Vayu (was 02A) – Northern Indian Ocean

June 17 Update – NASA-NOAA Satellite Finds Dry Air Affecting Tropical Cyclone Vayu

Tropical Cyclone Vayu was fading as it neared the coast of southwestern Pakistan and northwestern India. Dry air and wind shear were preventing development the development of thunderstorms, making the clouds on the storm’s western side appear wispy in an image from NASA-NOAA’s Suomi NPP satellite.

satellite image of Vayu
NASA-NOAA’s Suomi NPP satellite passed over the Arabian Sea on June 17 and saw the effects of dry air on Tropical Cyclone Vayu’s western quadrant where only wispy clouds were seen. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image of the storm on June 17, 2019. The VIIRS image showed that dry air that moved into the storm on the western side had prevented further development of the thunderstorms that make up a tropical cyclone. Clouds on that side of Vayu appeared wispy and were precipitation free. Thicker clouds were visible on Vayu’s eastern side where some had already spread over the coast of northwestern Indian near Naliya. Vayu is forecast to make landfall near Naliya later in the day.

On June 17 at 0300 UTC (June 16 at 11 p.m. EDT), the Joint Typhoon Warning Center issued the final warning on Vayu. At that time, Tropical Cyclone Vayu was located near 21.8 degrees north latitude and 66.8 degrees east longitude, approximately 180 nautical miles south of Karachi, Pakistan. Vayu was moving to the northeast and had maximum sustained winds near 35 knots (40 mph/65 kph) making it a minimal tropical storm.

In addition to dry air sapping the tropical cyclone’s ability to create more thunderstorms, wind shear is pushing the remaining storms to the east of the center.

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.

Vayu is forecast to dissipate later in the day on June 17.

By Rob Gutro
NASA’s Goddard Space Flight Center  

Vayu (was 02A) – Northern Indian Ocean

June 14, 2019 – Update #2 – NASA Finds Tropical Cyclone Vayu Getting Stretched

When NASA’s Aqua satellite passed over the Northern Indian Ocean, it captured an infrared image that revealed Tropical Cyclone Vayu was elongating. That’s never a good sign for a tropical cyclone, because they need a circular rotation to maintain strength.

AIRS image of Vayu
On June 14, at 0359 UTC (0859 UTC) the AIRS instrument aboard NASA’s Aqua satellite analyzed cloud top temperatures of Tropical Cyclone Vayu in infrared light. AIRS found coldest cloud top temperatures (purple) of strongest thunderstorms were as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius). Credit: NASA JPL/Heidar Thrastarson

On June 14, warnings remained in effect for India’s Gujarat coast.

Infrared light enables NASA to take the temperatures of clouds and thunderstorms that make up tropical cyclones. The stronger the storms are indicate that they extend high into the troposphere and have cold cloud top temperatures.

An infrared look by NASA’s Aqua satellite on June 14, at 0359 UTC (0859 UTC) revealed strongest storms within Tropical Cyclone Vayu. The Atmospheric Infrared Sounder or AIRS instrument aboard NASA’s Aqua satellite analyzed cloud top temperatures and found cloud top temperatures of strongest thunderstorms as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) circling the center and in thunderstorms northwest of the center. Cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

On June 14 at 11 a.m. EDT (1500 UTC), the center of Tropical Cyclone Vayu was located near latitude 20.8 degrees south and longitude 68.2 degrees east. Vayu was moving to the southwest and had weakened. Maximum sustained winds were near 75 knots (75 mph/120 kph) making the storm a category one hurricane on the Saffir-Simpson Hurricane Wind Scale. The AIRS imagery showed that the storm appeared more elongated, indicating that vertical wind shear was increasing and having an adverse effect on it, so Vayu was weakening.

The Joint Typhoon Warning Center expects Vayu to turn to the northeast in a day and a half and make landfall near the India/Pakistan border by June 17.

For updated forecasts from the India Meteorological Department, visit: http://www.imd.gov.in

By Rob Gutro
NASA’s Goddard Space Flight Center  

Vayu (was 02A) – Northern Indian Ocean

June 14, 2019 – NASA Finds Tropical Cyclone Vayu off India’s Gujarat Coast

NASA’s Terra satellite showed Tropical Cyclone Vayu still lingering near the northwestern coast of India, and its cloud-filled eye remained offshore.

Terra image of Vayu
On June 14, 2019, the MODIS instrument aboard NASA’s Terra satellite provided a visible image of Tropical Cyclone Vayu off India’s Gujarat coast, western India. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

On June 14, 2019, t the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Terra satellite provided a visible image of Tropical Cyclone Vayu located off western India’s Gujarat coast. Animated enhanced infrared satellite imagery revealed a compact area of asymmetric central deep convection (building thunderstorms) with well-organized spiral banding wrapping into a cloud-filled ragged eye.

JTWC forecasters noted that there are several things happening with the storm that is affecting the strength and shape of it. Dry air continues to feed into the storm, which prevents the development of thunderstorms (that make up the tropical cyclone). However, that is offset by low vertical wind shear (outside winds blowing at different speeds at different levels of the atmosphere that if strong enough, can blow a storm apart). Vayu is also moving through very warm waters, as warm as 30 to 31 degrees Celsius (86 to 87.8 degrees Fahrenheit) that is keeping the storm together. Tropical cyclones require sea surface temperatures of at least 80 degrees Fahrenheit (26.6 degrees Celsius) to maintain them. Warmer sea surface temperatures help keep storms together or give them fuel to strengthen further.

At 5 a.m. EDT (0900 UTC), the Joint Typhoon Warning Center or JTWC reported that Tropical Cyclone Vayu was located near 20.8 degrees north latitude and 68/0 east longitude. That is 248 nautical miles south-southeast of Karachi, Pakistan. Vayu has turned to the west-southwest. Maximum sustained winds had dropped to 85 knots (98 mph/157 kph) and the storm is forecast to continue weakening.

The JTWC has forecast Vayu to curve back to the northeast and make landfall in four days along the northwestern India/Pakistan border on June 17.

By Rob Gutro
NASA’s Goddard Space Flight Center

Vayu (was 02A) Northern Indian Ocean

June 13, 2019 – Satellite Sees Tropical Cyclone Vayu Centered Off India Coastline

Tropical Cyclone Vayu’s eye was just off the western coast of India when the NOAA-20 satellite passed overhead and captured a visible image of the storm.

JPSS image of Vayu
NOAA’s JPSS satellite passed over the Northern Indian Ocean and the VIIRS instrument captured a visible image that showed the eye off the Gujurat coast of India. Credit: NOAA/NRL

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the NOAA-20 polar orbiting satellite provided a visible image of the storm. The VIIRS image revealed an eye surrounded by powerful thunderstorms. However, the majority of the strongest storms appeared to be displaced southwest of the eye.

The Joint Typhoon Warning Center or JTWC noted that dry air is wrapping into the system, which will limit its ability to intensify further.

At 11 a.m. EDT (1500 UTC) on June 13, 2019, Vayu had maximum sustained winds near 95 knots (109 mph/176 kph). Vayu’s eye was centered near 20.9 degrees north latitude and 68.8 degrees east longitude. It is approximately 264 nautical miles south-southeast of Karachi, Pakistan. Vayu has tracked north-northwestward.

JTWC forecasters noted that “the track is expected to shift westward in the near term as another subtropical ridge (elongated area of high pressure) located over Saudi Arabia builds in to the northwest. In one and a half days, increasing outside winds and more dry air moving into the system is expected to begin weakening it.

By Rob Gutro 
NASA’s Goddard Space Flight Center

Vayu (was 02A – Northern Indian Ocean)

June 12, 2019 – NASA Reveals Tropical Cyclone Vayu’s Compact Center

Visible imagery from NASA’s Aqua satellite showed Tropical Cyclone Vayu has a compact central dense overcast cloud cover. Vayu’s center was off-shore from India’s Gujarart coast.

Aqua image of Vayu
On June 12 at 4:05 a.m. EDT (0905 UTC), the MODIS instrument aboard NASA’s Aqua satellite provided a visible image of Tropical Cyclone Vayu and showed a compact center of circulation. Credit: NASA /NRL

On June 12 at 4:05 a.m. EDT (0905 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite provided a visible image of Vayu. Vayu’s center was off the western coast of India, in the Arabian Sea. Although hurricane-strength, the MODIS image showed a cloud-filled center of circulation and compact central dense overcast feature, approximately 90 to 100 nautical miles in diameter. The MODIS visible image also showed a thick band of thunderstorms wrapped into the low-level center from the western and southern quadrants. Meanwhile, satellite microwave imagery revealed a small eye beneath that overcast.

At 11 a.m. EDT (1500), the Joint Typhoon Warning Center reported that Tropical Cyclone Vayu was located near 19.4 degrees north latitude and 69.7 east longitude. That is 376 nautical miles south-southeast of Karachi, Pakistan. Vayu has tracked to the north-northwest. Maximum sustained winds were near 90 knots (104 mph/167 kph).

The Joint Typhoon Warning Center forecasts Vayu to strengthen slightly over the next day. Vayu is forecast to continue tracking north and turn to the northwest, with its center keeping off shore from India as it moves toward Pakistan. The latest forecast turns Vayu to the west, keeping it from a landfall through June 17.

By Rob Gutro
NASA’s Goddard Space Flight Center

Vayu (was 02A – Northern Indian Ocean)

June 11, 2019 – NASA Takes Tropical Cyclone‘s Vayu’s Temperature

NASA’s Aqua satellite passed over the Northern Indian Ocean and took the temperature of Tropical Cyclone Vayu as it moved northward in the Arabian Sea. NASA found the storm intensifying. Warnings are now in effect for India’s Gujarat coast.

AIRS Image of Vayu
On June 10, at 0511 UTC (0911 UTC) the AIRS instrument aboard NASA’s Aqua satellite analyzed cloud top temperatures of Tropical Cyclone Vayu in infrared light. AIRS found coldest cloud top temperatures (purple) of strongest thunderstorms were as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius). Credit: NASA JPL/Heidar Thrastarson

Infrared light enables NASA to take the temperatures of clouds and thunderstorms that make up tropical cyclones. The stronger the storms are indicate that they extend high into the troposphere and have cold cloud top temperatures.

An infrared look by NASA’s Aqua satellite on June 10, at 0511 UTC (0911 UTC) revealed where the strongest storms were located within Tropical Cyclone Vayu, formerly known as Tropical Cyclone 02A. The Atmospheric Infrared Sounder or AIRS instrument aboard NASA’s Aqua satellite analyzed cloud top temperatures and found cloud top temperatures of strongest thunderstorms as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) circling the center and in thunderstorms northwest of the center. Cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

On June 11, cloud top temperatures continued to cool, as Vayu intensified. The Joint Typhoon Warning Center stated, “multi-spectral satellite imagery showed “tightly-curved banding wrapping into a formative, small eye, which supports the initial position with good confidence.” Satellite imagery showed Vayu has a compact core, approximately 90 nautical miles in diameter with bands of thunderstorms wrapping around it from the western quadrant.

On June 11 at 5 a.m. EDT (0900 UTC), the center of Tropical Cyclone Vayu was located near latitude 16.4 degrees south and longitude 70/9 degrees east. Vayu was moving to the north and had maximum sustained winds were near 65 knots (75 mph/120 kph) making the storm a category one hurricane on the Saffir-Simpson Hurricane Wind Scale.

The Joint Typhoon Warning Center expects Vayu to intensify quickly, peaking at 95 knots (109 mph/176 kph) on June 12 before starting to weaken on June 13. That means hurricane-force winds, storm surge and heavy rain can be expected along the western coast of India is Vayu moves north over the next several days.

For updated forecasts from the India Meteorological Department, visit: http://www.imd.gov.in

By Rob Gutro
NASA’s Goddard Space Flight Center  

02A (Northern Indian Ocean)

June 10, 2019 – NASA Catches Development of Tropical Cyclone 02A

Visible imagery from NASA’s Terra satellite provided confirmation of the development of Tropical Cyclone 02A in the Arabian Sea, Northern Indian Ocean.

Terra image of 02A
On June 10, 2019, the MODIS instrument aboard NASA’s Terra satellite provided a visible image of Tropical Cyclone 02A in the Northern Indian Ocean, off the western coast of India. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

On June 10, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Terra satellite provided a visible image of 02A that showed thunderstorms circling the low-level center. MODIS imagery also showed some clouds and thunderstorms were offset to the northwest of the center. That’s a result of outside winds or vertical wind shear, blowing from the southeast and pushing some clouds to the northwest.

Satellite imagery revealed that the sea surface temperatures are warm enough to support further development of Tropical Cyclone 02A, and forecasters at the Joint Typhoon Warning Center expect some strengthening over the next couple of days.

At 11 a.m. EDT (1500 UTC) on Monday, June 10, 2019, Tropical Cyclone 02A was centered near 13.7 degrees north latitude and 70.8 east longitude. That puts the center about 350 nautical miles south-southwest of Mumbai, India. 02A was moving to the north-northwest at 8 knots (9 mph/15 kph). Maximum sustained winds were near 45 knots (52 mph/83 kph).

The Joint Typhoon Warning Center forecast noted that the storm is expected to peak on June 12 when maximum sustained winds reach 60 knots (69 mph/111 kph). ”The cyclone is expected to continue tracking generally northward along the western periphery of a subtropical ridge (elongated area of high pressure) anchored over India, making landfall near Jamnagar around 96 hours [June 14] and track inland.”

By Rob Gutro
NASA’s Goddard Space Flight Center

91L (Atlantic Ocean)

June 05, 2019 – NASA Estimates Heavy Texas and Louisiana Rainfall from Gulf Weather System

Earlier in the week, NOAA’s National Hurricane Center was monitoring a low-pressure system in the Gulf of Campeche that has now moved along the Texas and Louisiana coastlines, bringing heavy rainfall. On June 5, NASA used a constellation of satellites to estimate that rainfall.

IMERG image of 91L
An IMERG precipitation product shows rainfall estimates of 10 inches between June 3 at 0000 UTC (June 2 at 8 p.m. EDT) to June 5 at 5:30 a.m. EDT (0930 UTC). Credit: NASA/JAXA, Matt Lammers

On June 5, the National Weather Service National Prediction Center in College Park, Maryland noted that there is a “High risk for flash flooding across parts of southeast Texas and southern Louisiana Today into Tonight.”

Estimating Heavy Rainfall

Forming in the Bay of Campeche on June 3, tropical disturbance 91L looked ripe to develop into a minor tropical cyclone before making landfall along the Gulf Coast of Texas, but high wind shear inhibited its development. On June 4, the National Hurricane Center dropped the chances that it would consolidate into a depression to 20 percent. On June 5, although the low-pressure area is expected to remain disorganized, it is expected to generate a lot of rainfall for the Gulf coast states.

“NASA’s IMERG data showed the tropical rainfall it brought has led to flash flooding throughout the Houston area on the morning of June 5, dumping more than 10 inches on a large region southwest of the city,” said Matt Lammers of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The Integrated Multi-satellitE Retrievals for GPM (IMERG) creates a merged precipitation product from the Global Precipitation Measurement mission or GPM constellation of satellites. At NASA Goddard an IMERG rainfall accumulation image was created from June 3 at 0000 UTC (June 2 at 8 p.m. EDT) to June 5 at 5:30 a.m. EDT (0930 UTC). Most of the precipitation in the Houston area has fallen since the latest IMERG Early processing, so rainfall totals will be higher.

The National Weather Service noted that the moisture interacting with an upper level low moving into the Southern Plains. Heavy to excessive rainfall is likely across southeast Texas and into the Lower Mississippi Valley today, with a high risk for flash flooding where as much as 4 to 7 plus inches more of rain is in the forecast from extreme southeast Texas into southwest Louisiana.

What Is NASA’s IMERG?

NASA’s GPM or Global Precipitation Measurement mission satellite provides information on precipitation from its orbit in space. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency or JAXA. GPM also utilizes a constellation of other satellites to provide a global analysis of precipitation that are used in the IMERG calculation.

At NASA’s Goddard Space Flight Center in Greenbelt, Maryland, those data are incorporated into NASA’s IMERG or Integrated Multi-satellitE Retrievals for GPM. IMERG is used to estimate precipitation from a combination of passive microwave sensors, including the Global Precipitation Measurement (GPM) mission’s core satellite’s GMI microwave sensor and geostationary IR (infrared) data. IMERG real-time data are generated by NASA’s Precipitation Processing System every half hour and are normally available within six hours.

IMERG creates a merged precipitation product from the GPM constellation of satellites. These satellites include DMSPs from the U.S. Department of Defense, GCOM-W from the Japan Aerospace Exploration Agency (JAXA), Megha-Tropiques from the Centre National D’etudies Spatiales (CNES) and Indian Space Research Organization (ISRO), NOAA series from the National Oceanic and Atmospheric Administration (NOAA), Suomi-NPP from NOAA-NASA, and MetOps from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).  All of the instruments (radiometers) onboard the constellation partners are inter-calibrated with information from the GPM Core Observatory’s GPM Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR).

Flood Watches

There is a moderate to high risk for flash flooding across parts of southeast Texas and southern Louisiana on Wednesday, June 5.

The National Weather Service in Houston/Galveston, Texas noted, “Numerous showers and thunderstorms are expected today. Rainfall will be locally heavy at times. A Flash Flood Watch is in effect through this evening. Rainfall totals will average 3 to 5 inches with isolated totals approaching 8 inches. Strong onshore winds will will produce elevated tides today and water levels at high tide could exceed 3.5 feet. Minor coastal flooding will be possible and a Coastal Flood Advisory is in effect.

Movement of the Weather System

The National Weather Service noted that “heavy to excessive rainfall threat shifts from the lower Mississippi Valley on Wednesday into the Central Gulf Coast states and eventually the U.S. Southeast by the end of the week.” For updated forecasts, visit: www.weather.gov

By Rob Gutro/with forecast information from weather.gov
NASA’s Goddard Space Flight Center

91L (Atlantic Ocean)

June 04, 2019 – NASA-NOAA Satellite Sees System 91L’s Reach into the Western Gulf of Mexico

System 91L is an area of tropical low pressure located in the Bay of Campeche. On June 3, when NASA-NOAA’s Suomi NPP satellite passed the western Gulf of Mexico, it captured an image of the storm that showed its extensive reach.

Suomi NPP image of 91L
NASA-NOAA’s Suomi NPP satellite passed over the Gulf of Mexico and captured a visible image of developing low pressure System 91L on June 3, 2019. Clouds associated with the system filed the Bay of Campeche and stretched north into the western Gulf of Mexico. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image of the storm. The VIIRS image showed fragmented bands of thunderstorms around System 91L’s circulation center which filled the Bay of Campeche and stretched north into the western Gulf of Mexico. System 91L’s clouds extend from Mexico’s Yucatan state to the west bordering and including the states of Campeche, Tabasco, Veracruz and as far north as Tamaulipas.

At 8 a.m. EDT on June 4, NOAA’s National Hurricane Center or NHC noted that System 91L now has a 40 percent chance to form into a depression over the next two days. “Shower and thunderstorm activity associated with a broad area of low pressure located over the southwestern Gulf of Mexico has decreased since yesterday and remains disorganized. This system could briefly become a tropical depression before moving inland over northeastern Mexico later today or tonight. “

Even if System 91L doesn’t develop into a depression, it’s still packing a punch with rainfall.

The NHC noted “the disturbance will likely produce heavy rainfall over portions of eastern Mexico, southeastern Texas and the Lower Mississippi Valley during the next few days.   Interests along the Gulf coast of Mexico should monitor the progress of this system.”

By Rob Gutro 
NASA’s Goddard Space Flight Center

91L (Atlantic Ocean)

June 03, 2019 – NASA Sees Strong Storms in Developing Gulf System 91L

NASA’s Aqua satellite used infrared light to analyze the strength of storms in the developing low pressure area designated as System 91L as it moved through the Gulf of Campeche just  north of Mexico’s Yucatan Peninsula.

Aqua image of 91L
On June 3 at 4:05 a.m. EDT (0805 UTC), the MODIS instrument that flies aboard NASA’s Aqua satellite gathered infrared data on developing System 91L. Strongest thunderstorms (yellow) created a southern ring around the center from west to east, where cloud top temperatures were as cold as minus 80 degrees Fahrenheit (minus 62.2 Celsius). Credit: NASA/NRL

Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

On June 3 at 4:05 a.m. EDT (0805 UTC),  the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite gathered infrared data on developing System 91L. Strongest thunderstorms created a southern ring around the center from west to east, where cloud top temperatures were as cold as minus 80 degrees Fahrenheit (minus 62.2 Celsius). Cloud top temperatures that cold indicate strong storms with the potential to generate heavy rainfall. Those strongest storms were located just off the coast of the state of Campeche and the eastern part of the state of Tabasco.

On June 3 at 2 p.m. EDT, the National Hurricane Center (NHC) noted that System 91L has a medium chance to develop into a depression within the next 24 hours. NHC Forecaster Zelinsky noted in the update, “Showers and thunderstorms associated with a broad area of low pressure located over the Bay of Campeche have become a little better organized since yesterday. However, recent satellite-based wind data indicate that the circulation of the low is elongated and poorly defined.”

This system is forecast to move slowly northwestward toward the northeastern coast of Mexico, and could become a tropical cyclone before it moves inland in a day or two.

Even if System 91L does not develop into a tropical cyclone, forecasters at NHC said the  disturbance will likely produce heavy rainfall over portions of southern and eastern Mexico during the next few days. Heavy rainfall is also likely to spread over southeastern Texas and Louisiana through Thursday.

Several computer models take System 91L on a northerly path, and interests along the Gulf coast of Mexico should monitor the progress of this system.

For updated forecasts, visit: https://www.nhc.noaa.gov

By Rob Gutro
NASA’s Goddard Space Flight Center