Tropical Update – Cristobal Weakens, Tropical Wave 05 Nears T&T

Tropical Update Overview:
Tropical Depression Cristobal – This tropical cyclone continues to weaken as it moves across the Yucutan Peninsula, but it is forecast reemerge in the Gulf of Mexico this weekend, heading towards the U.S. Gulf Coast.
Tropical Wave 05 – This tropical wave is just east of Trinidad and Tobago, forecast to bring severe weather to both islands beginning tonight (Thursday) through Friday. Thunderstorms are also possible on Saturday. See below for details.
Tropical Wave 06 – This tropical wave is located in the Central Atlantic, moving westward. This wave is forecast to affect the Lesser Antilles on Monday into Tuesday, with isolated thunderstorms possible, favoring Trinidad.
Tropical Wave 07 – This tropical wave, not yet analyzed by the National Hurricane Center, is located in the Eastern Atlantic, forecast to move across the region Thursday into Friday next week. It is too soon to tell definitive impacts this wave may bring to T&T.

Total Precipitable Water Imagery showing the Tropical Waves (analyzed by the National Hurricane Center, Weather Prediction Center and TTWC) that exist in the Atlantic Basin, as well as Tropical Depression Cristobal.

Impacts to T&TNo direct tropical threats to Trinidad and Tobago are forecast over the next week but locally heavy rainfall is possible particularly between Thursday night and Saturday afternoon, with the highest chances for rainfall on Friday due to Tropical Wave 05. Street flooding, gusty winds generally between 25-45 KM/H, occasionally in excess of 60 KM/H, and frequent lightning are possible. Flash flooding and landslides are less likely but possible.

Before we dive into the Tropical Update, a few notes:

  • Tropical waves are a normal part of the rainy season.
  • Not every tropical wave will form into a tropical cyclone.
  • Weaker tropical waves produce more rainfall across Eastern parts of the islands with mostly cloudy conditions and a few showers across western parts of the islands.
  • Rainfall will be more isolated and intermittent with weaker tropical waves that do not have ITCZ or upper-level support.
  • Saharan Dust may weaken tropical waves.

You can read more about the weather associated with Tropical Waves, as well as what to expect as these waves move through the region below.

Tropical Depression Cristobal

Tropical Depression Cristobal affecting parts of Central America Credit: Weathernerds
Tropical Depression Cristobal affecting parts of Central America Credit: Weathernerds

The National Hurricane Center (NHC) continues to monitor now Tropical Depression Cristobal, which continues to bring locally heavy rainfall across parts of Central America.

At 5:00 PM AST, the center of Tropical Depression Cristobal was located near latitude 17.5 North, longitude 90.8 West.

The depression is moving toward the east-southeast near 3 MPH (6 KM/H). A turn toward the east and northeast is expected tonight, and a subsequent generally northward motion should occur through Sunday.

On the forecast track, the center will move over extreme northwestern Guatemala and eastern Mexico tonight and Friday. The center is forecast to move back over the southern Gulf of Mexico late Friday, over the central Gulf of Mexico on Saturday, and approach the northern Gulf of Mexico coast Sunday and Sunday night.

No threat to the Lesser Antilles, including T&T.

Tropical Wave 05

Tropical Wave 05 is analyzed along 58/59W, producing showers and thunderstorms east of Trinidad and Tobago. Credit: Weathernerds
Tropical Wave 05 is analyzed along 58/59W, producing showers and thunderstorms east of Trinidad and Tobago. Credit: Weathernerds

As of the 7:00 PM Tropical Update, the fifth tropical wave for the 2020 Atlantic Hurricane Season is located along 58/59W, from 14N southward based on our analysis based on total precipitable imagery and satellite imagery.

Based on our analysis, the axis of the wave is approximately just over 200 kilometers east of Trinidad and Tobago, but much of the active weather follows the wave axis.

Scattered showers are ongoing on both sides of the wave axis, with stronger convection and thunderstorms following the wave axis. The wave is moving west at 10 to 15 knots (18.5-28 KM/H) and is forecast to traverse the Lesser Antilles on Friday.

Presently, favorable low-level convergence and upper-level divergence are coinciding with these showers and thunderstorms, as well as abundant total precipitable moisture moving associated with the wave. Wind shear (from the west) remains strong, preventing persisting showers and thunderstorms from moving westward. During the latter half of Friday, shear is forecast to diminish slightly.

Guidance from the top global models is in agreement with periods of showers and isolated thunderstorms beginning overnight through the afternoon on Saturday, with locally heavy rainfall possible on Friday.

See below for details.

Tropical Wave 06 & Tropical Wave 07

Activity associated with Tropical Wave 06 in the East Atlantic, along 37W with activity mainly where the wave axis interacts with the ITCZ. the activity further east is associated with the ITCZ, interacting with Tropical Wave 07 (not analyzed by the NHC). Credit: Weathernerds

As of the 7:00 PM Tropical Update, the axis of Tropical Wave 06 is approximately along is along 40/41W, from 11N southward, moving westward 10-15 knots (18.5-28 KM/H).

Convection is limited near the wave axis, but abundant moisture is present ahead of and behind the wave. This wave is forecast to bring isolated thunderstorms to parts of Trinidad on Monday into Tuesday, but no widespread severe weather is forecast.

As of the 7:00 PM Tropical Update, the axis of Tropical Wave 07 is approximately along is along 28W, from 14N southward, moving westward 10-15 knots (18.5-28 KM/H).

Scattered moderate convection is associated with this wave axis, interacting with the ITCZ. It is too soon to tell any definitive impacts as this wave traverses the region later next week.

What does all of this mean for Trinidad and Tobago?

Friday: The axis of Tropical Wave 05 will be moving across T&T, but active weather follows the axis. After midnight Thursday into Friday, and throughout the day, periods of light to moderate rain, isolated to scattered showers and isolated thunderstorms are forecast, generally interrupting mostly cloudy to cloudy skies. Mostly cloudy (meaning brief peeks of sunshine may be seen through the clouds) to cloudy skies will continue throughout the day, with isolated thunderstorms and isolated to scattered showers. Thunderstorms to favor the predawn hours as well as the late morning through the afternoon hours.

Note that overall heavier rainfall is forecast to remain offshore (east of Trinidad, south of Tobago) and across the eastern halves of both islands. Conditions to mostly settle by nightfall, with isolated showers and light rain persisting in localized areas across Trinidad.

Particularly during heavy to violent showers and thunderstorms on Friday, gusty winds in excess of 60 KM/H are possible. Seas to remain moderate, with waves up to 2 meters in open waters, but may become choppy during heavy showers and thunderstorms. Street flooding and frequent lightning are likely in heavy downpours and thunderstorms respectively. Flash flooding and landslides are less likely, but also possible.


Saturday: Isolated early to mid-morning showers are forecast, becoming heavier closer to daybreak but still favoring eastern coastal areas of Trinidad, gradually moving westward. Conditions to become partly cloudy by the mid to late morning, with isolated to scattered showers possible, favoring Trinidad. There is the low to medium chance of isolated thunderstorms favoring Trinidad between 10 AM and 3 PM. Conditions to settle by the evening, barring the odd isolated shower favoring eastern areas.

As abundant low-level moisture is forecast to continue moving across Trinidad and Tobago Saturday into Sunday, with southeasterly winds, sea-breeze convergence, daytime heating, and orographic effects is forecast to trigger showers and isolated thunderstorms during the late morning through the afternoon.

Gusty winds up to 60 KM/H, street flooding is possible in heavy to violent showers and isolated thunderstorms. Seas to remain slight to moderate, with waves up to 1.5 meters in open waters, but may become choppy during heavy showers and thunderstorms.


Sunday: After an initially sunny morning, isolated to scattered showers and isolated thunderstorms are possible by the late morning through the afternoon (10 AM through 3 PM). Heavier activity to favor western and hilly areas. Conditions to settle by the evening, barring the odd isolated shower favoring eastern areas.

Gusty winds up to 55 KM/H, street flooding is possible in heavy to violent showers and isolated thunderstorms. Seas to remain slight to moderate, with waves up to 1.5 meters in open waters, but may become choppy during heavy showers and thunderstorms.


Monday: A weak tropical wave is forecast to traverse the region Sunday into Monday, with isolated to scattered showers and isolated thunderstorms possible, with much of the activity favoring Trinidad, though widespread showers or heavy rainfall is not expected.

Gusty winds up to 55 KM/H, street flooding is possible in heavy to violent showers and isolated thunderstorms. Seas to remain slight to moderate, with waves up to 1.5 meters in open waters, but may become choppy during heavy showers and thunderstorms.

Impacts Following Tropical Wave 05

Impacts associated with Tropical Wave 05 across Trinidad and Tobago. Note that heavy rainfall to favor offshore areas as well as Eastern Coastal Trinidad and Tobago.
Impacts associated with Tropical Wave 05 across Trinidad and Tobago. Note that heavy rainfall to favor offshore areas as well as Eastern Coastal Trinidad and Tobago.

Winds: Sustained surface winds between 25 KM/H and 45 KM/H with gusts in excess of 60 KM/H are likely in heavy showers or thunderstorms across Trinidad and Tobago, particularly between Thursday night through Saturday afternoon.

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: Modelled rainfall accumulations have generally increased, though this is still not forecast to be a widespread, heavy rainfall event. Much of the heavy rainfall is forecast to remain offshore – south of Tobago & east of Trinidad. Generally, most areas through Sunday that receive rainfall are forecast to see daily totals less than 15-20 millimeters, with in excess of 25-45 millimeters in isolated thunderstorms or heavy/violent downpours.

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.

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. Thunderstorms are forecast to generally remain offshore, more so in the Gulf of Paria.

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.

This week, isolated to scattered activity is forecast.

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

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the month of June. Though much of the points of origin are west or north of T&T as we move through the first month of the Hurricane Season, we still need to pay attention to some of these waves and the ITCZ, which have historically brought major flooding events to T&T, hence all low-pressure systems in the Atlantic should be closely monitored, as we do in the Tropical Update.

List of names for the 2020 Atlantic Hurricane Season, which will be updated each tropical update as new systems develop.
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