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Hurricane Season 2009: Tropical Storm Linda (Eastern Pacific)
09.11.09
 
September 11, 2009

Linda was still showing some areas of moderate rainfall when the TRMM satellite passed over on September 10. > View larger image
Linda was still showing some areas of moderate rainfall (red areas in the center) when the Tropical Rainfall Measuring Mission (TRMM) satellite passed overhead on September 10, 2009 at 2010 UTC (4:10 p.m. EDT).
Credit: NASA/SSAI, Hal Pierce
AIRS captured a visible image of Tropical Storm Linda on September 10 at 5:35 p.m. EDT. > View larger image AIRS captured a visible image of Tropical Storm Linda on September 10 at 5:35 p.m. EDT. The Baja California coast is visible to the top right corner of the image. The white areas on the sides of the image were areas outside of the satellite's field of vision.
Credit: NASA/JPL, Ed Olsen
NASA's TRMM Satellite Saw Linda's Dying Burst of Moderate Rainfall

NASA's Tropical Rainfall Measuring Mission satellite (TRMM) has been eyeing Linda's rainfall as a way to help determine her strength. In a satellite image captured late yesterday, Linda had several areas of moderate rainfall around her center. As of 11 a.m. today, September 11, however, there were no more visible areas of organized deep convection.

At 11 a.m. EDT Tropical Storm Linda was 1,355 miles west of the southern tip of Baja California, near 20.6 north and 130.9 west. Linda's winds were down to 45 mph, and she was moving north-northwest near 6 mph. Minimum central pressure is 1000 millibars.

The TRMM rainfall analysis derived from the TRMM Microwave Imager (TMI) and Precipitation Radar (PR) instruments was overlaid on a combined Visible and Infrared image from the Visible and Infrared Scanner (VIRS). This rainfall analysis showed that moderate rainfall was associated with Linda, particularly to the north of her center of circulation.

Now that Linda is in sea surface temperatures colder than 80F and is being pummeled by a southerly wind shear, plus dry air, she's weakening at a fast rate. The National Hurricane Center noted that it's unlikely she'll pull through these tough environmental factors, and will likely be declared a remnant low pressure system tonight.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center













September 10, 2009

The cold areas in this image (yellow-green) indicate where there is precipitation or ice in the cloud tops. > View larger image
NASA's Aqua satellite AIRS and AMSU instrument data created a microwave image of Hurricane Linda on September 10 at 6:41 a.m. EDT. The cold areas in this image (yellow-green) indicate where there is precipitation or ice in the cloud tops. The microwave image suggests cold, high thunderstorms, and a partial opening in her eyewall.
Credit: NASA/JPL, Ed Olsen
NASA Microwave Image Sees Eyewall Opening in Hurricane Linda

Linda managed to power up to hurricane status at 11 p.m. EDT last night (September 9), and she's running into cooler waters and wind shear, so she's not expected to hold that strength through tomorrow. Microwave imagery from NASA's Aqua satellite revealed a 10 percent opening in her eyewall and that's a clue that the storm can weaken.

At 11 a.m. EDT on September 10, Linda had maximum sustained winds near 85 mph and weakening is expected. Her hurricane force winds only extend to 25 miles out from the center, while tropical storm force winds extend out 140 miles from the center. She's moving north-northwest near 9 mph, and expected to slow a little in the next day or two. Minimum central pressure is 985 millibars. The center of hurricane Linda was located near latitude 18.4 north and longitude 130.1 west or about 1,340 miles west of the southern tip of Baja California.

The National Hurricane Center (NHC) uses all kinds of satellite imagery to enhance their tropical cyclone forecasts, and they looked at data from NASA's Aqua satellite and NOAA's GOES-11 satellite to see that Linda is poised for weakening. One sign of weakening came from GOES-11 infrared images taken from 11 p.m. EDT last night that indicated Linda's eye had disappeared.

Microwave images are created when data from NASA's Aqua satellite Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instruments are combined. These microwave images indicate where there is precipitation or ice in the cloud tops and the latest microwave image revealed Linda had cold, high thunderstorms.

This morning at 11 a.m. EDT, the NHC said "enhanced BD-curve infrared imagery and an Aqua-1 AMSR-E color composite microwave overpass suggest that Linda has strengthened some this morning."

The NHC discussion said, "Subsequent microwave imagery depicted a partial eyewall that was open over the southern semicircle. The overall cloud pattern has become slightly less organized in appearance and elongated from south to north...indicative of southerly or south-southwesterly [wind] shear." The microwave data, such as that from Aqua, indicated Linda's center is a little south and west of where it appears to be on geostationary images.

Linda is forecast to move into an environment with westerly wind shear between 23-28 mph and sea surface temperatures below 75F. Tropical cyclones need warm sea surface temperatures of at least 80F to maintain strength.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



September 9, 2009

This NASA image from the AIRS instrument on shows Linda's cold clouds (blue and purple) are still not symmetric. > View larger image
This NASA infrared satellite image from the AIRS instrument on September 9 at 5:59 a.m. EDT shows Linda's cold clouds (blue and purple) are still not symmetric, indicating her struggle to strengthen further.
Credit: NASA/JPL, Ed Olsen
NASA Satellite Imagery Shows a Non-Symmetric Linda

Tropical Storm Linda doesn't appear to be strengthening, and NASA infrared satellite imagery has shown that her shape isn't symmetric confirming that. Satellite data also shows the bulk of her clouds and thunderstorms are northwest of her center.

Infrared imagery from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite on September 9 around 6 a.m. EDT showed the bulk of Linda's thunderstorms and high clouds lie to the northwest of Linda's center of circulation. The other clouds and associated thunderstorms are scattered to her south and southeast.

At 11 a.m. EDT on September 9, Linda had maximum sustained winds near 65 mph. Based on satellite data and forecasts from the National Hurricane Center, she isn't expected to strengthen in the next 24 hours. Linda is moving northwest near 8 mph and is expected to turn north-northwest in the next day or two. She poses no threat to land, however as her center is 1,300 miles west-southwest of the southern tip of Baja California, near 16.5 north and 128.7 west. Her estimated minimum central pressure is 994 millibars.

Forecasters at the National Hurricane Center noted that she still has the opportunity to strengthen a little in the next 24 hours, but thereafter she'll be in cooler waters and the wind shear will increase, shooting down her chances of becoming a hurricane unless it happens before that time.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



September 8, 2009

This NASA infrared AIRS satellite image shows Linda coming together on September 7 at 6:11 a.m. EDT. > View larger image
This NASA infrared AIRS satellite image shows Linda coming together on September 7 at 6:11 a.m. EDT.
Credit: NASA/JPL, Ed Olsen
Tropical Storm Linda Born in the Eastern Pacific

Tropical Storm Linda is now meandering around in the Eastern Pacific Ocean, born yesterday, September 7 at 5 a.m. EDT. Infrared satellite imagery from NASA's Aqua satellite shows that the storm is still trying to come together, and atmospheric and oceanic conditions lead forecasters to believe that she'll be a "short-timer."

At 11 a.m. EDT today, September 8, 2009, Linda's maximum sustained winds are near 60 mph with higher gusts. Although she has the opportunity to strengthen a little in the next day, Linda is not expected to become a hurricane. After that, wind shear is expected to increase and Linda will move into cooler waters, two major factors that will weaken the storm.

Linda is a long way from land the southern tip of Baja California. In fact, she's about 1,320 miles west-southwest of there, near latitude 15.2 north and longitude 128.4 west. Linda is moving toward the west near 2 mph and a slow turn to the northwest should begin later today. Her estimated minimum central pressure is near 997 millibars.

NASA's infrared satellite imagery showed that the thunderstorm cloud tops in Tropical Storm Linda were somewhat scattered in the storm's circulation. The Atmospheric Infrared Sounder (AIRS), instrument that flies aboard NASA's Aqua satellite, captured an image of Tropical Storm Linda yesterday.

AIRS Infrared imagery is false-colored and higher cloud tops of stronger storms are depicted in purple. However, the AIRS imagery from yesterday revealed that the center of Linda's circulation was devoid of those highest, strongest thunderstorms, confirming her tropical storm status.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center