(ABOVE IMAGE) A National Weather Service image shows the latest 5 day track for Tropical Storm Ana.

NEWS BRIEFS

• Hawaii County remains under a Tropical Storm Watch
• Tropical Storm Ana is 410 miles south southeast of Hilo, Hawaii. The storm is moving west northwest at 12 miles per hour, a direction that is expected to continue tonight with a turn to the northwest on Friday and Saturday.
• Maximum sustained winds are near 60 miles per hour, with higher gusts. Some strengthening is expected during the next 24 hours, with Ana possibly becoming a hurricane on Friday. Weakening is expected Friday night and Saturday.
• Civil Defense reports surf of 5 to 10 feet is already occurring at Pohoiki. The surf is expected to peak Friday night for the Big Island. Surf heights up to 20 feet are possible Friday night during the closest approach of Ana to the Big Island. Elevated surf up to 20 feet is possible along the Kona coasts late Friday into Saturday.

PRIMARY SOURCES

A persistent band of deep convection has been observed along the eastern edge of the low level circulation center through much of the day… And the low level circulation has become better defined. Dvorak current intensity estimates from all agencies came in at 3.0/45 kt… And given the latest satellite trend… The intensity will be held at 50 kt. U.S. Air Force Reserve Hurricane Hunters will be sampling Ana after midnight… Providing crucial data.

The long anticipated turn toward the west-northwest appears to have begun. A 2224z trmm pass helped to locate a better defined low level circulation center… And the higher temporal resolution of goes rapid scan has helped to determined the shift in forward motion… Which is set at 295/10 kt. A gradual turn toward the northwest is expected on Friday as the deep layer anticyclone centered to the northeast of Ana is nudged eastward. This anticyclone has held stronger than was previously thought… And the dynamic guidance has been shifting slowly to the left during each forecast cycle in the past 24 hours. The forecast track has also been steadily shifting to the left… Though it still remains on the right side of the dynamic and consensus guidance envelope. Even with the shift in the track… The Big Island of Hawaii is still under a tropical storm watch… And only a slight change in the track could lead to tropical storm warnings being posted for that island. The NOAA Gulfstream iv has been sampling the environment… Including the ridge… And the aircraft/s efforts have been greatly appreciated. A ridge building north of the state on Sunday is expected to cause Ana to turn toward the west-northwest… With the timing and extent of the turn having significant implications as to the potential impacts felt on the rest of the main Hawaiian Islands this weekend. By day 5… Ana is forecast to be entering the Papahanaumokuakea Marine National Monument.

Slow intensification is expected through Friday… As vertical wind shear has decreased to less than 10 kt according to cimss and ocean temperatures remain conducive. In addition… The outflow in all but the western quadrant has shown signs of improvement today. That said… All of the intensity guidance holds ana as a strong tropical storm in the next couple of days… But given the conducive environment… The forecast still calls for the system to briefly strengthen to a hurricane late Friday. The window for strengthening is expected to close late Friday night and Saturday as the upper ridge to the north of Ana gives way to an upper level trough that is forecast to impart vertical wind shear. The official forecast follows ships during this weakening phase.

It is important for people in the main Hawaiian Islands not to focus too closely on the exact forecast track of Ana. With an average 48 hour track error of approximately 80 miles… It is still too soon to say with much certainty which islands have the greatest chance of experiencing direct impacts from Ana. It is also important to keep in mind that significant impacts from tropical cyclones can extend well away from the center.
National Weather Service discussion on Oct. 16 at 5 p.m. HST