Tropical Storm Humberto Has Formed, Forecast to Affect the Abacos, Grand Bahama & NW Bahamas.

At 11:00 PM Friday AST, the National Hurricane Center upgraded Tropical Depression Nine to Tropical Storm Humberto, 210 kilometers east-southeast of Great Abaco Island.

The center of Tropical Storm Humberto was located near latitude 25.6 North, longitude 75.2 West. Humberto is moving toward the northwest near 9 KM/H. A turn toward the north-northwest is expected by Sunday, with a slower northward motion forecast to occur by Monday. On the forecast track, the system is anticipated to move very near the northwestern Bahamas on Saturday, and offshore of the east coast of Florida this weekend and early next week.

Maximum sustained winds have increased to near 65 KM/H with higher gusts up to 85 KM/H. Gradual strengthening is forecast, and Humberto is expected to become a hurricane in two or three days.

Tropical-storm-force winds extend outward up to 150 kilometers from the center. The estimated minimum central pressure based on data from the NOAA Hurricane Hunters is 1008 millibars.

Forecast Track for Tropical Storm Humberto as of 11:00 PM Friday 13th September 2019. Credit: National Hurricane Center
Forecast Track for Tropical Storm Humberto as of 11:00 PM Friday 13th September 2019. Credit: National Hurricane Center

Watches & Warnings

Watches and Warnings in effect for Tropical Storm Humberto as of 11:00 PM Friday 13th September 2019. Credit: National Hurricane Center
Watches and Warnings in effect for Tropical Storm Humberto as of 11:00 PM Friday 13th September 2019. Credit: National Hurricane Center

A Tropical Storm Warning is in effect for the Northwestern Bahamas excluding Andros Island.

The government of the Bahamas has issued a Tropical Storm Warning for the following islands in the northwestern Bahamas the Abacos, Berry Islands, Bimini, Eleuthera, Grand Bahama Island, and New Providence.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch has been discontinued for Jupiter Inlet to Flagler-Volusia County line, Florida.

Interests elsewhere along the east coast of Florida should monitor the progress of this system.

Hazards Affecting Land

Wind: Tropical storm conditions are expected within the warning area in the northwestern Bahamas by early Saturday.

Rainfall: The tropical depression is expected to produce total rainfall accumulations through Sunday:

  • The Bahamas – 2 to 4 inches (50-100 mm), isolated maximum amounts 6 inches (150 mm).
  • The U.S. Atlantic Coast from central Florida into South Carolina – 2 to 4 inches (50-100 mm).

    Street and flash flooding are likely.

Storm Surge: This system is not expected to produce significant storm surge in the northwestern Bahamas.

Seas: Swells generated by the depression are expected to increase and affect the coasts of Central Florida to South Carolina late this weekend and early next week. These swells could cause life-threatening surf and rip current conditions.

This tropical storm is of no threat to the Lesser Antilles, including Trinidad and Tobago.

Tropical Storm Humberto Discussion

Deep convection has been gradually increasing this evening, and it is currently most organized in a curved band to the east of the estimated center. In addition, data from the NOAA Hurricane Hunters indicate that the depression has strengthened. The maximum flight-level wind at 700 mb was 41 kt and reliable SFMR values were 35 kt. Based on that data, the initial intensity is increased to 35 kt, making the cyclone Tropical Storm Humberto. The data from the aircraft indicate that the cyclone is titled to the northeast with height, likely due to southwesterly wind shear.

Humberto has been moving erratically during the past 12 to 18 hours as the cyclone has been trying to organize, but my best guess at the initial motion is 320/5. During the next few days, a ridge to the north of the system over the eastern United States and the western Atlantic is expected to slide southeastward, with a weakness in the ridge developing due to a mid- to upper-level trough over the northeastern U.S. This change in the steering pattern should cause the depression to slow down and turn northward off the east coast of Florida in 36 to 48 hours. The models show the trough over the northeastern U.S. amplifying early next week, which should cause Humberto to turn northeastward and then eastward away from the U.S. The NHC track forecast has been nudged south and east of the previous one to be in better agreement with the latest consensus models. Since there is increasing confidence that the storm will remain well offshore of the coast of Florida, the Tropical Storm Watch for that area has been discontinued.

The storm is still feeling some effects of southwesterly shear and drier air, which is causing its lopsided appearance in satellite images and strong tilt in the aircraft data. The atmospheric conditions are expected to gradually become more conducive for strengthening while Humberto moves over the warm Gulf Stream waters. These environmental parameters support intensification, and the cyclone is expected to become a hurricane in 2 to 3 days. The NHC intensity forecast is largely an update of the previous one and in line with the HCCA and IVCN guidance.

Key Messages:

  1. Humberto will likely bring tropical-storm-force winds and heavy rainfall to portions of the northwestern Bahamas on Saturday. Significant storm surge is not expected in the northwest Bahamas from this system. Residents there should follow any advice given by local officials.
  2. Heavy rainfall and scattered flash flooding is possible this weekend in coastal sections of eastern Florida, Georgia, and South Carolina. The chance of heavy rainfall affecting coastal North Carolina early next week continues to diminish.

Discussion by National Hurricane Center’s Forecaster Cangialosi.

Facebook Comments