Featured Images

Text Size

Hurricane Season 2011: Tropical Storm Fernanda (Eastern Pacific Ocean)
08.19.11
 
GOES-11 saw Tropical Storm Fernanda on August 19 at 5 a.m. local Hawaii time. › View larger image
GOES-11 saw Tropical Storm Fernanda 970 miles east-southeast of Honolulu on August 19 at 5 a.m. local Hawaii time. Fernanda has lost her 'comma shape' indicating she has weakened in the last 24 hours. Hawaii is seen to the top left.
Credit: NASA/NOAA GOES Project
GOES-11 Satellite Notices Tropical Storm Fernanda Lost Her "Comma Shape"

Tropical Storm Fernanda lost her "comma." A "comma shape" is a typical indication of a strong tropical storm, and satellite imagery today revealed Fernanda to more closely resemble a period instead, as the storm has weakened. Fernanda is struggling against wind shear and cooler waters as it continues to move west and infrared imagery from the GOES-11 satellite shows a much less impressive storm today.

Early on August 19, infrared satellite imagery showed no convection in the storm, but that changed as the day progressed and some thunderstorms flared up. Sea surface temperatures are just below 80F (26.6C), which is the threshold for maintaining a tropical cyclone's strength.

The Geostationary Operational Environmental Satellite called GOES-11 captured an image of Fernanda on August 19 at 1500 UTC (5 a.m. local time, Hawaii). Fernanda did not appear as organized as it did over the last several days, and has lost its signature comma shape. The image was created at NASA's GOES Project, located at NASA Goddard Space Flight Center in Greenbelt, Md. NOAA manages the GOES-11 satellite and NASA uses its data to create images and animations.

At 5 a.m. HST (11 a.m. EDT) Fernanda was located about 780 miles east-southeast of South Point, Hawaii, and 970 miles east-southeast of Honolulu near latitude 15.1 north, longitude 144.6 west. Fernanda is moving toward the west near 12 mph and she is expected to continue in this direction. Maximum sustained winds are near 40 mph (65 kmh) and some additional weakening is forecast today. Estimated minimum central pressure is 1002 millibars.

Fernanda is being weakened by southerly wind shear which is expected to increase throughout the weekend. The tropical storm is expected to become a depression or non-tropical low pressure area over the next 48 hours and pass far to the south of the big island of Hawaii.

Elsewhere in the eastern Pacific, tropical storm Greg, located 455 miles south of the southern tip of Baja California also continues to weaken. Only one other area of showers and thunderstorms in the eastern Pacific is being watched this weekend, and that has just a 20% chance of development.

Text Credit: Rob Gutro, NASA Goddard Space Flight Center, Greenbelt, Md.



August 18, 2011

GOES-11 caught Tropical Storm Fernanda (left) and Hurricane Greg (right) on August 18 at 1200 UTC. › View larger image
The GOES-11 satellite caught an image of eastern Pacific on August 18 at 1200 UTC (8 a.m. EDT) saw Tropical Storm Fernanda (left) approaching the central Pacific Ocean and Hurricane Greg (right) behind her in the eastern Pacific Ocean.
Credit: NASA/NOAA GOES Project
NASA Satellite Data Confirms Greg a Hurricane, Fernanda a Tropical Storm

Big sisters don't like being overshadowed by their younger brothers and that's what has happened in the eastern Pacific Ocean with Tropical Storm Fernanda and now Hurricane Greg. Despite the difference in strength, NASA satellite imagery shows some strong convection happening in both tropical cyclones and that they're now matched in size.

Greg grew into a hurricane today is it continues moving near the western coast of Mexico, while Fernanda has maintained tropical storm strength.

The Geostationary Operational Environmental Satellite called GOES-11 caught an image of eastern Pacific on August 18 at 1200 UTC (8 a.m. EDT) saw Tropical Storm Fernanda approaching the central Pacific Ocean and Hurricane Greg behind her in the eastern Pacific Ocean. The image was created at NASA's GOES Project, located at NASA Goddard Space Flight Center in Greenbelt, Md. NOAA manages the GOES-11 satellite and NASA uses its data to create images and animations.

At 11 a.m. EDT (5 a.m. Hawaii Standard Time) Fernanda's maximum sustained winds were near 65 mph, just 9 mph shy of hurricane status. She was located about 1040 miles east-southeast of South Point, Hawaii near latitude 13.7 North and longitude 141.0 West. Fernanda is moving toward the west-northwest near 13 mph and is expected to take a more westerly track in the next 48 hours after which she's expected to weaken because of adverse atmospheric conditions.

Infrared imagery from the AIRS instrument on NASA's Aqua satellite today shows that deep convection (rapidly rising air that creates the thunderstorms that power the cyclone) is still occurring within 60 nautical miles of Fernanda's center, and a small area southwest of the center with cloud tops as cold as -112 Fahrenheit (-80 Celsius)! Cloud tops that high indicate very strong thunderstorms and heavy rainfall, exceeding 2 inches (50 mm) per hour.

That strength isn't expected to hold for the next 48 hours, though. The National Hurricane Center noted "by the time Fernanda passes south of the main Hawaiian Islands it is expected to have weakened to a remnant low."

Fernanda and Greg are now about the same size. Fernanda's tropical storm-force winds extend outward up to 80 miles from the center. Greg's tropical storm-force winds extend to about 85 miles from the center, while his hurricane-force winds extend 25 miles out.

At 11 a.m. EDT (8 a.m. PDT) Greg's maximum sustained winds were near 85 mph, making him a category one hurricane on the Saffir-Simpson Scale. He was moving to the west-northwest near 18 mph and is forecast to move in a more westerly direction in the next couple of days.

Greg was centered about 320 miles south-southwest of the southern tip of Baja California near 18.5 North and 111.5 West and was passing Mexico's Socorro Island. The automated weather station on the island reported sustained winds of 38 mph and a wind gust of 53 mph.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite saw Greg as a tropical storm on August 17 at 0534 UTC. At that time, TRMM's Microwave Imager showed that intense convective thunderstorms within the developing storm were dropping rainfall at rates greater than 30mm/hr (1.2 inches) in an area near the center of the storm. Greg's rainfall rates have increased as he strengthened into a hurricane. Greg is forecast to move into cooler waters in three days, at which time he will begin to weaken. In the meantime, he continues to chase Fernanda through the Eastern Pacific Ocean.

Text Credit: Rob Gutro, NASA Goddard Space Flight Center, Greenbelt, Md.



August 17, 2011

On August 17 at 1200 UTC (8a.m. EDT), GOES-11 caught Fernanda (left) and Greg (right). › View larger image
GOES-11 caught an image of the eastern Pacific on August 17 at 1200 UTC (8 a.m. EDT) and showed Fernanda (left) moving into the Central Pacific Ocean while Greg (right) is in the far Eastern Pacific.
Credit: NASA/NOAA GOES Project
GOES-11 Satellite Sees Tropical Storms Fernanda and "Little Brother" Greg Chasing Each Other

The Eastern Pacific Ocean is fired up with two tropical storms today, Fernanda and Greg, and both were caught in one image from the GOES-11 satellite. Both appear to be chasing each other to the west, and Fernanda appears a little more organized in satellite imagery and stronger than her "little brother."

The newest tropical storm, Greg, formed this morning, August 17 off the west coast of Mexico from a low previously known as System 99E. Greg is about 135 miles (220 km) south-southwest of Zihuatanejo, Mexico. Because Greg is close to the western coast of Mexico, the National Hurricane Center noted that heavy rainfall is possible in the next day or two along the coasts of two Mexican states: Guerrero and Michoacan.

The Geostationary Operational Environmental Satellite called GOES-11 caught an image of eastern Pacific on August 17 at 1200 UTC (8 a.m. EDT) and showed Fernanda moving into the Central Pacific Ocean while Greg is in the far Eastern Pacific. The image was created at NASA's GOES Project, located at NASA Goddard Space Flight Center in Greenbelt, Md. NOAA manages the GOES-11 satellite and NASA uses its data to create images and animations.

In the image, Fernanda far west of Greg, has a signature shape of a mature tropical storm, while Greg shows high clouds and powerful convection and thunderstorms in the center of circulation, but had not yet fully developed the signature comma shape. The eastern quadrant of Greg's clouds extended over the southwestern Mexico coastline, and his thunderstorms were dropping moderate to heavy rainfall.

On August 17 at 5 a.m. EDT (0900 UTC), Tropical Storm Greg's maximum sustained winds were near 40 mph. Those tropical storm-force winds extend outward up to 45 miles, making the storm 90 miles in diameter. Estimated minimum central pressure is 1004 millibars. Greg was centered near 15.8 North and 102.2 West and moving to the west-northwest near 16 mph (26 kmh). Greg's center is expected to remain well offshore from the southwestern Mexico coastline.

Greg is located in a decent environment for strengthening: moist air, moderate wind shear from the northeast and warm sea surface temperatures near 86 Fahrenheit (30 Celsius). It takes sea surface temperatures of at least 80F (26.6C) to support a tropical cyclone

Tropical Storm Fernanda is stronger than her "little brother" Greg, with maximum sustained winds near 50 mph (85 kmh) and some slight strengthening is still possible, according to the National Hurricane Center. Greg is not only Fernanda's "little" brother in terms of winds but also in terms of extent of tropical storm-force winds. Fernanda's tropical storm-force winds extend out 70 miles from the center making her 50 miles wider in diameter than Greg.

On August 17 at 5 a.m. EDT, Fernanda was still very far from Hawaii. In fact, she was centered about 1,350 miles (2, 715 km) east-southeast of South Point, Hawaii near 11.6 North and 136.9 West. She's moving to the west near 7 mph (11 kmh) and is expected to turn to the west-northwest over the next couple of days. Fernanda is not expected to reach hurricane status as she continues to move west and Greg continues to chase her.

Text Credit: Rob Gutro, NASA Goddard Space Flight Center, Greenbelt, Md.



August 16, 2011

TRMM passed over Fernanda at 4 a.m. EDT on Aug. 16 › View larger image
When TRMM passed over Fernanda at 4 a.m. EDT on Aug. 16, it revealed that the center was just northeast of the main band of thunderstorms where the heaviest rain was falling. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20-40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
NASA's TRMM Satellite Helped Forecasters Determine TD6E is now Tropical Storm Fernanda

The National Hurricane Center (NHC) upgraded tropical depression 6E to tropical storm Fernanda on 16 August 2011 at 0800 UTC after seeing data from a TRMM satellite pass at that time.

The Tropical Rainfall Measuring Mission Satellite or TRMM satellite is managed by NASA and the Japanese Space Agency and provides rainfall rate estimates from its orbit in space. A rainfall analysis from TRMM Microwave Imager (TMI) rainfall data today, August 16, showed that Fernanda contains areas of heavy rainfall, falling at more than 2 inches (50 mm) per hour. When TRMM passed over Fernanda at 0800 UTC (4 a.m. EDT) today, it revealed that the center was just northeast of the main band of thunderstorms where the heaviest rain was falling.

Fernanda was located about 1,478 miles (2,378 km) east-southeast of the Hawaiian Islands near 12.3 North and 134.5 West. Fernanda's maximum wind speeds are about 45 knots (~52 mph) and it was moving toward the west at about 8 mph (13 kmh). Her tropical storm-force winds extend out to 35 miles (55 km) from the center.

The NHC discussion says that computer guidance indicates considerably more intensification is possible with Fernanda in the next day or so.

Text Credit: Hal Pierce, SSAI/NASA Goddard Space Flight Center, Greenbelt, Md.



GOES-11 image from August 15 at 0600 UTC shows Tropical Depression 6E as a small rounded area of clouds. › View larger image
This GOES-11 image from August 15 at 0600 UTC (2 a.m. EDT) shows Tropical Depression 6E as a small rounded area of clouds in the eastern Pacific headed west. Hawaii lies over 1,500 miles to the west of TD6E.
Credit: NASA/NOAA GOES Project
Tropical Depression 6E Forms in the Eastern Pacific: GOES-11 Observes

The sixth tropical depression of the eastern Pacific Ocean season formed today, and was seen this morning on infrared imagery from the GOES-11 satellite.

The Geostationary Operational Environmental Satellite called GOES-11 caught an image of eastern Pacific on August 16 at 0600 UTC (2 a.m. EDT) and right in the center of the image is Tropical Depression 6E, appearing as a small rounded area of clouds. The image was created at NASA's GOES Project, located at NASA Goddard Space Flight Center in Greenbelt, Md. NOAA manages the GOES-11 satellite and NASA uses its data to create images and animations.

At 5 a.m. EDT (2 a.m. PDT) on August 16, Tropical Depression 6E (TD6E) had maximum sustained winds near 35 mph (55 kmh) and moving to the west near 9 mph (15 kmh). TD6E is about 1,710 miles (2,755 km) west-southwest of the southern tip of Baja California near 12.4 North and 133.5 west. In fact, TD6E is closer to Hawaii. It's about 1,515 miles east southeast of Hilo, Hawaii.

TD6E has some deep convection (rapidly rising air that creates thunderstorms that power tropical cyclones) in its southwestern quadrant, although experiencing wind shear. The National Hurricane Center reported that it will likely become a tropical storm before it moves over cooler waters which will weaken it back to a depression. If it does make tropical storm status later today or tomorrow, it will be named Fernanda.

According to the Central Pacific Hurricane Center, TD6E is not expected to cross longitude 140°W and in their area of responsibility until sometime on Thursday, August 18.

Text Credit: Rob Gutro, NASA Goddard Space Flight Center, Greenbelt, Md.



August 15, 2011

TRMM revealed numerous heavy thunderstorms in an area west of the low pressure center › View larger image
On Aug. 14, TRMM's Precipitation Radar of System 98E revealed that numerous heavy thunderstorms in an area west of the low pressure center were dropping rain at the rate of over 50mm/hr (~2 inches). TRMM's PR also showed that a few thunderstorm towers near the center of the developing tropical cyclone were reaching heights of about 13km (~8 miles) The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20-40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
TRMM Satellite Sees Heavy Rain in System 98E

A low pressure area in the Eastern Pacific that appears to have a good chance of becoming the next tropical depression is dropping heavy rainfall, according to NASA's TRMM satellite.

The Tropical Rainfall Measuring Mission (TRMM) satellite, managed by NASA and the Japanese Space Agency, has the unique ability to measure rainfall from space. Rainfall rates are a gauge of the power within a tropical cyclone.

When the TRMM satellite flew over this disturbance it was located about 2,680km (~1,665 miles) east-southeast of the Hawaiian Islands, on August 14, 2011 at 2306 UTC (7:06 p.m. EDT). At that time, System 98E was near 12.3 North and 131.1 West, about 1600 miles west-southwest of Cabo San Lucas, Mexico.

TRMM's Precipitation Radar (PR) revealed that numerous heavy thunderstorms in an area west of the low pressure center were dropping rain at the rate of over 50mm/hr (~2 inches). TRMM's PR also showed that a few thunderstorm towers near the center of the developing tropical cyclone were reaching heights of about 13km (~8 miles).

The National Hurricane Center (NHC) has given an area of disturbed weather in the eastern Pacific Ocean a high probability (70%) of becoming a tropical cyclone as the environment is conducive to development. It could become a tropical depression later today or tomorrow.

For more information about how TRMM looks at rainfall, visit NASA's TRMM website at: http://trmm.gsfc.nasa.gov/. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Text Credit: Rob Gutro, NASA Goddard Space Flight Center, Greenbelt, Md.