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| |  | | | | Hurricane Season 2005: Katrina
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10.13.05
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Latest Update - October 13, 2005
Hurricanes Katrina and Rita Storm Track Map and Animation
+ Avi (1 Mb): Tracking map animation
The above images, derived from NASA QuikSCAT satellite data, show the extensive pattern of rain water deposited by Hurricanes Katrina and Rita on land surfaces over several states in the southern and eastern United States. These results demonstrate the capability of satellite scatterometers to monitor changes in surface water on land.
The color scale depicts increases in radar backscatter (in decibels) between the current measurement and the mean of measurements obtained during the previous two weeks. The backscatter can be calibrated to measure increases in surface soil moisture resulting from rainfall. The yellow color corresponds to an increase of approximately 10 percent or more in surface soil moisture according to the calibration site of Lonoke, Ark.
The two hurricanes deposited excessive rainfall over extensive regions of the Mississippi River basin. Basins the size of the Mississippi can take up to several weeks before such excess rainfall significantly increases the amount of river discharge. With hurricane season not over until November 30, the potential exists for significant flooding, particularly if new rain water is deposited by new hurricanes when river discharge peaks up as a result of previous rainfalls. River discharge should be closely monitored to account for this factor in evaluating potential flood conditions in the event of further hurricanes.
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Earlier Images and Information
NASA Katrina Poster
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Pumping Water Out of New Orleans
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The floods that buried up to 80 percent of New Orleans had noticeably subsided by September 15, 2005, when the top image was taken by the Landsat 7 satellite. In the two and a half weeks that had passed since Hurricane Katrina flooded the city, pumps had been working nonstop to return the water to Lake Pontchartrain. As portable pumps were brought in to supplement the permanent pumps already hard at work, as much as 380 cubic meters (380,000 liters or 23,190,000 cubic inches) of water were being pumped out of New Orleans every second, according to the U.S. Army Corps of Engineers.
The progress in draining the city is evident when the September 15 image is compared with an image taken one week earlier. In the lower image, taken by the Landsat 5 satellite on September 7, black flood water covers much of the city. By September 15, the dark flood water had all but disappeared, lingering only in a few sections of the city. The September 7 image does not show the full extent of the flooding. Taken more than a week after the hurricane struck New Orleans, the image shows a flooded city that had already started to drain. In a similar (but cloudy) image taken on August 30, the flood water in St. Bernard Parish, image right, extends almost to the Mississippi River. Credit: Images provided courtesy of the United States Geological Survey Center for Earth Resources Observation & Science (CEROS).
Flooding in the Aftermath of Hurricane Katrina
MISR Images of Katrina
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These views of the Louisiana and Mississippi regions were acquired before and one day after Katrina made landfall along the Gulf of Mexico coast, and highlight many of the changes to the rivers and vegetation that occurred between the two views. The images were acquired by NASA's Multi-angle Imaging SpectroRadiometer (MISR) on August 14 and August 30, 2005. These multiangular, multispectral false-color composites were created using red band data from MISR's 46° backward and forward-viewing cameras, and near-infrared data from MISR's nadir camera. Such a display causes water bodies and inundated soil to appear in blue and purple hues, and highly vegetated areas to appear bright green. The scene differentiation is a result of both spectral effects (living vegetation is highly reflective at near-infrared wavelengths whereas water is absorbing) and of angular effects (wet surfaces preferentially forward scatter sunlight). The two images were processed identically and extend from the regions of Greenville, Mississippi (upper left) to Mobile Bay, Alabama (lower right).
There are numerous rivers along the Mississippi coast that were not apparent in the pre-Katrina image; the most dramatic of these is a new inlet in the Pascagoula River that was not apparent before Katrina. The post-Katrina flooding along the edges of Lake Pontchartrain and the city of New Orleans is also apparent. In addition, the agricultural lands along the Mississippi floodplain in the upper left exhibit stronger near-infrared brightness before Katrina. After Katrina, many of these agricultural areas exhibit a stronger signal to MISR's oblique cameras, indicating the presence of inundated soil throughout the floodplain. Note that clouds appear in a different spot for each view angle due to a parallax effect resulting from their height above the surface.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe between 82° north and 82° south latitude every nine days. Each image covers an area of about 380 kilometers by 410 kilometers. The data products were generated from a portion of the imagery acquired during Terra orbits 30091 and 30324 and utilize data from blocks 64-67 within World Reference System-2 path 22.
MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is managed for NASA by the California Institute of Technology.
Image credit: NASA/GSFC
Text credit: Clare Averill (Raytheon RIS/Jet Propulsion Laboratory), David J. Diner and Barbara J. Gaitley (Jet Propulsion Laboratory)
Katrina Rolls Barrier Island Landward
Images Above: Three-dimensional views of island topography (A-C), post-Katrina oblique aerial photograph (D)
Barrier islands are highly dynamic places that move and change in response to ocean waves and currents. Over long time scales, barrier islands move slowly landward as sea level rises. Large storms contribute significantly to an island's landward migration, a process also known as 'barrier island rollover.' Increased water levels, large waves and strong flows remove sand from the beach and then deposit it on the bay-side of the island. + Read More
Earlier Images and Information
Katrina's Aftermath from Space
The extent of flooding in the greater New Orleans metropolitan area is clearly visible in this image, acquired from the International Space Station on September 8, 2005, of areas damaged by Hurricane Katrina. Flooded areas are dark greenish brown, while dry areas to the west of the 17th Street Canal and along the banks of the Mississippi River (lower half of image) are light brown to gray. This cropped image (from the parent frame ISS011-E-12527) is oriented with north to the top. Credit: NASA
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 + Feature Story on Sea Height in the Gulf, Ocean Heat, and Hurricane Intensification - Posted September 16, 2005
ASTER Images of New Orleans
Seventeen days after Hurricane Katrina flooded New Orleans, much of the city is still under water. In this pair of images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer on NASA's Terra satellite, the affected areas can clearly be seen. The top image mosaic was acquired in April and September 2000, and the bottom image was acquired September 13, 2005.
The flooded parts of the city appear dark blue, such as the golf course in the northeast corner, where there is standing water. Areas that have dried out appear light blue gray, such as the city park in the left middle. On the left side of the image, the failed 17th Street canal marks a sharp boundary between flooded city to the east, and dry land to the west. The images cover an area of 10.4 x 7.1 kilometers and are centered near 30 degrees north, 90.1 degrees west. Image credit: NASA/JPL
+ High resolution JPEG
EAARL Images of the Gulf Coast
The image above was taken from NASA's Experimental Advanced Airborne Research Light Detection and Ranging (EAARL) system that has been surveying the coastline of the Gulf of Mexico this week. The aircraft is taking high-resolution observations that can be used to assess the amount of damage to communities and the environment. This activity is being conducted at the request of the U.S. Geological Survey in cooperation with the Federal Emergency Management Agency and the Army Corps of Engineers. + For more images like this and additional information, click this link.
University of Wisconsin-Madison's Space Science and Engineering Center's role in Hurricane Katrina
Cloud Spirals and Outflow in Tropical Storm Katrina
Click on image to view full resolution.
On Tuesday, August 30, 2005, NASA's Multi-angle Imaging SpectroRadiometer retrieved cloud-top heights and cloud-tracked wind velocities for Tropical Storm Katrina, as the center of the storm was situated over the Tennessee valley. At this time Katrina was weakening and no longer classified as a hurricane, and would soon become an extratropical depression. Measurements such as these can help atmospheric scientists compare results of computer-generated hurricane simulations with observed conditions, ultimately allowing them to better represent and understand physical processes occurring in hurricanes.
Because air currents are influenced by the Coriolis force (caused by the rotation of the Earth), Northern Hemisphere hurricanes are characterized by an inward counterclockwise (cyclonic) rotation towards the center. It is less widely known that, at high altitudes, outward-spreading bands of cloud rotate in a clockwise (anticyclonic) direction.
The image on the left shows the retrieved cloud-tracked winds as red arrows superimposed across the natural color view from MISR's nadir (vertical-viewing) camera. Both the counter-clockwise motion for the lower-level storm clouds and the clockwise motion for the upper clouds are apparent in these images. The speeds for the clockwise upper level winds have typical values between 40 and 45 m/s (144-162 km/hr). The low level counterclockwise winds have typical values between 7 and 24 m/s (25-86 km/hr), weakening with distance from the storm center.
The image on the right displays the cloud-top height retrievals. Areas where cloud heights could not be retrieved are shown in dark gray. Both the wind velocity vectors and the cloud-top height field were were produced by automated computer recognition of displacements in spatial features within successive MISR images acquired at different view angles and at slightly different times.
The Multi-angle Imaging SpectroRadiometer observes the daylit Earth continuously, viewing the entire globe between 82° north and 82° south latitude every nine days. This image covers an area of about 380 kilometers by 1970 kilometers. These data products were generated from a portion of the imagery acquired during Terra orbit 30324 and utilize data from blocks 55-68 within World Reference System-2 path 22.
MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Science Mission Directorate, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is managed for NASA by the California Institute of Technology.
Image credit: NASA/GSFC/LaRC/JPL, MISR Team
Text acknowledgment: Clare Averill (Raytheon ITSS/Jet Propulsion Laboratory), David J. Diner, Mike Garay (Jet Propulsion Laboratory) and Greg McFarquhar (University of Illinois at Urbana-Champaign).
Updated - September 01, 2005 - 9:24 a.m. EDT
The animated GIF above shows the Gulf Coast area before Katrina hit on August 27 and after on August 30 and August 31, 2005. Flooding can be seen at Lake Pontchartrain near New Orleans and at Mobile Bay. This GIF will play four times in succession. To see it play again, please refresh the page.
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The images above show data from NASA's MODIS instrument, received and processed at the University of South Florida's Institute for Marine Remote Sensing (IMaRS). In the color scheme in the images, red normally indicates dry land, while blue indicates water. The top image shows the same area before Katrina hit, showing red throughout New Orleans, meaning dry land. The second image was captured on August 31, 2005, showing large areas of New Orleans and the adjacent Gulf Coast inundated with water. Credit: NASA/USF/IMaRS
+ Click for more images of flooding in the Gulf Coast area including New Orleans and Biloxi.
+ Click for USGS site showing before and after images of Gulf Coast flooding.
Updated August 31, 2005
This image pair and animation (Click on image to view animation) from NASA's Multi-angle Imaging SpectroRadiometer (MISR) shows the strong convective development of Hurricane Katrina on Saturday, August 27 as it moved west through the Gulf of Mexico. Over 7 minutes during which all 9 MISR cameras viewed Katrina, the animation captures the cloud-top sides, the counterclockwise rotation of the eyewall, and the bubbling growth of the towering cloud structures. At this time, Katrina was undergoing rapid development -- it had just been upgraded to a Category 3 hurricane, and within 24 hours it would reach Category 5. On Monday morning when the eyewall made landfall over the United States, it was again a Category 4 storm. Hurricane Katrina is one of the most powerful and destructive storms on record for the Atlantic Basin. + Click on this link for the rest of the story.
In the wake of Hurricane Katrina, much of New Orleans is under water in the top satellite image, taken on August 30, 2005, at 11:45 a.m. CDT by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite. Early news reports say that as much as 80 percent of the city is flooded after levies failed to hold Katrina’s massive storm surge back. The flooding is getting worse as water slowly seeps into the city from Lake Pontchartrain.
On Saturday, August 27, 2005, New Orleans formed a tan and green grid sandwiched between the lake shore and the river in the lower image. Three days later, dark pools of water covered the eastern half of the city, and a large section of Lake Pontchartrain ballooned into the region immediately west of the city. Widespread flooding is visible elsewhere in the top image. Lake Pontchartrain and Lake Maurepas have nearly blended into a single body of water, separated only by a narrow strip of land. Dark smudges line the rivers flowing into both lakes, a sign that water covers the ground around them.
The images are shown in false color to make water visible against the land. Water is black or dark blue where it is colored with mud, vegetation is bright green, and clouds are light blue and white. The large images provided above provide a broader view of the region. They show flooding along the Mississippi and Alabama coast, particularly around Mobile Bay and parts of coastal Mississippi. The large images are at MODIS’ maximum resolution, but both the August 30 and August 27 images are available in additional resolutions from the MODIS Rapid Response Team. Credit: NASA images courtesy Jeff Schmaltz, MODIS Land Rapid Response Team at NASA GSFC
Above are images of Hurricane Katrina created from AIRS infrared and microwave observations at 1:30 AM local time on Monday, August 29, 2005 as it makes landfall on the Gulf Coast. At the time of these images, Katrina was a Category 5 storm with peak winds of approximately 150 mph. The images to the right were taken at 2:00 AM local time on August 30, 2005.
The infrared image shows how the storms look through an AIRS Infrared window channel. Window channels measure the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures are associated with high, cold cloud tops that make up the top of the hurricane. The infrared signal does not penetrate through clouds, so the purple color indicates the cool cloud tops of the storm. In cloud-free areas, the infrared signal is retrieved at the Earth's surface, revealing warmer temperatures. Cooler areas are pushing to purple and warmer areas are pushing to red.
The microwave images reveal where the heaviest precipitation in the hurricane is taking place. The blue areas within the storm show the location of this heavy precipitation. Blue areas outside of the storm where there are moderate or no clouds are where the cold (in the microwave sense) sea surface shines through. Click on image to enlarge. Credit: NASA JPL
Updated August 30, 2005 - 4:15 p.m. EDT
At 1:30 a.m. local time this morning, the remnants of (now Tropical Depression) Katrina were centered on the Mississippi-Tennessee border. This microwave image from the Atmospheric Infrared Sounder instrument on NASA's Aqua spacecrat shows that the area of most intense precipitation was concentrated to the north of the center of activity.
NASA/JPL
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Updated August 30, 2005 - 2:05 p.m. EDT
This slide shows different views of the Precipitation-Energy-Winds in Katrina. These satellite images are from the Tropical Rainfall Measuring mission (TRMM),
Advanced Microwave Scanning Radiometer (AMSR-E) instrument from the Aqua satellite, and QuickSCAT respectively. Note the high energy content in the northern Gulf of Mexico (reds) prior to Katrina's arrival.
Credit: NASA
Katrina's Category 4 hurricane force winds were observed by NASA’s QuikSCAT satellite on August 29, 2005, just before she made landfall.
The image depicts wind speed in color and wind direction with small barbs. White barbs point to areas of heavy rain. The highest wind speeds, shown in purple, surround the center of the storm. Measurements of the wind strength of Hurricane Katrina show sustained winds similar to those shown by these QuikSCAT observations, though not identical. This is because the power of the storm makes accurate measurements difficult. The scatterometer sends pulses of microwave energy through the atmosphere to the ocean surface, and measures the energy that bounces back from the wind-roughened surface. The energy of the microwave pulses changes depending on wind speed and direction, giving scientists a way to monitor wind around the world.
Image Credit: NASA JPL
Warm ocean waters fuel hurricanes, and there was plenty of warm water for Katrina to build up strength once she crossed over Florida and moved into the Gulf of Mexico. This image depicts a 3-day average of actual sea surface temperatures (SSTs) for the Caribbean Sea and the Atlantic Ocean, from August 25-27, 2005. Every area in yellow, orange or red represents 82 degrees Fahrenheit or above. A hurricane needs SSTs at 82 degrees or warmer to strengthen. The data came from the Advanced Microwave Scanning Radiometer (AMSR-E) instrument on NASA's Aqua satellite. Click on image above to view an animation which depicts the sea surface temperatures for the period June 9 through August 9, 2005. Also note the different tracks of Hurricanes Dennis, Emily, and at the very end Katrina. + Click for high resolution image. Credit: NASA/SVS
Latest National Hurricane Center Update on Katrina for August 29, 2005: At 10 a.m. CDT the center of Hurricane Katrina moved ashore near the Louisiana-Mississippi border. The center of Hurricane Katrina was located near the mouth of the Pearl River about 35 miles east-northeast of New Orleans, Louisiana and about 45 miles west-southwest of Biloxi, Mississippi. Katrina is moving toward the north near 16 mph, and maximum sustained winds are near 125 mph, with higher gusts. Katrina is now a Category Three hurricane. Coastal storm surge flooding of 15 to 20 feet above normal tide levels along with large and dangerous battering waves can be expected near and to the east of the center. Rainfall totals of 5 to 10 inches with isolated maximum amounts of 15 inches are possible along the path of Katrina across the gulf coast and the Tennessee valley. A few tornadoes are possible over portions of southern and eastern Mississippi, southern and central Alabama, and the western Florida panhandle today. This information was derived from the National Hurricane Center website.
The map below (dated August 28, 2005) from the National Hurricane Center shows Katrina's predicted path for the next three to five days.
Updated August 29, 2005 1:14 p.m. EDT
This is an image of Hurricane Katrina on Sunday, August 28, 2005 at 10:25 PM EDT (Or 2:27 UTC Monday, August 29) as seen by the Tropical Rainfall Measuring Mission (TRMM) satellite's PR (Precipitation Radar), VIRS (Visible Infrared Scanner), TMI (Tropical Microwave Imager) and the GOES spacecraft. TRMM looks underneath of the storm's clouds to reveal the underlying rain structure. Blue represents areas with at least 0.25 inches of rain per hour. Green shows at least 0.5 inches of rain per hour. Yellow is at least 1.0 inches of rain and red is at least 2.0 inches of rain per hour. The Tropical Rainfall Measuring Mission (TRMM) is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall. + Click here for high resolution TRMM image. Credit: NASA/JAXA
The Tropical Rainfall Measuring Mission (TRMM) is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall. Credit: NASA/JAXA
Updated August 29, 2005, 11:55 a.m. EDT
This is an image of Hurricane Katrina on Sunday, August 28, 2005 at 5:30 PM EDT (21:33 UTC) as seen by the Tropical Rainfall Measuring Mission (TRMM) satellite's PR (Precipitation Radar), VIRS (Visible Infrared Scanner), TMI (Tropical Microwave Imager) and the GOES spacecraft. TRMM looks underneath of the storm's clouds to reveal the underlying rain structure. Blue represents areas with at least 0.25 inches of rain per hour. Green shows at least 0.5 inches of rain per hour. Yellow is at least 1.0 inches of rain and red is at least 2.0 inches of rain per hour.
The Tropical Rainfall Measuring Mission (TRMM) is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall. + Click here for high resolution TRMM image. Credit: NASA/JAXA
Updated August 29, 2005 8:20 a.m. EDT
Hurricane Katrina turned slightly eastward before slamming into shore redirecting the storm's most potent winds and rain away from the vulnerable, low lying New Orleans area. Katrina weakened slightly overnight to a Category 4 storm and her eastward movement put the western eyewall - the weaker side of the strongest winds - over New Orleans. This doesn't mean New Orleans has been spared her wrath completely, the city is still getting hit with 145 mph winds today and the possibility of a 20 foot storm surge.
Katrina, which cut across Florida last week leaving nine dead and massive damage, had intensified into a Category 5 storm over the warm waters of the Gulf of Mexico, reaching top winds of 175 mph before weakening as it neared the coast.
A hurricane warning is in effect for the north-central Gulf Coast from Morgan City, La., to the Alabama-Florida line. Tornado warnings were posted for Louisiana, Mississippi, Alabama and Florida. + Click for high resolution satellite image. Credit: Credit: NASA/Jeff Schmaltz, MODIS Land Rapid Response Team
Updated August 28, 2005 8:42 a.m. EDT
Hurricane Katrina strengthened into a powerful Category Five hurricane overnight with sustained winds of 160 mph. The National Hurricane Center put out a special advisory on the hurricane's gain in strength just before 8 a.m. EDT. The boost came just hours after Katrina reached Category 4, with wind of 145 mph, as it gathered energy from the warm water of the Gulf of Mexico.
According to the National Hurricane Center, a Category Five hurricane causes storm surges generally greater than 18 ft above normal, complete roof failure on many residences and industrial buildings. All shrubs, trees, and signs are blown down. Severe and extensive window and door damage can occur. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the center of the hurricane. Major damage to lower floors of all structures located less than 15 ft above sea level and within 500 yards of the shoreline occurs and massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required. This is especially essential in the New Orleans area where most of the city lies below sea level and exists with the help of levees and pumps. To date, only 3 Category Five Hurricanes have made landfall in the United States since records began. + Click for high resolution of image above. Credit: NASA/Jeff Schmaltz, MODIS Land Rapid Response Team
Updated August 27, 2005 10:42 a.m. EDT
Hurricane Katrina left much destruction in her wake in South Florida killing as many as nine persons and causing upwards of $600 million dollars in estimated damage. And she was only a Category 1 when she struck South Florida. Gaining strength as she blows across the warm Gulf of Mexico Katrina is currently a Category 3 and experts are warning that by the time she reaches land on Monday, she may be a full blown Category Four storm. At 8 a.m. Saturday, the eye of the hurricane was located about 180 miles west of Key West or about 430 miles southeast of the mouth of the Mississippi River. It was moving west at nearly 7 mph. + Click here for high resolution image. Credit: NASA/Jeff Schmaltz, MODIS Land Rapid Response Team
Hurricane Katrina had just become a category 1 hurricane when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image on August 25, 2005, at 12:30 p.m., Eastern Daylight Savings Time. The hurricane formed as a tropical depression late on August 23 and developed quickly into a tropical storm by 11 a.m. the next morning. By the time MODIS acquired this image, the storm continued to develop into a category 1 hurricane, the lowest strength category in the hurricane strength scale. Katrina had winds of 120 kilometers per hour (75 miles per hour). + Click for high resolution image. Credit: NASA/Jeff Schmaltz, MODIS Land Rapid Response Team
Quikscat Image of Katrina
Tropical Storm Katrina is shown here as observed by NASA’s QuikSCAT satellite on August 25, 2005, at 08:37 UTC (4:37 a.m. in Florida). At this time, the storm had 80 kilometers per hour (50 miles per hour; 43 knots) sustained winds. The storm does not appear to yet have reached hurricane strength.
The greater danger may be not with her winds, but with Katrina’s rains. The storm is moving slowly, just 13 km/hr (8 mph), and is expected to slow as it moves over land. This means that Katrina’s heavy rains will linger longer over one area, dumping 15-25 centimeters (6-10 inches) of rain over Florida and the Bahamas and possibly up to 38 cm (15 inches) in some regions, the National Hurricane Center warns.
The image depicts wind speed in color and wind direction with small barbs. White barbs point to areas of heavy rain. The highest wind speeds, shown in purple, surround the center of the storm.
Measurements of the wind strength of Tropical Storm Katrina show sustained winds similar to those shown by these QuikSCAT observations, though not identical. This is because the power of the storm makes accurate measurements difficult. The scatterometer sends pulses of microwave energy through the atmosphere to the ocean surface, and measures the energy that bounces back from the wind-roughened surface. The energy of the microwave pulses changes depending on wind speed and direction, giving scientists a way to monitor wind around the world.
Tropical cyclones (the generic term for hurricanes and typhoons) and to a lesser extent, weaker storm systems like Katrina, are difficult to measure. To relate the radar energy return to actual wind speed, scientists compare measurements taken from buoys and other ground stations to data the satellite acquired at the same time and place. Because the high wind speeds generated by cyclones are rare, scientists do not have corresponding ground information to know how to translate data from the satellite for wind speeds above 50 knots (about 93 km/hr or 58 mph). Also, the unusually heavy rain found in a cyclone distorts the microwave pulses in a number of ways, making a conversion to accurate wind speed difficult. Instead, the scatterometer provides a nice picture of the relative wind speeds within the storm and shows wind direction. Image credit: NASA/JPL.
For more information about the storm, please visit the National Hurricane Center.
+ High resolution image
Katrina Closes in on Florida
All eyes are on Tropical Storm Katrina as it nears the south Florida
coastline. The storm, which is in the process of strengthening as it passes
over the warm waters of the Gulf Stream, is forecast to become a Category 1
hurricane by the time it makes landfall. But, as it is already close to the
Florida coast, it will not have time to develop into a major hurricane.
However, the storm is moving very slowly, which poses a risk for flooding.
Katrina formed into a tropical depression (TD #12) from a broad area of low
pressure in the central Bahamas on the afternoon of 23 August 2005 (LST).
Over the next day, the system slowly moved northwest through the central
Bahamas, becoming a minimal tropical storm on the morning (LST) of the 24th.
Katrina then turned westward and started to intensify as it passed south of
Grand Bahama Island on a heading for south Florida.
The Tropical Rainfall Measuring Mission (TRMM) satellite was launched back in
November of 1997 to measure rainfall over the global Tropics but has proven
itself to be instrumental in observing tropical cyclones. This first image
was taken at 04:34 UTC (12:34 am EDT) on 25 August 2005 as Katrina was passing
south of Grand Bahama Island. The image above displays the horizontal distribution
of rain intensity within Katrina as obtained from TRMM's sensors. Rain rates
in the center part of the swath are from the TRMM Precipitation Radar (PR),
the only radar capable of measuring precipitation from space. The PR can
provide fine resolution rainfall data and details on the vertical structure.
Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The
rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared
Scanner (VIRS). At the time of the image, Katrina was a tropical storm with
maximum sustained winds reported at 45 knots (52 mph) by the National Hurricane
Center (NHC). In this image, an eye is visible along the western side of the
central area of precipitation (blue ring). Most of the rainfall, however, is
east of the center (green and blue area). Although, there is evidence of
banding in the surrounding rain areas, the banding is not as distinct as with
a more mature system. Also, rainfall in the eyewall is still fairly weak.
These features indicate that Katrina is still in the process of organizing. + Click for high resolution image.
The second image (above) was taken at the same time and shows a 3D perspective of
Katrina via the vertical height of the precipitation-sized particles (as
defined by the 15 dBZ isosurface). At few isolated tall towers (in red) are
visible in the outer rain bands, but the core of Katrina is devoid of deep
convection. This, coupled with the lack of intense rain near the center,
indicates that the storm is not likely to intensify quickly very soon. TRMM is a joint mission between NASA and the Japanese space agency JAXA. + Click for high resolution image. Credit: NASA/Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang
(SSAI/NASA GSFC).
Tropical Storm Katrina
Tropical Storm Katrina had just become the eleventh named storm of the 2005 Atlantic Hurricane season when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on August 24, 2005, at 11:50 a.m., Eastern Daylight Savings Time. The storm formed late on August 23 and developed quickly into a tropical storm by 11 a.m. the next morning. By the time MODIS acquired this image, the storm was just starting to take the recognizable swirling shape of a hurricane. Katrina had winds of 64 kilometers per hour (40 miles per hour) and was expected to get stronger as it approaches the south Florida coast, possibly becoming a Category 1 hurricane before coming ashore.
A more serious danger is Katrina's rains. The storm is moving slowly, just 13 km/hr (8 mph), and is expected to slow as it moves over land. This means that Katrina's heavy rains will linger longer over one area, dumping 15-25 centimeters (6-10 inches) of rain over Florida and the Bahamas and possibly up to 38 cm (15 inches) in some regions, the National Hurricane Center warns. Credit: NASA image courtesy Jeff Schmaltz at NASA GSFC
For more information about the storm, please visit the National Hurricane Center. This image is available in multiple resolutions from the MODIS Rapid Response Team.
Goddard Space Flight Center
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