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

NEWS BRIEFS

• Ana is now a Category 1 hurricane. Hawaii County remains under a Tropical Storm Watch, and the rest of the state has been also been issued a Tropical Storm Watch, as well.
• Hurricane Ana is 230 miles south of Hilo, Hawaii. The storm is moving toward the west-northwest near 14 mph, 22 km/h. A slight turn to the northwest is expected today and Saturday. A decrease in forward speed is expected Saturday night and Sunday. On this forecast track, the center of Ana will pass about 115 miles southwest of the Big Island tonight and about 115 miles southwest of the rest of the main Hawaiian islands this weekend.
• Maximum sustained winds are near 75 mph with higher gusts. Some additional strengthening is expected today, followed by gradual weakening late Saturday and Sunday. Hurricane force winds extend outward up to 25 miles from the center, and tropical storm force winds extend outward up to 90 miles.

INSIGHTS

The 11 a.m. National Weather Service update is a reminder that Ana still bears watching. The Tropical Storm has become a Category 1 Hurricane and is expected to get stronger. The forecast track is following the right side of the dynamic and consensus model guidance envelope. That means the rest of the state has been issued a Tropical Storm Watch. The storm is still expected to turn northwest, and the National Weather Service says, “the timing and extent of the turn has significant implications as to the potential impacts felt on the main Hawaiian Islands this weekend.”

PRIMARY SOURCES

Persistent deep convection has been wrapping around the low level circulation center during the past several hours… While well-defined outflow continues in all but the western quadrant. All three fix agencies came in at 4.0/65 kt… And Ana has been upgraded to a hurricane. U.S. Air Force Reconnaissance Aircraft will be sampling Ana this afternoon… While the NOAA Gulfstream iv continues to probe the surrounding environment at this time.

The forecast track has been changed little since the previous package… Closely following the tvcn on the right side of the dynamic and consensus model guidance envelope. The guidance has changed little in the past couple of runs also… But only a slight shift to the right in the forecast track could mean significant differences in the potential impacts to the main Hawaiian Islands. As a result… A tropical storm watch has been issued for Maui County… Oahu… And Kauai County and remains posted for the Big Island of Hawaii.

The initial motion reflects the expected turn to the northwest and is set at 300/12 kt. Ana will turn on a northwesterly track later today as the deep anticyclone steering the system is nudged eastward and weakened by an upper level trough passing well to the north. Late Saturday and Sunday… A new deep layered anticyclone will build to the north of Ana and should push the system back on a west-northwest track. The timing and extent of the turn has significant implications as to the potential impacts felt on the main Hawaiian Islands this weekend… Hence the expansion of the Tropical Storm Watch to Maui County… Oahu… And Kauai County. By days 4 and 5… Ana is forecast to be near the Papahanaumokuakea Marine National Monument.

Some additional intensification is expected today. An upper levelridge lying to the north and west of Ana is producing minimal vertical wind shear and is maintaining a well defined outflow channel in all but the western quadrant. These conditions should change little today while ocean temperature remain conducive for intensification. As a result… Ana should strengthen slightly. The window for intensification will close on saturday as the upper level ridge moves south of the system and westerly winds aloft begin to impart vertical wind shear. Slow weakening is expected late Saturday through Monday… But Ana will remain a dangerous tropical storm. Some reintensification is called for on day 5 as upper level winds are expected to relax. The official forecast closely follows the lgem and ships.

It is important for to understand that the exact track that Ana takes will be critical to the weather and ocean impacts that the main Hawaiian Islands will have to endure. It is still too soon to try to nail down details… Particularly for the smaller islands.National Weather Service on Oct. 17 discussion at 11 a.m. HST