Adverse Weather Alert – Yellow Level In Effect For Tuesday From 9 AM to 4 PM For T&T

Key Messages:
— An Adverse Weather Alert Yellow Level is in effect from 9:00 AM on Tuesday through 4:00 PM on Tuesday for both Trinidad and Tobago. Note that showers and thunderstorms will continue through Wednesday, favoring the southern half of Trinidad.
— Through Thursday, 2 to 3 inches (50 to 75 millimeters) are possible across Trinidad and Tobago with heavier totals across Eastern and Southern halves of Trinidad, as well as Eastern Tobago. There is an elevated threat of street flooding and flash flooding.
— Seas will remain moderate to occasionally rough, with waves up to 2.5 meters are possible in open waters, occasionally up to and in excess of 3.0 meters and less than 1.0 meter but choppy in sheltered areas.
— Gusty winds in excess of 55 to 60 KM/H possible, particularly on Tuesday. Winds of this strength will produce wind damage including downed trees, utility poles and roof damage. Localized power outages possible.
Landslides possible in elevated areas.

The Adverse Weather Alert

As we’ve forecast since Saturday, Tropical Wave 68 is forecast to traverse the region on Tuesday, bringing gusty winds and locally heavy rainfall. Because of this, the Trinidad and Tobago Meteorological Service has issued an Adverse Weather Alert (Yellow Level) at 4:00 PM Monday as Tropical Wave 68 nears the Southern Windwards.

The alert begins at through 9:00 AM Tuesday 26th November 2019 through 4:00 PM Tuesday 26th November 2019. Note that inclement weather may continue beyond the end of the adverse weather alert’s end time, particularly on Wednesday.

Trinidad and Tobago is NOT under any tropical storm watch or warning AT THIS TIME.

Based on the latest model guidance and analysis, much of the severe weather is forecast to begin after midnight tonight into the mid-afternoon Tuesday, and another flare-up of showers and thunderstorms early Wednesday morning subsiding by the afternoon.

Information from the Trinidad and Tobago Meteorological Service concerning the Adverse Weather Alert for November 26th 2019.

Heavy showers and thunderstorms are expected in isolated areas of Trinidad and to a lesser extent over Tobago with accumulated rainfall approximating 20 – 25 mm. Winds likely to gust in excess of 60 kph at times.” 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 alert 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
Image Credit: Trinidad and Tobago Meteorological Service

What We Know

The axis of Tropical Wave 68 is approximated to be along 57/58W from 16N southward, moving west at 15 knots. The tropical wave shows up well in total precipitable moisture imagery, model diagnostics, and visible imagery. Scattered moderate convection (showers and thunderstorms) are noted from 08N-15N between 50W-59W.

The passage of Tropical Wave 68 is forecast to bring periods of showers and thunderstorms, triggering the Adverse Weather Alert. Credit: Weathernerds
The passage of Tropical Wave 68 is forecast to bring periods of showers and thunderstorms, triggering the Adverse Weather Alert. Credit: Weathernerds

Activity associated with this wave is supported by favorable upper-level divergence and low-level convergence. Strong low-level winds and very strong wind shear will keep showers and thunderstorms moving briskly westward, and limit the strengthening of convective activity but also producing gusty winds as showers and thunderstorms weaken as it moves westward.

The Weather Forecast

Tuesday: The axis of Tropical Wave 68 is forecast to move across T&T, with showers and thunderstorms developing after daybreak, affecting both islands. Periods of showers and thunderstorms are forecast to interrupt partly cloudy to overcast conditions. Note that activity will be intermittent throughout the day. Lingering showers, remaining isolated and interrupting partly cloudy skies, are forecast by the late evening through the night mainly across Eastern Trinidad and Tobago. Locally heavy rainfall and gusty winds, in excess of 55 KM/H possible. Seas may become moderate to occasionally rough, between 12:00 PM Tuesday through 12:00 PM Wednesday in Eastern Coastal Waters.

Wednesday: The axis of Tropical Wave 68 is forecast progress westward. However, trailing moisture and instability will also for overnight through early morning showers and thunderstorms, favoring the Southern and Eastern halves of Trinidad, gradually becoming settled by daybreak. Lingering showers, remaining isolated and interrupting partly cloudy skies, are forecast by the late evening through the night mainly across Eastern and Southern Trinidad and Tobago.

Impacts This Upcoming Week

Impacts from the upcoming Adverse Weather Alert event to Trinidad and Tobago
Impacts from the upcoming Adverse Weather Alert event to Trinidad and Tobago

Winds: Sustained surface winds between 20 KM/H and 35 KM/H with gusts in excess of 60 KM/H are likely in heavy showers or thunderstorms across Trinidad and Tobago throughout the week.

With wind gusts in excess of 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, bringing down utility poles and lines.

High Wind Event Precautions
High Wind Event Precautions

Rainfall: Rainfall accumulations are forecast to be scattered totals of 15-25 millimeters, with in excess of 50-75 millimeters in isolated thunderstorms or heavy downpours over the next 60 hours

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. No riverine flooding is expected.

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.

Landslides: Particularly across Northwestern Trinidad, soils are very saturated with persistent heavy afternoon thunderstorms at the end of the last week. With additional rainfall in the forecast, landslides are possible through Tuesday in landslide-prone and elevated areas.

Hazardous Seas: An increase in strong low-level winds will keep seas at moderate levels, with waves up to 2.5 meters in open waters and even at occasional rough levels, with waves in excess of 2.5 meters, particularly along the Eastern coasts of both islands.

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.

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