Tropical Update: Keeping Our Eyes on Invest 95L & 3 Tropical Waves East of T&T

Tropical Update:
Tropical Wave 29: This tropical wave is located west of the Lesser Antilles and northwest of Trinidad and Tobago. It has been designated as Invest 95L by the National Hurricane Center which is monitoring this area of low pressure for tropical development. As of 8:00 AM, Invest 95L has low chances of development over the next 5 days. No direct impacts to T&T.
Tropical Wave 30: This tropical wave is located in the east of Trinidad and Tobago. It is forecast to move across T&T and the Lesser Antilles tonight into Tuesday, increasing shower chances across T&T, but much of the showers and thunderstorms associated with this wave is forecast to move across the Leewards, well north of T&T. Street/Flash Flooding, gusty winds may occur, particularly across the Leewards. Light winds throughout today and tomorrow may support localized thunderstorms and showers, favoring Western Trinidad and in hilly areas.
Tropical Wave 31: This tropical wave is located in the far Eastern Atlantic. There is no operational model support for tropical cyclone development. This wave is forecast to move across the Lesser Antilles Thursday into Friday. Model analysis is showing a dry mid-level atmoshpere during it’s traverse over the region, limiting heavy showers and thunderstorms. A slight increase in showers are forecast.
Tropical Wave 32: A strong tropical wave has just entered the Eastern Atlantic Ocean. It is forecast to move across the Lesser Antilles by the end of next weekend. None of the top global operational models show development at this time, but there is some ensemble support. It is too soon to tell a definitive track.

Before we dive into the Tropical Updates on the tropical waves, a few notes:

  • Tropical waves are a normal part of the rainy season.
  • Not every tropical wave will form into a tropical cyclone.
  • Tropical waves at the beginning of the Hurricane Season are typically weak, producing 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 Wave 29/Invest 95L

Tropical Wave 29/Invest 95L, along 65W. This wave is forecast to move northwest across the Greater Antilles over the next several days, bringing locally heavy rainfall, street/flash flooding and inclement weather to the islands. Credit: Weathernerds.org
Tropical Wave 29/Invest 95L, along 65W. This wave is forecast to move northwest across the Greater Antilles over the next several days, bringing locally heavy rainfall, street/flash flooding and inclement weather to the islands. Credit: Weathernerds.org

Tropical Wave 29 is located in the Central Atlantic, along 65W, between 22N southward to 6N, moving west at approximately 15 knots. This strong tropical wave has brought inclement weather to much of the Lesser Antilles on Saturday and Sunday. Street/flash flooding was reported across numerous islands across the Eastern Caribbean, with gusty winds during thunderstorms.

Much welcome rainfall occurred, with some islands recording between 25 millimeters to 50 millimeters. Isolated areas, mainly offshore, got up to 100 millimeters of rainfall.

This tropical wave is being monitored by the National Hurricane Center for tropical cyclone development as of 8:00 AM Monday 29th July 2019. As of present, it was given a 10% chance of development over the next 48 hours and 20% chance over the next 5 days, as it moves northwestward.

8:00 AM Monday 29th July 2019 Tropical Weather Outlook for Invest 95L/Tropical Wave 29
8:00 AM Monday 29th July 2019 Tropical Weather Outlook for Invest 95L/Tropical Wave 29

95L will be moving northwest across the eastern Caribbean—a region so notorious for strong wind shear and dry air, especially early in the season, that it’s sometimes called a hurricane graveyard. At first, a small upper ridge building over the eastern Caribbean could give 95L enough support to maintain itself over this hostile region. As the wave approaches the Greater Antilles around midweek, it will encounter strong westerly shear, and interaction with the larger islands will disrupt any circulation. Heavy thunderstorms can be expected to spread westward from Puerto Rico across Hispaniola toward Cuba, and some localized flash flooding will be possible.

On its continued northwest path, 95L is projected to move over the very warm waters of the Florida Straits late this week at the same time a large upper ridge is projected to sharpen there. Together, these may give 95L its best shot at intensification.

None of the top global models presently support tropical cyclone development over the next few days. However, few ensembles of the GFS (GEFS) and EMCWF (EPS/EMCF) support development of Invest 95L, mainly after it moves into the Southwestern Atlantic out of the Caribbean Sea.

Another update on this system will be posted later today, in a brief tropical update.

While no further impacts are forecast for Trinidad and Tobago resulting from Tropical Wave 29/Invest 95L. light winds from the south/southeast resulting from Invest 95L’s weakening of low-level winds are forecast to remain across the Southern Windwards. This weak wind regime will remain through Tuesday, allowing for daytime heating and sea breeze convergence to trigger showers and possible isolated thunderstorms across Trinidad and Tobago.

Parts of interior Central Trinidad, Western Coastal Trinidad and along the Northern Range of Trinidad may see heavy showers and thunderstorms today (Monday). Street/flash flooding, landslides possible.

Tropical Wave 30

Tropical Wave 30, in the Central Atlantic, along 50W. This wave is forecast to move across the Lesser Antilles tonight into Tuesday but will begin to affect Trinidad and Tobago by late Monday. Much of the heavier showers and thunderstorms are forecast to remain north of T&T. Credit: Weathernerds.org
Tropical Wave 30, in the Central Atlantic, along 50W. This wave is forecast to move across the Lesser Antilles tonight into Tuesday but will begin to affect Trinidad and Tobago by late Monday. Much of the heavier showers and thunderstorms are forecast to remain north of T&T. Credit: Weathernerds.org

Tropical Wave 30 is located in the Central Atlantic, along 50W, 18N southward, moving west at approximately 15 knots. This tropical wave is forecast to begin affecting Trinidad, Tobago, and the Southern Windwards by late Monday into Tuesday.

Isolated to scattered showers are occurring near the wave axis. This tropical wave is forecast to bring some isolated showers overnight into tomorrow across the Southern Windwards. No significant rainfall forecast across T&T.

Heavier showers are likely to remain north of Trinidad and Tobago, mainly affecting the Leewards.

However, with the light wind regime mentioned above, a few showers may become heavy or develop into thunderstorms. Parts of interior Central Trinidad, Western Coastal Trinidad and along the Northern Range of Trinidad may see heavy showers and thunderstorms today (Monday). Street/flash flooding, landslides possible.

This wave has no operational model support for tropical cyclone formation at this time.

Why I May Not/Will Not See Constant Rainfall?

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.

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.

Generally, because of winds associated with tropical waves, showers and thunderstorms tend to follow a west-northwest track, generally missing areas across Southwestern Trinidad and even Northwestern Trinidad – though activity due to local climatic effects such as daytime heating may trigger shower and thunderstorm development across these areas. See the below graphic for a simple explanation.

With Tropical Wave 30, mostly isolated activity is forecast. Hence, we are likely to see intermittent showers and thunderstorms, interrupting partly cloudy to overcast skies, particularly on Tuesday.

Tropical Wave 31

Tropical Wave 31, in the Eastern/Central Atlantic, along 39/40W. This wave is forecast to move across the Lesser Antilles Thursday into Friday. Credit: Weathernerds.org
Tropical Wave 31, in the Eastern/Central Atlantic, along 39/40W. This wave is forecast to move across the Lesser Antilles Thursday into Friday. Credit: Weathernerds.org

Tropical Wave 31 is located in the Central/Eastern Atlantic, along 39/40W, 20N southward, moving west at approximately 15 knots. This tropical wave is forecast to move across the Lesser Antilles Thursday into Friday, bringing increased chances of showers and the isolated thunderstorm.

However, based on present model guidance, moisture at mid-levels of the atmosphere may be less than optimal, inhibiting deep convection from development. Still, shallow convection may become heavy at times but the chances for thunderstorms remain low. Additional updates to follow in our next tropical update, tomorrow.

Tropical Wave 32

Tropical Wave 32, in the Far Eastern Atlantic, along 21/22W. This wave is forecast to move across the Lesser Antilles late next weekend, but it is too soon to tell any specific impacts across the region. Credit: Weathernerds.org
Tropical Wave 32, in the Far Eastern Atlantic, along 21/22W. This wave is forecast to move across the Lesser Antilles late next weekend, but it is too soon to tell any specific impacts across the region. Credit: Weathernerds.org

Tropical Wave 31 is located in the Far Eastern Atlantic, along 21/22W, 18N southward, moving west at approximately 15 knots. This tropical wave is forecast to move across the Lesser Antilles late next weekend.

Late July is usually a bit too soon to worry about Cape Verde-type waves developing in the eastern Atlantic, but we have a potential candidate on our hands. A very potent easterly wave, with plenty of spin already evident on satellite imagery, is now moving off the African coast into the deep Northeast Atlantic tropics, centered near latitude 10°N.

Scattered moderate to strong showers and thunderstorms are occurring near the wave axis, with some noticeable spin.

Models, as of the 00Z and 06Z runs on Monday morning, keep this system as a strong tropical wave as it moves across the Atlantic, bringing its heaviest showers and thunderstorms across the Leewards, well north of Trinidad, by next weekend.

This is a wave to keep an eye on due to its already impressive appearance. Additional updates in our next tropical update tomorrow.

These tropical waves are likely benefitting from the rising motion at upper levels provided by a large-scale feature called a convectively coupled Kelvin wave (CCKW) moving across the region, as noted by Philippe Papin (Naval Research Laboratory) on Friday.

Tropical Cyclone Climatology

Tropical Cyclone Points of Origin during the month of July. This month, the attention goes to tropical waves moving across the Atlantic, particularly as they near the Lesser Antilles, as well as low-pressure systems in the Gulf of Mexico and troughs Southeast of the United States.

In July, we turn our eyes to East of the Lesser Antilles, the Southeastern areas of the United States and the Gulf of Mexico for the formation of tropical cyclones in the Atlantic Basin, historically. However, tropical cyclones can form in the Atlantic Basin, without regard for the location once conditions support development. Stay updated with the latest tropical update!

There are NO tropical cyclone threats to the Eastern Caribbean, including Trinidad and Tobago at this time in the latest Tropical Update.

2019 Atlantic Hurricane Season Names
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