Tropical Depression Ela, First Named Storm of Central Pacific Hurricane Season to Track North of Hawaii

Jon Erdman
Published: July 9,2015

Highlights

• Ela has been downgraded to a tropical depression as of late Thursday afternoon (Hawaiian Standard Time).
• Ela was briefly a tropical storm from late Wednesday night into Thursday afternoon (Hawaiian Standard Time).
• This system is expected to pass north of Hawaii this weekend with minimal impacts.

(MORE: Hurricane Season Outlook | Hurricane Central | Tropical Update)

Latest Status

Projected Path

Shower and thunderstorm activity has had difficulty persisting near the surface circulation due to southwesterly wind shear, displacing it from the center of circulation. This wind shear will only increase as the system moves northwestward, which means additional weakening is likely.
A U.S. Air Force Reserve Hurricane Hunter mission late Wednesday night sampled sufficiently strong winds in the northeast side of the circulation to merit upgrading to the 2015 Central Pacific hurricane season's first named storm, Tropical Storm Ela. The storm was then downgraded to a tropical depression late Thursday afternoon.
Interestingly, Ela began as Tropical Depression Four-E – a designation pertaining to the Eastern Pacific tropical cyclone basin – because the National Hurricane Center determined that it became a tropical cyclone just east of the 140-degree West longitude benchmark. By the time NHC issued its first advisory, though, the depression had already drifted over that invisible line into the Central Pacific basin, which is where it became a tropical storm and therefore took its name from the Central Pacific naming list and not the Eastern Pacific list. According to hurricane specialist Michael Lowry, this has happened three other times since 1949, including Lala in 1984, Iniki in 1992 and Lana in 2009.
(The Eastern Pacific name would have been Dolores; that name remains available for the next tropical storm that forms between 140 degrees West longitude and the Pacific coast of North America.)
If it wasn't for Ekeka on Jan. 28, 1992 and Hali on Mar. 29, 1992, Ela would've been the earliest in the calendar forming central Pacific tropical storm on record, according to hurricane specialist Michael Lowry.

Enhanced Satellite

Hawaiian Concern?

Virtually every system approaching Hawaii from the east since 1950 tracking at least as far north as the latitude of the Big Island of Hawaii eventually weakened to a tropical storm or depression by the time it reached the islands.
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.
This system will not be another Iselle.
First, an extension of upper-level low pressure currently swirling off the California coast will carve southwestward over the next several days, eventually taking it over Hawaii.
The winds aloft from this so-called "tropical upper-tropospheric trough," or TUTT, should have two impacts on the tropical system as it approaches:
1) Hostile wind shear – changing wind direction and speed with height – which tends to displace thunderstorms from the core of a tropical cyclone, limiting its strengthening potential.
2) Steering winds that would deflect the tropical system to the north of the Hawaiian Islands.

Late-Week Steering Scenario

In fact, it's possible this wind shear could ultimately degrade the system so much it could be downgraded to a remnant low anytime over the next few days, after which the remnant would bend to a more westerly direction, steered by lower-level winds.
Interests in Hawaii should still continue to monitor the progress of this system, however.
At this time, here are the main impacts in the Hawaiian Islands this weekend from this system:

• Elevated surf, particularly on the north shore of the islands
• Locally heavy rainfall from bands of rain and thundershowers on the south side of the circulation are possible, not just in typical windward and mauka locations, but also in typically leeward locations.
• Lighter trade winds (Note the strongest winds with the system should remain north of the islands)

(FORECASTS: Honolulu | Hilo | Kona Coast | Maui)
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.
This disturbance may not be the season's last to gain Hawaii's attention.
NOAA's 2015 central Pacific hurricane season outlook cited El Niño'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.
Colorado State University tropical scientist Phil Klotzbach found tropical cyclones are about three times more likely to impact Hawaii in El Niño years vs. La Nina years.
MORE: Hurricanes By the Numbers (PHOTOS)