CPHC: Ana Now Expected to Become Hurricane Friday

The latest update on Tropical Storm Ana was just released by the Central Pacific Hurricane Center. There is not much change in intensity or forecast track. Ana is getting closer and expected to intensify over the next 24 to 36 hours to hurricane status.

Summary of Alerts

HURRICANE WARNING – All Hawaiian Offshore Waters starting Friday morning

TROPICAL STORM WARNING – All Hawaiian Offshore Waters starting late Thursday

TROPICAL STORM WATCH – Currently in effect for Hawai’i County

FLASH FLOOD WATCH – For Hawai’i County starting Friday at noon until Sunday at 6pm

Current Situation (5 a.m. Update)

Tropical Storm with 60 mph maximum sustained winds, gusts up to 70 mph

Tropical storm force winds extend 60 miles from the center

Moving West at 10 mph

Tropical Storm Ana was last located near 14.1 N and 150.3 W, about 495 milessoutheast of Hilo; 540 miles southeast of Kailua-Kona, 490 miles southeast of South Point, 620 miles southeast of Kahului, Maui; 665 miles southeast of Kaunakakai, Molokaʻi; 635 miles southeast of Lānaʻi City; and 705 miles southeast of Honolulu, Oʻahu.

Ana was looking ragged last night but the outflow pattern is improving, which tells us that shear is not affecting the storm right now as much as it was yesterday. Satellite imagery is showing a storm that’s pretty torn up but a burst of deep convection is present near the center of the storm this morning.

The Central Pacific Hurricane Center is indicating that the intensity forecast is quite tricky with this storm. Sea surface temperatures are more than sufficient to fuel Ana and vertical wind shear is expected to decrease so further intensification is the likely result of that. However, some models are still indicating that Ana will not become a hurricane. The current intensity forecast takes all models into account. Gradual intensification is expected over the next 24 to 36 hours.

The Central Pacific Hurricane Center’s satellite image and forecast track. CPHC image.

Forecast & Uncertainty

The current track has not changed much with Ana passing 75 miles south and west of the island of Hawai’i Friday night and Saturday, passing Maui County Saturday into Sunday and nearing Oahu and Kauai over the weekend and into Monday.

The probability of tropical storm conditions over Big Island leeward and southeast coastal waters is 71 percent; 36 percent in Hilo; 51 percent in Kailua-Kona and 62 percent near South Point.

Remember, these systems are notoriously difficult to predict and the center of the storm has a 66% chance of landing anywhere within the cone of uncertainty. The margin of error going out 48 hours is still a whopping 80 miles. Even small shifts in the track can mean major differences in where the worst conditions will occur. Damaging effects can extend far from the center so it’s important that residents prepare just in case.

Potential Impacts (if the track holds)

Heavy rain may reach the Big Island late Friday, potentially causing dangerous flash flooding with excessive runoff causing possible mud slides and rock slides.

Large dangerous surf conditions are expected to begin impacting the eastern end of the Hawaiian islands late Thursday.

Big Island residents could possibly expect 10 to 15 inches  of rain with, locally, up to 20 inches along southeast facing slopes beginning Friday afternoon.

Winds of 25 to 40 mph, gusting to 60 mph, are possible Friday and Saturday.

Seas of 20 to 30 feet are expected late Friday along the Puna & Kau coastlines during the closest approach, peaking Friday night.