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Hurricane Season 2009: Tropical Depression 1 (Atlantic Ocean)
06.01.09
 
June 1, 2009

NASA's AIRS instrument captured TD#1's cold clouds > Larger image
NASA's AIRS instrument captured TD#1's cold clouds (blue circle south of Nova Scotia) as it was fading away on May 29.
Credit: NASA JPL, Ed Olsen
Atlantic Ocean's First Tropical Depression… Gone

The Atlantic Ocean's first tropical depression broke down on Friday, May 29, and by June 1 it was a memory.

On May 29, Tropical Depression One (TD#1) weakened into a remnant low pressure area over colder waters and winds that helped tear it apart.

By 5 p.m. EDT that evening, the National Hurricane Center said it lost its tropical characteristics. At that time, it remnants were near 40.3 north latitude and 62.3 west longitude, about 305 miles south-southeast of Halifax, Nova Scotia, Canada. It was later absorbed by a cold front that developed northeast of its center.

The infrared imagery of the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite that's used to identify the cloud temperatures in tropical cyclones captured TD#1 before it "died."

The infrared image, taken on May 29, at 1:35 p.m. EDT (17:35 UTC) shows the cold cloud temperatures in TD#1. There's a large temperature difference between typhoon's cloudtops and the warmer ocean waters. The lowest temperatures (in purple) are associated with high, cold cloud tops in the fading TD#1. The blue areas are around 240 degrees Kelvin, or minus 27 Fahrenheit. In this image, TD#1 is seen as the small round blue area southeast of Nova Scotia, Canada.

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



May 29, 2009

Tropical Depression One Fading in the Atlantic Ocean's Colder Waters > Larger image
Credit: NASA JPL/ Ed Olsen
Tropical Depression One Fading in the Atlantic Ocean's Colder Waters

Atlantic Ocean temperatures in the Northern Atlantic are in the 60 and 50 degree Fahrenheit range, and that's way too cold for a tropical depression to survive. Now that Tropical Depression One is approaching those cold waters it is forecast to fade quickly.

NASA's Aqua satellite flew over Tropical Depression One (TD#1) and the Atmospheric Infrared Sounder (AIRS) instrument onboard captured this infrared image on May 29 at 2:29 a.m. EDT (06:29 UTC). In the AIRS image, TD#1 is the small round blue area located far to the east of the New Jersey coast and south of Nova Scotia, Canada. The blue coloration in this image represents cold high cloud tops that make up TD#1. The warmer ocean waters that surround it are seen in orange, and the cooler waters that TD#1 is moving toward are shown in yellow. The blue area stretching from Canada through New England, New York and eastern Pennsylvania down to North Carolina is a cold front that is moving east.

At 11 a.m. EDT on May 29, TD#1 was located near 39.6 north latitude and 64.0 west longitude, about 345 miles south of Halifax, Nova Scotia, Canada. TD#1 was moving east-northeast near 18 mph, and will continue on that track until it fades away. Estimated minimum central pressure is near 1006 millibars.

Maximum sustained winds are near 35 mph, but are expected to wane as TD#1 moves into those cooler waters of the North Atlantic Ocean. Already the main area of thunderstorms are separated from the actual center of circulation because of westerly wind shear, and the thunderstorms lie to the southeast of the center. That's an indication that the storm has severely weakened.

The depression is also beginning to merge with a frontal system that is developing northeast of the center of the storm, so TD#1 "isn't long for the world" as the saying goes.

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



May 28, 2009

NASA's TRMM Satellite Captures Tropical Depression One's Rainfall from Space > Larger image
Credit: NASA/SSAI, Hal Pierce
NASA's TRMM Satellite Captures Tropical Depression One's Rainfall from Space

The formation of Tropical Depression number one (TD#1) has sent a signal that the 2009 Atlantic hurricane season is right around the corner. The Atlantic hurricane season doesn't officially begin until June but it isn't unusual for tropical cyclones to form in the Atlantic in May. This depression is predicted by the National Hurricane Center to become extratropical within 24 hours and dissipate.

The first Atlantic tropical storm this season will be called Ana, but this storm won't make it to the strength of a tropical storm, so it won't get the name. In 2003 the first named tropical storm was called Ana and formed in April!

The image above was produced using data from the Tropical Rainfall Measuring Mission (TRMM) satellite when it flew above TD#1 on May 28 at 0246 UTC (May 27 at 10:46 pm EDT). TRMM revealed that TD#1 was very small but did have a few areas of potent thunderstorms near it's center.

Text credit: Hal Pierce Goddard Space Flight Center/SSAI



The GOES Satellite captures the first tropical depression of the Atlantic Ocean hurricane season > Larger image
The GOES Satellite captures the first tropical depression of the Atlantic Ocean hurricane season.
Credit: NASA/NOAA GOES Project
First Atlantic Ocean Tropical Depression Forms

Forecasters at the National Hurricane center have been saying there's a probability that the Low pressure area off the North Carolina coast could become the Atlantic Ocean Hurricane Season's first tropical depression. They were right.

The Geostationary Operational Environmental Satellite GOES-12 captured image of Tropical Depression 1 on May 28 at 10:31 a.m. EDT (14:31 UTC). The tight circular area of clouds in the top right area of this image in the Atlantic Ocean is Tropical Depression 1 (TD-1). The U.S. mainland is to the left of TD-1.

TD-1 has maximum sustained winds near 35 mph and is now forecast to become a tropical storm over the next day or so. After that, it is expected to weaken or dissipate over colder waters on Saturday.

At 11:00 a.m. EDT TD-1's center was near latitude 37.3 north and longitude 71.0 west or about 310 miles south of Providence, Rhode Island. Estimated minimum central pressure is 1007 millibars. TD-1 is moving toward the northeast near 17 mph and this general motion is expected to continue over the next 24-48 hours. The depression is not expected to threaten any land areas.

GOES-12 is operated by the National Oceanic and Atmospheric Administration. The image 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



The scattered thunderstorms (blue) show disorganization of the coastal Low in this Aqua satellite AIRS image > Larger image
The scattered thunderstorms (blue) show disorganization of the coastal Low in this Aqua satellite AIRS image.
Credit: NASA JPL, Ed Olsen
Coastal Low Moves Away, Could Still Become Tropical at Sea

The low pressure system off the North Carolina coast is now moving further away from the U.S., but the National Hurricane Center says there's still a "30 percent chance" that it could become a tropical depression before it hits cooler waters that will squelch that transformation.

The low pressure area will continue pushing northeast away from the North Carolina coast today as an elongated area of low pressure (called a trough) develops inland to the west forcing the coastal low out to sea. On Friday a cold front also approaching from the west will sweep eastward over North Carolina and offshore Saturday, pushing the coastal low even further out to sea.

The National Hurricane Center issued their latest notice on the low on May 28 at 7:55 a.m. EDT. It noted "shower activity increased this morning in association with the area of low pressure located about 225 miles east-northeast of Cape Hatteras, North Carolina." The low is moving about 15 mph in a northeast direction in the warm waters of the Gulf Stream, which still provides potential for it to become tropical.

If the system is going to make the tropical transition, it has to happen before 8 a.m. Saturday morning, May 30, because by then it will be in cooler waters near the 80 degree Fahrenheit threshold needed to power storms.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured an infrared image of the low on May 27 at 1:47 p.m. EDT (17:47 UTC. In the infrared image, the cold clouds from the low are seen in several areas in blue and purple off the North Carolina coast. Because the high clouds are broken, it's indicative of a very weak storm. The white border in this image circles the center of the low's circulation.

The infrared image shows a large temperature difference between the storm's cloud-tops and the warm ocean temperatures. In this image, the orange temperatures are 80F (300 degrees Kelvin) or warmer. 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.

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



May 27, 2009

Low Pressure Area Off North Carolina Coast Being Watched for Development > Larger image
GOES-12 satellite image of the coastal low off the North Carolina coast..
Credit: NASA GOES Project
Low Pressure Area Off North Carolina Coast Being Watched for Development

It’s not June 1 yet, but the National Hurricane Center (NHC) is watching an area of low pressure 120 miles south of Cape Hatteras, North Carolina for possible development into a tropical depression.

June 1 is the official first day of hurricane season in the Atlantic Ocean basin, and it runs through November 30, but storms don’t have to follow a calendar. Those dates are an average of the dates most storms have formed historically.

On Wednesday, May 27, the NHC issued a “Special Tropical Weather Outlook” about the low pressure area. Although the statement noted that conditions are not favorable for significant development, the system does have a brief opportunity to become a tropical cyclone before it reaches the colder ocean surface temperatures north of the Carolinas. “There’s a 30 percent chance” of the low becoming a tropical depression, according to the NHC.

The low is moving north near 10-15 mph, and is expected to bring showers to coastal North Carolina today. It was located near 29 degrees north latitude and 75 degrees west longitude. U.S. Air Force investigators are flying into the storm later today to investigate.

This satellite image was captured on May 27 at 11:31 UTC (7:31 a.m. EDT) from the Geostationary Operational Environmental Satellite (GOES-12). The low pressure system that the National Hurricane Center is watching is the circular area of clouds to the right of the North Carolina coast.

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.

The low is expected to generate scattered showers and rip currents today along the North Carolina coast. The National Weather Service issued a statement today, May 27, for Carteret, Outer Banks Dare, and Outer Banks Hyde counties for a high threat of rip currents north of Cape Lookout through this evening. High winds will also produce rough surf. The greatest threat for rip currents will be near low tide around 4 p.m. this afternoon.

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