Adverse Weather Alert In Effect From 4:00 AM Friday Through 2:00 PM Friday

The Adverse Weather Alert

The Trinidad and Tobago Meteorological Service has issued an Adverse Weather Alert as Tropical Wave 15 nears Trinidad and Tobago, interacting with the ITCZ. Heavy showers and thunderstorms are likely to begin at 4:00 AM Friday 5th July 2019 (tomorrow) through 2:00 PM Friday 5th July 2019. 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 beginning at 4:00 AM, through 2:00 PM, showers and thunderstorms are possible before this alert expires, due to favorable conditions in place.

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 floodingflash 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 4:00 PM Thursday 4th July 2019, valid from 4:00 AM Friday until 4:00 PM Friday according to the Trinidad and Tobago Meteorological Service. This time frame is in line with TTWC’s latest timeline on the progress of Tropical Wave 15.

Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for July 5th, 2019.

Showers and thunderstorms are likely to affect T&T from early morning till early afternoon on Friday 5th July 2019. Street/flash flooding, landslides/landslips and gusty winds of in excess of 45km/hr are possible.” 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.

Image Credit: Trinidad and Tobago Meteorological Service

The 15th tropical wave of the 2019 Atlantic Hurricane Season is over Trinidad and Tobago as of 4:30 PM Thursday 5th July 2019.

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.
Image Credit: Trinidad and Tobago Meteorological Service

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 Thursday model runs as well as rainfall accumulations over the last 18 hours, from Thursday night (8:00 PM) through Saturday morning (2:00 AM), generally, between 10-20 millimeters of rainfall is forecast over the next 24 hours across both islands. Isolated parts of Eastern, Central and Southern Trinidad, may see rainfall accumulations between 20-60 millimeters.

The heaviest activity is forecast to occur just before sunrise tomorrow, through the mid-afternoon. 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. Thunderstorms are forecast to occur overnight tonight through the mid-afternoon tomorrow (Friday)

Gusty Winds: Gusty winds, generally between 40-50 KM/H are likely. Gusty winds are most likely on Friday, by the late morning through the afternoon, with breezy conditions persisting into Saturday. These wind gusts will generally occur 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.

High Wind Event Precautions
High Wind Event Precautions

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.

Other severe weather: The threat for tornadoes and waterspouts is very low. However, straight-line winds associated with downbursts are likely, hence the gusty wind threat.

What’s Causing This Inclement Weather?

The axis of Tropical Wave 14 is moving across T&T presently, forecast to bring additional 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.

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.

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.

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