Tropical Depression Four-E: A Tropical Storm Threat For Hawaii?

Jon Erdman
Published: July 7,2015

 

Highlights

• Tropical Depression Four-E formed Tuesday night and is currently located about 1,025 miles east-southeast of Hawaii.
• Tropical Depression Two-E may strengthen into a Tropical Storm Ela on Wednesday.
• This system is expected to move to the west-northwest over the next few days and pass north of Hawaii late this week.

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

Latest Status and Infrared Satellite

Projected Path

The Western Pacific Basin has roared back to life, with three tropical cyclones, one of which is headed for landfall late this week.
Now, Hawaii needs to pay attention.
If this system becomes a tropical storm – maximum sustained winds at least 39 mph – its name will be the next central Pacific name, Ela as it will form west of 140 degrees west longitude.
The Air Force Reserve hurricane hunters are schedule to investigate the system Wednesday.

Enhanced Satellite

Hawaiian Worry?

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.
Are we looking at another Iselle this time? In short, it doesn't appear so at this time.
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, assuming it becomes deep enough a circulation, to the north of the Hawaiian Islands.

Late-Week Steering Scenario

But it's still early and this forecast could change.
Furthermore, as noted by Eric Blake, hurricane specialist with the National Hurricane Centerm sea-surface temperatures near Hawaii have set records in June.
All other factors being equal, a warmer sea-surface adds instability to the lower levels of the atmosphere, making a more ripe environment for thunderstorms helping to organize, intensify and sustain a tropical cyclone.
Interests in Hawaii should continue to monitor the progress of this system this week.
(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.1
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.
MORE: Hurricanes By the Numbers (PHOTOS)