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Hurricane Season 2009: Eastern Pacific Low (Pacific)
06.12.09
 
June 12, 2009

The broken areas of thunderstorms (blue) indicate disorganization of the Low in this Aqua satellite AIRS image The broken areas of thunderstorms (blue) indicate disorganization of the Low in this Aqua satellite AIRS image.
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Image Credit: NASA JPL, Ed Olsen
Winds and Dry Air Taking the Life Out of the Eastern Pacific Low

The Eastern Pacific Low pressure system forecasters have been watching since Monday, June 8, hasn't made the leap to a tropical depression because of wind shear. It now appears that the low's chances for becoming the first tropical depression of the eastern Pacific have dissipated, which is likely what the low will do over the weekend.

At 5 a.m. PDT (8 a.m. EDT) on Friday, June 12, that broad area of low pressure and its associated scattered showers and thunderstorms were about 850 miles southwest of the southern tip of Baja California, or 520 miles west southwest of Socorro Island, near 14.1 degrees north latitude and 118.7 west longitude. Socorro Island is a volcanic island in the Revillagigedo Islands. The island belongs to Mexico and is about 372 miles (600 kilometers) off the country's western coast.

The National Hurricane Center noted that the satellite imagery indicated the system has become less organized than it was on June 11. In fact, the center of circulation is now becoming more "exposed" or less circular and the convective activity or building thunderstorms are becoming fewer and weaker and scattered. Microwave imagery from the early morning hours of June 12 showed that there aren't any strong thunderstorms in the system anymore.

Winds and dry air are the two factors weakening the low and tearing it apart. Strong winds from the southwest, associated with a mid-upper atmospheric trough, that is, an extended area of relatively lower atmospheric pressure to the northwest of the storm's center. In addition, dry air ahead of that trough (located to the northeast of the eastern Pacific Low's center) is working its way into the low. Dry air wicks away the moisture needed to build the thunderstorms in a low pressure area, and the thunderstorms make up a tropical cyclone.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured the fading Low pressure system in an infrared image on June 12 at 6:05 a.m. EDT. In the infrared image, the Low's cold clouds are now several scattered areas (in blue) indicating a weak and unorganized storm.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



June 11, 2009

This infrared Aqua satellite AIRS image shows the Low's thunderstorms (purple and blue) are getting well organized in a circular shape. This infrared Aqua satellite AIRS image shows the Low's thunderstorms (purple and blue) are getting well organized in a circular shape. > Larger image
Image Credit: NASA JPL, Ed Olsen
Eastern Pacific Low Sending Swells to Mexico, Central America, May Become Tropically Depressed

The low pressure system sitting 1,000 miles away from Baja California in the eastern Pacific Ocean now has a very good chance of becoming that region's first tropical depression of the season. But it doesn't have to be tropical to cause trouble on the coastlines. It's already helping generate large and dangerous breaking surf along the coasts from Baja California to Colombia.

At 8:00 a.m. EDT on Thursday, June 11, the National Hurricane Center (NHC) in Miami, Fla. said that satellite images indicate that a tropical depression could be forming about 1000 miles southwest of the southern tip of Baja California. This is the area they've been watching since June 8. The NHC said that there's now a chance "greater than 50 percent" that it will be classified as a tropical depression, and advisories could be started later today.

Meanwhile, the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite is keeping track of the low. It captured an infrared image of the Low on June 11 at 5:23 a.m. EDT (2:23 a.m. PDT). The storm's lowest temperatures (in purple) are associated with high, cold cloud tops. Those temperatures are as cold as or colder than 220 degrees Kelvin or minus 63 degrees Fahrenheit (F). The blue areas are around 240 degrees Kelvin, or minus 27F. The orange temperatures in the ocean are 80F (300 degrees Kelvin) or warmer, which is what is helping to strengthen and organize the storm.

The Low is helping to stir up the surf along the eastern Pacific coastlines from Central America to Mexico. The National Hurricane Center issued a special bulletin on June 11 about a long period of high swell for those areas.

The NHC said "Very long period south to southwesterly swell is emanating from a strong cyclone that has begun to affect the coasts of Central America and Mexico overnight, and will build during the next 48 hours." The swell is expected to reach its highest levels over the weekend, and will create large and dangerous breaking surf along the coasts from Baja California to Colombia. The NHC said "Long period swell of 2 to 2.5 meters (7 to 8 feet) will reach the coastlines from southern Mexico to Panama at intervals of 15 to 16 seconds. Select deep water breaks and beaches across this area may see breaking waves approaching 6 meters (20 feet) during the weekend." Beachgoers along those coastal areas should stay out of the water.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



June 9, 2009

GOES-12 captured this image of the low pressure area in the Eastern Pacific on June 9, 2009 GOES-12 captured this image of the low pressure area on June 9, 2009.
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Image Credit: NASA GOES Project
Shrinking Chances for the First Eastern Pacific Tropical Storm

On Monday, forecasters gave a low pressure system sitting about 1,000 miles south-southwest of Baja California between a 30 and 50 percent chance of developing into a tropical cyclone. Atmospheric conditions today are not helping the storm come together so the chance or organization has dropped to "less than 30 percent."

At 8 a.m. EDT on June 9, the showers and thunderstorms that are part of the low pressure area are noticeably less organized than they were yesterday. Dry air nearby is wicking the moisture away from the low and inhibiting any organization and growth of thunderstorms.

Meanwhile, the National Hurricane Center in Miami, Fla. is still keeping an eye on the eastern Pacific Low for potential development, but says it will be slow to occur as the Low's center moves west-northwestward. It is expected to take a more northwesterly track over the next 48 hours.

The Geostationary Operational Environmental Satellite (GOES-12) captured images of the Low on June 9 at 10:45 a.m. EDT. The low pressure system is the circular area of clouds in the lower center of the image.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center



June 8, 2009

A GOES-12 satellite close up view of the low pressure area (circular area of clouds) located in the left part of this image A GOES-12 satellite close up view of the low pressure area (circular area of clouds) located in the left part of this image. > Larger image
Image Credit: NOAA/NASA GOES Project
Eastern Pacific Low Could Become Season's First Tropical Storm

There's a low pressure system about 1,200 miles southwest of the southern tip of the Baja California in the eastern Pacific Ocean that looks ripe for development into a tropical depression.

On Monday, June 8, 2009, the National Hurricane Center (NHC) in Miami, Fla. stated in their tropical weather outlook at 5 a.m. EDT, that the showers and thunderstorms associated with the area of low pressure have "increased in organization overnight" from Sunday, June 7.

The Geostationary Operational Environmental Satellite (GOES-12) captured images of the Low on June 8 at 4:45 a.m. (8:45 UTC) from its vantage point in space. The low pressure system is the circular area of clouds on the left side of both the "full-disk" or full Earth view and the close up images.

A full satellite image of the Earth taken from the GOES-12 satellite. The Low is located to the far left as the circle of clouds in the open waters of the eastern Pacific Ocean. A full satellite image of the Earth taken from the GOES-12 satellite. The Low is located to the far left as the circle of clouds in the open waters of the eastern Pacific Ocean. Credit: NOAA/NASA GOES Project > Larger image
Image Credit: NOAA/NASA GOES Project
The NHC said that "Conditions appear favorable for continued development and the system could become a tropical depression in the next day or two as it moves slowly west-northwestward." What's the chance that the low will become a tropical depression? Between 30 and 50 percent. That's a good chance that this storm could become the first named storm of the eastern Pacific Ocean hurricane season. If it does, it would be named Andres.

GOES is operated by the National Oceanic and Atmospheric Administration. It was created by NASA's GOES Project, located at NASA's Goddard Space Flight Center, Greenbelt, Md.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center