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Hurricane Season 2011: Tropical Storm Bret (Atlantic Ocean)
07.22.11
 
Infrared image from the GOES-13 satellite on July 22 shows Bret, Cindy, Low#1 and Hurricane Dora. › View larger labeled image
› View larger unlabeled image
In this infrared image from the GOES-13 satellite on July 22 at 0845 UTC (4:45 a.m. EDT) Bret and Cindy are in the Atlantic, Low#1 (from a tropical wave) is in the Caribbean and Hurricane Dora is in the eastern Pacific, off the coast of Mexico.
Credit: NASA/NOAA GOES Project, Dennis Chesters
NASA Catches 3 Tropical Cyclones at One Time

It's not often that a satellite can capture an image of more than one tropical cyclone, but the GOES-13 satellite managed to get 3 tropical cyclones in two ocean basins in one image today. Bret and his "sister" Cindy are racing through the North Atlantic, while another area tries to develop far to their south. "Cousin" Dora is still a hurricane in the eastern Pacific.

In infrared image taken on July 22 at 0845 UTC (4:45 a.m. EDT), GOES-13 captured Tropical Depression Bret, Tropical Storm Cindy in the north Atlantic and low pressure area associated with a tropical wave in the Caribbean and Hurricane Dora is in the eastern Pacific, off the coast of Mexico. Cindy is 910 miles west-northwest of the Azores and Bret 295 miles northwest of Bermuda.

NASA's GOES Project issued an infrared image of both Bret and Cindy today from the GOES-13 satellite, which is operated by NOAA. The NASA GOES Project is housed at NASA's Goddard Space Flight Center in Greenbelt, Md. and uses GOES-13 data from NOAA to create images and animations.

Bret Being Battered

During the morning of July 22 Bret has sped up on his track through the north Atlantic and weakened. Bret is being battered by winds and cooler waters.

Bret was a tropical depression at 8 a.m. EDT on July 22, with maximum sustained winds near 35 mph (55 kmh). He was speeding to the northeast near 21 mph (33 kmh). Bret's center was near 36.7 North and 66.5 West. Bret's minimum central pressure was near 1008 millibars.

Bret is now experiencing very strong wind shear and moving into cooler waters, two factors that will help dissipate the depression over the weekend. Those waters that Bret is moving into are cooler than 71 Fahrenheit (22 Celsius), about 9 degrees cooler than the threshold of warmth needed to keep a tropical cyclone going.

Tropical Storm Cindy Racing North

As Bret has sped up in his race across the Atlantic, so has his sister Cindy. Cindy is actually out-racing Bret, as she's moving to the northeast near 29 mph (46 kmh) in the far north Atlantic Ocean. She is expected to continue moving in this direction over the weekend. GOES-13 satellite data showed that her cloud pattern has become ragged overnight.

She was located about 805 miles northwest of the Azores near 44. 5 North and 39.9 West. Her maximum sustained winds were near 50 mph (85 kmh), so she's stronger than her "brother" Bret, who is now down to tropical depression status. Because Cindy is now in very cold water (68F/20C), weakening is forecast and like Bret, she could dissipate over the weekend well to the west of the British Isles.

A Tropical Wave Trying to Get Organized

Far to the south of both Bret and Cindy a low pressure area belonging to a tropical wave in the Caribbean is trying to get organized. As of July 22, the National Hurricane Center noted that there's only a 20 percent chance that the low will get its act together over the weekend.

The low pressure area is located about 425 miles east of the Windward Islands, near 15 N and 50 W, and is kicking up scattered showers and thunderstorms. It is moving almost as fast as Bret, and is headed west-northwest between 15 and 20 mph. During July 22 and 23, that low pressure area is expected to bring locally heavy rainfall and gusty winds to parts of the Lesser Antilles.

Hurricane Dora Weakening Hurricane Dora continues to weaken from northerly wind shear as it moves northwest into cooler waters as cool as 23 Celsius.

At 8 a.m. EDT on July 22, Dora has weakened to a category one hurricane on the Saffir-Simpson scale as it continues to parallel the western coast of Mexico and move in a northwesterly direction about 9 mph (15 kmh). Dora's maximum sustained winds are now near 90 mph (150 kmh). It is centered about 255 miles (415 km) south of Cabo San Lucas, Mexico near 19.2 North and 109.2 West. Minimum central pressure is 977 milibars.

There is a tropical storm warning in effect in Mexico from Agua Blanca to Buenavista including Cabo San Lucas. That means that tropical storm conditions exist somewhere in the warning area or will within 24 hours. Tropical Storm-force winds are likely in the warning area as Dora's center stays off the coast, and hurricane-force winds only extend out 35 miles from her center.

Southwestern Mexico and Baja California beaches and coastal areas will be hit with large and dangerous ocean swells. These swells will likely cause life-threatening surf and rip current conditions.

By Monday, July 25, Bret and Cindy may be off the books while Dora is expected to last through the weekend. As for the tropical wave in the Atlantic, GOES-13 will keep a close eye on it.

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



July 21, 2011

GOES-13 captured Tropical Storm Bret (lower left) and Tropical Storm Cindy (upper right) in the North Atlantic. › View larger image
This infrared image from the GOES-13 satellite captured both Tropical Storm Bret (lower left) and newborn Tropical Storm Cindy (upper right) at 0845 UTC (4:45 a.m. EDT) in the North Atlantic.
Credit: NASA/NOAA GOES Project
NASA Sees Tropical Storms Bret and Now Cindy Frolic in North Atlantic

Two tropical storms are now in the open waters of the North Atlantic: Bret and Cindy. Both were captured on one image from NASA today. Both storms are hundreds of miles to the east-northeast of Bermuda and pose no threat to land areas.

NASA's GOES Project issued an infrared image of both Bret and Cindy today from the GOES-13 satellite, which is operated by NOAA. The NASA GOES Project is housed at NASA's Goddard Space Flight Center in Greenbelt, Md. and uses GOES-13 data from NOAA to create images and animations. The image was captured at 0845 UTC (4:45 a.m. EDT) and shows Bret about 405 miles east-southeast of Bermuda, while Cindy is about 975 miles east-northeast of Bermuda.

At 5 a.m. EDT, Bret was still holding on to tropical storm status with maximum sustained winds near 40 mph, just over the 39 mph threshold. It was moving to the northeast near 8 mph and is expected to continue in this direction while speeding up and weakening over the next couple of days. Bret's center was near 33.1 North latitude and 71.7 West longitude. Bret is expected to dissipate by the weekend. Infrared satellite data from the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite indicated that the cloud top temperatures in the southern quadrant of the Bret are as cold as -70 Celsius, indicating strong, high thunderstorms and strong convection.

Meanwhile Tropical Storm Cindy developed overnight from System 99L that NASA was watching yesterday afternoon. Cindy developed into Tropical Depression 3, and quickly grew into a tropical storm and got her name.

As of 5 a.m. EDT today, July 21, Cindy's maximum sustained winds were near 60 mph, and she's expected to strengthen over the next day before colder waters sap her energy. She's centered near 38.3 North and 49.1 West and moving to the northeast at a speedy 28 mph. Cindy's forward speed is also expected to increase over the next couple of days. Her minimum central pressure is near 1002 millibars.

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



July 20, 2011

TRMM captured this image of rainfall happening within Tropical Stort on July 19. › View larger image
NASA's TRMM satellite captured this image of rainfall happening within Tropical Stort on July 19. The strongest thunderstorms were as high as 9.3 miles (15 km) and had the heaviest rainfall (red) on the east side of the storm, falling at 2 inches (50 mm) per hour. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce NASA's AIRS infrared imagery showed strong thunderstorms east of the center of circulation (purple). › View larger image
NASA's Aqua satellite passed over Tropical Storm Bret on July 19 at 18:35 UTC (2:35 p.m. EDT). NASA's AIRS infrared imagery showed strong thunderstorms east of the center of circulation (purple).
Credit: NASA/JPL, Ed Olsen
NASA Satellites Confirm Tropical Storm Bret's Heaviest Rains on the Eastern Side

Two NASA Satellites confirmed that the heaviest rainfall in Tropical Storm Bret is occurring in the eastern side of the storm. One satellite using precipitation radar measured rainfall, and another satellite using infrared light measured cloud-top temperatures which indicate strength of thunderstorms.

The Tropical Rainfall Measuring Mission (TRMM) satellite flew over tropical storm Bret in the Atlantic Ocean north of the Bahamas on July 19, 2011 at 1118 UTC ( 7:18 a.m. EDT). The early morning pass showed that Bret was very small but TRMM's Precipitation Radar showed that the storm had some powerful thunderstorms reaching to heights of 15km (9.3 miles) in the eastern quadrant of the storm.

NASA's Aqua satellite passed over Tropical Storm Bret seven hours later than TRMM did on July 19 at 18:35 UTC (2:35 p.m. EDT). NASA's Atmospheric Infrared Sounder (AIRS) imagery confirmed what TRMM showed by measuring very cold (-63F/-52C) cloud top temperatures. Bret still had strong thunderstorms east of the center of circulation.

At 5 a.m. EDT Tropical Storm Bret's maximum sustained winds were near 50 mph (85 kmh) although gradual weakening is forecast to occur over the next two days. Bret's center is near latitude 31.1 North and longitude 74.4 West. Bret is moving toward the northeast near 7 mph (11 kmh) and is expected to continue in that direction while speeding up. Bret's minimum central pressure is 1001 millibars.

Bret is forecast to run into strong wind shear and dry air, two factors that will take the wind out of his sails in the next couple of days.

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










July 19, 2011

Infrared image of Tropical Storm Bret captured by AIRS on July 18 at 17:53 UTC (1:53 p.m. EDT). › View larger image
This infrared image of Tropical Storm Bret was captured from the AIRS instrument on NASA's Aqua satellite on July 18 at 17:53 UTC (1:53 p.m. EDT). The purple area in the center indicate strong thunderstorms with cloud top temperatures as cold as -63 Fahrenheit (-52 Celsius). The blue areas are warmer, less strong thunderstorms.
Credit: NASA/JPL, Ed Olsen
Visible imagery from the GOES-13 satellite on July 19 shows a Tropical Storm Bret in the Atlantic Ocean. › View larger image
Visible imagery from the GOES-13 satellite at 1131 UTC (7:31 a.m. EDT) on July 19 shows a compact Tropical Storm Bret spinning in the Atlantic Ocean, some 410 miles (660 km) south of Cape Hatteras, N.C.
Credit: NASA/NOAA GOES Project
NASA's Infrared Satellite Data Shows Warming Cloud Tops in Tropical Storm Bret

Tropical Storm Bret's cloud tops are getting warmer on NASA infrared satellite imagery. That's an indication that the cloud top heights are dropping and Bret is weakening.

High cloud tops in thunderstorms are a clue that there's strong convective uplift. Uplift is the force of warm, moist, and unstable air upward into the atmosphere that condenses into the thunderstorms that power a tropical cyclone. When the uplift is weak, the convection is weak and thunderstorms are less intense than they could be. Bret is now experiencing a weaker convective uplift.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite took an infrared look at Tropical Storm Bret on July 18 at 17:53 UTC (1:53 p.m. EDT). It showed cold high thunderstorm cloud tops to the south and west of the center of circulation. The coldest cloud top temperatures were cold as -63 Fahrenheit (-52 Celsius).

So what caused the weakening in uplift and thunderstorm creation? Dry air moved into the center of Tropical Storm Bret and sapped the energy (moisture). Infrared data from AIRS on early on July 19 showed that strong convection and strong thunderstorms have almost disappeared from Bret's center.

At 5 a.m. EDT on July 19, Bret's maximum sustained wind were near 50 mph. It was located about 205 miles north-northeast of Great Abaco Island, bear 29.3 North and 76.4 West. In relation to the U.S. mainland, it's about 410 miles (660 km) south of Cape Hatteras, N.C. Bret continues to move to the open waters of the Atlantic in a north-northeasterly direction at 7 mph (11 kmh). Minimum central pressure is near 1000 millibars.

The National Hurricane Center noted today that all watches and warnings have been dropped. The forecasters there also expect Bret to speed up in the next day or two. Over that time, Bret will continue battling dry air and increasing wind shear. Those two ingredients will help weaken Bret. As a result of those two factors, the National Hurricane Center forecast indicates that Bret will likely dissipate by the weekend.

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



July 18, 2011

This visible image of Bret from GOES-13 on July 18 shows the storm over the northwestern Bahamas. › View larger image
This visible image of Bret was taken from the GOES-13 satellite on July 18 at 11:31 UTC (7:31 a.m. EDT) and shows the storm over the northwestern Bahamas.
Credit: NASA/NOAA GOES Project, Dennis Chesters
GOES-13 shows Bret developing from a low pressure area in the northwestern Bahamas. View GOES-13 movie
GOES-13 satellite imagery in 15 minute intervals from July 16 at 3:45 p.m. EDT until July 18 at 3:40 p.m. EDT shows Bret developing from a low pressure area in the northwestern Bahamas.
Credit: NASA/NOAA GOES Project, Dennis Chesters
GOES-13 Movie Catches Tropical Storm Bret Form and Intensify

The GOES-13 satellite that monitors weather over the eastern U.S. recorded a movie of the birth and strengthening of the Atlantic Ocean season's second tropical storm. Tropical Storm Bret was born in the northwestern Bahamas and continues to strengthen.

The Geostationary Operational Environmental Satellite called GOES-13 provides continuous visible and infrared imagery of the eastern U.S. and Atlantic Ocean basin from its position in space. GOES satellites are operated by NOAA, and the NASA GOES Project located at NASA's Goddard Space Flight Center in Greenbelt, Md. creates images and compiled them into the video of the storm as it developed on July 17 and developed in the early morning hours of July 18th into a tropical storm.

The animation includes sped up infrared and visible frames of data from the GOES-13 satellite and is squeezed down to 27 seconds. The movie shows satellite imagery that was captured from July 16 at 1945 UTC (3:45 p.m. EDT) until July 18 at 1940 UTC (3:40 p.m. EDT).

Tropical Depression 2 formed at 5 p.m. EDT on Sunday, July 17. At that time it had maximum sustained winds near 35 mph and was just 100 miles northwest of Great Abaco Island, near 27.5 N and 78.2 W. The Abaco Islands are located in the northern Bahamas and are made up of the main islands of Great Abaco and Little Abaco with many smaller islands called "cays."

On July 18 at 8 a.m. EDT, Tropical Depression 2 strengthened into Tropical Storm Bret. Maximum sustained winds were up to 50 mph. At that time, Bret was just 65 miles north-northwest of Great Abaco Island (and about 200 miles off the eastern Florida coast) near 27.4N 77.5W, trudging along at 3 mph to the northeast. Minimum central pressure is 1001 millibars.

A tropical storm warning is in effect for Grand Bahama Island and the Abaco Islands in the northwest Bahamas. As a result, the northwestern Bahamas are 'under the gun' for the greatest impacts from Bret. Rainfall could reach between 2 and 4 inches, while winds can reach tropical storm-force today. Those winds should diminish tonight as Bret pulls away. Beach goers will have stay away from the ocean as locally high surf conditions are expected along northern and western facing beaches today.

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