Hurricane Norman forecast for gradual weakening as it moves west

Central Pacific Infrared Images

Hurricane Norman

At 11 a.m. HST (2100 UTC), the center of Hurricane Norman was located near latitude 19.5 North, longitude 138.4 West. Norman is moving toward the west near 20 mph (31 km/h). A westward motion with some decrease in forward speed is expected over the next couple of days. A turn toward the west-northwest is anticipated on Thursday.

Maximum sustained winds are near 105 mph (165 km/h) with higher gusts. Some gradual weakening is forecast during the next few days, but Norman is forecast to remain a hurricane through mid-week.

Hurricane-force winds extend outward up to 35 miles (55 km) from the center and tropical-storm-force winds extend outward up to 105 miles (165 km).

The estimated minimum central pressure is 971 mb (28.68 inches).

Visible satellite images continues to depict a fairly symmetric hurricane with a ragged eye, however, a 1615 UTC SSMIS microwave overpass indicated that the eye was open over the southeastern portion of the circulation. Dvorak data T-numbers are slowly decreasing, and a consensus of the various objective and subjective Dvorak CI-numbers support lowering the initial intensity to 90 kt. Norman is forecast to move over marginally warm sea surface temperatures (SSTs) and into a drier mid-level environment during the next couple of days. Since the shear is expected to remain fairly low over the hurricane, weakening is anticipated to be gradual through mid-week. After that time, a significant increase in southwesterly vertical wind shear should cause a more rapid rate of filling. The new forecast is similar to the previous advisory and is a blend of the HFIP corrected consensus model and the IVCN intensity consensus aid.

Norman is moving quickly westward or 280/17 kt. The hurricane is being steered by a large subtropical ridge to the north and it should keep Norman on a westward heading with some decrease in forward speed over the next couple of days. A weakness in the ridge near 150W should cause Norman to turn west-northwestward, then northwestward after 72 hours. There is still considerable spread in the model guidance as to exactly when and where the turn will take place. The NHC track forecast is again close to the consensus models at the longer range, but the overall guidance envelope changed little, so the updated NHC track forecast is similar to the previous track forecast.

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Actions to take whenever a tropical storm or hurricane nears Hawaii

All of Hawaii’s citizens should know what to do during a hurricane, tropical storm watches and warnings. Watches and warnings are prepared for the Hawaiian Islands by the National Weather Service Central Pacific Hurricane Center in Honolulu. When watches and warnings are issued, people should closely monitor the Internet, radio, TV, or NOAA Weather Radio for official bulletins of the storm’s progress and instructions from civil defense authorities. Jim Weyman, director of the Central Pacific Hurricane Center, said, “Although you and your family may have never experienced a hurricane, don’t be complacent! It’s not a matter of if a hurricane will occur, but when one will occur. All of the Hawaiian Islands are at risk for a hurricane and we should all know what actions to take.”

For the Central Pacific Ocean a Hurricane/Tropical Storm Watch means hurricane/tropical storm conditions are possible in the specified area of the Watch, usually within 48 hours.

When a Hurricane or Tropical Storm Watch is issued:

For the Central Pacific Ocean a Hurricane/Tropical Storm Warning means hurricane/tropical storm conditions are expected in the specified area of the Warning, usually within 36 hours.

When a Hurricane or Tropical Storm Warning is issued:

The Central Pacific Hurricane Center (CPHC) issues tropical cyclone warnings, watches, advisories, discussions, and statements for all tropical cyclones in the Central Pacific from 140 Degrees West Longitude to the International Dateline. The season officially begins on June 1 and ends on November 30. However, tropical cyclones can occur at any time. The National Weather Service Forecast Office in Honolulu activates the CPHC when: (1) a tropical cyclone moves into the Central Pacific from the Eastern Pacific, (2) a tropical cyclone forms in the Central Pacific, or (3) a tropical cyclone moves into the Central Pacific from the West.