Tropical Update: Monitoring Two Areas For Development, Tropical Wave 30 To Affect T&T on Tuesday.

Image courtesy BrohavWeatherFax

Tropical Update:
Tropical Wave 29: This tropical wave is located well 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 PM, Invest 95L has low chances of development over the next 5 days. No direct impacts to T&T, though there is still some influence on our wind field.
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 on Tuesday. Street/Flash Flooding, gusty winds may occur. Light winds throughout tomorrow may support localized thunderstorms and showers, favoring Northern and Central Trindad. Severe Weather possible.
Tropical Wave 31: This tropical wave is located in the Central 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: This strong tropical wave has is located Eastern Atlantic Ocean. It is forecast to move across the Lesser Antilles by the end of next weekend. Over the course of today, this wave has gained model support from two of the top three models for tropical development and is now being monitored by the National Hurricane Center for tropical cyclone formation. Low chances of development over the next 5 days.

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 67W. 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 67W. 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 67W, between 21N southward to 7N, moving west at approximately 15-20 knots. Widely scattered moderate convection is over the Leeward Islands from 15N-21N between 61W-68W. Scattered moderate convection is over the Windward Islands and N Venezuela from 07N-12N between 60W-69W.

This strong tropical wave has brought inclement weather to much of the Lesser Antilles on Saturday through today. 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 50 millimeters to 75 millimeters. Isolated areas, mainly offshore, got up to 200 millimeters of rainfall.

This tropical wave is being monitored by the National Hurricane Center for tropical cyclone development as of 8:00 PM Monday 29th July 2019. As of present, it was given a 0% chance of development over the next 48 hours and a 10% chance over the next 5 days, as it moves northwestward.

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

The wave known as Invest 95L weakened on Monday while traversing the northeast Caribbean, known as the “hurricane graveyard” for its tendency toward strong wind shear and dry air. Squally weather was increasing across eastern parts of the Greater Antilles, though. 95L could produce localized downpours as it moves across the Greater Antilles from Tuesday to Wednesday. A flash flood watch is in effect for Puerto Rico and the U.S. Virgin Islands through at least Tuesday night.

Later in the week, 95L will approach the very warm waters of the western Bahamas. About 10% of the 12Z Monday GFS and European model runs showed the development of 95L in this region late next week.

Shower activity associated with a tropical wave over the eastern Caribbean Sea remains disorganized. This system is expected to move west-northwestward with no significant development, producing locally heavy rainfall over Puerto Rico, Hispaniola, and portions of the southeastern Bahamas during the next few days. Over the weekend, conditions could become a little more conducive for development when the disturbance moves near Florida and the central and northwestern Bahamas.

Another update on this system will be posted later tomorrow in the 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.

Tropical Wave 30

 Tropical Wave 30, in the Central Atlantic, along 48W. This wave is forecast to move across the Lesser Antilles on Tuesday. Credit: Weathernerds.org
Tropical Wave 30, in the Central Atlantic, along 48W. This wave is forecast to move across the Lesser Antilles on Tuesday. Credit: Weathernerds.org

Tropical Wave 30 is located in the Central Atlantic, along 48W, 18N southward to 3N, moving west at approximately 15 knots. Scattered moderate to isolated strong convection is from 06N-10N between 43W-51W

This tropical wave is forecast to begin affecting Trinidad, Tobago, and the Southern Windwards on Tuesday.

During the second half of Tuesday, showers and thunderstorms associated with the leading edge of this tropical wave is forecast to begin affecting T&T, combined with likely daytime convective activity across the island. This is forecast to result in periods of showers and thunderstorms through the evening into nightfall.

Based on the latest development of convection along the southern portion of the wave axis, there is the increasing likelihood of showers and thunderstorms affecting T&T. This may result in rainfall totals between 20-40 millimeters across mainly Trinidad.

With the light wind regime mentioned above, 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 tomorrow (Tuesday). 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 scattered activity is forecast. Hence, we are likely to see intermittent showers and thunderstorms, interrupting partly cloudy to overcast skies, particularly the latter half of Tuesday.

Tropical Wave 31

Tropical Wave 31, in the Eastern/Central Atlantic, along 39W. 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 39W. 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 39W, 18N southward to 3N, 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/Invest 96L

Tropical Wave 32, in the Far Eastern Atlantic, along 20W. This wave is forecast to move across the Lesser Antilles late next weekend. Models are hinting at a possible tropical depression late next weekend as it approaches the Lesser Antilles. Credit: Weathernerds.org
Tropical Wave 32, in the Far Eastern Atlantic, along 20W. This wave is forecast to move across the Lesser Antilles late next weekend. Models are hinting at a possible tropical depression late next weekend as it approaches the Lesser Antilles. Credit: Weathernerds.org

Tropical Wave 32 is located in the Far Eastern Atlantic, along 20W, 18N southward to 3N, moving west at approximately 10-15 knots. This tropical wave is forecast to move across the Lesser Antilles late next weekend.

In the eastern Atlantic, the strong tropical wave that emerged from Africa on Sunday is suffering from the ingestion of the dry Saharan air just to its north. Convection has diminished on the wave’s north side. The wave remains fairly well organized, though, and ensemble models indicate it has a modest chance of development later this week as it reaches warmer waters in the western part of the deep Atlantic tropics (the so-called main development region between the Caribbean and Africa).

About 60% of European ensemble members and about 50% of GFS members develop this wave to at least some extent in the 3- to 5-day period. Any such development could affect the Leeward Islands about a week from now.

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

Models, as of the 12Z and 18Z runs on Monday evening, keep this system as a tropical depression or minimal tropical storm as it nears the Lesser Antilles next weekend. It is definitely too soon to tell the exact track of this system. However, based on large scale steering patters, as this system nears the Lesser Antilles, a west-northwest path is possible. Islands as south as Barbados to as north as the Greater Antilles need to monitor this system closely.

EMCWF (EPS) Ensemble Model Runs for tropical waves in the Atlantic Ocean. Credit: Alan Barammer
EMCWF (EPS) Ensemble Model Runs for tropical waves in the Atlantic Ocean. Credit: Alan Barammer

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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