NASA HS3 Mission Reveals Tropical Storm Humberto's Hybrid Core[image-36]

Dropsonde data from lower and higher levels within Tropical Storm Humberto between Sept. 16 at 1839 UTC and Sept. 17 at 0522 UTC, overlaid on an infrared GOES satellite image of Sept. 17 at 0000 UTC shows temperature (colored circles) and wind barbs at 800 (left) and 400 (right) hPa. Full wind barbs are 10 knots. At 800 hPa, a warm (orange-red colors) core is found at the circulation center ("X"). At 400 hPa, a cold (blue colors) core and circulation center was north-northwest of low level center.

NASA's Global Hawk 872 flew over Tropical Storm Humberto on Sept. 16 and 17 after it was reborn from remnants of its earlier life cycle. Data from NASA 872 showed that the core had a hybrid structure.

NASA's Global Hawk 872 unmanned aircraft took off at 10:42 a.m. EDT from NASA's Wallops Flight Facility, Wallops Island, Va., Sept. 16 to investigate newly reformed Tropical Storm Humberto. NASA 872 dispersed dropsondes throughout Humberto and gathered data on the environment of the storm.

A sonde is a device that measures winds, temperature, and humidity. The instrument is called a dropsonde because it is dropped out of the tail of the Global Hawk. The dropsonde is an 11-inch long tube - about the size of the cardboard paper tube for a paper towel roll. [image-330]

HS3 mission scientists at NASA Wallops combined dropsonde data with a satellite image from NOAA's GOES-East satellite. The dropsonde data, centered on 0000 UTC/8 p.m. EDT Sept. 17, was overlaid over a GOES infrared image and revealed that Humberto was a hybrid storm. "In a typical tropical storm or hurricane, a warm core would be found at most levels," said Scott Braun, HS3 Mission Principal Investigator from NASA's Goddard Space Flight Center in Greenbelt, Md. "The structure of Humberto was the result of a union of the tropical storm with an upper-level cold low, so it had a structure that was more of a hybrid of a tropical and extratropical system."

The image showed temperature at 800 hPa or Hectopascals and 400 hPa. The height of the pressure surfaces varies, but 400 hPa is roughly 7.5 km (24,600 feet) and 800 hPa is about 2.1 km (6,890 feet). The images also showed wind speed and direction using wind barbs. At 800 hPa, a warm core was found at the center of the circulation while at 400 hPa, a cold core was found with the center of circulation located to the north-northwest of the low level center.

HS3 is a mission that brings together several NASA centers with federal and university partners to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin. The HS3 mission will operate in 2013 between Aug. 20 and Sept. 23.

For more information about dropsondes, visit: www.nasa.gov/content/goddard/what-the-heck-is-a-dropsonde/

For more information about NASA's HS3 mission, visit: www.nasa.gov/HS3

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

Sept. 19, 2013 - Tropical Depression Humberto Fizzling, Two Areas Developing [image-298]

Imagery from NOAA's GOES-East satellite on Sept. 19 showed Tropical Depression Humberto had lost its organization, while one tropical low struggled near Bermuda, and another one was taking shape in the southwestern Gulf of Mexico. NASA's HS3 hurricane mission is sending an unmanned Global Hawk aircraft to investigate the developing system in the Gulf.

NOAA's GOES-East satellite provided a visible image of the Atlantic Ocean on Sept. 19 at 7:45 a.m. EDT that showed the three tropical systems. The image was created by the NASA GOES Project at NASA's Goddard Space Flight Center in Greenbelt, Md. The image showed Humberto as a ghost of its former self, while an area near the Bahamas appeared elongated, and a low pressure area in the southwestern Gulf of Mexico appears more organized than it was on Sept. 18.

Tropical Depression Humberto About to be Swallowed Up

According to the National Hurricane Center, Tropical Depression Humberto is poised to be absorbed within a large extra-tropical cyclone in a day or two. At 11 a.m. EDT on Sept. 19 Humberto was in the North Central Atlantic, near latitude 32.8 north and longitude 43.3 west. It was far from land areas. In fact, it was about 985 miles/1,585 km west-southwest of the Azores. It was moving toward the north-northeast near 6 mph/9 kph. Maximum sustained winds were near 35 mph/ 55 kph.

The environment around Humberto is interesting. Although the extra-tropical cyclone approaching Humberto is expected to swallow it up, sea surface temperatures and atmospheric stability around the depression are conducive for convection today, Sept. 19. However, According to the National Hurricane Center, dry conditions and strong northerly vertical wind shear are likely to lead toward the System becoming a remnant low by 24 hours before it becomes absorbed.

NASA's Global Hawk Headed for System 95L[image-312]

System 95L is a low pressure system sitting in the Bay of Campeche with a high chance for tropical development. So, NASA's Hurricane Severe Storms Sentinel or HS3 mission has sent an unmanned Global Hawk aircraft to the storm to investigate. On Thursday, Sept. 19 at 8:10 a.m. EDT, NASA's Global Hawk 872 departed from Runway 10 at NASA's Wallops Flight Facility, Wallops Island, Va.

NASA's Global Hawk 872 carries the environmental payload of instruments that include the CPL or Cloud Physics Lidar, S-HIS or Scanning High-Resolution Interferometer Sounder Instrument, and NOAA's AVAPS dropsonde system.

NASA 872 is going to investigate the environment of System 95L. System 95L was producing disorganized shower and thunderstorm activity during the morning of Sept. 19. The National Hurricane Center noted that conditions still appear conducive for the formation of a tropical depression during the next day or two. System 95L has a high chance of becoming a tropical depression in the next day as it moves west-northwestward to northwestward at 5 to 10 mph. The low pressure area is expected to spread heavy rain over portions of eastern and southern Mexico drenching areas already soaked by Hurricane Ingrid.

Another Developing Area in the Atlantic

Another low pressure area (a frontal trough) located between the Bahamas and Bermuda are producing clouds and showers. Upper-level winds do not appear conducive for significant tropical development

The National Hurricane Center noted that the low could develop some subtropical characteristics while it moves generally northeastward over the western Atlantic through early next week. The low has a low chance of becoming a subtropical cyclone during the next two days.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

Sept. 18, 2013 - Tropical Storm Humberto Makes an "A" for Atlantic on Satellite Imagery [image-282]

When NASA's Terra satellite passed over Tropical Storm Humberto on Sept. 17, the MODIS instrument aboard took a picture of the storm and it resembled the letter "A" as it moves through the northeastern Atlantic Ocean.

The strongest band of thunderstorms appear in the eastern quadrant of the storm, and the northern and western quadrants also have clouds and showers, but a section of the southern quadrant appears cloud-free, causing Humberto to resemble a letter "A." Forecasters at the National Hurricane Center or NHC noted, however, that the low-level center has been very difficult to locate, in part due to clouds associated a nearby upper-level low that have been masking the lower cloud motions.

MODIS imagery is created by the MODIS Rapid Response Team at NASA's Goddard Space Flight Center in Greenbelt, Md.

At 5 a.m. EDT/0900 UTC Tropical Storm Humberto had maximum sustained winds near 40 mph/65 kph and some strengthening is possible during the next 48 hours, according to the National Hurricane Center. The center of Tropical Storm Humberto was located near latitude 31.4 north and longitude 43.7 west , about 1,050 miles/1,690 km west-southwest of the Azores Islands. Humberto is moving toward the north-northwest near 8 mph/13 kph and is expected to turn north then north-northeast over the next two days.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

[image-234][image-250][image-266]Sept. 17. 2013 - NASA's TRMM Satellite and HS3 Mission Checking out Tropical Storm Humberto

NASA's TRMM satellite watched Tropical Storm Humberto's rainfall pick up over two days as it re-formed, and as part of NASA's HS3 mission, two of NASA's Global Hawk unmanned aircraft have been investigating the zombie storm. The two Global Hawks also celebrated a combined 100 flights.

NASA's Global Hawk 871 departed from NASA's Wallops Flight Facility, Wallops Island, Va. today, Sept. 17, at 10 a.m. EDT from Runway 04. This marked the twenty-fifth flight for NASA 871. Meanwhile, NASA 872 was returning to home base after making its seventy-fifth flight. These flights over Tropical Storm Humberto brought forth the one-hundredth flight of NASA's Global Hawks.

NASA's Global Hawk 872 unmanned aircraft took off at 10:42 a.m. EDT from Runway 22 at NASA's Wallops Flight Facility, Wallops Island, Va. on Sept. 16 to investigate Humberto and dispersed dropsondes throughout the storm. NASA 872 gathered data on the environment of the storm. Global Hawk aircraft are well-suited for hurricane investigations because they can fly for as long as 28 hours and over-fly hurricanes at altitudes greater than 60,000 feet (18.3 km).

Tropical storm Humberto had little deep convection and was classified by the National Hurricane Center (NHC) as a post-tropical cyclone on September 14, 2013. By September 16, Humberto was showing bursts of strong convection and thunderstorms were developing with heavy rainfall, so Humberto was again classified a tropical storm.

NASA's Tropical Rainfall Measuring Mission or TRMM satellite observed Humberto on September 15, 2013 at 1652 UTC (12:52 p.m. EDT) and on September 16, 2013 at 1557 UTC (11:57 a.m. EDT). A comparison of the two TRMM orbits showed significant changes that occurred within Humberto in less than 24 hours. In the first orbit on September 15, 2013 Humberto's center of circulation was rain free and only contained a small area of convective rainfall that was located well to the north of Humberto's surface location. Areas of strong convective rainfall were associated with rebounding Tropical Storm Humberto when TRMM viewed the same area on September 16, 2013.

The Atmospheric Infrared Sounder instrument aboard NASA's Aqua satellite captured an infrared image of Humberto on Sept. 17 at 4:29 UTC/12:289 a.m. EDT. The image showed the highest storms and coldest cloud top temperatures were still east and northeast of the center and were dropping the heaviest rainfall. .

At 11 a.m. EDT on Sept. 17 the center of Tropical Storm Humberto was located near latitude 29.4 north and longitude 42.5 west, about 1070 miles/1,720 km west-southwest of the Azores Islands. Humberto's maximum sustained winds were near 45 mph/75 kph and the National Hurricane Center expects some slight strengthening. Humberto is moving to the north at 10 mph/17 kph and is expected to turn to the northwest and slow down before heading north again on Sept. 18.

HS3 is a mission that brings together several NASA centers with federal and university partners to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin. Among those factors, HS3 will address the controversial role of the hot, dry and dusty Saharan Air Layer in tropical storm formation and intensification and the extent to which deep convection in the inner-core region of storms is a key driver of intensity change. The HS3 mission will operate between Aug. 20 and Sept. 23.

Humberto is forecast to again become a post-tropical low in about four days.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

Sept. 16, 2013 - NASA to Investigate Tropical Storm Humberto: Atlantic's Second "Zombie Tropical Storm"

[image-202][image-218]Humberto is the second "zombie" tropical storm of the Atlantic Ocean season. That is, it's the second tropical storm that degenerated into a remnant low pressure area only to make a comeback as a tropical storm. NASA's HS3 hurricane mission sent an unmanned Global Hawk Aircraft out to the eastern Atlantic to investigate Humberto on Sept. 16.

On Sunday, Sept. 15, Humberto weakened to a remnant low pressure area when it hit an area of strong wind shear. The wind shear eased and Humberto regained tropical storm strength on Sept. 16, making it the second "zombie" storm in the Atlantic Ocean basin this year. The first was Tropical Storm Gabrielle that fell apart and re-formed in early September in the western Atlantic.

NASA's GOES Project at the NASA Goddard Space Flight Center uses the data gathered by NOAA's GOES series of satellites and makes them into images and animations. On Sept. 16 an image was created that showed Humberto had regained form as a tropical storm.

At 11 a.m. EDT/1500 UTC, re-born Tropical Storm Humberto had maximum sustained winds near 40 mph/65 kph. The National Hurricane Center expects slow strengthening over the next couple of days. It was centered near latitude 27.2 north and longitude 43.2 west, about 1,200 miles/1,930 km southwest of the Azores Islands. Humberto is moving toward the west-northwest near 8 mph/13 kph and is expected to move northwest and then the north-northwest

NASA's Global Hawk 872 unmanned aircraft took off at 10:42 a.m. EDT from Runway 22 at NASA's Wallops Flight Facility, Wallops Island, Va., Sept. 16 to investigate the zombie storm. NASA 872 will disperse dropsondes throughout Humberto and gather data on the environment of the storm as it did on Sept. 5 with Gabrielle, the first zombie storm of the season.

Global Hawk aircraft are well-suited for hurricane investigations because they can fly for as long as 28 hours and over-fly hurricanes at altitudes greater than 60,000 feet (18.3 km).

HS3 is a mission that brings together several NASA centers with federal and university partners to investigate the processes that underlie hurricane formation and intensity change in the Atlantic Ocean basin. Among those factors, HS3 will address the controversial role of the hot, dry and dusty Saharan Air Layer in tropical storm formation and intensification and the extent to which deep convection in the inner-core region of storms is a key driver of intensity change. The HS3 mission will operate between Aug. 20 and Sept. 23.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

Sept. 13, 2013 - NASA Sees Southwesterly Wind Shear Weakened Hurricane Humberto [image-172]

Southwesterly wind shear has taken its toll on hurricane Humberto, and NASA's TRMM satellite noticed that in rainfall data.

When NASA's Tropical Rainfall Measuring Mission or TRMM satellite passed over Hurricane Humberto on September 12, 2013 at 1625 UTC/12:25 p.m. EDT the eye was no longer visible. An analysis derived from

TRMM Microwave Imager (TMI) and Precipitation Radar (PR) data showed that most of the precipitation with Humberto was located in the northwestern quadrant, pushed there by the strong southwesterly wind shear.[image-188]

TRMM found that the most intense rain was falling at a rate of over 99 mm/~3.9 inches per hour near Humberto's center. TRMM PR also found that the highest storm towers were reaching heights of about 13.7 km/8.5 miles in the same area.

At 5 a.m. EDT/0900 UTC on Sept. 13, Hurricane Humberto's maximum sustained winds were near 75 mph/120 kph, but the National Hurricane Center expects weakening over the next two days. Humberto is expected to drop to tropical storm status late on Sept. 13. The center of Hurricane Humberto was located near latitude 24.4 north and longitude 30.2 west, about 705 miles/1,135 km northwest of the Cape Verde Islands. Humberto is moving toward the north-northwest near 12 mph/19 kph and it is expected to turn toward the west-northwest.

Humberto is expected to weaken to a tropical storm late on Sept. 13, and continue moving through the open waters of the Central North Atlantic Ocean over the next several days.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

Sept. 12, 2013 - NASA's Terra Satellite Spots Hurricane Humberto's Cloud-filled Eye [image-156]

The MODIS instrument aboard NASA's Terra satellite captured a visible image of Hurricane Humberto that showed it's eye was cloud-filled. Humberto was moving away from the Cape Verde Islands in the Atlantic Ocean.

On Thursday, Sept. 12 at 11 a.m. EDT/1500 UTC, Hurricane Humberto has maximum near 85 mph/140 kph, and the National Hurricane Center (NHC) expects gradual weakening later in the day. The center of Hurricane Humberto was located near latitude 21.8 north and longitude 29.0 west, about 515 miles/830 km northwest of the Cape Verde Islands. Humberto is moving toward the north near 15 mph/24 kph and NHC expects a gradual turn toward the northwest and west-northwest. The estimated minimum central pressure is 982 millibars.

Hurricane force winds extend outward up to 35 miles/55 km from the center and tropical storm force winds extend outward up to 175 miles/280 km.

Satellite data indicates that there is some wind shear blowing from the south-southwest over Hurricane Humberto. However, Humberto appears fairly well organized in visible and infrared imagery. The Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Terra satellite captured a visible image of Hurricane Humberto on Sept. 11 at 9 a.m. EDT that showed a very small eye and bands of thunderstorms feeding into the storm.

The NHC expects the wind shear to increase from the west-southwest and Humberto will track into cooler waters. Both of those factors are expected to weaken Humberto below hurricane strength in the next couple of days.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center

Sept. 11, 2013 - Two NASA Satellites Analyze Hurricane Humberto's Clouds and Rainfall [image-110]

Two NASA satellites passed over the hurricane in the Eastern Atlantic on Sept. 10 gathering information about the environment of Hurricane Humberto. NASA's Aqua satellite gathered infrared and visible data on Humberto's clouds while NASA's TRMM satellite measured the rainfall rates occurring from those clouds. Humberto is the first hurricane of the Atlantic Ocean hurricane season.

NASA's Tropical Rainfall Measuring Mission satellite called TRMM had an excellent daytime view of strong Humberto on September 10 at 1636 UTC/12:36 p.m. EDT. At NASA's Goddard Space Flight Center in Greenbelt, Md. rainfall derived from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data were overlaid on a combination visible/infrared image from TRMM's Visible and InfraRed Scanner (VIRS) to provide a picture of rainfall rates within the storm. TRMM PR found that the heaviest rainfall associated with Humberto was not near the center of circulation but in convective storms west of the storm. TRMM saw rainfall rates of up to 2 inches/50 mm per hour in the large band of thunderstorms west of Humberto's center. At that time, Humberto was a tropical storm with highest winds near 55 knots (~63 mph).[image-142]

NASA's Aqua satellite passed over Hurricane Humberto and analyzed the storm in infrared light using the Atmospheric Infrared Sounder known as AIRS and visible light using the MODIS instrument. AIRS gathered data on Sept. 11 at 03:29 UTC/Sept. 10 at 11:29 p.m. EDT and revealed cloud cloud-top temperatures in excess of -63F/-52C in thunderstorms around the hurricane's center of circulation and in bands of thunderstorms west of the center. The MODIS or Moderate Resolution Imaging Spectroradiometer instrument showed a thick band of thunderstorms wrapping into the center from the west.[image-126]

At 11 a.m. EDT on Sept. 11, Hurricane Humberto made a turn to the north and is expected to continue in that direction for another day or two. It was centered about 340 miles/550 km west of the Cape Verde Islands, near 16.7 north and 29.1 west. Humberto has maximum sustained winds near 80 mph/130 kph and is moving to the north near 9 mph/15 kph.

The National Hurricane Center noted that Humberto could strengthen a little today before weakening on Sept. 12. Humberto is headed for cooler waters and an environment where wind shear is expected to increase which is why it is expected to weaken.

Text credit: Rob Gutro/Hal Pierce

NASA's Goddard Space Flight Center

Sept. 10, 2013 - Sees Heavy Rainfall in Strengthening Tropical Storm Humberto [image-94]

NASA's TRMM satellite saw heavy rain falling south of Tropical Storm Humberto's center as it continues to strengthen in the Eastern Atlantic.

NASA's Tropical Rainfall Measuring Mission satellite called TRMM passed near Humberto on September 10, 2013 at 0147 UTC (9:47 p.m. Sept. 9) and collected data used in this rainfall analysis. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) showed a large area of heavy rain south of Humberto's center of circulation. Rain was falling at a rate of 2 inches/50 mm per hour.

At 11 a.m. EDT on Sept. 10, Humberto's maximum sustained winds were near 65 mph/100 kph, just 9 mph shy of hurricane-force. Humberto is now predicted by the National Hurricane Center (NHC) to become a hurricane later today, Sept. 10.

The center of Tropical Storm Humberto was located near latitude 14.6 north and longitude 27.7 west, about 220 miles/355 km west of the southernmost Cape Verde Islands. Humberto is moving toward the west-northwest near 9 mph/15 kph and is expected to turn to the northwest later today then north. The estimated minimum central pressure is 998 millibars.

If Humberto becomes a hurricane, it would be the first of the Atlantic Ocean season.

Text credit: Hal Pierce

SSAI/NASA's Goddard Space Flight Center

Sept. 09, 2013 - NASA Investigates Gabrielle's Remnants and New Tropical Storm Humberto [image-51]

Tropical Depression Nine formed yesterday, Sept. 8 in the far eastern Atlantic, and NASA's Aqua satellite saw it strengthen into Tropical Storm Humberto today, Sept. 9 at 5 a.m. EDT. As that storm strengthened, the remnants of the once-tropical-storm Gabrielle continued to struggle near the Bahamas as NASA's HS3 mission investigated.

Tropical Storm Humberto is affecting the Cape Verde Islands, so there's a tropical storm warning in up for the southern islands of Maio, Santiago, Fogo, and Brava.

NASA's Aqua satellite passed over Tropical Storm Humberto hours before it was designated a tropical storm, and the Atmospheric Infrared Sounder instrument called "AIRS" captured infrared data on the storm. The AIRS data showed that some strong thunderstorms had developed around the center of circulation that were acting as a "heat engine" for the storm and strengthening it. Cloud-top temperatures of those powerful thunderstorms were colder than -63F/-52C, and forecasters at the National Hurricane Center expect Humberto to continue strengthening in the short term. The image also showed that the most powerful thunderstorms, the ones with the coldest cloud top temperatures, were just south of the Cape Verde Islands at the time Aqua flew overhead. Humberto has since moved closer to some of the southern islands bringing rain and gusty winds today.

Both Tropical Humberto the remnants of Gabrielle, located on the other side of the Atlantic, were captured in an image from NOAA's GOES-East satellite today. The image, created by the NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md. showed how far east Humberto is compared to Gabrielle's remnants.[image-78]

NASA's Hurricane and Severe Storms Sentinel or HS3 mission gathered data over Gabrielle's remnants over the weekend of Sept. 7 and 8. NASA's Global Hawk 872, or NASA 872 departed from NASA's Wallops Flight Facility, Wallops Island, Va. on Saturday, Sept. 7 at 8:07 a.m. EDT and flew over the remnants of Gabrielle as it lingered north of the Dominican Republic. NASA 872 dropped dropsondes and took various measurements of the remnants during its flight.NASA 872 ended flight upon landing back at NASA's Wallops Flight Facility, Wallops Island, Va. on Sunday, Sept. 9 at 7:17 a.m. EDT.

At 8 a.m. on Sept. 9 the center of Tropical Storm Humberto was located near latitude 13.4 north, longitude 23.3 west, just 92 nautical miles south of Praia, in the Cape Verde Islands. Humberto is moving toward the west near 12 mph/19 kph, and the storm is expected to turn to the west-northwest. Maximum sustained winds are near 40 mph/65 kph and is expected to briefly become a hurricane over the next day or two before weakening again.

The National Hurricane Center noted that the center of Humberto will pass south of the southern Cape Verde Islands this afternoon and tonight and pass west of the islands on Tuesday, Sept. 10.

Meanwhile, an elongated area of low pressure that include the remnants of tropical depression Gabrielle are still lingering in the western Atlantic. That broad area of low pressure is located about 500 miles south-southwest of Bermuda. Because of wind shear on Sept. 9, the shower and thunderstorm activity remains displaced to the east of the center as it was on Sunday, Sept. 8. Upper-level winds are not expected to be conducive for significant development while the low moves northeastward to north-northeastward during the next several days. This system has a low chance, 10 percent, of becoming a tropical cyclone during the next two days

Farther west, the National Hurricane Center noted that a low pressure area could form over the Bay of Campeche in the southwestern Gulf of Mexico in the next couple of days.

For more information about NASA's HS3 mission, please visit: www.nasa.gov/HS3.

Text credit: Rob Gutro

NASA's Goddard Space Flight Center