379 WTNT33 KNHC 080850 TCPAT3 BULLETIN Tropical Storm Helene Advisory Number 4 NWS National Hurricane Center Miami FL AL082018 500 AM AST Sat Sep 08 2018 ...HELENE FORECAST TO BECOME A HURRICANE ON SUNDAY... ...TROPICAL STORM CONDITIONS EXPECTED TO REACH PORTIONS OF THE CABO VERDE ISLANDS TONIGHT... SUMMARY OF 500 AM AST...0900 UTC...INFORMATION ---------------------------------------------- LOCATION...13.7N 19.6W ABOUT 330 MI...530 KM ESE OF THE SOUTHERNMOST CABO VERDE ISLANDS MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...W OR 275 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Santiago, Fogo, and Brava A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area in this case within the next 24 to 36 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 AM AST (0900 UTC), the center of Tropical Storm Helene was located near latitude 13.7 North, longitude 19.6 West. Helene is moving toward the west near 13 mph (20 km/h). This general motion will likely continue through the weekend. A gradual turn toward the west-northwest with an increase in forward speed is expected early next week. On the forecast track, Helene will pass very close to the southern Cabo Verde Islands tonight and early Sunday. Maximum sustained winds have increased to near 45 mph (75 km/h) with higher gusts. Additional strengthening is forecast for the next couple of days and Helene is expected to become a hurricane on Sunday. Tropical-storm-force winds extend outward up to 80 miles (130 km) from the center. The estimated minimum central pressure is 1001 mb (29.56 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are expected to first reach the warning area tonight or early Sunday. Hurricane conditions are possible in the southernmost Cabo Verde Islands on Sunday. RAINFALL: Helene is expected to produce total rain accumulations of 3 to 5 inches over the southern Cabo Verde Islands through Sunday, with isolated maximum amounts of 8 inches. This rainfall may produce life-threatening flash floods. NEXT ADVISORY ------------- Next intermediate advisory at 800 AM AST. Next complete advisory at 1100 AM AST. $$ Forecaster Zelinsky