MAHALO MAHALO MAUNA KEA…She does her magic again and keeps Darby mostly away from The Big Island and prevents major damage. Read the highlighted text below relating to the National Weather Service’s short description of Darby’s deterioration.
DARBY MOVING NORTHWESTWARD TOWARD OAHU AND KAUAI... SUMMARY OF 500 AM HST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...19.8N 157.3W ABOUT 110 MI...180 KM SSE OF HONOLULU HAWAII ABOUT 205 MI...330 KM SE OF LIHUE HAWAII MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 9 MPH...15 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Watch has been issued for portions of the Papahanaumokuakea Marine National Monument...from Nihoa Island to French Frigate Shoals. The Tropical Storm Watch has been cancelled for the Big Island of Hawaii. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * All islands in the state of Hawaii, except the Big Island. A Tropical Storm Watch is in effect for... * Papahanaumokuakea Marine National Monument...from Nihoa Island to French Frigate Shoals. A Tropical Storm Warning means that tropical storm conditions are imminent or already occurring. In this case, Tropical Storm conditions are expected over Maui County and Oahu today through tonight, and over Kauai late tonight and Monday. A Tropical Storm Watch means that Tropical Storm conditions are possible within the watch area...generally within 36 to 48 hours. For storm information specific to your area, please monitor products issued by the National Weather Service office in Honolulu Hawaii. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ At 500 AM HST (1500 UTC), the center of Tropical Storm Darby was located near latitude 19.8 North, longitude 157.3 West. Darby is moving toward the west-northwest near 9 mph (15 km/h) and this general motion is expected to continue over the next 48 hours. Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Little change in strength is forecast through Monday, with slow weakening Monday night. Tropical-storm-force winds extend outward up to 80 miles (130 km) from the center. The estimated minimum central pressure is 1004 mb (29.65 inches).
1100 PM HST SAT JUL 23 2016 Darby was difficult to find this evening after it emerged from the Big Island. A 0732z ASCAT pass seems to confirm the current position estimate. However, the system is likely continuing to organize after its encounter with volcanic peaks of nearly 14 thousand feet, earlier today. This terrain severely disrupted the low level center, which appears to have emerged slightly south of its previous forecast track. This is often the case with tropical cyclones that encounter major land areas, especially when mountainous terrain is present. In addition, the amount of time the center was over land removed it from its primary energy source, which is the Pacific Ocean. Since the center is again over water, all of the satellite fix agencies estimated the current intensity to be 2.5/35 kt, while the CIMSS ADT estimates was 2.3/33 kt. We are maintaining Darby as a 35 kt tropical storm for this advisory. The initial motion is estimated to be 290/09 kt, with the poorly-defined center of Darby currently located just west of the Big Island coast. The system is expected to eventually turn toward the northwest, with Darby moving generally northwest through the remainder of the forecast period. There remains some spread in the track guidance, but the models continue to suggest this northwest motion is likely to continue. The models appear to be influenced by a forecast weakness developing in the mid-level ridge to its north over the next 18 to 24 hours, due to a deep-layer low that remains nearly stationary far north of the Hawaiian Islands. The updated track forecast is close to the previous and closely follows the latest multi-model consensus TVCN and the latest GFEX. The intensity forecast is maintaining Darby as a minimal tropical storm through 36 hours. The warm water temperatures and ample ocean heat content depicted in the most recent CIRA analysis south of the main Hawaiian Islands are likely sufficient to maintain a tropical storm. The latest SHIPS guidance appears to indicate Darby may not weaken as fast as it had in the previous run. However, within 48 hours, all of the guidance indicates steady weakening will occur, as increasing vertical wind shear and gradually cooling waters lie along the forecast track. The latest forecast again indicates weakening to a remnant low in 72 hours, with dissipation expected by the end of the forecast period. Of note, a recent 0836z observation from the Oahu Forest NWR RAWS site in the Koolau mountain range indicated sustained winds of 29 mph with gusts to 60 mph. Note that another flight by the 53rd Weather Reconnaissance Squadron is scheduled to fly into Darby after dawn Sunday morning to determine what the intensity of Darby is after its circulation spends several more hours over the warm ocean waters west of the Big Island. FORECAST POSITIONS AND MAX WINDS INIT 24/0900Z 19.5N 156.8W 35 KT 40 MPH 12H 24/1800Z 20.2N 157.8W 35 KT 40 MPH 24H 25/0600Z 21.4N 159.1W 35 KT 40 MPH 36H 25/1800Z 22.7N 160.6W 35 KT 40 MPH 48H 26/0600Z 24.1N 162.1W 30 KT 35 MPH 72H 27/0600Z 27.3N 165.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 28/0600Z 30.0N 169.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 29/0600Z...DISSIPATED