Tropical Storm Watches Issued For Parts Of Hawaii As Guillermo Spins in Central Pacific

August 4,2015

Highlights:

• Former Hurricane Guillermo was downgraded to a tropical storm Monday morning.
• As of 5 p.m. Hawaii Standard Time, Guillermo was located about 350 miles east of Hilo, Hawaii.
• A tropical storm watch continues for the islands of Hawaii, Maui, Molokai, Lanai and Kahoolawe
• Guillermo's intensity is holding steady now, but over the next couple of days as Guillermo encounters unfavorable upper-level winds and dry air, weakening is forecast.
• Guillermo's center should pass well to the north of Hawaii later Wednesday into Thursday as a weakening tropical storm.
• However, some peripheral impacts such as locally heavy rain, high surf and some tropical storm-force gusts are possible.

(MORE: Expert Analysis | Hurricane Central)

Storm Information

Watches and Warnings

Projected Path

Model Forecast Wave Heights

Probability of Tropical Storm-Force Winds

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hawaiian Worry?

At this time, the trend in the computer forecast models continues to track Guillermo's center of circulation north of the Hawaiian Islands. Guillermo will also weaken as it approaches Hawaii due to increasing wind shear and dry air.
Monday evening, tropical storm watches were posted for Hawaii and Maui counties, which means tropical storm conditions are possible within 48 hours.
Given the size of Guillermo's tropical storm-force wind field, and lingering uncertainty in the exact track of the center, some tropical storm-force winds -- primarily in gusts -- are still possible in parts of the Hawaiian Islands.
Interests in Hawaii should still continue to monitor the progress of this system. Here is an early look at what impacts we could see depending on the track and strength of Guillermo as it moves near Hawaii:
- LIKELY: High surf and rip currents seems like a good bet no matter what path Guillermo takes. The National Weather Service has issued a high surf advisory for the east facing shores of Hawaii through Tuesday evening. Also, Guillermo's circulation will likely disrupt trade winds by Tuesday.
- POSSIBLE: Enhanced rainfall chances, including locally heavy amounts in some mauka -- mountain -- locations and some tropical storm-force gusts are possible Wednesday and Thursday depending on the exact path and strength of Guillermo. A flash flood watch has also been issued for the Big Island and Maui as rainfall totals of 1 to 3 inches are possible with isolated amounts up to 7 inches in the higher terrain. Rock and mudslides are also possible with the heavy rainfall.
(FORECASTS: Honolulu | Hilo | Kona Coast | Maui)
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.
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.
Hurricane specialist Michael Lowry says 17 tropical cyclones of at least tropical storm intensity have tracked within 100 nautical miles of Hawaii dating to 1950. Three of those -- Tropical Storm Flossie (2013), Tropical Storm Iselle (2014) and Hurricane Ana (2014) -- have done so since 2013.
Guillermo may not be the season's last 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.
MORE: Amazing Hurricane Images (PHOTOS)