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Hurricane Season 2008: Tropical Storm Kyle (Atlantic Ocean)
 
Sept. 30, 2008

Kyle Fizzling in the Canadian Gulf of St. Lawrence

QuikScat image of Kyle's winds on Sept. 28 Credit: NASA JPL
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Kyle's remnants will be a memory by the end of today, Sept. 30, as the storm is fizzling fast in the Gulf of Saint Lawrence. That's "a rather unusual demise for a post-tropical storm," noted the discussion from Environment Canada's Canadian Hurricane Centre in Nova Scotia.

On Sept. 29 at noontime, EDT, Kyle was located about 65 miles north of Charlottetown, Canada, near latitude 47.4 and longitude 63.0. At that time, Kyle still had maximum sustained winds near 40 knots (46 mph), and it was moving northeast at 11 knots (13 mph). Minimum central pressure was 998 millibars.

QuikScat Captured Kyle's Winds from Space

NASA's Quick Scatterometer satellite (QuikScat) has been watching Kyle's winds by using microwaves to peer into the clouds. QuikScat can determine the speed of the rotating winds. This image from QuikScat shows Kyle's wind speeds in different colors and wind direction are indicated by small barbs. White barbs point to areas of heavy rain. The highest wind speeds, are shown in purple, which indicate winds over 40 knots (46 mph). This image was captured on Sept. 28 at 23:12 UTC (7:12 p.m. EDT) just before Kyle's center made landfall in eastern Canada.

What Did Kyle Do to Eastern Canada?

In Canada Kyle Made landfall near Yarmouth, Nova Scotia at 9 p.m. EDT on Sept. 28. At that time, the central pressure was around 986 millibars and the maximum sustained winds were estimated to be at Category one Hurricane force: 65 knots (74 mph). The center of the storm tracked north of Yarmouth to Digby then across the Bay of Fundy to the Nova Scotia/New Brunswick border and across western Prince Edward Island.

According to the Canadian Weather Centre, a buoy at George's Bank registered Kyle's maximum sustained winds near 65 knots (74 mph), and 60 knots (69 mph) at Baccaro Point at Nova Scotia's southwestern tip. Because the winds were sustained for 3-4 hours, they caused tree damages and power outages. Flooding from storm surge was also an issue along the Yarmouth and Shelburne County coasts. Rainfall amounts ranged from 1.9-2.7 inches (50-70 millimeters) over the western half of New Brunswick, and .78-1.6 inches (20-40 millimeters) of rain were recorded over Nova Scotia and Prince Edward Island.

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



Sept. 29, 2008

Kyle Brushed by New England, Now Crawling Out of Canada

Composite image of Kyle off the North Carolina coast on Sept. 27 (left) and over Maine and Nova Scotia on Sept. 28 (right). Composite image of Kyle off the North Carolina coast on Sept. 27 (left) and over Maine and Nova Scotia on Sept. 28 (right).
Credit: NASA/JPL/Colorado State University/Naval Research Laboratory-Monterey
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Hurricane Kyle was a fast mover over the weekend. On Saturday, Sept. 27, Kyle was off the mid-Atlantic coast. During the day Sunday, Kyle raced north past New England to make landfall in eastern Canada at 9 p.m. local time that night.

Environment Canada's Canadian Hurricane Centre reported that Kyle made landfall as a category one hurricane on the Saffir-Simpson Scale with winds just over 74 mph. It came ashore just north of Yarmouth on the southern tip of Nova Scotia province. Once inland, Kyle weakened to a tropical storm.

On Monday, Sept. 29, at 9:00 a.m. EDT, Extra-tropical Storm Kyle was near 47.0 north and 62.6 west, or about 45 miles north-northwest of Charlottetown, Canada. Kyle was moving north of Prince Edward Island. Kyle's maximum sustained winds were down to 40 knots (46 mph). Minimum central pressure was at 995 millibars, and Kyle was moving northeast at 11 knots (13 mph).

The Canadian Hurricane Centre forecast for Kyle's remnants say "Kyle will crawl into the middle of the Gulf of St. Lawrence. The low is expected to be nearly stationary tonight and Tuesday between the Magdalen Islands and Anticosti island.

Kyle's strongest sustained winds were near 80 mph on Sunday, Sept. 28th from the time it was 165 miles south-southeast of Nantucket, Massachusetts until it was off the coast of Maine. Kyle passed Massachusetts, New Hampshire and Maine without a landfall, only bringing gusty winds and 2-4 inches of rain to eastern New England.

At 11:00 p.m. EDT, Kyle lost its tropical characteristics while passing Nova Scotia, Canada. At that time, Kyle's center was near 44.8 north and 65.9 west, or about 60 miles south of St. John, New Brunswick. He was speeding north near 26 mph, while still packing maximum sustained winds near 70 mph, just under hurricane strength. Minimum central pressure was 986 millibars.

Aqua Satellite Tracked Kyle Over the Weekend

These infrared images were created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. They were taken on Saturday, Sept. 27 at 1:59 p.m. EDT, and Sunday, Sept. 28 at 12:59 p.m. EDT. The infrared image shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

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



Sept. 27, 2008

Tropical Storm Kyle forms in the Western Atlantic

Satellite image of Kyle Credit: Hal Pierce, SSAI/NASA's Goddard Space Flight Center
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Tropical Storm Kyle became the 11th named storm of the season Thursday afternoon the 25th of September 2008 when it formed in the southwestern Atlantic about 360 km (~225 miles) northeast of Grand Turk Island or about 1000 km (~625 miles) south- southwest of Bermuda. Although it is expected to become a minimal hurricane before heading towards the Canadian Maritimes, the system was responsible for several fatalities and flooding damage in the northern Caribbean before it was officially named.

Kyle developed from an area of low pressure that had been hovering in the vicinity of Puerto Rico and Hispaniola for several days. This area of low pressure originated from an African easterly wave (AEW) that had propagated across the central Atlantic. There are about 60 of these westward-moving waves in a given year, but only a fraction develop into tropical cyclones in the Atlantic. This particular wave entered the eastern Caribbean on the 18th of September. An area of low pressure associated with the wave became nearly stationary in the northern Caribbean just south of Puerto Rico. This low became the focus for numerous showers and thundershowers, which streamed northward over Puerto Rico and the Dominican Republic resulting in significant flooding over the region. Launched back in November of 1997 with the primary purpose of measuring rainfall in the Tropics, the Tropical Rainfall Measuring Mission satellite (better known as TRMM) has been in service for over 10 years now. TRMM obtained this first image at 11:11 UTC (7:11 am EDT) 22 September 2008. It shows the the horizontal pattern of rain intensity associated the showers and thundershowers rotating around the area of low pressure. Rain rates in the center swath are based on the TRMM Precipitation Radar (PR), and those in the outer swath on the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). A broad area of light to moderate to heavy rain (blue, green and red areas, respectively) covers Puerto Rico and the north central Caribbean. Within this broader area of rain are organized bands of moderate to heavy rain (elongated green and red areas, respectively). Most of the rain is east of the center of low pressure. After the time of this image, the area of low pressure slowly drifted over the Dominican Republic before finally pulling away to the north.

Satellite image of Kyle Credit: Hal Pierce, SSAI/NASA's Goddard Space Flight Center
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TRMM can be used to calibrate rainfall estimates from other satellites. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA) at the NASA Goddard Space Flight Center provides estimates of rainfall over the global Tropics. TMPA rainfall totals associated with the passage of the tropical low are shown here for the period 10 to 26 September 2008 for Puerto Rico, the Dominican Republic and the surrounding region. The highest rainfall totals for the period are over eastern Puerto Rico and the southeastern Dominican Republic and exceed 400 mm (~16 inches, shown in red). Almost all of Puerto Rico received at least 300 mm (~12 inches, shown in orange) of rain. So far 4 fatalities are being blamed on the flooding there. As a whole, the northern Caribbean has been hit hard this year. The combined effects of previous storms Fay, Gustav, Hanna and Ike, caused several hundred fatalities across Hispaniola, mostly in Haiti.

Satellite image of Kyle Credit: Hal Pierce, SSAI/NASA's Goddard Space Flight Center
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The low finally began to pull away from Hispaniola on the 24th and become better organized as it freed itself from the effects of land. This last image from TRMM was collected at 01:51 UTC 25 September (8:51 pm EDT 24 September) 2008 as the low was moving northward away from the Dominican Republic. Although it would be nearly a day before it became an official tropical storm, banding features (curvature) are evident in the rain field east of the center (note the arc shape in the moderate intensity rain bands) and reflect the presence of the cyclonic circulation.

TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Text credit: Steve Lang, SSAI/NASA's Goddard Space Flight Center



Sept. 26, 2008, second update

NASA Satellites Catch Two Views of Kyle's Clouds Heading North

Satellite image of Kyle Credit: NASA/JPL/Colorado State University/Naval Research Laboratory-Monterey
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What's it like to see a tropical storm from space and from the side? NASA has the answers, thanks to two satellites: CloudSat, that takes a "profile" view of a storm, and Aqua, that sees it from the top down. Those are just two of NASA's earth-watching satellites that are helping forecasters figure out what Kyle will do next.

Forecasters do know that Kyle will rain on Bermuda through Saturday, generating rainfall totals between 1 and 3 inches. By Sunday, forecasters expect Kyle to be far off the coast of New Jersey as a hurricane, stirring up high surf along the northeast U.S. on its way to Quebec and Nova Scotia, Canada.

By mid-afternoon on Friday, Sept. 26, Tropical Storm Kyle was still packing maximum sustained winds near 60 mph and is expected to strengthen into a hurricane over the weekend. At 2:00 p.m. EDT on Sept. 26, Kyle's center was only 445 miles south-southwest of Bermuda. That's near 26.9 degrees north latitude and 68.6 degrees west longitude. Because of the distance tropical storm force winds reach out from Kyle's center, they're only 225 miles from the Bahamas. Kyle's tropical storm force winds extend 205 miles out from his center.

Kyle is moving toward the north-northwest near 12 mph and should continue in that direction, but will speed up overnight and into Saturday morning, Sept. 27. On the 27th, Kyle is expected to turn north. Kyle's minimum central pressure is 1000 millibars.

CloudSat Gives a Side View of Kyle's Clouds

NASA's CloudSat satellite's Cloud Profiling Radar captured a sideways view of Kyle on Sept. 26 at 6:00 UTC (2:00 a.m. EDT). For comparison, the top image is from the National Oceanic and Atmospheric Administration's Geostationary Operational Environmental Satellite (GOES-11) around the same time.

The red line through the GOES satellite image shows the vertical cross section of radar, basically what Kyle's clouds looked like sideways. The colors indicate the intensity of the reflected radar energy. The top of Kyle's clouds are almost 15 kilometers (9.3 miles) high.

The blue areas along the top of the clouds indicate cloud ice, while the wavy blue lines on the bottom center of the image indicate intense rainfall. Notice that the solid line along the bottom of the panel, which is the ground, disappears in this area of intense precipitation. It is likely that in the area the precipitation rate exceeds 30mm/hr (1.18 inches/hour) based on previous studies.

Taking Kyle's Cloud Top Temperature from Space

Satellite image of Kyle Credit: NASA/JPL
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Imagine taking a cloud's temperature from space. Well, that's what infrared satellite instruments basically do. This infrared image was created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. The image was taken on Sept 26 at 6:17 UTC (2:17 a.m. EDT). The infrared image shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

For an updated track on Kyle, visit www.nhc.noaa.gov

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



Sept. 26, 2008, first update

Kyle Forms in the Caribbean, U.S. Coastal Low Not Named

Satellite image of Kyle Credit: NASA/JPL
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After watching a low pressure area in the Caribbean for five days, the National Hurricane Center confirmed late Thursday, Sept. 25 that it developed into Tropical Storm Kyle.

Meanwhile, the area of low pressure system off the mid-Atlantic coast hasn't developed into a tropical storm, but is bringing showers and gusty winds to the region on Friday, September 26 and Saturday, Sept. 27 as it moves up the U.S. east coast. That low is also causing coastal flooding, high surf and dangerous rip currents along the coast.

Bermuda Already Under a Watch for Kyle

At 5 a.m. EDT on Sept. 26, the government of Bermuda has issued a tropical storm watch for Bermuda. A tropical storm watch means that tropical storm conditions are possible within the watch area generally within 36 hours. Rainfall totals of up to 3 inches will be possible on Bermuda through Saturday. If Kyle follows its current forecast track, Kyle's center and the strongest winds are forecast to remain west of Bermuda.

Tropical Storm Kyle Likely to Become a Hurricane by Saturday

At 5:00 a.m. EDT on Sept. 26, Kyle's maximum sustained winds have increased to near 60 mph with higher gusts. Additional strengthening is forecast during the next 48 hours, and the National Hurricane Center forecast says that Kyle could become a hurricane by Saturday.

Kyle's center was located about 510 miles south-southwest of Bermuda, near latitude 25.6 north and longitude 68.3 west. Kyle is moving toward the north near 12 mph and is expected to turn toward the north-northwest accompanied by a gradual increase in forward speed is expected later today and on Saturday. The minimum central pressure recently measured by reconnaissance aircraft was 997 millibars.

Aqua Satellite Tracking Kyle and the Coastal Low

This infrared image was created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. The image was taken on Sept 25 at 18:05 UTC (2:05 p.m. EDT). The infrared image shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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.

The coastal Low is visible in blue and purple that stretches from the coast of Connecticut all the way south to the Virginia coast. Some of the Low's clouds and rains still even stretch as far as South Carolina and eastern Georgia (as seen in blue over those areas). Kyle is shown to the lower right side of the image as a circular area of purple and blue, north of Puerto Rico.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

Where is Kyle Expected to Go?

The National Hurricane Center notes that "The cyclone is expected to turn more toward the north-northwest over the next 24-36 hours. After that a turn back toward the north with eventual recurvature to the northeast is forecast by all of the global models." Interests in the northeastern U.S. and the Canadian Maritimes region should closely monitor the progress of Kyle during the next couple of days.

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



Sept. 25, 2008

U.S. Coastal Low Still Not Tropical, But Feels Like it to Coastal Residents

Satellite image of low pressure system Credit: NASA/JPL
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The area of low pressure that hurricane hunters have been examining has still not taken on tropical characteristics as of 8:00 a.m. EDT on Thursday, September 25, but forecasters are still watching it.

At that time, the National Hurricane Center noted that it still has a potential to become a tropical or sub-tropical system.

Regardless of whether or not it becomes a tropical system, it's still going to feel like one to the residents along the Mid-Atlantic, with strong winds, coastal flooding, high surf and dangerous rip currents from South Carolina northward to the Mid-Atlantic region.

Forecasts in the Baltimore/Washington, D.C. area, Virginia Beach and coastal Virginia, and coastal Delaware, New Jersey and Maryland have coastal flood advisories and wind advisories posted. Winds could gust to 45 mph and higher. Coastal areas also have heavy surf advisories posted. All areas can possibly see as much as 2 inches of rain through Saturday morning.

Aqua Satellite Tracking the Low

This infrared image was created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. The image was taken on Sept 25 at 7:05 UTC (3:25 a.m. EDT). The infrared image shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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. The coastal Low is visible in blue and purple off the North Carolina and Virginia coasts.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

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



Sept. 24, 2008

Two Chances for a Tropical Storm Kyle, Which Will it Be?

Wednesday, September 24, marks the third day that the National Hurricane Center has labeled the area of low pressure near the Dominican Republic as having "Potential for Development" into a tropical cyclone. Well, now forecasters are also looking at an area of low pressure off the North Carolina coast which has a better probability of getting a name.

The low, located 250 miles southeast of Wilmington, North Carolina was associated with a frontal system, but has developed a life of its own. Forecasters think that it also has "high potential" to become a subtropical (out of the tropics) storm with tropical characteristics. The National Hurricane Center reports "There is still the potential for this system to become a tropical or subtropical cyclone later today or tonight as it drifts westward. The low is partly responsible for an area of winds to hurricane force well to the north and northwest of the center.

The North Carolina Off-Shore Low to Bring Dangerous Coastal Conditions

Despite not having achieved a tropical storm status, or even that of a tropical depression, it's behaving like one. The National Hurricane Center forecast says "This system will bring strong winds, coastal flooding, high surf and dangerous rip currents to portions of the U.S. east coast during the next couple of days."

The Dominican Republic Low

As for the low over the Dominican Republic, well, meteorologists are still watching it and have dropped the probability of it organizing to "Medium." As of Sept 24, the showers and thunderstorms associated with the low remain "disorganized" and the system doesn't have a well-defined circulation to it. The upper level winds are now only "marginally favorable" for further development of the system into a tropical depression. Whether it becomes one or not, however, it has the deadly potential to bring life-threatening rains and flash floods and mud slides to both Puerto Rico and Hispaniola today and tonight.

Aqua Satellite Tracking Storm's Development

AIRS image of Kyle on September 24, 2008
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Credit: NASA/JPL
This infrared image was created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. The image was taken on Sept 24 at 6:23 UTC (2:23 a.m. EDT). The infrared image shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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.

The North Carolina Low is visible in blue and purple off the North Carolina coast, while the Dominican Republic Low appears in blue and purple near the bottom center of the image.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters. Text credit: Rob Gutro (from NHC discussion)/Goddard Space Flight Center


September 23, 2008

Winds Cooperating for Possible Development of Tropical Storm Kyle

Visible AIRS image of Kyle on Sept. 22, 2008
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Credit: NASA JPL
For the second day in a row, the National Hurricane Center has labeled the area of low pressure now near the Dominican Republic as "High Potential for Development" into a tropical cyclone. Now it seems that the storm will be able to come together as a tropical depression, as winds are now "cooperating."

On Tuesday, Sept. 23, the low pressure system had moved over the Dominican Republic, from Puerto Rico, where it was the previous day. Surface weather reports on the 23rd have revealed falling atmospheric pressure, one sign that a low is intensifying. In addition, upper-level winds are now expected to cooperate with organization of the low, and allow it to develop further.

The National Hurricane Center noted in its 8:00 a.m. EDT discussion today, Sept. 23, "This system has the potential to become a tropical depression at any time during the next day or two as it moves north or northwest away from Hispaniola. Heavy rainfall with potentially life-threatening flash flooding is expected to continue over the area through early Wednesday, Sept. 24."

Infrared AIRS image of Kyle on Sept. 22, 2008
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Credit: NASA JPL
Aqua Satellite Tracking Storm's Development

This infrared image was created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. The visible and infrared images were taken on Sept 22 at 17:35 UTC (1:35 p.m. EDT). The infrared image shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters. Text credit: Rob Gutro (from NHC discussion)/Goddard Space Flight Center


September 22, 2008

High Potential for Development into Tropical Storm Kyle Near Puerto Rico

Puerto Rico is getting another soaking this hurricane season. Low pressure embedded in a tropical wave is bringing large amounts of rainfall over Puerto Rico on Monday, Sept. 22. Forecasters at the National Hurricane Center have labeled the area "high potential" for a developing tropical cyclone.

The National Weather Service office in San Juan, Puerto Rico noted in their morning discussion on Sept. 22, that "Moisture continues to stream north over Puerto Rico, Vieques and Culebra. The U.S. Virgin Islands remain on the fringe as the band of moisture moves very slowly to the west. Storm total rainfall amounts have exceeded 20 to 30 inches in parts of southeast Puerto Rico where rivers are well above flood stage."

The National Hurricane Center noted that that area of low pressure doesn't have a well-defined center as of 8:00 a.m. EDT on Sept. 22. But, because upper-level winds are forecast to become more favorable for development, forecasters say the Low still has the potential to become a tropical depression during the next day or so as it moves slowly to the north or north-northwest.

Meanwhile, Puerto Rico, and the U.S. and British Virgin Islands will continue to receive a drenching through Sept. 23, Tuesday. Flash Flood Warnings have already been posted, and flooding is happening today, the 22nd. A Flash Flood Watch has been posted until Sept. 23 for eastern Puerto Rico. The National Weather Service forecast for San Juan on Sept. 23 calls for "Showers and possibly a thunderstorm. Some of the storms could produce gusty winds and heavy rain. High near 87. Heat index values as high as 97. South southeast wind between 13 and 15 mph. Chance of precipitation is 100%. New rainfall amounts between two and three inches possible." Storms are expected to continue overnight and on Tuesday.

Aqua Satellite Shows Difference Between Freezing Storm Clouds and Warm Ocean

This infrared image was created by data from the Atmospheric Infrared Sounder (AIRS), an instrument that flies aboard NASA's Aqua satellite. The image was created on Sept. 21, at 5:59 UTC or 1:59 a.m. EDT and shows a huge temperature difference between the tops of the clouds in a tropical cyclone and the warm ocean waters that power it.

AIRS image of Kyle from Sept. 21, 2008
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Credit: NASA JPL
The AIRS image shows the temperature of the cloud tops or the surface of the Earth in cloud-free regions. The lowest temperatures (in purple) are associated with high, cold cloud tops that make up the top of the area of low pressure. 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.

The infrared signal of the AIRS instrument does not penetrate through clouds. Where there are no clouds the AIRS instrument reads the infrared signal from the ocean and land surfaces, revealing warmer temperatures in orange and red. The orange temperatures are 80F (300 degrees Kelvin) or greater (the darker they are, the warmer they are), and tropical cyclones need sea surface temperatures of 80F to strengthen and maintain their strength.

The data from AIRS is also used to create an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

Who Should Be on Guard?

The National Hurricane Center noted in their discussion that "Interests in Puerto Rico, the Virgin Islands, Hispaniola, the Turks and Caicos Islands and the southeastern Bahamas should continue to monitor the progress of this system and products issued by their local weather forecast offices."

Text credit: Rob Gutro (from NHC discussion)/Goddard Space Flight Center