| While the current forecast is for Olivia to weaken some as it approaches the Hawaiian Islands, at the moment it is strengthening. It needs to be watched. Track from Central Pacific Hurricane Center: http://www.prh.noaa.gov/cphc/tcpages/?storm=Olivia Floater: http://www.ssd.noaa.gov/PS/TROP/floaters/17E/17E_floater.html Central Pacific Imagery (showing Hawaii): http://www.ssd.noaa.gov/imagery/cpac.html Some tropical storm watches are already in effect and tropical storm warnings may be required sometime today (Monday). Hurricane Olivia Discussion Number 39 NWS Central Pacific Hurricane Center Honolulu HI EP172018 1100 PM HST Sun Sep 09 2018 Olivia's small eye surrounded by cold cloud tops is evident in infrared satellite imagery this evening. The U.S. Air Force Reserves 53rd Weather Reconnaissance Squadron aircraft just completed a mission sampling the inner core and outer winds of Olivia. They found the pressure was lower and the surface winds stronger than their previous mission Sunday morning. Their SFMR, flight-level and dropsonde measurements suggested the maximum winds are near 75 kt. In addition, the satellite fix agencies (JTWC, SAB, and PHFO) provided unanimous subjective Dvorak current intensity estimates of 4.5/77 kt. Based on all of this information, we are increasing the initial intensity to 75 kt for this advisory. Olivia continues to move due west, but has slowed slightly, so the current motion is 270/8 kt. This motion is being induced by a deep layer ridge to the north and northwest of the tropical cyclone. In 12 to 24 hours, the ridge is expected to strengthen and build southward ahead of Olivia, forcing the tropical cyclone to shift toward a west-southwest track. This motion is expected to continue through day 4. The track guidance appears to be more tightly clustered through 48 hours now, but the spread increases from days 3 through 5. The current forecast track is very close to the previous, except it is slightly slower during the first 72 hours. This closely follows the latest TVCE, FSSE, GFEX and HCCA guidance. Again, since there remains some spread in the track guidance, this emphasizes the uncertainty in our track forecast. It is important to not focus on the exact forecast track of Olivia's center across the islands. Vertical wind shear remains relatively weak in the vicinity of Olivia. Water temperatures, as well as ocean heat content values, are expected to increase along the forecast track. Therefore, Olivia will likely remain a hurricane through 36 hours. After that, increasing vertical wind shear is forecast to take its toll on Olivia, so that it may be a strong tropical storm within 48 hours. Additional slow weakening is expected to persist during days 3 through 5. The latest forecast is close to the IVCN and CTCI. Note that based on the latest track and intensity along with the wind speed probabilities, Tropical Storm Warnings will likely be required for portions of the Hawaiian Islands on Monday. KEY MESSAGES: 1. It is important to not focus on the exact forecast track and intensity when planning for Olivia. Persons on all of the main Hawaiian Islands should continue preparing for the likelihood of direct impacts from this system Monday and early Tuesday. Those impacts could include intense flooding rainfall, damaging winds, large and dangerous surf, and storm surge. 2. Regardless of the exact track and intensity that Olivia takes as it approaches the islands, significant effects often extend far from the center. In particular, the mountainous terrain of Hawaii can produce localized areas of strongly enhanced winds and rainfall, even well away from the tropical cyclone center. FORECAST POSITIONS AND MAX WINDS INIT 10/0900Z 21.7N 146.9W 75 KT 85 MPH 12H 10/1800Z 21.6N 148.3W 75 KT 85 MPH 24H 11/0600Z 21.5N 150.2W 75 KT 85 MPH 36H 11/1800Z 21.2N 152.2W 70 KT 80 MPH 48H 12/0600Z 20.8N 154.5W 60 KT 70 MPH 72H 13/0600Z 19.9N 159.3W 45 KT 50 MPH 96H 14/0600Z 19.5N 164.5W 40 KT 45 MPH 120H 15/0600Z 20.5N 169.5W 35 KT 40 MPH $$ Forecaster Houston Hurricane Olivia Advisory Number 39 NWS Central Pacific Hurricane Center Honolulu HI EP172018 1100 PM HST Sun Sep 09 2018 ...HURRICANE OLIVIA INTENSIFIES AS IT TRACKS TOWARD HAWAII... SUMMARY OF 1100 PM HST...0900 UTC...INFORMATION ----------------------------------------------- LOCATION...21.7N 146.9W ABOUT 545 MI...880 KM ENE OF HILO HAWAII ABOUT 705 MI...1140 KM E OF HONOLULU HAWAII MAXIMUM SUSTAINED WINDS...85 MPH...140 KM/H PRESENT MOVEMENT...W OR 270 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...980 MB...28.94 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Watch is in effect for... Oahu Maui County...including the islands of Maui, Molokai, Lanai, and Kahoolawe Hawaii County A Tropical Storm Watch means that tropical storm conditions are possible in the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Warning may be required for some areas that are in the watch area on Monday. Interests on Kauai and Niihau should closely monitor the progress of Olivia. For storm information specific to your area, please monitor products issued by the National Weather Service office in Honolulu Hawaii. DISCUSSION AND OUTLOOK ---------------------- At 1100 PM HST (0900 UTC), the center of Hurricane Olivia was located near latitude 21.7 North, longitude 146.9 West. Olivia is moving toward the west near 9 mph (15 km/h). This general motion is expected to continue through early Monday, followed by a turn toward the west-southwest starting late Monday. This west-southwest motion is expected to continue through Tuesday evening. On this forecast track, tropical storm conditions are possible over some parts of Hawaii starting Tuesday. Maximum sustained winds measured by Hurricane Hunter aircraft are near 85 mph (140 km/h) with higher gusts. Little change in strength is forecast through late Monday, with gradual weakening possible starting some time on Tuesday. Hurricane-force winds extend outward up to 30 miles (45 km) from the center and tropical-storm-force winds extend outward up to 120 miles (195 km). The estimated minimum central pressure is 980 mb (28.94 inches). HAZARDS AFFECTING LAND ---------------------- WIND: Tropical storm conditions are possible within the watch area starting Tuesday. RAINFALL: Olivia is expected to produce total rainfall accumulations of 10 to 15 inches. Isolated maximum amounts of 20 inches are possible, especially over windward sides of Maui and the Big Island. This rainfall may produce life-threatening flash flooding. SURF: Large swells generated by Olivia are expected to continue to increase across the main Hawaiian Islands. Surf will build as Olivia approaches, and may become damaging along some exposed east facing shorelines starting Tuesday or Wednesday. NEXT ADVISORY ------------- Next intermediate advisory at 200 AM HST. Next complete advisory at 500 AM HST. $$ Forecaster Houston |