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Hurricane Season 2009: Tropical Depression Ana (Atlantic)
08.19.09
 
August 19, 2009

August 18 when Ana was mostly over Cuba and partially over southern Florida. > View larger image
AIRS captured Ana's remnant cold clouds with infrared imagery on August 18 at 2:11 p.m. EDT. At that time she was mostly over Cuba, and partially over southern Florida.
Credit: NASA/JPL, Ed Olsen
Remnants of Ana Still Gasping to Regenerate

Ana has had a tough life since she started struggling for life in the eastern Atlantic, now satellite imagery show her remnants continue to weaken.

Today, August 19, Ana's clouds and scattered showers are over the northwestern Bahamas, south Florida and the northwestern Caribbean Sea but they're expected to gradually diminish. The National Hurricane Center still gives Ana a slim chance to regenerate, less than a 30 percent.

Today's National Weather Service forecast in the Florida Everglades calls for a mostly cloudy day with "showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. High near 89. East wind between 8 and 13 mph." Tonight, the chance of shower drops to 30 percent with skies becoming mostly clear. To see live radar of the Everglades: http://radar.weather.gov/radar.php?rid=AMX&product=NCR&overlay=11101111&loop=yes.

NASA's Atmospheric Infrared Sounder (AIRS) instrument on the Aqua satellite captured Ana's remnants with infrared imagery on August 18 at 2:11 p.m. EDT. The infrared revealed that there are still some thunderstorms with strong convection, bringing some heavy rainfall in isolated areas, which corresponds with today's forecast for the Everglades.

Although Ana is considered a remant low pressure area, she's still bringing some heavy rains to isolated areas in south Florida's Everglades and areas in Cuba.

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



August 18, 2009

GOES image of Claudette and Ana > High resolution image
The latest NOAA's GOES-12 satellite imagery from August 18 at 7:31 a.m. EDT doesn't show any circulation from what was once Claudette over Mississippi or Alabama. In fact, it appears that what's left of her clouds stretch from Mississippi up the Appalachian Mountain range.
Credit: NASA GOES Project
Claudette and Ana Now Disorganized on GOES Satellite Imagery

Satellite imagery from the National Oceanic and Atmospheric Administration's Geostationary Operational Environmental Satellite, GOES-12 shows clearly that both former Tropical Storms Claudette and Ana are now disorganized and are moving on.

Ana's life has been a struggle since its beginnings as tropical depression Two. Late on August 17, it really started to fall apart. Today, August 18, the remnants of Ana are in the form of disorganized showers and thunderstorms that stretch from Haiti, across eastern Cuba to southeastern and central Bahamas. That cluster of storms is moving west between 20-25 mph. The showers and thunderstorms associated with Ana's remnant will cover all of Cuba, move into south Florida and the Bahamas. There's still a chance it could all come together again and be reborn as Ana, but it's less than 30 percent right now.

Claudette made a much more memorable impression, particularly over the Florida Panhandle, southern Alabama and Mississippi. NOAA's National Hydrometeorological Prediction Center noted that the precipitation associated with Claudette's remnants have diminished now that it's over the southeastern U.S. They note "showers and thunderstorms may develop and produce isolated heavier amounts across the southeastern U.S. [today, August 18]." Surface observations and satellite imagery don't even detect any surface circulation, so Claudette has truly dissipated.

The latest NOAA's GOES-12 satellite imagery doesn't show any circulation from what was once Claudette over Mississippi or Alabama. In fact, it appears that what's left of her clouds stretch from Mississippi up the Appalachian Mountain range. The image, taken on August 18 at 7:31 a.m. EDT (1131 UTC) was created by the NASA GOES Project at NASA Goddard Space Flight Center in Greenbelt, Md.

Claudette didn't go without leaving a very wet mark, however. From the National Hydrometeorological Prediction Center, here are some rainfall totals through 10 p.m. EDT, August 17:

...FLORIDA...

4.62 - MILLIGAN
4.49 - CRESTVIEW 1.9 SE
3.90 - PORT ST. JOE 0.6 SE
3.69 - APALACHICOLA MUNI ARPT
2.67 - MIRAMAR BEACH 9.5 ESE
2.42 - TYNDALL AFB/PANAMA CITY
2.15 - PANAMA CITY/BAY CO. ARPT
2.04 - NICEVILLE 3.4 ESE
1.90 - CALLAWAY 0.3 W
1.82 - BAKER 8.2 NE

...ALABAMA...

2.11 - BRADLEY
1.21 - MOBILE DOWNTOWN ARPT

...GEORGIA...

2.37 - FORT BENNING -COLUMBUS
1.95 - COLUMBUS METRO ARPT

Text credit: Rob Gutro (from NHPC reports), NASA's Goddard Space Flight Center

August 17, 2009

Tropical Depression Claudette over Alabama, and Tropical Depression Ana raining on Puerto Rico. > View larger image
Another satellite that NASA uses is the Geostationary Operational Environmental Satellite, or GOES. GOES-12 covers the Atlantic Ocean, and is managed by NOAA. On August 17 at 12:15 p.m. EDT, GOES-12 captured Tropical Depression Claudette over Alabama, and Tropical Depression Ana raining on Puerto Rico.
Credit: NASA/GOES Project
Ana's clouds when she was a tropical storm on Aug. 15. > View larger image
This AIRS infrared satellite image shows Ana's clouds (depicted in blue) when she was a tropical storm on Aug. 15. By mid-day on Aug. 16, she weakened to a tropical depression.
Credit: NASA/JPL, Ed Olsen
Ana's Path Being Mapped by NASA Satellites, She's Drenching Puerto Rico

Tropical Depression Ana is currently drenching Puerto Rico, and tropical storm watches are posted for Puerto Rico and the Virgin Islands as Ana continues westward. Both the Aqua and GOES satellites have captured Ana on her westward track in the Atlantic.

For a live look at the National Weather Service Radar in Puerto Rico, go to: http://radar.weather.gov/radar.php?rid=JUA&product=NCR&overlay=11101111&loop=yes. Ana is expected to produce rainfall amounts of 2 to 4 inches over Puerto Rico, the U.S. and British Virgin Islands and the Dominican Republic with isolated maximum amounts of 6 inches over mountainous terrain.

Tropical Depression Ana has taken a long time to get going and she's still squeaking by as a tropical depression. Over the weekend, NASA satellite imagery captured her short stint as a tropical storm, but she's weakened again and is expected to now rain on Hispaniola before heading to Florida.

By 11 a.m. EDT on Monday, August 17, Ana's center was located 75 miles south of San Juan, Puerto Rico, near 17.3 north and 66.2 west. She was moving at a good clip toward the west-northwest near 28 mph, which means that she won't linger as long and dump as much rain. However, she's expected to slow down in the next day or two. Maximum sustained winds remain near 35 mph, and minimum central pressure is 1008 millibars.

The Atmospheric Infrared Sounder (AIRS) flies on Aqua and provides visible, infrared and microwave images and measures cloud top temperature and pressure. AIRS captured an image of Ana on August 15 when she was a tropical storm and had good cloud formation. By mid-day on August 16, Ana deteriorated into a tropical depression.

How does infrared imagery know how high clouds are in the sky? The coldest ones are higher in the sky (because in the troposphere, the lowest layer of atmosphere where weather happens, temperatures fall the higher up you go until you get to the stratosphere). The highest clouds are as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F) and second highest level of clouds are about 240 Kelvin, or minus 27F. The colder the clouds are, the higher they are, and the more powerful the thunderstorms are that make up the cyclone.

Another satellite that NASA uses is the Geostationary Operational Environmental Satellite, or GOES. GOES-12 covers the Atlantic Ocean, and is managed by NOAA. On August 17 at 12:15 p.m. EDT, GOES-12 captured Tropical Depression Claudette over Alabama, and Tropical Depression Ana raining on Puerto Rico.

Forecasters are closely watching Ana because she may degenerate further. However, her remnants or the depression, whichever she becomes, is expected to track to Florida's west coast.

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



GOES-12 captured TD4 about to make landfall in the Florida Panhandle on August 16 (far left). > View larger image
GOES-12 captured TD4 about to make landfall in the Florida Panhandle on August 16 (far left), Tropical Storm Ana approaching the Leeward Islands (center) and Tropical Storm Bill (far right).
Credit: NASA/GOES Project
TD4 to Make Florida Panhandle Landfall as Claudette; Ana and Bill Following

Tropical Depression 4 formed from the low pressure area that NASA's GOES satellite saw on Friday, August 14. On Sunday, August 16 the low was poised to make landfall in the Florida panhandle but not until it strengthens into Tropical Storm Claudette later on Sunday.

Tropical Storm Warnings are in effect on Sunday, August 16 from the Alabama/Florida border east to Suwanee River. At 8 a.m. EDT August 16, Tropical Depression 4 was 125 miles south-southeast of Apalachicola, FL with sustained winds near 35 mph. It was centered near 28.1 north and 84.1 west with a minimum central pressure near 1011 millibars.

TD4 is expected to make landfall tonight on the Florida panhandle bringing 3-5 inches of rain with isolated areas up to 10 inches, and a 3-5ft. storm surge along the coast. It will then track north into Alabama on Monday.

Residents should be prepared for gusty winds and flooding rains. For updates, visit the National Hurricane Center website at http://www.nhc.noaa.gov.

Live Radar of the Florida Panhandle: http://radar.weather.gov/radar.php?rid=EVX&product=NCR&overlay=11111111&loop=yes.

Tropical Depression 2 did become Tropical Storm Ana on Saturday, August 15 and is moving west toward Leeward Isles, Puerto Rico, Dominican Republic over the next couple of days. Maximum sustained winds are near 40mph.

The third area in Atlantic forecasters were watching near Africa has now strengthened into Tropical Storm Bill with sustained winds near 45 mph. 1,640 miles east of the Lesser Antilles.

The GOES-12 satellite captured TD4 poised to make landfall in the Florida Panhandle, Tropical Depression Ana just east of the Lesser Antilles, and Tropical Storm Bill far to the east in the open ocean. The NASA GOES Project is operated out of the NASA Goddard Space Flight Center in Greenbelt, Md. and creates imagery from the GOES satellite data.

Finally, in the Eastern Pacific, Hurricane Guillermo weakened with sustained winds near 100mph. He is still in the open ocean about 1,150 miles east of Hilo, Hawaii and no threat to land.

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



August 14, 2009

Tropical Depression 2 on Shaky Ground, 3 Other Areas to Watch on Weekend

The Atlantic Ocean's second Tropical Depression has been on shaky ground since it formed early in the week of August 11. It meandered westward from the African coast and maintained its tropical depression status until weakening to a remnant low. Now it has the potential to come back. In addition to Tropical Depression 2, there are three other areas forecasters are watching in the Atlantic Basin. Residents of Florida should particularly be watchful as there's a potential for tropical development on both the east and west coasts this weekend.

TD2 Quickscat image> View larger image
QuikScat image taken on August 12 at 4:40 p.m. EDT showed a good circulation around the center of tropical depression 2. However, since then, the winds have waned. Credit: NASA JPL, Peter Falcon
At 5 p.m. EDT on Aug. 13, Tropical Depression 2 (TD2) in the Atlantic Ocean was downgraded to a remnant low pressure area. If you're a tropical cyclone, you can't get any lower than that, aside from total dissipation. At that time, TD2's remnants were about 930 miles west of the southernmost Cape Verde Islands off the African coast.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite measures cloud top temperature and pressure, and it captured a look at the remnants of Tropical Depression 2, and it was still maintaining somewhat of a circular shape. In infrared imagery, NASA's false-colored purple clouds are as cold as or colder than 220 Kelvin or minus 63 degrees Fahrenheit (F). The blue colored clouds are about 240 Kelvin, or minus 27F. The colder the clouds are, the higher they are, and the more powerful the thunderstorms are that make up the cyclone.

In addition to TD2's struggle for life, there other three areas forecasters will be watching over the weekend and residents of Florida should keep an eye on both coasts for tropical development of two of the three systems.

TD2 AIRS image> View larger image
The AIRS instrument on NASA's Aqua satellite captured an image of Tropical Depression 2's cloud temperatures on August 13 at 2:17 p.m. EDT. Credit: NASA JPL, Ed Olsen
Farthest from the U.S. is the area of showers and thunderstorms with the greatest potential for developing into a tropical cyclone over the weekend. On Aug. 14, that area of disturbed weather was located 250 miles west-southwest of the southern Cape Verde Islands. It has a "greater than 50 percent chance of developing."

Much closer to the U.S. are two areas with less than a 30 percent chance of development. One area of showers and thunderstorms are associated with a tropical wave that stretches from the Bahamas to Hispaniola. The other area is in the Gulf of Mexico, associated with a weak elongated area of low pressure. The area is centered off the coast from Tampa, Florida. Residents of Florida should be on watch this weekend, as tropical development is possible around them on both the east and west coasts. For the latest updates, visit: www.nhc.noaa.gov.

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

August 13, 2009

NASA's Terra Satellite Sees TD2 Clinging to Life in Atlantic

NASA's Terra satellite reveals very sparse cloud cover associated with the depression. > View larger image
NASA’s Terra satellite flew over Tropical Depression Two at 9:11 a.m. EDT (1311 UTC) on August 13 and the image revealed very sparse cloud cover associated with the depression, indicating a weak storm.
Credit: NASA/NRL
The second tropical depression in the Atlantic Ocean is stubbornly clinging to life, and NASA satellite imagery confirms that it’s a weak storm. Meanwhile, there are two other areas in the Atlantic that forecasters are eyeing for possible development.

Today, August 13, Tropical Depression number 2 is holding onto maximum sustained winds near 30 mph, and isn't expected to strengthen much in the next several days. It's just expected to stay "depressed" as it keeps moving westward near 9 mph. The depression is located about 885 miles west of the southernmost Cape Verde Islands, near latitude 14.0 north and longitude 37.6 west. Minimum central pressure was 1008 millibars.

Satellite imagery indicated this morning, August 13 that there were only a few showers and thunderstorms associated with Tropical Depression 2 (TD2), and if it continues to be this weak, the system will be downgraded to a remnant low pressure area. NASA's Advanced Microwave Scanning Radiometer-E, which looks at precipitable water, that is, water in the clouds that can rain down, indicated an area of drier air has almost totally wrapped around the depression, and dry air can kill a tropical cyclone.

The Moderate Resolution Imaging Spectroradiometer on NASA’s Terra satellite flew over TD2 at 9:11 a.m. EDT (1311 UTC) on August 13 and revealed a very weak system in terms of its cloud cover.

There are other two areas in the Atlantic that forecasters are watching, and one may hold greater promise in becoming a tropical storm. The first area, which has a low chance of organizing (less than 30 percent) is associated with a tropical wave stretching north to south and about to move through Puerto Rico. It's producing disorganized showers and thunderstorms.

The second, more favorable area is located to the east of TD2, just off the African coast. In that area, showers and thunderstorms are associated with a broad area of low pressure some 250 miles south-southeast of the Cape Verde Islands. The National Hurricane Center is giving that area a 50 percent chance of development. Right now, it's a tropical race to see which system, either this one, or Tropical Depression 2 strengthens enough to become Tropical Storm Ana

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



August 12, 2009

NASA's Terra Satellite Captures a "Well-Rounded" Atlantic Tropical Depression 2

Tropical Depression 2 on August 12 showed a good round circulation. > View larger image
NASA's Terra satellite captured Tropical Depression 2 on August 12 using the Moderate Imaging Spectroradiometer (MODIS) instrument. It showed a good round circulation, indicating that the storm is likely strengthening.
Credit: NASA, MODIS Rapid Response
Tropical Depression 2 has a good round shape, at least that's how it appears on the latest satellite imagery from NASA's Terra satellite on August 12.

Terra flew over Tropical Depression 2 (TD2) on August 12 at 8:25 a.m. EDT (12:25 UTC), and its Moderate Imaging Spectroradiometer (MODIS) instrument captured a good image of the storm. Although the storm is 630 miles west of the southernmost Cape Verde Islands (off the African coast).

TD2 is currently still just below tropical storm strength, and when she becomes a tropical storm, she'll be the first in the Atlantic Ocean and will get the name "Ana."

At noon time EDT on Wed. August 12, TD2 had maximum sustained winds near 35 mph and was forecast to strengthen slowly. It was located near 14.3 north and 33.8 west, and was moving west near 13 mph. Its minimum central pressure was 1006 millibars.

Another NASA Satellite came into play with the forecast on Tropical Depression 2: QuikScat. The National Hurricane Center uses QuikScat wind imagery to get a look at the winds around the center of a storm. The discussion from today says, "A Quikscat overpass at (4:12 a.m. EDT) 0812z did not show Tropical-storm-force wind vectors that looked reliable. Thus...the Initial intensity remains 30 knots (35 mph) for this advisory."

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



August 11, 2009

The Second Atlantic Tropical Depression Arrives!

This image from August 11 showstropical depression 2 in the Atlantic Ocean. > View larger image
This AIRS Infrared image from Aug 11 shows cold high clouds (in blue) from tropical depression 2 in the Atlantic Ocean (the circular blue area). The land to the east is the African continent.
Credit: NASA/JPL, Ed Olsen
The second tropical depression of the Atlantic hurricane season has finally formed. It's been a long time since that forecasters have seen any tropical activity in the Atlantic Ocean as the first Atlantic depression formed in late May. Tropical Depression 2 (TD2) formed at 6 a.m. EDT today, August 11 far in the eastern Atlantic Ocean about 280 miles west of the southernmost Cape Verde Islands.

At 11 a.m. EDT, TD2 had sustained winds near 30 mph, and was moving west near 13 mph. It had moved about 70 miles west since its birth and was now located near 14.6 north and 29.6 west. TD2's minimum central pressure is 1006 millibars.

Data from NASA's Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite, captured an infrared image of TD2 late on August 10 at 11:53 p.m. EDT.

NASA false-colors the AIRS infrared imagery to indicate the location of the highest clouds in a storm. In the AIRS imagery, purple coloration indicates the highest clouds, while blue coloration indicates lower clouds. The AIRS image indicated only the lower clouds in TD2. Those clouds however are still icy cold, about 240 Kelvin, or minus 27F.

The National Hurricane Center in Miami, Fla., who forecasts storms in the Atlantic Ocean noted in their discussion today, "Sea surface temperatures along the forecast track will be marginally warm...and the depression will have to endure some dry air in the mid-levels. Nonetheless, vertical [wind] shear is expected to be light enough during the first four days or so to allow some slow strengthening.

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