Oct. 28, 2019 – NASA Sees Tropical Cyclone Olga Merge with a Cold Front
Tropical Depression 17 strengthened briefly into a tropical storm on the same day it formed, Oct. 25. NASA’s Terra satellite captured a look at the clouds associated with its remnants merging with a cold front over the southern U.S.
When NASA’s Terra satellite passed over the eastern U.S. on Oct. 26, it found post-tropical cyclone Olga’s clouds spreading into the Mississippi Valley, but there was no discernable center of circulation as the storm became embedded in a cold front. Credit: NASA Worldview
Tropical Depression 17 formed early on Friday, Oct. 25 and by 5 p.m. EDT it had strengthened and organized into a tropical storm and was renamed Olga. However, by 11 p.m. EDT, Olga transitioned again into a post-tropical storm.
The last advisory on Tropical Storm Olga was issued at 11 p.m. EDT on Oct. 25 by the National Hurricane Center or NHC. At that time, the center of Post-Tropical Cyclone Olga was located near latitude 27.8 degrees north and longitude 92.2 degrees west. The post-tropical cyclone was moving toward the northeast near 17 mph (28 kph) and maximum sustained winds were near 50 mph (85 kph) and weakening.
At that time, the NHC discussion said, “Earlier this evening, the last 2 passes through Olga made by an Air Force Reserve Hurricane Hunter aircraft showed that the cyclone had become embedded within a cold front. Strong northwesterly flow was observed within 10 nautical miles northwest of Olga’s center and a sharp temperature and dew point gradient was measured across the cyclone. It does not appear that Olga has separated from the front in any significant way since the plane left. In fact, recent surface observations suggest that either the front passes through the center of the cyclone or its circulation has become poorly defined. Based on all these data, Olga is now classified as post-tropical and this is the last NHC advisory.”
Since Olga became entangled with the front, the winds and seas associated the front were then considered to be representative of the overall system.
Olga’s remnants moved through the Mississippi Valley today and toward the Great Lakes on Sunday, Oct. 27.
Oct. 25, 2019 – NASA Observes Tropical Storm Kyarr Form Near Southwest India Coast
Tropical Storm Kyarr formed near the southwestern coast of India, and NASA’s Aqua satellite provided forecasters with a visible image of the storm that revealed it organized quickly.
On Oct. 25 at 5:10 a.m. EDT (0910 UTC), the MODIS instrument that flies aboard NASA’s Aqua satellite took this image of Tropical Storm Kyarr off the coast of southwestern India. Credit: NASA/NRL
Kyarr formed early on Oct. 25 from a low-pressure area designated as System 97A in the northern Indian Ocean. Once the storm consolidated, it intensified quickly and became a tropical storm just off the southwest India coast.
The India Meteorological Department issued some warnings on Kyarr on Oct. 25. There is a heavy rainfall warning in effect that calls for light to moderate rainfall in most places. Heavy to very heavy falls are predicted at isolated places very likely over coastal districts of Karnataka, Goa and south Konkan and isolated heavy rainfall over north Konkan during next 24 hours. There is also a wind warning in effect calling for gale-force winds with speeds reaching 70-80 kph (43 to 50 mph) gusting to 90 kph (56 mph), prevailing around the system center over east-central Arabian Sea. It is very likely to increase gradually becoming 90-100 kph (56 to 62 mph).
On Oct. 25 at 5:10 a.m. EDT (0910 UTC), the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite provided a visible image of Kyarr. The image showed that there is a large band of powerful thunderstorms circling Kyarr’s low-level center of circulation. In addition, infrared satellite imagery showed that Kyarr has a solid core of strong convection – that is, rising air which forms the thunderstorms that make up a tropical cyclone, wrap around the low-level circulation center. Microwave satellite imagery revealed the storm had developed an eye, a sign of strengthening.
The shape of the storm is a clue to forecasters that a storm is either strengthening or weakening. If a storm takes on a more rounded shape it is getting more organized and strengthening. Conversely, if it becomes less rounded or elongated, it is a sign the storm is weakening.
At 11 a.m. EDT (1500 UTC) on Oct. 25, the Joint Typhoon Warning Center or JTWC noted Tropical Cyclone Kyarr was located near latitude 16.3 degrees north and longitude 71.9 degrees east, about 579 nautical miles south-southeast of Karachi, Pakistan. Maximum sustained winds were 55 knots (63 mph/102 kph).
Kyarr is drifting generally northward while located between two subtropical ridges (elongated areas of high pressure) located to the northwest and northeast of the tropical storm. As those ridges strengthen and build, Kyarr is forecast to turn to the northwest and rapidly intensify.
The JTWC expects the storm will peak after three days, but will then start to weaken on approach to the Oman coastline.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
Oct. 25, 2019 – NASA-NOAA Satellite Catches Development of Gulf Tropical Depression 17
NASA-NOAA’s Suomi NPP satellite passed over the Gulf of Mexico and revealed that a low pressure area was developing into a depression. On Oct. 25, that low pressure area became Tropical Depression 17.
NASA-NOAA’s Suomi NPP satellite passed over the Gulf of Mexico and the VIIRS instrument aboard captured this image of developing Tropical Depression 17 on Oct. 24. Suomi NPP showed that the center of circulation was west of the bulk of clouds. Credit: NASA/NOAA/NRL
On Oct. 24, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite captured a visible image of the structure of the low pressure area that became Tropical Depression 17 on Oct. 25. The storm appeared elongated from south to north, but the center was actually located west of all of the clouds and showers. In satellite imagery on Oct. 25, the National Hurricane Center said, “Satellite imagery indicates that the low pressure system in the western Gulf of Mexico has developed a well-defined circulation. In addition, a cluster of strong convection is located near and to the northeast of the low-level center.”
Status of Tropical Depression 17
At 11 a.m. EDT (1500 UTC) on Oct. 25, the center of Tropical Depression 17 was located near latitude 25.6 degrees north and longitude 94.4 degrees west. That puts the center about 320 miles (515 km) south-southwest of Lake Charles, Louisiana.
The depression was moving toward the north near 16 mph (26 kph). A motion toward the north-northeast at a faster forward speed is expected later in the day and through Sunday [Oct 27]. Maximum sustained winds are near 35 mph (55 kph) with higher gusts. The estimated minimum central pressure is 1006 millibars.
The National Hurricane Center or NHC said, “Some strengthening is expected and the depression could become a tropical storm later in the day on Oct. 25. The cyclone is then expected to merge with a cold front and become a post-tropical low with gale-force winds tonight before the center reaches the Gulf coast.”
On the forecast track, the center of the cyclone should move across the northwestern Gulf of Mexico this afternoon and then move over the northern Gulf coast tonight or Saturday morning.
NHC Forecasts Conditions Expected
The NHC noted the following conditions are forecast: Gale-force winds associated with this system should spread over portions of the northern Gulf coast tonight and Saturday morning. The depression and rainfall ahead of the system along and north of the frontal boundary across the Central Gulf coast is expected to produce total rainfall accumulations of 2 to 4 inches with maximum totals of 8 inches across the Central Gulf coast into the Lower Mississippi Valley through Saturday morning. These rains may produce flash flooding across the Central Gulf coast into the Lower Mississippi Valley.
Above-normal tides and associated coastal flooding are possible across portions of the northern Gulf coast. A couple tornadoes are possible through tonight across southeast portions of Louisiana and Mississippi into southwest Alabama.
Forecasting a Merge With a Cold Front
The NHC noted, “Since the depression is expected to merge with a cold front and become post-tropical by tonight, hazards related to wind, rainfall and coastal flooding will be covered by products issued by local National Weather Service forecast offices, available at weather.gov.”
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
NASA-NOAA’s Suomi NPP satellite passed over the Northwestern Pacific Ocean revealed that Typhoon Bualoi continued to look asymmetric because of ongoing wind shear. The Joint Typhoon Warning Center issued the final bulletin on Bualoi as it was beginning the transition into an extra-tropical cyclone.
NASA-NOAA’s Suomi NPP satellite passed over Typhoon Bualoi and the VIIRS instrument aboard captured this image of the storm on Oct. 25. Suomi NPP showed that Bualoi continued to appear asymmetric as it was transitioning into an extra-tropical cyclone. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)
On Oct. 25, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite captured a visible image of the structure of Bualoi. The storm appeared elongated from southwest to northeast, indicating that it had begun its transition into an extra-tropical cyclone. The image was generated by NASA Worldview, Earth Observing System Data and Information System (EOSDIS), at NASA’s Goddard Space Flight Center in Greenbelt, Md.
What Wind Shear Does to a Tropical Cyclone
In general, wind shear is a measure of how the speed and direction of winds change with altitude. Tropical cyclones are like rotating cylinders of winds. Each level needs to be stacked on top each other vertically in order for the storm to maintain strength or intensify. Wind shear occurs when winds at different levels of the atmosphere push against the rotating cylinder of winds, weakening the rotation by pushing it apart at different levels.
What does Extra-tropical Mean?
When a storm becomes extra-tropical it means that a tropical cyclone has lost its “tropical” characteristics. The National Hurricane Center defines “extra-tropical” as a transition that implies both poleward displacement (meaning it moves toward the north or south pole) of the cyclone and the conversion of the cyclone’s primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force.
Bualoi’s Final Advisory
When the Joint Typhoon Warning Center issued their final bulletin on Bualoi at 5 a.m. EDT (0900 UTC), the storm was centered near latitude 33.7 degrees north and longitude 148.0 degrees east, about 421 nautical miles east of Yokosuka, Japan. The storm was speeding to the northeast at 25 knots (28 mph/44 kph) and had maximum sustained winds near 65 knots (75 mph/120 kph).
Forecasters at the Joint Typhoon Warning Center said that Bualoi was moving north-northeast and will continue to weaken. The storm is forecast to make its transition to an extra-tropical cyclone well to the east of Japan by the end of the day on Oct. 25.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
NASA-NOAA’s Suomi NPP satellite and NASA’s Aqua satellite both passed over the Northwestern Pacific Ocean and both used infrared light to obtain temperature data and shape information on Typhoon Bualoi.
NASA’s Aqua satellite passed over Typhoon Bualoi and the AIRS instrument aboard captured this image of the storm on Oct. 23 at 11:29 p.m. EDT (0329 UTC). Aqua found that the strongest thunderstorms around west of center had cloud top temperatures as cold as or colder than 210 Kelvin (minus 81.6 degrees Fahrenheit/minus 63.5 Celsius). Credit: NASA JPL, Heidar Thrastarson
The shape of a storm says a lot about what is happening to it. Symmetrical storms are stronger, more organized storms. It is like a spinning tire that is well rounded. It can spin faster. Asymmetric storms cannot rotate as fast as symmetrical storms. It is similar to a flat tire cannot go as fast as a rounded tire. Satellite data provides a look at the symmetry of storms and found that Typhoon Bualoi is now an asymmetric storm, indicating it is weakening.
Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures. This data is helpful to forecasters because storms are not uniform around tropical cyclones and it helps pinpoint where the strongest storms are located.
NASA-NOAA’s Suomi NPP satellite passed over Typhoon Bualoi and the VIIRS instrument aboard captured this image of the storm on Oct. 23 at 12:12 p.m. EDT (1612 UTC). Suomi NPP found that the strongest thunderstorms west of center had cloud top temperatures as cold as 190 Kelvin (minus 117 degrees Fahrenheit/minus 83.1 Celsius). Credit: NASA/NOAA/UWM-CIMSS, William Straka III
On Oct. 23 at 12:12 p.m. EDT (1612 UTC), the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP found strongest thunderstorms west of center had cloud top temperatures as cold as 190 Kelvin (minus 117 degrees Fahrenheit/minus 83.1 Celsius). NASA research has shown that cloud top temperatures that cold indicate strong storms have the potential to generate heavy rainfall.
William Straka III, a researcher at the University of Wisconsin – Madison, Space Science and Engineering Center (SSEC) created imagery of the storm using the Suomi-NPP satellite. The strongest thunderstorms were on the western side of the eye, while the eastern side showed tropospheric gravity waves created by overshooting cloud tops into the stratosphere. An overshooting cloud top is a dome-like protrusion above a cumulonimbus anvil cloud, often penetrating into the lower stratosphere. It indicates a very strong updraft in the convective cloud or thunderstorm.
Gravity waves are the mark of a powerful storm. They are created when air moving around the atmosphere gets pushed to another place as in the case of tropical cyclones. Powerful thunderstorms around a tropical cyclone’s center can move air up and down and generate these waves in quick, short bursts. They can be seen as ripples in some imagery of clouds in a tropical cyclone.
“The brightness temperature showed an asymmetrical orientation with the circulation being hidden in the convection. Also, the southern part of the storm seems to have some dry air intruding in on it, simply based on the infrared appearance,” Straka said.
When NASA’s Aqua satellite passed over Typhoon Bualoi, the Atmospheric Infrared Sounder or AIRS instrument aboard captured an image of the storm on Oct. 23 at 11:29 p.m. EDT (0329 UTC). Aqua found that the strongest thunderstorms around west of center had cloud top temperatures as cold as or colder than 210 Kelvin (minus 81.6 degrees Fahrenheit/minus 63.5 Celsius). The Joint Typhoon Warning Center said that animated enhanced infrared satellite imagery depicts decaying deep convective banding wrapping into a ragged eye.
On Oct. 24 at 11 a.m. EDT (1500 UTC), Typhoon Bualoi was located near latitude 29.4 degrees north and longitude 143.5 degrees east. That is about 670 nautical miles south of Misawa, Japan. Bualoi was moving to the north-northeast with maximum sustained winds near 90 knots (103 mph/167 kph).
The Joint Typhoon Warning Center noted that Bualoi is moving north-northeast and will continue to weaken. The storm will become extra-tropical east of Japan within 24 hours.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
Oct. 23, 2019 – NASA Analysis Shows Heavy Rain in Typhoon Bualoi
Typhoon Bualoi continues to move through the Northwestern Pacific Ocean and the Global Precipitation Measurement mission or GPM core satellite measured rainfall rates throughout the storm.
The GPM core satellite passed over strengthening Typhoon Bualoi in the Northwestern Pacific Ocean on Oct. 22 at 12:11 p.m. EDT (1611 UTC) and found the heaviest rainfall (white/pink) falling at a rate of over 50 mm (about 2 inches) per hour. Credit: NASA/JAXA/NRL
The GPM’s core satellite passed over Typhoon Bualoi on Oct. 22 at 12:11 p.m. EDT (1611 UTC). GPM found the heaviest rain around the eye, falling at a rate of over 50 mm (about 2 inches) per hour. Forecasters at NOAA’s National Hurricane Center or NHC incorporate the rainfall data into their forecasts.
At 5 a.m. EDT (7 p.m. ChST/0900 UTC) the center of Typhoon Bualoi was located near latitude 23.5 degrees north and longitude 142.0 degrees east. The National Weather Service in Tiyan, Guam noted that it is about 405 miles northwest of Agrihan. Bualoi is now moving north-northwest at 13 mph and will continue a gradual turn to the north tonight and then toward the north-northeast through Thursday night. Maximum sustained winds have decreased to 115 mph and Bualoi is expected to continue this weakening trend the next several days. Bualoi is expected to gradually increase in forward speed as it heads farther into the north Pacific east of Japan.
Both the Japan Aerospace Exploration Agency (JAXA) and NASA manage GPM.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
Oct. 22, 2019 – NASA Finds Heavy Rain Potential in Typhoon Bualoi Over Marianas
Typhoon Bualoi was lashing the Marianas Islands in the Northwestern Pacific Ocean when NASA’s Aqua satellite passed overhead and analyzed the cloud top temperatures to give forecasters insight into the storm’s rain potential.
On Oct. 22 at 0335 UTC (Oct. 21 at 11:35 p.m. EDT) NASA’s Aqua satellite analyzed the clouds in Typhoon Bualoi using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found coldest cloud top temperatures as cold as or colder than 210 Kelvin (purple) which is minus 81 degrees Fahrenheit (minus 63.1 degrees Celsius) around the center. Credit: NASA JPL/Heidar Thrastarson
On Oct. 22, a Tropical Storm Warning remained in effect for the islands of Agrihan, Pagan and Alamagan in the Northern Mariana Islands.
One of the ways NASA researches tropical cyclones is by using infrared data that provides temperature information. Cloud top temperatures identify where the strongest storms are located. The stronger the storms, the higher they extend into the troposphere, and the colder the cloud top temperatures.
Tropical cyclones do not always have uniform strength, and some sides have stronger sides than others, so knowing where the strongest sides of the storms are located helps forecasters. NASA then provides data to tropical cyclone meteorologists so they can incorporate the data in their forecasts.
On Oct. 22 at 0335 UTC (Oct. 21 at 11:35 p.m. EDT) NASA’s Aqua satellite analyzed the storm using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found coldest cloud top temperatures as cold as or colder 210 Kelvin (purple) which is minus 81 degrees Fahrenheit (minus 63.1 degrees Celsius) around the center. NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.
The AIRS infrared imagery also hinted at an eye, but the eye was more apparent in the AIRS microwave imagery. The Joint Typhoon Warning Center estimated that the eye is about 8 nautical miles wide.
At 11 a.m. EDT (1 a.m. CHST local time/1500 UTC) NOAA’s National Weather Service (NWS) in Tiyan, Guam noted that the center of Typhoon Bualoi was located near latitude 19.7 degrees north and longitude 143.2 degrees east. That puts the eye about 175 miles west-northwest of Agrihan, and about 440 miles north-northwest of Guam.
Bualoi is moving northwest at 16 mph. It is expected to make a slight turn toward the north-northwest with a slight decrease in forward speed over the next 24 hours. Maximum sustained winds have increased to 145 mph. Bualoi is forecast to intensify through Thursday and then begin weakening as it moves in a northerly track.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
The AIRS instrument is one of six instruments flying on board NASA’s Aqua satellite, launched on May 4, 2002.
Oct. 22, 2019 – NASA Imagery Reveals Neoguri Now Extra-Tropical
Formerly a typhoon, now an extra-tropical storm, Neoguri has taken on more of a frontal system appearance in imagery from NASA’s Aqua satellite. The final warning on the system has been issued.
On Oct. 22, the MODIS instrument that flies aboard NASA’s Aqua provided a visible image of Extra-Tropical Storm Neoguri, east of Japan. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).
On Oct. 22, the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite provided a visible image of Neoguri. The MODIS imagery indicated that Neoguri had an elongated and poorly defined low-level circulation center with the bulk of clouds and convection (rising air that forms the thunderstorms that make up a tropical cyclone) pushed to the northeast of the center because of strong southwesterly wind shear.
What is Wind Shear?
In general, wind shear is a measure of how the speed and direction of winds change with altitude. Tropical cyclones are like rotating cylinders of winds. Each level needs to be stacked on top each other vertically in order for the storm to maintain strength or intensify. Wind shear occurs when winds at different levels of the atmosphere push against the rotating cylinder of winds, weakening the rotation by pushing it apart at different levels.
What does Extra-tropical Mean?
When a storm becomes extra-tropical, it means that a tropical cyclone has lost its “tropical” characteristics. The National Hurricane Center defines “extra-tropical” as a transition that implies both poleward displacement (meaning it moves toward the north or south pole) of the cyclone and the conversion of the cyclone’s primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and retain winds of hurricane or tropical storm force.
Neoguri on Oct. 22
On Oct. 22 at 5 a.m. EDT (0900 UTC), the Joint Typhoon Warning Center issued the final warning on Extra-tropical Storm Neoguri. At that time, Neoguri was centered near latitude 34.1 degrees north and longitude 141.4 degrees east. That is about 119 nautical miles south-southeast of Yokosuka, Japan. Neoguri was moving to the east-northeast and had maximum sustained winds near 45 knots (52 mph/83 kph). Neoguri is expected to intensify slightly and continue tracking northeastward.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
Oct. 21, 2019 – NASA Catches Short-lived Tropical Storm Priscilla’s Landfall in Mexico
Tropical Storm Priscilla was short-lived because it formed on Sunday, Oct. 20 very close to the coast of western Mexico and made landfall that same day. NASA’s Terra satellite provided a visible picture of the storm as it was making landfall.
Tropical Storm Priscilla was short-lived because it formed on Sunday, Oct. 20 very close to the coast of western Mexico and made landfall that same day. NASA’s Terra satellite provided a visible picture of the storm as it was making landfall. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).
On Oct. 20, a Tropical Storm Warning was in effect for Punta San Telmo to Playa Perula as Tropical Storm Priscilla moved toward southwestern Mexico.
The National Hurricane Center noted on Sunday, Oct. 20 at 10 a.m. CDT, the center of Tropical Storm Priscilla was located off the west coast of Mexico about 65 miles (105 km) south-southeast of Manzanillo. It was moving toward the north near 7 mph (11 kph), and this motion is expected to continue through tonight. On the forecast track, the center of Priscilla will approach the southwestern coast of Mexico within the warning area later today, and move inland by tonight. Maximum sustained winds are near 40 mph (65 kph) with higher gusts. Tropical-storm-force winds extend outward up to 35 miles (55 km) from the center.
When NASA’s Terra satellite passed over western Mexico at 1:30 p.m. PDT (4:30 p.m. EDT), the Moderate Resolution Imaging Spectroradiometer provided a visible image. The image showed that Priscilla was already affected by its interaction with land and was somewhat elongated. The clouds associated with the tropical storm had spread out over Jalisco, Nayarit and Colima states.
Priscilla dissipated by 11 p.m. EDT on Oct. 20. At that time, the remnants of Priscilla were located near latitude 20.0 degrees north and longitude 104.7 degrees west. The remnants were moving toward the north-northwest near 10 mph (17 kph). Maximum sustained winds were near 30 mph (45 kph) with higher gusts.
NOAA’s National Hurricane Center said that rainfall accumulations of 5 to 10 inches, with local amounts to 15 inches, were expected across portions of Nayarit, Jalisco, Colima, and Michoacan in southwestern Mexico through Tuesday night, Oct. 22.
Oct. 21, 2019 – NASA Finds a Transitioning Tropical Storm Neoguri
NASA’s Terra satellite passed over the Northwestern Pacific Ocean on Oct. 21 and captured a visible image of Tropical Storm Neoguri. Satellite imagery revealed that the storm is becoming extra-tropical.
On Oct. 21, the MODIS instrument that flies aboard NASA’s Terra provided a visible image of Tropical Storm Neoguri along Japan’s East coast. The storm was becoming extra-tropical. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).
On Oct. 21, the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite provided a visible image of Neoguri. The MODIS imagery indicated that Neoguri appeared elongated and large storm, where the bulk of clouds and convection (rising air that forms the thunderstorms that make up a tropical cyclone) were pushed to the northeast of the center as a result of southwesterly wind shear. Sheared convection and initial frontal features indicate that the system is undergoing extratropical transition.
What is Wind Shear?
In general, wind shear is a measure of how the speed and direction of winds change with altitude. Tropical cyclones are like rotating cylinders of winds. Each level needs to be stacked on top each other vertically in order for the storm to maintain strength or intensify. Wind shear occurs when winds at different levels of the atmosphere push against the rotating cylinder of winds, weakening the rotation by pushing it apart at different levels.
What does Extra-tropical Mean?
When a storm becomes extra-tropical it means that a tropical cyclone has lost its “tropical” characteristics. The National Hurricane Center defines “extra-tropical” as a transition that implies both poleward displacement (meaning it moves toward the north or south pole) of the cyclone and the conversion of the cyclone’s primary energy source from the release of latent heat of condensation to baroclinic (the temperature contrast between warm and cold air masses) processes. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force.
Neoguri on October 21
On Oct. 21 at 11a.m. EDT (1500 UTC) the Joint Typhoon Warning Center said that Neoguri was centered near latitude 31.4 degrees north and longitude 125.6 degrees east. That is about 311 miles southwest of Yokosaka, Japan. Neoguri was moving to the northeast and had maximum sustained winds near 40 knots (46 mph/74 kph).
Neoguri is expected to continue to weaken and will become entirely extra-tropical within 12 hours.
Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.
