The Adverse Weather Alert
The Trinidad and Tobago Meteorological Service has updated an Adverse Weather Alert as Tropical Wave 29 moves Trinidad and Tobago, interacting with the ITCZ. Heavy showers and thunderstorms are likely, according to the TTMS through 6:00 PM Sunday 28th July 2019.
Note that due to favorable atmospheric conditions, locally severe thunderstorms are possible, producing heavy rainfall and gusty winds.
Trinidad and Tobago is NOT under any tropical storm threat, watch or warning.
Based on the latest model guidance, these showers, with isolated heavy showers and thunderstorms may produce severe weather particularly across Trinidad and lesser so Tobago. Street flooding, flash flooding, particularly across Trinidad where showers and thunderstorms may continue to move across. Gusty winds are likely 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. See below for more details on what impacts to expect.
Because of the ongoing and forecast adverse weather, the Trinidad and Tobago Meteorological Service has updated the Adverse Weather Alert at 10:00 AM Sunday 28th July 2019, valid from 8:00 PM Saturday until 6:00 PM Sunday according to the Trinidad and Tobago Meteorological Service.
Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for July 27-28th, 2019.
“Last night was generally settled, however, the resurgence in activity has recently started and will now likely linger into the evening. Atmospheric features, including the trailing end of a tropical wave, are in favor of the production of significant showers and thunderstorms over various parts of Trinidad and Tobago. Street/flash flooding and landslips are possible in areas that are usually susceptible, and it is also possible for winds to gust in excess of 50km/hr. ” 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 likely.
The color of the watch 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.
The 29th tropical wave of the 2019 Atlantic Hurricane Season is now over Trinidad and Tobago as of 10:00 AM Sunday 28th July 2019.
What to Expect Over Next 24-36 Hours (From the earlier Update)
The Takeaway: Scattered showers and thunderstorms are forecast to move across mainly Trinidad on Sunday, with locally heavy rainfall amounts
There is an elevated threat of street flooding across Trinidad due to the slow movement of showers and thunderstorms today.
Generally, widespread or scattered severe weather is not likely. Localized severe weather reports are possible, with locally (isolated) heavy rainfall.
Presently, winds are from the south to southeast and are fairly weak. This will result in slow-moving showers and thunderstorms expected later today across mainly Trinidad with some showers and possible thunderstorms across Tobago. Street/Flash Flooding and gusty winds possible.
Between 8:00 AM and 10:00 AM, showers and thunderstorms have benefitted from the weak wind shear, but dry mid-levels have inhibited persisting deep convection (heavy showers and thunderstorms) as activity moves across T&T.
Based on the latest model guidance, heavier showers and thunderstorms are forecast to favor interior Central Trinidad, particularly after midday through the late afternoon. Note that showers and thunderstorms are possible elsewhere, some of which may become heavy and produce street/flash flooding.
This activity is forecast to subside by the late evening, and a similar pattern is forecast on Monday.
Initially settled conditions will give way to cloudy to overcast skies by the late morning, with afternoon showers and thunderstorms favoring interior central Trinidad, but possible elsewhere.
Locally Heavy Rainfall & Flooding: Based on the latest model runs on Sunday morning, from Sunday (2:00 AM) through Tuesday (2:00 AM), generally, over the 48 hour period, models are in agreement of fewer than 15 millimeters across Southern half of Trinidad and the Northern half Tobago and between 15-30 millimeters across the Northern half of Trinidad and the Southern half of Tobago. Isolated rainfall totals up to 50 millimeters are possible across interior Central Trinidad due to slow-moving showers and thunderstorms later today and on Monday.
Generally, with heavy showers and thunderstorm activity, street flooding, particularly in flood-prone areas or areas with poor drainage, is possible as well as flash flooding in areas where more prolonged heavy rainfall may occur, based on the above-mentioned forecast rainfall totals.
Frequent Lightning: In addition, with thunderstorms, frequent lightning is likely. As of midnight, through 10:30 AM, over 1600 lightning strikes have occurred near Trinidad and Tobago, with 1178 being dangerous cloud to ground strikes. Note most of these strikes have occurred offshore T&T, north of the area.
Gusty Winds: Gusty winds, generally between 40 and 50 KM/H are possible Gusty winds are most likely prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 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.
Landslides: Though there is a low chance of landslides, heavy showers across the Northern Range may trigger landslides in landslide-prone areas. Particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur across both islands. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.
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.
With this tropical wave (Tropical Wave 29), mostly scattered showers are forecast. Hence, we are likely to see intermittent showers and thunderstorms, interrupting partly cloudy to overcast skies between Sunday.