Tropical Storm Laura Just East of Antigua

Tropical Storm Laura (previously INVEST 98L and Tropical Depression Thirteen) formed on Friday morning, breaking the previous record for the earliest ‘L’ Atlantic named storm is Luis on August 29, 1995.

This tropical cyclone is not forecast to directly impact Trinidad, Tobago and the Windward Islands. However, strong low-level convergence following this system, as well as its influence on our wind regime and moisture will bring inclement weather to the area Friday into Saturday.

At 5:00 PM AST, the center of Tropical Storm Laura was located near latitude 17.1 North, longitude 61.2 West. Laura is moving toward the west near 17 MPH (28 KM/H), and a generally west-northwestward motion at a faster forward speed is expected over the next couple of days. On the forecast track, the center of Laura will move near or over portions of the Leeward Islands later today, near or over Puerto Rico Saturday morning, and near the northern coast of Hispaniola late Saturday and early Sunday.

Maximum sustained winds are near 45 MPH (75 KM/H) with higher gusts. Some slow strengthening is forecast during the next 48 hours. Tropical-storm-force winds extend outward up to 115 miles (185 KM) from the center. The estimated minimum central pressure is 1007 millibars.

Tropical Storm Laura Forecast Track as of 5:00 PM AST Friday 21st August 2020. (National Hurricane Center)
Tropical Storm Laura Forecast Track as of 5:00 PM AST Friday 21st August 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Laura Watches and Warnings as of 5:00 PM AST Friday 21st August 2020. (National Hurricane Center)
Tropical Storm Laura Watches and Warnings as of 5:00 PM AST Friday 21st August 2020. (National Hurricane Center)

A Tropical Storm Warning is in effect for:

  • Puerto Rico, Vieques and Culebra
  • U.S. Virgin Islands
  • British Virgin Islands
  • Saba and St. Eustatius
  • St. Maarten
  • St. Martin and St. Barthelemy
  • Antigua, Barbuda, St. Kitts, Nevis, Anguilla, and Montserrat
  • The northern coast of the Dominican Republic from Cabo Engano to the border with Haiti
  • The northern coast of Haiti from Le Mole St. Nicholas to the border with the Dominican Republic

A Tropical Storm Watch is in effect for:

  • The southeastern Bahamas and the Turks and Caicos Islands

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours.

Interests in Cuba and the remainder of the Bahamas should monitor the progress of Laura.

For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service.

Hazards Affecting Land

Tropical Storm Laura probabilities for tropical-storm-force winds as of 5:00 PM AST Friday 21st August 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)
Tropical Storm Laura probabilities for tropical-storm-force winds as of 5:00 PM AST Friday 21st August 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

RAINFALL: Laura is expected to produce 3 to 6 inches of rain over Puerto Rico and the Virgin Islands, the Dominican Republic, the southern Haitian Peninsula, and eastern Cuba through Sunday. Maximum amounts up to 8 inches are possible along eastern portions and the southern slopes of Puerto Rico, as well as over Haiti, the Dominican Republic, and eastern Cuba. This heavy rainfall could lead to flash and urban flooding, as well as an increased potential for mudslides with minor river flooding in Puerto Rico.

1 to 3 inches of rain with isolated maximum totals of 5 inches are expected over the remainder of Haiti, the northern Leeward Islands, the Turks and Caicos, and the southeast Bahamas.

WIND: Tropical storm conditions are expected within portions of the warning area later today through Saturday. Tropical storm conditions are possible within portions of the watch area Saturday night and early Sunday.

This system is of no direct threat to the Windward Islands, including Trinidad and Tobago.

Tropical Storm Laura Forecast Discussion

Tropical Storm Laura affecting weather across the Lesser Antilles (Weathernerds)
Tropical Storm Laura affecting weather across the Lesser Antilles (Weathernerds)

A poorly-defined convective band has become evident over the southeastern portion of the circulation. However, there is little or no deep convection near the estimated center. Overall, the system’s cloud pattern still has a ragged appearance. Dvorak intensity estimates range from 35 to 45 knots, and the current intensity is held at 45 knots based on continuity from hurricane hunter observations from earlier today. There is a fairly well-defined upper-level outflow pattern at this time, but an upper-level trough to the west of Laura could be an impediment to future strengthening. The official intensity forecast is a little below the intensity consensus, mainly due to the influences of the landmasses of the Greater Antilles. At days 4-5, the intensity forecast is also a bit below the consensus due to uncertainties at these longer forecast ranges.

The center is not very easy to see, even on visible or radar images, but the best guess at initial motion is 275/15 kt. The track forecast reasoning has not changed much from the previous advisory package. Laura should move generally west-northwestward along the southern periphery of a subtropical ridge for about the next 72 hours. Later in the forecast period, the cyclone is expected to turn northwestward as it begins to move around the western side of the ridge. The track guidance has shifted westward at days 4-5, and so has the official forecast, which is mostly close to the model consensus but not quite as far west as that guidance in the latter part of the forecast period.

Another NOAA Hurricane Hunter aircraft is scheduled to investigate Laura shortly.

Key messages:

  1. Tropical storm conditions are expected across portions of the northern leeward islands, the virgin islands, and Puerto Rico today through Saturday; tropical storm conditions are also expected along the northern coasts of the Dominican Republic and Haiti from Saturday into Sunday. Heavy rainfall is likely across these areas beginning today and could cause mudslides and flash and urban flooding through Sunday.
  2. Tropical storm conditions are possible over portions of the southeastern Bahamas and the Turks and Caicos Islands on Sunday.
  3. The details of the long-range track and intensity forecasts remain more uncertain than usual since Laura is forecast to move near or over portions of the Greater Antilles through Monday. However, Laura could bring storm surge, rainfall, and wind impacts to portions of Cuba, the Bahamas, and Florida early next week and the Northern U.S. Gulf Coast by the middle of next week. Interests there should monitor the progress of Laura and updates to the forecast over the next few days.

Forecast Discussion by Forecaster Pasch from the NHC.

Facebook Comments