ITCZ, Tropical Wave 32 Affecting T&T With Showers, Thunderstorms

Shortly after midnight, as forecast and we’ve been updating, thunderstorms associated with the Intertropical Convergence Zone began to affect parts of Trinidad. Frequent lightning was reported across the northern half of Trinidad, with heavy rainfall.

Isolated to scattered showers and thunderstorms are forecast throughout Saturday as the ITCZ remains across T&T, with activity enhanced by Tropical Wave 32 nearing the islands.

Update: Trinidad and Tobago Meteorological Service issued an Adverse Weather Alert Yellow Level on Saturday morning at 2:06 AM, which went into effect at 2:00 AM Saturday 8th August 2020 and will remain in effect through 5:00 PM Sunday 9th August 2020.

The Forecast

After midnight, through the afternoon, heavy showers and isolated thunderstorms are forecast, with heavier activity favoring southern and eastern areas of both islands initially, gradually moving westward.

These showers and thunderstorms will interrupt mostly cloudy to overcast periods. Activity with the ITCZ tends to have peaks after midnight through 6 AM-8 AM and again during the late morning (10-11 AM) through the afternoon (3 PM-4 PM)

Conditions are forecast to settle with isolated showers possible through the evening, generally interrupting partly cloudy skies. However, with the ITCZ sticking around into Sunday, a resurgence in showers and isolated thunderstorms are forecast after midnight.

The axis of Tropical Wave 32 is forecast to move across T&T later on Saturday through Sunday, with a surge of Saharan Dust accompanying this wave passage, limiting inclement weather, particularly on Sunday through Monday.

The main hazards include isolated to scattered areas of heavy rainfall across both islands, reducing visibility, and gusty winds up to and in excess of 55 KM/H. Street or flash flooding will be possible in slow-moving showers and thunderstorms. In thunderstorm activity, frequent lightning is also possible. Gusty winds may cause power dips/outages, downed trees, and localized wind damage. Note that with weak winds, with sea breeze convergence, heat, and orographic effects acting as triggers for shower and thunderstorm development.

Seas forecast to be moderate, with waves between 1.5 and 2.0 meters in open waters. In sheltered areas, below 1.0 meter, but becoming choppy in showers and thunderstorms. Air quality is forecast to decrease to moderate levels at times.


Possible Impacts From ITCZ, Tropical Wave 32

Winds

Sustained surface winds will be weak, generally below 25 KM/H during the afternoon at its peak. However, Gusts up to and in excess of 55 KM/H possible in heavy showers or thunderstorms across Trinidad and Tobago.

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.

High Wind Event Precautions
High Wind Event Precautions

Rainfall

Saturday: Between 20-30 millimeters are forecast, with isolated totals up to 50 millimeters possible. In slow-moving downpours or thunderstorms, up to and in excess of 75 millimeters possible. These isolated higher totals are forecast to favor eastern and northern areas of Trinidad.

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. There is a low chance of riverine flooding.

Frequent Lightning: In addition, with forecast thunderstorms, frequent lightning is likely. Lightning can cause power outages, voltage dips, damage to life and property, particularly during cloud-to-ground lightning strikes.

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. Widespread showers mean that nearly all persons and areas may experience rainfall.

Isolated to scattered activity is forecast.

Forecast - Isolated, Scattered, Widespread - What do they mean?

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