NASA spots Tropical Storm Darby as warnings posted in Hawaii

July 22, 2016

On July 22, NASA-NOAA's Suomi NPP satellite and NASA's RapidScat instrument gathered data on Tropical Storm Darby as it neared Hawaii and triggered warnings.

A Tropical Storm warning was in effect for Hawaii County and a Tropical Storm watch was in effect for Maui County, including the islands of Maui, Molokai, Lanai and Kahoolawe

On July 22 at 00:00 UTC (July 21 at 8 p.m. EDT) the Suomi NPP satellite saw Tropical Storms Darby in the Central Pacific Ocean. To the east of Darby were post-tropical cyclone Estelle, and new tropical storms Georgette and Frank. In the image the bulk of clouds and thunderstorms appeared in the northern quadrant.

Forecaster Powell of NOAA's Central Pacific Hurricane Center (CPHC) said, "After decreasing through much of the night, deep convection around Darby has once again flared along the northern quadrant. Exposed low cloud bands across the southern semicircle show a reasonably well organized system, with good outflow to the northeast."

NASA's RapidScat instrument flies aboard the International Space Station and measures Earth's ocean surface wind speed and direction over open waters. On July 22, RapidScat saw sustained along the northern side of Tropical Storm Darby's center as strong as 24 meters per second (53.6 mph/86.4 kph).

RapidScat is an important tool for meteorologists, because it shows forecasters the location of the strongest winds in different quadrants of an area of low pressure area as they are not always equally distributed.

At 5 a.m. HST (11 a.m. EDT/1500 UTC), the center of Tropical Storm Darby was located near latitude 18.6 north and longitude 149.2 west. That puts the center of Darby about 390 miles (630 km) east of Hilo, Hawaii, and 595 miles (955 km) east-southeast of Honolulu, Hawaii.

NOAA's CPHC said that Darby was moving toward the west near 12 mph (19 kph) and that motion is expected to continue through Saturday, then become northwesterly Sunday. Maximum sustained winds were near 60 mph (95 km/h) with higher gusts. Little change in strength is forecast through Sunday.

CPHC cautions that interests outside of the watch and warning areas in the Hawaiian Islands should keep informed on the progress of Darby as it may eventually have impacts on all islands through early next week.

For updated forecasts, visit:

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