Highlights:
- Hurricane Hilda has weakened from this weekend and has maximum sustained winds of 90 mph as of Monday evening, Hawaii time. This makes Hilda a Category 1 hurricane on the Saffir-Simpson Hurricane Wind Scale.
- The center of Hilda is about 365 miles southeast of Hilo, Hawaii, and is moving to the northwest.
- Hilda is expected to weaken due to increasing wind shear as it moves over open water the next few days.
- It remains too soon to tell what, if any, impacts Hilda will bring to Hawaii sometime late this week. The latest thinking suggests a weakened Hilda may move near or either side of the Big Island Thursday into Friday. See below for more information on what impacts are likely or possible in Hawaii.
- Hilda reached its maximum intensity as a Category 4 hurricane with top sustained winds of 140 mph late Saturday.
Hawaiian Concern?
Latest Information and Infrared Satellite
Hilda may still be a hurricane now, but by late this week, it appears it will limp toward Hawaii's Big Island in a much weaker state, either as a tropical depression or a weak tropical storm.
Already a rather small tropical cyclone, Hilda will feel intensifying shearing winds aloft from a strong subtropical jet stream blanketing the Hawaiian Islands and areas to the east of the island chain. Shearing winds push a tropical cyclone's thunderstorms away from its center, weakening it, as we saw with Guillermo last week. Another factor in the expected weakening of Hilda is its slow motion could result in upwelling of colder sub-surface water.
The latest thinking is this wind shear will leave an increasingly shallow circulation of Hilda to migrate west-northwest toward the islands.
For now, here are what impacts we're expecting, based on the current forecast:
LIKELY: High surf will continue on east-facing shores of the Big Island and Maui, reaching a peak by early Tuesday, but persisting into Wednesday, according to the National Weather Service. Waves of up to 8-12 feet and dangerous rip currents are expected.
POSSIBLE: Depending on the exact path and strength of Hilda, the Big Island could see heavy rain possibly starting as early as Tuesday. Gusty winds are possible too. Again, all of this is dependent on Hilda's future path and the chance of impacts are increasing.
Despite this weakening trend, all interests in the Hawaiian Islands should continue to monitor the progress of Hilda. Tropical storm watches may be posted in the next day or so.
Projected Path
(FORECASTS: Honolulu | Hilo | Kona Coast | Maui)
We discussed the reasoning behind this in a piece written in August 2014.
Last August, Iselle became only the second tropical storm to landfall on the Big Island dating to 1950, after strengthening to a Category 4 hurricane.
Incidentally, hurricanes Julio and Ana also passed near the Hawaiian Islands in 2014. Ana was one of only four hurricanes since 1950 to pass within 150 nautical miles of Honolulu, dumping locally heavy rain and generating high surf.
Dating
to 1950, the probability of a named storm tracking within 100 miles of
Hawaii is greatest in El Nino years, less in La Nina years.This may not be the season's last named storm to gain Hawaii's attention.
NOAA's 2015 central Pacific hurricane season outlook cited El Nino's tendency for reduced wind shear and more storm tracks coming from the eastern Pacific as reasons to expect an active season in the central Pacific Basin.
Lowry says dating to 1950, there is a 13 percent increase in the chance of a named storm to track within 100 miles of the Hawaii islands during an El Nino year than a neutral year.
MORE: Hurricanes By the Numbers (PHOTOS)
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