On Monday, due to Tropical Wave 08 and favorable atmospheric conditions, periods of heavy to violent rainfall are forecast associated with thunderstorms and showers. Another, less impactful tropical wave is forecast by Wednesday, with the return of Saharan Dust shortly after.
What you need to know
— Saharan Dust: Low levels of Saharan Dust are forecast from Monday through late Tuesday, with a gradual increase in dust concentrations on Wednesday. By Thursday, moderate to high concentrations of Saharan Dust returns to T&T.
— Rainfall: On Monday, periods of light to moderate rain, heavy to violent showers, and isolated thunderstorms are forecast, continuing into early Tuesday. Isolated to scattered showers are possible again on Wednesday, with rainfall subsiding by the latter half of the week.
— Hazards: The main hazards remain street/flash flooding from Monday through Wednesday. The chances for riverine flooding across the country remain low at this time. Close attention should be paid to the North and South Oropouche River Basins, as well as the Ortire River Basins through Tuesday. Gusty winds are possible through Wednesday, up to and in excess of 45 KM/H accompanying heavy showers or thunderstorms. Lightning will accompany thunderstorms.
— Alerts/Watches/Warnings: The Adverse Weather Alert (Yellow Level) has been discontinued by the Trinidad and Tobago Meteorological Service at 2:34 PM Monday. There are no alerts, watches, or warnings in effect for T&T at this time.
Sunday Night – Approach of Tropical Wave 08Sunday Night – Approach of Tropical Wave 08
Monday – Tropical Wave 08Monday – Tropical Wave 08
Tuesday – Lingering Influence Of Tropical Wave 08Tuesday – Lingering Influence Of Tropical Wave 08
Wednesday – Tropical Wave 09Wednesday – Tropical Wave 09
Thursday – Saharan Dust SurgeThursday – Saharan Dust Surge
Marine: Seas are forecast to be mostly moderate, with waves generally up to 2.0 meters, during the forecast period in open waters. In sheltered areas, waves are forecast to be between near calm and 1.0 meter but occasionally choppy during heavy showers or thunderstorms. King tides are also forecast through the next five days. Mariners and beachgoers should exercise caution due to stronger tidal currents.
Through the forecast period, the minimum low in Trinidad and Tobago is forecast to be between 22.0°C and 26.0°C.
Maximum highs across the country are forecast to be generally up to 31.0°C in Trinidad and Tobago. In urbanized areas like Port of Spain, Scarborough, San Fernando, and Chaguanas, the maximum high temperatures could exceed 32.0°C.
Over the next five days, temperatures are forecast to be cooler overall due to increased cloud cover and anticipated rainfall.
There is a high chance of street and flash flooding, mainly on Monday into Tuesday, when the heaviest rainfall is expected over the five-day forecast period. Chances of riverine flooding are now at medium, particularly across the North Oropuche and Ortoire River Basins as well as the eastern extent of the Caroni River Basin. Particular attention should also be paid to the South Oropouche River Basins, where upwards of 75 millimeters of rain are possible on Monday into Tuesday.
Forecast Rainfall Totals
- Monday: Rainfall accumulations from 15 to 45 millimeters are forecast across most of the country, trending as high as 75 millimeters across southern and eastern areas of Trinidad and eastern areas of Tobago. Across the southern and eastern halves of Trinidad, rainfall totals could reach or exceed 150 millimeters.
- Tuesday: Between 5 and 15 millimeters across the country, trending higher across northern and western areas of Trinidad and across Tobago with isolated totals up to and in excess of 25 millimeters.
- Wednesday: Between 5 and 15 millimeters across the country, trending higher across northern and western areas of Trinidad with isolated totals up to and in excess of 25 millimeters. Across Tobago, isolated totals could reach/exceed 30 millimeters.
- Thursday: Between 5 and 15 millimeters across the country, trending higher across eastern Trinidad and Tobago with isolated totals up to 25 millimeters. Across Tobago, isolated totals could exceed 25 millimeters.
- Friday: Less than 5 millimeters of rain across the country, with isolated higher pockets favoring eastern and southern coastal areas.
Putting the rainfall forecast into context, rainfall rates in excess of 50 millimeters per hour or areas that receive in excess of 25 millimeters within an hour tend to trigger street flooding across the country or flash flooding in northern Trinidad. For riverine flooding to occur, a large area of the country (not just in highly localized areas of western coastal Trinidad) would have to record upwards of 75 millimeters within 24 hours, and rainfall would have to fall across major rivers’ catchment areas.
Strong ThunderstormsStrong Thunderstorms
While thunderstorms are forecast over the next five days, strong wind shear and Saharan Dust (during the latter half of the week) will limit strong thunderstorms from forming.
On Monday, a highly favorable low-level environment will be in place initially, with an increasingly favorable mid- to upper-level environment by the latter half of the day. These conditions may support stronger or severe thunderstorm activity on Monday morning through the early afternoon.
Additionally, funnel cloud development will be possible on Monday through early Wednesday, with light low-level winds and a supportive environment for thunderstorm activity. If a funnel cloud touches down on a body of water, it becomes a waterspout; if it touches down on land, it becomes a tornado.
Throughout the week, frequent cloud-to-ground lightning will be likely, with heavy to violent rainfall rates in thunderstorms.
Gusty WindsGusty Winds
With wind gusts up to and in excess of 50 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.
As rainfall continues through the week and soils become increasingly saturated, landslides are possible across elevated areas of Tobago, southern and northern Trinidad.
Saharan Dust will increase by late Wednesday into Thursday, reducing air quality and affecting visibility.
Why I May Not/Will Not See 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. Widespread showers mean that nearly all persons and areas may experience rainfall.
Scattered to widespread rainfall is forecast on Monday, isolated to scattered rainfall Tuesday through Wednesday, becoming isolated by Thursday and highly isolated by Friday.
Tropical Waves East of T&T: Based on the Tropical Analysis and Forecast Branch’s 18Z surface analysis on June 12th, 2022, as well as the latest satellite and model guidance:
- The eighth tropical wave for 2022 is along 55/56°W, south of 20°N, moving west at 20 knots (37 KM/H). This wave is forecast to move across Trinidad and Tobago overnight tonight (Sunday) into Monday. Scattered moderate to isolated strong convection is ongoing, mainly near the coast of South America.
- The ninth tropical wave for 2022 is along 35°W, south of 14°N, and moving west at 20 knots (37 KM/H). This wave is forecast to move across T&T late Tuesday, June 14th, 2022, into Wednesday, June 15th, 2022. Few showers have been noted near the wave axis.
Trinidad is set to see some of the highest 24-hour rainfall totals for 2022 to date on Monday as a highly moist and favorable environment associated with the approach and passage of Tropical Wave 08 will fuel heavy showers and thunderstorms.
The wave has a large moisture envelope. Low-level conditions will be favorable through Monday morning. In contrast, upper-level conditions become increasingly favorable as the day progresses due to an upper-level trough drifting westward, placing T&T and much of the Windwards under an upper-level diffluent pattern (winds move away and apart, enhancing convection).
Lingering, abundant moisture from Tropical Wave 08, favorable upper-level conditions, and a weakening of low-level winds will allow for additional, slow-moving showers and thunderstorms on Tuesday.
Strong westerly to southwesterly wind shear (up to 60 knots) will persist, keeping heavier rainfall, showers, and thunderstorms south and east of the country through Tuesday.
Tropical Wave 09 is forecast to enter the region by Wednesday, under similar conditions as the last two days, and bring additional inclement weather and increased low-level winds by Wednesday evening. However, most rainfall is set to occur north of Trinidad, potentially placing Tobago in the crosshairs of additional flooding rainfall by Wednesday into Thursday.
From here, uncertainty increases. Dust models show a gradual rise in Saharan Dust from Wednesday, with high concentrations returning by Thursday. Saharan Dust negatively impacts rainfall, resulting in cloudy and hazy but dry weather. The ECMWF shows precipitation still occurring as Tropical Wave 09 moves west, but much lower overall rainfall totals. The GFS, on the other hand, shows higher rainfall totals both on Wednesday and Thursday, with a trailing band of showers and thunderstorms mainly affecting Northern Trinidad and Tobago, seemingly unphased by the increase in dust. For now, the forecast for Wednesday into Thursday lies closer to the GFS solution, as other top global models, like the UKMET and Australia’s ACCESS-G, indicate a similar setup to the GFS.
By Friday into the weekend, though, the atmosphere dries out as a deep-layered high-pressure ridge returns, along with our dusty norm – Saharan Dust.