Tropical Storm Laura Forecast to Become A Hurricane

Tropical Storm Laura continues to strengthen as it moved across the Dominican Republic and Haiti over the last 12 hours, producing torrential rainfall and life-threatening flooding across the area.

Flash flooding as a result of Tropical Storm Laura in Haiti

Tropical Storm Laura knocked out power, washed out roads and is being blamed for at least eight deaths as Haiti, the Dominican Republic and Puerto Rico were battered by high winds and flooding Saturday into Sunday.

At least five people died in Haiti, according to the country’s civil protection authority.

“I share the sorrow of the families whose loved ones were killed on August 23 when Tropical Storm Laura passed through the country,” Prime Minister Jovenel Moise said in a Twitter post Sunday afternoon. “I urge the population to respect the instructions of the authorities to protect themselves from the damage that this bad weather could cause.”

Three people in the Dominican Republic were also reported killed.

At 5:00 PM AST, the center of Tropical Storm Laura was located near latitude 19.5 North, longitude 75.2 West. Laura is moving toward the west-northwest near 21 MPH (33 KM/H), and this general motion with some decrease in forward speed is expected over the next couple of days. A turn toward the northwest is forecast by Wednesday. On the forecast track, the center of Laura will move near or over southern coast Cuba tonight and Monday, and move over the southeastern Gulf of Mexico Monday night and Tuesday. Laura is expected to move over the central and northwestern Gulf of Mexico Tuesday night and Wednesday.

Data from an Air Force Reserve reconnaissance aircraft indicate that the maximum sustained winds are near 60 MPH (95 KM/H) with higher gusts. Little change in strength is forecast while Laura moves near the southern coast of Cuba tonight. However, strengthening is forecast after the storm moves over the Gulf of Mexico, and Laura is forecast to become a hurricane late Tuesday or Tuesday night. Tropical-storm-force winds extend outward up to 140 miles (220 KM) from the center. The minimum central pressure estimated from reconnaissance aircraft data is 1000 millibars.

Tropical Storm Laura Forecast Track as of 5:00 PM Sunday 23rd August 2020. (National Hurricane Center)

Watches & Warnings

Tropical Storm Laura Watches and Warnings as of 5:00 PM Sunday 23rd August 2020. (National Hurricane Center)
Tropical Storm Laura Watches and Warnings as of 5:00 PM Sunday 23rd August 2020. (National Hurricane Center)

A Tropical Storm Warning is in effect for…

  • Entire coast of the Haiti
  • Inagua and the Ragged Islands in southeastern Bahamas
  • Little Cayman and Cayman Brac
  • Cuban provinces of Camaguey, Las Tunas, Holguin, Guantanamo, Santiago de Cuba, Granma, Ciego De Avila, Sancti Spiritus, Villa Clara, Cienfuegos, Matanzas, Mayabeque, La Habana, Artemisa, Pinar del Rio, and the Isle of Youth

A Tropical Storm Watch is in effect for…

  • Florida Keys from Craig Key to Key West and the Dry Tortugas

The Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 12 to 24 hours.

A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, in this case within the next 24 hours.

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 Sunday 23rd 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 Sunday 23rd August 2020, as well as the most likely time of arrival of tropical-storm-force winds. (National Hurricane Center)

WIND: Tropical storm conditions are expected within portions of the warning area in Haiti through this evening. Tropical storm conditions are expected within portions of the warning area in Cuba later tonight through Monday. Tropical storm conditions are expected in Little Cayman and Cayman Brac on Monday. Tropical storm conditions are possible within portions of the watch area in the Florida Keys Monday.

Tropical Storm Laura forecast rainfall as of 5:00 PM Sunday 23rd August 2020. This graphic is created by the NWS/NCEP Weather Prediction Center (WPC) and shows rainfall potential for the United States when a tropical cyclone threatens land. The graphic is displayed as a Quantitative Precipitation Forecast (QPF), which shows rainfall totals for a specified time period, based on forecaster discretion. (National Hurricane Center)
Tropical Storm Laura forecast rainfall as of 5:00 PM Sunday 23rd August 2020. This graphic is created by the NWS/NCEP Weather Prediction Center (WPC) and shows rainfall potential for the United States when a tropical cyclone threatens land. The graphic is displayed as a Quantitative Precipitation Forecast (QPF), which shows rainfall totals for a specified time period, based on forecaster discretion. (National Hurricane Center)

RAINFALL: Laura is expected to produce the following storm total rainfall accumulations through Tuesday:

  • Dominican Republic, Haiti, Jamaica, and Cuba: 4 to 8 inches, with maximum amounts of 12 inches.
  • Cayman Islands: 2 to 4 inches, maximum amounts of 6 inches.
  • Florida Keys, Turks and Caicos, and the southeast Bahamas: 1 to 2 inches.
  • Across the Greater Antilles, this heavy rainfall could lead to life-threatening flash and urban flooding, and the potential for mudslides.
  • By later Wednesday into Friday Laura is expected to produce rainfall of 5 to 10 inches, with isolated maximum amounts of 15 inches across portions of the west-central U.S. Gulf Coast near the Texas and Louisiana border north into portions of the Lower Mississippi Valley. This rainfall could lead to flash, urban, and small stream flooding.

SURF: Swells generated by Laura are affecting portions of Puerto Rico, Hispaniola, eastern Cuba, the southeastern Bahamas and the Turks and Caicos Islands. These swells are expected to spread across central and western Cuba, the central and northwestern Bahamas, and the Florida Keys during the next couple of days. Please consult products from your local weather office.

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

Satellite imagery and radar data from eastern Cuba show that the center of Laura has been moving over water between Haiti and eastern Cuba this afternoon. There has been a recent uptick in convection near the center and the radar imagery has shown an increase in banding. An Air Force reconnaissance aircraft investigating Laura this afternoon has reported a minimum pressure that has fallen to around 1000 mb, and winds to support an intensity of 50 kt. The plane very recently found a small area of stronger flight-level winds, but these winds may be associated with a mesocyclone, and not representative of the large scale circulation.

Laura continues to move briskly west-northwestward or 285/18 kt. The track forecast reasoning remains the same as the previous advisory. Laura should continue to move west-northwestward to the south of a deep-layer ridge that is forecast to build westward across Florida and the eastern Gulf of Mexico during the next day or two. The track guidance has continued to edge southward for the portion of the forecast near Cuba, and the NHC forecast has again been moved in that direction. Laura should continue moving west-northwestward over the southeastern Gulf on Tuesday, but a turn toward the northwest is expected Tuesday night as the cyclone nears the western portion of the ridge. A northwestward to north-northwestward motion should then continue around the western portion of the ridge until the cyclone reaches the northwestern Gulf coast. The latest run of the ECMWF has shifted significantly eastward, however its ensemble mean and many of the stronger ensemble members remain farther west as a stronger cyclone is likely to be steered more westward by the deep-layer ridge. The GFS, UKMET, and HWRF remain close to the previous NHC track, so little change was made to the official forecast was made after 48 hours.

The intensity forecast during the next 24 hours is highly dependent on the track and the amount of interaction Laura has with Cuba. If the storm stays along the southern coast or just offshore, the environment of warm water and low vertical wind shear could allow for some slight strengthening, but little overall change in intensity is indicated during the next 24 hours. After the center clears western Cuba, the upper-level wind pattern is predicted to quite favorable while the storm traverses the warm waters of the Gulf of Mexico. The GFS, UKMET, and regional hurricane models all indicate significant deepening, and the NHC intensity forecast has been adjusted slightly upward. Although not explicitly shown, Laura could threaten the northwestern Gulf coast near major hurricane strength.

Users are again reminded to not to focus on the exact details of the track or intensity forecast at the longer range as winds, storm surge, and rainfall hazards will extend far from the center.

Key Messages:

Tropical storm conditions are expected across portions of Haiti, the southeastern Bahamas, and Cuba through Monday. Heavy rainfall is likely across Haiti, Cuba, and Jamaica through Monday and these rains could cause mudslides and life-threatening flash and urban flooding.

  1. Tropical storm conditions are possible over the Middle and Lower Florida Keys and the Dry Tortugas on Monday.
  2. While the details of the long-range track and intensity forecasts remain uncertain, Laura is forecast to strengthen over the Gulf of Mexico and there is an increasing risk of dangerous storm surge, wind, and rainfall impacts along portions of the U.S. Gulf Coast by the middle of the week. This could result in a prolonged period of hazardous weather for areas that are likely to be affected by Marco. Interests along the Gulf Coast should monitor the progress of Laura and Marco and updates to the forecast during the next few days.

Forecast Discussion by Forecaster Brown from the NHC.

Facebook Comments