The Adverse Weather Alert
The Trinidad and Tobago Meteorological Service has issued an Adverse Weather Alert as Tropical Wave 14 nears Trinidad and Tobago, interacting with the ITCZ. Heavy showers and thunderstorms are likely through 4:00 PM Monday, July 1st, 2019 (tomorrow). Note that due to favorable atmospheric conditions, locally severe thunderstorms are possible, producing heavy rainfall and gusty winds. We (TTWC) went into detail about this system in our earlier Tropical Update.
Note that although this alert has been issued by the TTMS through 4:00 PM for Trinidad, quite a bit of the heavy showers and thunderstorms are now nearing Tobago and Southern Trinidad, likely to move across the area by 8:30 PM. A lull in activity is forecast elsewhere across Trinidad, until later tonight.
Trinidad and Tobago is NOT under any tropical storm threat, watch or warning.
Based on the latest model guidance, these isolated to scattered showers, with isolated heavy showers and thunderstorms may produce severe weather across Trinidad and Tobago. Street flooding, flash flooding, and even brief riverine flooding may be possible, particularly across Northeastern Trinidad where showers and thunderstorms are “training” across the region (see below). 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 impending and ongoing adverse weather, the Trinidad and Tobago Meteorological Service has issued the Adverse Weather Alert at 7:00 PM Sunday 30th June 2019, valid from 8:00 PM Sunday until 4:00 PM Monday according to the Trinidad and Tobago Meteorological Service. However, based on TTWC’s analysis, showers and thunderstorms are likely to subside before this, by late morning, as another round of Saharan Dust moves into the area by the early afternoon.
Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for June 30th, 2019.
“Adverse weather conditions are possible over Trinidad from 08:00 PM local time on Sunday 30th June 2019. Intense rainfall may result in Street or flash flooding in susceptible areas, and may be accompanied by damaging gusty winds. This adverse weather is associated with the passage of a Tropical Wave, interacting with the ITCZ ( Inter Tropical Convergence Zone). Some areas are presently experiencing heavy showers,” 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 14th tropical wave is nearing Trinidad and Tobago as of 7:00 PM Sunday 30th June 2019 of the 2019 Atlantic Hurricane Season.
What to Expect Over Next 24 Hours (Amended from the earlier Tropical Update)
Possible Impacts to Trinidad and Tobago
Locally Heavy Rainfall & Flooding: Based on the 12Z Sunday model runs as well as rainfall accumulations over the last 8 hours, from Sunday night (8:00 PM) through Tuesday morning (2:00 AM), generally, between 20-40 millimeters of rainfall is forecast over the next 24 hours across both islands. Isolated parts of Eastern, Central and Southern Trinidad, as well as Eastern Tobago, may see rainfall accumulations between 40-60 millimeters.
Western and Northwestern Trinidad may see the “lowest” totals, as expected with weaker tropical waves in June, with generally less than 20 millimeters of rainfall forecast over the 24 hour period, though isolated heavier totals are possible in the vicinity of thunderstorms or heavy showers.
The heaviest activity is forecast to occur overnight tonight. 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.
TTWC’s 5:30 PM Update: Increased risk of street/flash flooding across Northeastern Trinidad
In meteorology, training denotes repeated areas of rain, typically associated with thunderstorms, that move over the same region in a relatively short period of time. Training thunderstorms are capable of producing excessive rainfall totals, often causing flash flooding. The name training is derived from how a train and its cars travel along a track (moving along a single path), without the track moving.
East of Trinidad, a favorable area of low-level convergence has developed, triggering a line of persisting showers moving westward. Based on recent trends, these showers are likely to bring intermittent showers throughout the night to parts of Northeastern Trinidad.
Note that between 5:00 PM and 7:00 PM, parts of Northeastern Trinidad received upwards of 30-40 millimeters of rainfall, as was forecast above. Street/Flash flooding is likely imminent or ongoing across the aforementioned areas.
Frequent Lightning: In addition, with thunderstorms, frequent lightning is likely. Thunderstorms are forecast to occur mainly during the late evening, through the early morning of Monday, across T&T.
Gusty Winds: Gusty winds, generally between 50-60 KM/H are likely. Gusty winds are most likely overnight tonight, through 8:00 AM Monday. These wind gusts will generally occur prior to, in the vicinity of, or occur during heavy showers or thunderstorms. With wind gusts up to 60 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: In landslide-prone areas, particularly in areas that receive heavy rainfall, landslides and/or mudflows may occur. These landslides, in addition to gusty winds, may down trees, utility poles and impede traffic on roadways.
What’s Causing This Inclement Weather?
Tropical Wave 14 is forecast to move across T&T over the next 12 hours bringing showers, scattered thunderstorms and the ITCZ across the region. A deep surge in tropical moisture associated with this wave is moving across T&T presently and is forecast to persist over the next 12-18 hours. In addition, an upper-level trough is favorably positioned west of the region. This is creating favorable upper-level conditions for the development of heavy showers and thunderstorms across the Southern Windwards.
These favorable conditions are forecast to remain in place throughout the next 12-18 hours, with upper level divergent and low-level convergence aiding in the development of showers and thunderstorms with the passage of the wave axis. The Intertropical Convergence Zone, or the ITCZ, is also shifting across T&T as a result of this tropical wave.