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Hurricane Iselle May Reach Hawaii Late This Week, Tropical Storm Watches Issued (FORECAST)

August 6, 2014

Hurricane Iselle became the third major hurricane of 2014 in the Eastern Pacific basin Sunday. As it now churns west into the Central Pacific, the state of Hawaii may be in its sights.

Iselle has begun to weaken and is now a Category 1 hurricane as of 5 a.m. PDT Wednesday (2 a.m. Hawaiian Standard Time). Iselle is roughly 745 miles east of Hilo, Hawaii. Steering currents are expected to continue to take Iselle on a west-northwest track over the next few days.

While Iselle is forecast to continue to weaken, thanks to a combination of wind shear, drier, more stable air and cooler sea-surface temperatures in its path, it could still reach the Hawaiian Islands as a strong tropical storm Thursday into Friday, bringing bands of heavy rain, flash flooding, and strong wind gusts. Swells from Iselle will begin to be felt, particularly on east-facing coastlines, on Wednesday, building as the system approaches.

Above are the latest forecast path and wind speeds from the Central Pacific Hurricane Center in Honolulu. Note that the path shows the range of possibilities for the center of Iselle; impacts can extend well outside the center. The average intensity forecast error is about 15 knots (17 mph) for the fifth day of the forecast track.

Tropical Storm/Hurricane Watches/Warnings

A tropical storm or hurricane watch is issued when those conditions are possible within the area. Watches are typically posted 48 hours in advance of the onset of tropical storm-force conditions, since preparing for the storm becomes difficult once tropical storm-force winds begin. A tropical storm or hurricane warning means those conditions are expected in the area. Warnings are typically issued 36 hours in advance of the onset of tropical storm-force winds. When a warning is issued, you should complete all storm preparations and, if directed by local officials, evacuate the area immediately.

Residents of and visitors to Hawaii should pay attention to the forecast this week and be prepared for the potential of a tropical storm or low-end hurricane. Scroll down for the latest forecast maps and satellite imagery.

After Iselle, Hawaii could eventually feel the effects of Julio.

(MORE: Double Trouble | Hawaii Hurricane History)

Iselle's History

Iselle bypassed tropical depression status and formed as a tropical storm in the eastern Pacific Ocean about 1075 miles southwest of the tip of Baja California on Thursday, July 31.

(MORE: Why Hurricanes Have Names)

Iselle gained strength as it moved west-northwest through open waters and became a hurricane on August 1. This made Iselle the fourth hurricane of the 2014 eastern Pacific hurricane season. On Saturday, August 2, Iselle's maximum sustained wind speeds increased to 110 mph, making it a Category 2 hurricane.

Iselle became a major hurricane on Sunday morning, August 3 when its maximum sustained winds reached an estimated 115 mph. It fell back to Category 2 status early Sunday evening, but then quickly reintensified to Category 3 status late Sunday night with estimated winds to 125 mph. Monday afternoon, August 4, Iselle peaked as a category 4 hurricane with estimated maximum winds of 140 mph.

Iselle began weakening thereafter, and crossed the 140-degree West longitude line on Tuesday, August 5. This took Iselle from the Eastern Pacific basin into the Central Pacific basin. Per established convention, the storm retains its original name even while crossing into another basin with its own list of tropical cyclone names.

By maximum wind speed, Iselle is the third-strongest tropical cyclone of 2014 in the Eastern Pacific basin, behind Amanda and Cristina. However, Iselle stands second only to Amanda in terms of its accumulated cyclone energy (ACE) index, which combines maximum wind speed with the duration of the storm to estimate the total wind energy generated during a cyclone's lifetime.

Here's the latest satellite imagery of Iselle.

Infrared Satellite

This infrared satellite image shows how cold (and therefore how high) the cloud tops are. Brighter orange and red shadings concentrated near the center of circulation signify a healthy tropical cyclone.

 

Visible Satellite

This visible satellite image shows the clouds as they would appear from outer space to the naked eye. As a result, the image will not show any clouds during nighttime hours in the depicted area.

 

MORE: Hurricanes From Space

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