, but choppy, particularly during heavier showers or thunderstorms.
Why I May Not/Will Not See Constant 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 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.