| Watches dropped in Florida. Track: https://www.nhc.noaa.gov/refresh/graphics_at4+shtml/?cone#contents Tropical Storm Humberto Discussion Number 6...Corrected NWS National Hurricane Center Miami FL AL092019 1100 PM EDT Fri Sep 13 2019 Corrected to change depression to storm in the second paragraph 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 storm 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. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 25.6N 75.2W 35 KT 40 MPH 12H 14/1200Z 26.5N 76.5W 35 KT 40 MPH 24H 15/0000Z 27.6N 77.6W 40 KT 45 MPH 36H 15/1200Z 28.8N 78.2W 50 KT 60 MPH 48H 16/0000Z 29.8N 78.1W 60 KT 70 MPH 72H 17/0000Z 31.0N 75.5W 70 KT 80 MPH 96H 18/0000Z 31.3N 72.0W 75 KT 85 MPH 120H 19/0000Z 32.3N 67.2W 75 KT 85 MPH $$ Forecaster Cangialosi Tropical Storm Humberto Advisory Number 6 NWS National Hurricane Center Miami FL AL092019 1100 PM EDT Fri Sep 13 2019 ...DEPRESSION STRENGTHENS TO TROPICAL STORM HUMBERTO... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...25.6N 75.2W ABOUT 130 MI...210 KM ESE OF GREAT ABACO ISLAND ABOUT 225 MI...365 KM ESE OF FREEPORT GRAND BAHAMA ISLAND MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...NW OR 320 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The Tropical Storm Watch on the east coast of Florida has been discontinued. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... Northwestern Bahamas excluding Andros Island A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours. Interests along the east coast of Florida should monitor the progress of this system. 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. DISCUSSION AND OUTLOOK ---------------------- At 1100 PM EDT (0300 UTC), the center of Tropical Storm Humberto was located near latitude 25.6 North, longitude 75.2 West. Humberto is moving toward the northwest near 6 mph (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 40 mph (65 km/h) with higher gusts. 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 90 miles (150 km) from the center. The estimated minimum central pressure based on data from the NOAA Hurricane Hunters is 1008 mb (29.77 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are expected within the warning area in the northwestern Bahamas by early Saturday. RAINFALL: The depression is expected to produce these total rainfall accumulations through Sunday: The Bahamas...2 to 4 inches, isolated maximum amounts 6 inches. The U.S. Atlantic Coast from central Florida into South Carolina...2 to 4 inches. STORM SURGE: This system is not expected to product significant storm surge in the northwestern Bahamas. SURF: Swells generated by the depression are expected to increase and effect 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. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 200 AM EDT. Next complete advisory at 500 AM EDT. $$ Forecaster Cangialosi |