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Hurricane Season 2007: Cosme (Eastern Pacific)
No Problems for Hawaii From Tropical Depression Cosme

On Monday, by 11:30 UTC (1:30 a.m. Hawaii Standard Time) on July 23, 2007, Tropical Depression Cosme was centered about 950 miles west-southwest of Honolulu. The low was moving west near 20 miles an hour. Isolated thunderstorms continued to sputter within 135 miles east-southeast of the low.

The center of Tropical Depression Cosme passed south of the Big Island of Hawaii early Saturday, and brought some needed rainfall. The Big Island only received the fringes of the storm, and the center remained off-shore. However, Cosme was still able to bring between 3 and 5 inches of needed rainfall in a period of about 6 hours as it passed by late Friday night, according to reports from the Associated Press. It was noted that winds briefly gusted to between 30 and 40 mph during the storm.

Storm summary credit: Rob Gutro, Goddard Space Flight Center

Tropical Depression Cosme May Bring Heavy Rains and Surf to Hawaii's Big Island

Residents of the big island of Hawaii are keeping a close eye on Tropical Depression Cosme over the weekend of July 21-22, as it is expected to pass just south. A flash flood watch, high surf advisory, and wind advisory have been posted through Saturday for the big island of Hawaii.

Cosme heading towards Hawaii
Click image to enlarge

On Friday, July 20, 2007 at 900 UTC, (2:00 a.m. PDT), the center of Tropical Depression Cosme was located near 16.1 north and 149.1 west. Cosme was moving west at 15 knots (17 mph), and had an estimated minimum central pressure of 1008 millibars. On Monday, July 16, the pressure was 994 millibars, and Cosme was a tropical storm. The lower the pressure, the stronger the storm. Now, Cosme's pressure has risen and the storm has weakened to a tropical depression. Currently, Cosme's maximum sustained winds are around 30 knots (34 mph), with gusts to 40 knots (46 mph).

Flash Flood Watch up for Big Island of Hawaii Through Saturday

On Friday morning at 3:30 a.m. HST, the National Weather Service of Honolulu issued a Flash Flood Watch for the big island of Hawaii, effective through Saturday afternoon, July 21. The watch reads: "The passage of tropical depression Cosme south of the big island is expected to produce heavy rainfall with highest amounts along the east and southeast facing slopes. The initial rainfall will begin later today with the heaviest amounts occurring tonight into early Saturday. The runoff from this heavy rain may produce flash flooding."

According to the National Weather Service, the moisture north of Tropical Depression Cosme is expected to produce heavy rainfall. Totals are expected to be in the 5 to 10 inch range which may be sufficient to produce flash flooding.

High Surf Advisory in Effect for Eastern Shores of Big Island

The National Weather Service has also issued a high surf advisory from the afternoon of Friday, July 20 through Saturday morning, July 21, for east facing shores of the big island. The Advisory reads: "Large waves produced by the strong trade winds north of tropical depression Cosme will arrive along the east facing shores on the big island of Hawaii later today (7/20) and tonight. These waves combined with increasing local winds will result in rough and choppy surf along the affected shorelines.

A high surf advisory means that waves will be higher than usual. Stay out of the water and well away from the shore break to avoid the hazardous waves and strong rip currents."

Wind Advisory and Small Craft Advisories In Effect

The National Weather Service has also posted a Wind Advisory for the summits of Haleakala Mauna Kea and Mauna Loa. The advisory notes that east winds will increase over higher elevations of Maui and the Big Island this evening as Cosme passes south of the Big Island. The advisory may need to be upgraded to a High Wind Warning if winds are expected to reach the 45 mph threshold tonight. Other windy areas of the big island may need to have a Wind Advisory issued if winds are expected to increase to 30 mph tonight. Small Craft Advisories are also up through Saturday, July 21 at 6:00 p.m. HST for these areas: Big Island Southeast Waters; Big Island Leeward Waters; Alenuihaha Channel; Pailolo Channel, and Maalaea Bay.

Where is Cosme Headed?

The Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii has now taken over the forecasting for Tropical Depression Cosme as the storm is now in the Central Pacific Ocean. The discussion from the CPHC noted on Friday, July 20, 2007, that strong high pressure in the low levels of that atmosphere, located north of the storm's path has led forecasters to project a more westward track for Cosme. That means Cosme will move slightly further away than previously expected from the big island of Hawaii by tomorrow (Sat. July 21) night.

Weaken or Strengthen?

The forecast discussion notes that there are two things that will affect whether Cosme weakens or strengthens. Shearing winds (winds that help tear the storm apart) from the north will affect the storm once it gets west of 150 degrees west longitude. However, because Cosme is moving into warmer waters (80 degree Fahrenheit waters help power storms), it may make it to minimum tropical storm levels. The CPHC is keeping an eye on the storm as it continues moving westward.

For updates over the weekend on Cosme, please visit the Central Pacific Hurricane Center

For the local Hawaii forecast including updates to watches and warnings click on the link.

Storm summary credit: Rob Gutro (derived from NWS reports)/Goddard Space Flight Center

Hurricane Cosme Continues Moving Westward in the Pacific Ocean

On Wed. July 18, Tropical Storm Cosme continued its westward trek in the eastern Pacific Ocean, and is expected to pass south of Hawaii over the weekend of July 21-22. At 15:00 UTC (5:00 a.m. Hawaiian Time) on Wed. July 18, the center of Cosme was located near 15.3 north and 138.9 west. The storm was moving west at 12 knots (13 mph), and had maximum sustained winds of 35 knots (40 mph) with gusts to 45 knots (52 mph). Its minimum central pressure was 1004 millibars.

Hurricane Cosme was the third named storm in the 2007 Eastern Pacific hurricane season. Cosme formed in a common area for hurricanes to start off the Pacific coast of Mexico and it tracked north and west. Cosme built power from its initial Tropical Depression state on July 14 to a minimal Category 1 hurricane on July 16.

Tropical Storm Cosme
Click image to enlarge.

At 10:45 a.m. local time (19:45 UTC) on July 16, 2007, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image, Hurricane Cosme was at its brief peak as a Category 1 storm. The hurricane had a well-defined spiral shape, but it was relatively small and its central eye was filled with clouds (known as a closed eye). Sustained winds were measured at 120 kilometers per hour (75 miles per hour) according to the University of Hawaii's Tropical Storm Information Center, at the time of this MODIS image.

Conditions for Hurricane Cosme to intensify were poor, and by July 17, it had downgraded back to tropical storm status. The storm was projected to continue on a mostly westward track toward Hawaii, according to the Joint Typhoon Warning Center on July 17, 2007.

By early Saturday morning, the National Hurricane Center's current forecast projects that Cosme's eye will be south of the big Island of Hawaii.

Credit: NASA GSFC by Jesse Allen, using data provided courtesy of the MODIS Rapid Response team.

Tropical Storm Cosme Swirls in the Eastern Pacific

Tropical Depression number Six-E (TD #6-E) in the eastern Pacific Ocean came to life around 10:00 a.m. PDT about halfway between Mexico and the Hawaiian islands. By the early afternoon of Sunday, July 15, TD #6-E strengthened into a tropical storm and received the name "Cosme." Cosme is currently no threat to land areas.

On Monday, July 16, 2007 at 1500 UTC, (8:00 a.m. PDT), the center of Tropical Storm Cosme was located near 14.3 north and 130.5 west. Cosme was moving west-northwest at 9 knots (10 mph), and had an estimated minimum central pressure of 994 millibars. Cosme's maximum sustained winds are around 55 knots (63 mph), with gusts to 65 knots (74 mph).

The images below are two different satellite looks at Tropical Storm Cosme. The top image was taken by the Moderate Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite on July 15, 2007 at approximately 22:00 UTC.

The bottom image was taken from the NASA's CloudSat satellite, which carries a cloud radar. CloudSat flies in synch with the Aqua satellite, which means it passes over the same location approximately 1 minute after Aqua, generating a top-down look from Aqua, and a sideways look at the clouds from CloudSat.

Image of Tropical Storm Cosme from MODIS and CloudSat.
Click image to enlarge.
How do you read the CloudSat Image (below)?

The line from A to B on the Aqua image (upper) show the track that CloudSat took flying over the storm. That "sideways track" through the storm is shown in the CloudSat image (bottom). The vertical axis on the CloudSat image (bottom) represents the altitude from the ground to the top of the atmosphere. The variations of color intensity indicate the differing amounts of water and ice in the storm clouds. The bright line at the bottom of the panel is the ground return from the radar. This indicates that the radar penetrated to the ground most of the time, even through heavy rainfall. Where the ground return disappears is an indication that the radar was attenuated by heavy precipitation, likely exceeding 30 mm/hr, based on previous studies. From one side to the other, the bottom panel is approximately 800 km, and the scale from top to bottom is approximately 30 km. The CloudSat data provide analysts and forecasters with a view of hurricanes never before available. Cross-sections like these provide a view of the internal structure of these storms, giving information about the intensity, rainfall rates and cloud organization.

Image Credit: Alicia Muirhead and Deb Vane, NASA Jet Propulsion Laboratory /Rob Gutro, Goddard Space Flight Center from National Hurricane Center reports

Mike Bettwy
NASA Goddard Space Flight Center