Nestor – Atlantic Ocean

Oct. 18, 2019 – NASA-NOAA Satellite Finds Overshooting Tops, Gravity Waves in Tropical Storm Nestor

NASA-NOAA’s Suomi NPP satellite provided night-time and infrared views of developing Tropical Storm Nestor in the Gulf of Mexico and found over-shooting cloud tops and gravity waves. When the satellite passed over the potential tropical depression early on Oct. 18, it was consolidating. Less than 12 hours later, it became a tropical storm.

Suomi NPP image of NEstor
NASA-NOAA’s Suomi NPP satellite provided a night-time view of developing Tropical Storm Nestor in the Gulf of Mexico on Oct. 18 at 3:41 a.m. EDT. The image revealed lightning, overshooting cloud tops into the stratosphere and gravity waves. Credit: NASA/NOAA/UWM-CIMSS, William Straka III

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a night-time and an infrared image of the storm.

Night-time Imagery of Nestor: Overshooting Tops, Gravity Waves

The night-time image was captured on Oct. 18 at 3:41 a.m. EDT and revealed lightning, overshooting cloud tops into the stratosphere and gravity waves. 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.

Infrared Imagery Shows Very Cold Cloud Tops

Suomi NPP image of Nestor
NASA-NOAA’s Suomi NPP satellite provided an infrared view of developing Tropical Storm Nestor in the Gulf of Mexico on Oct. 18 at 3:41 a.m. EDT. Around the center of circulation cloud top temperatures were as cold as or colder than minus 112 degrees Fahrenheit (minus 80 Celsius) (n black). Credit: NASA/NOAA/UWM-CIMSS, William Straka III

The infrared imagery captured by Suomi NPP’s VIIRS instrument on Oct. 18 at 3:41 a.m. EDT showed powerful thunderstorms with cloud tops colder than minus 112 degrees Fahrenheit (minus 80 degrees Celsius) within the eastern part of the storm.

Visible satellite imagery and data from an Air Force Reserve Hurricane Hunter aircraft also showed a rather large and elongated surface circulation.

Warnings and Watches

NOAA’s National Hurricane Center or NHC said a Tropical Storm Warning is in effect from the Mississippi/Alabama border to Yankeetown, Florida and from Grand Isle, Louisiana to the Mouth of the Pearl River. A Storm Surge Warning is in effect from Indian Pass, Florida to Clearwater Beach, Florida.

Nestor’s Status on October 18, 2019

At 2 p.m. EDT (1800 UTC), the center of Tropical Storm Nestor was located near latitude 26.3 degrees north and longitude 89.5 degrees west. That is 195 miles (315 km) south of the mouth of the Mississippi River. Nestor is moving toward the northeast near 22 mph (35 kph), and this general motion is expected to continue through Sunday, followed by a turn toward the east-northeast by early Monday. Maximum sustained winds are near 60 mph (95 kph) with higher gusts. Some strengthening is expected later today, with weakening forecast after Nestor moves inland. Nestor is expected to lose tropical characteristics and become post-tropical on Saturday. The estimated minimum central pressure is 1001 millibars.

Nestor’s Forecast

The National Hurricane Center forecast calls for the center of Nestor to approach the northern Gulf Coast later on Oct. 18 and move inland across portions of the southeastern United States Saturday and Sunday as it becomes a post-tropical cyclone. Nestor is expected to move offshore of the coast of North Carolina into the western Atlantic by late Sunday.

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.

For updated forecasts. Visit: www.nhc.noaa.gov

By Rob Gutro 
NASA’s Goddard Space Flight Center

Neoguri – Northwestern Pacific Ocean

Oct. 18, 2019 – NASA-NOAA Satellite Finds Tropical Storm Neoguri Consolidating

NASA-NOAA’s Suomi NPP satellite provided forecasters at the Joint Typhoon Warning Center with a visible image of Tropical Storm Neoguri that showed it had become more organized over the previous 24 hours.

Suomi NPP image of Neoguri
NASA-NOAA’s Suomi NPP satellite passed over Tropical Storm Neoguri on Oct. 18 at 1:18 a.m. EDT (0518 UTC), and revealed powerful storms around the low-level center. The image showed strong bands of thunderstorms developing east of the center. Credit: NASA /NRL

Tropical Depression 21W lacked organization for a couple of days until early on Oct. 18 when the Suomi NPP satellite passed overhead and showed it had consolidated. The storm had strengthened from a depression to a tropical storm on Oct. 18.

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided a visible image of Neoguri that revealed powerful storms circled the low-level center. The image showed that bands of thunderstorms were also developing around the eastern quadrant.

On Oct. 19 at 11 a.m. EDT (1500 UTC) Tropical Storm Neoguri, known locally in the Philippines as Perla, was located near latitude 20.4 degrees north and longitude 129.2 degrees east. That is about 374 nautical miles south-southeast of Kadena Air Base, Okinawa Island, Japan. It was moving to the northwest and had maximum sustained winds near 45 knots (52 mph/83 kph).

Forecasters at the Joint Typhoon Warning Center expect Neoguri will strengthen to 50 knots (58 mph/92 kph), then weaken before becoming extra-tropical on its northward 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.

By Rob Gutro 
NASA’s Goddard Space Flight Center

Octave – Eastern Pacific Ocean

Oct. 18, 2019 – NASA-NOAA Satellite Observes Development of Tropical Storm Octave

NASA-NOAA’s Suomi NPP satellite provided infrared data that showed the development of Tropical Storm Octave in the Eastern Pacific Ocean.

Suomi NPP image of Octave
NASA-NOAA’s Suomi NPP satellite’s VIIRS instrument aboard captured this infrared image of the Tropical Storm Octave as it developed on Oct. 17 at 6:24 p.m. EDT (2224 UTC). There were several areas (red) around the center of circulation where cloud top temperatures were as cold as minus 70 degrees Fahrenheit (minus 56.6 Celsius). Credit: NASA/NRL

Octave formed on Oct. 17 by 5 p.m. EDT as a tropical depression. At that time, it was located about 1,410 miles (2,265 km) southwest of the southern tip of Baja California, Mexico.

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided an infrared image of the storm. The National Hurricane Center noted that, “The much improved cloud pattern consists of prominent convective curved bands in the east semicircle and recent bursts of deep convection.” Infrared imagery analyzes cloud top temperatures, and the higher the cloud top, the colder it is, and the stronger the storm. On Oct. 17 at 6:24 p.m. EDT (2224 UTC), a VIIRS image found several areas around the center of circulation where cloud top temperatures were as cold as minus 70 degrees Fahrenheit (minus 56.6 Celsius). Storms with cloud tops that cold have been found to generate heavy rainfall.

On Oct. 18, infrared data showed that cloud top temperatures had warmed, meaning they dropped in height. That drop in height indicates a weakening of the uplift of air and a weakening of the storm. NOAA’s National Hurricane Center or NHC said that at 5:41 a.m. EDT (0941 UTC), “Cloud tops have warmed during the past few hours, but the initial intensity is being held at 40 knots based on ASCAT [instrument] data from overnight.”

The Oct. 18 image indicated that wind shear was affecting the storm and pushing the bulk of clouds and precipitation west of the center. NHC noted “The GCOM [Japanese satellite] microwave overpass was instrumental in showing that Octave’s center is located to the east of the main convective mass, and also well to the east of a more notable mid-level circulation.” When the bulk of precipitation and clouds are pushed away from the center, the storm weakens.

At 11 a.m. EDT (1500 UTC) on Oct. 18, the center of Tropical Storm Octave was located near latitude 10.6 degrees north and longitude 126.6 degrees west.  That puts the center about 1,390 miles (2,240 km) southwest of the southern tip of Baja California.  Octave is now moving toward the north near 2 mph (4 kph), but the storm is expected to meander or make a slow clockwise loop during the next few days. Maximum sustained winds are near 45 mph (75 kph) with higher gusts. The estimated minimum central pressure is 1005 millibars.

Another issue affecting Octave is its movement out of the Intertropical Convergence Zone (ITCZ). NOAA defines the ITCZ as the region where the northeasterly and southeasterly trade winds converge, forming an often continuous band of clouds or thunderstorms near the equator.

As Octave moves out of the ITCZ, low-level dry air to the west is wrapping into the cyclone’s circulation, which is likely causing the recent waning of convection.  Therefore, weakening is forecast during the next couple of days, and Octave is expected to degenerate into a remnant low over the weekend.

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.

For updated forecasts. Visit: www.nhc.noaa.gov

By Rob Gutro 
NASA’s Goddard Space Flight Center

17E – Eastern Pacific Ocean

Oct. 16, 2019 – NASA-NOAA Satellite Catches Last Burst Before Demise of Tropical Depression 17E

NASA-NOAA’s Suomi NPP satellite passed over Mexico and found two small areas of very strong thunderstorms near two different coastlines. One area was in Potential Tropical Cyclone 17E in the Eastern Pacific Ocean and the other was for another system developing in the western Gulf of Mexico.

Suomi NPP image of 17E
NASA-NOAA’s Suomi NPP satellite passed over Potential Tropical Cyclone 17E located along Mexico’s west coast in the Eastern Pacific Ocean. Suomi NPP’s VIIRS instrument captured this image of the storm on Oct. 16 at 4:18 a.m. EDT (0818 UTC). There were two small areas (yellow) within where cloud top temperatures were as cold as minus 80 degrees Fahrenheit (minus 62.2 Celsius). One over the Eastern Pacific and the other in the western Gulf of Mexico associated with another system. Credit: NASA/NRL

Potential Tropical Cyclone Seventeen-E developed around 11 p.m. EDT on Oct. 15 and by 11 a.m. EDT on Oct. 16, the center of circulation made landfall over the Mexican state of Oaxaca.

The Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP provided an infrared image of the storm. Infrared imagery reveals cloud top temperatures, and the higher the cloud top, the colder it is, and as such the stronger the storm. On Oct. 16 at 4:18 a.m. EDT (0818 UTC), an infrared VIIRS image showed two small areas around southern Mexico where cloud top temperatures were as cold as minus 80 degrees Fahrenheit (minus 62.2 Celsius). One area, located in the Eastern Pacific Ocean is associated with Potential Tropical Cyclone 17E.  Both areas with strongest storms were over water. One in the Eastern Pacific and the other in the western Gulf of Mexico. Storms with cloud tops that cold have been found to generate heavy rainfall.

Potential Tropical Cyclone 17E

At 2 p.m. EDT (1800 UTC), the disturbance was centered near latitude 16.6 degrees north and longitude 96.6 degrees west. That is about 95 miles (155 km) west-northwest of Salina Cruz, Mexico. The system is moving toward the northwest near 14 mph (22 kph), and this motion is expected to continue through tonight.  Maximum sustained winds were near 30 mph (45 kph) with higher gusts.

NOAA’s National Hurricane Center or NHC said, “The disturbance is now unlikely to bring tropical-storm conditions to the coast of Mexico, although the rainfall threat continues for portions of southeastern Mexico.”

While the chances that the disturbance will become a tropical cyclone are decreasing, the NHC forecasters said there is still a small chance that a tropical depression could develop if the center can re-form along the coast later today or tonight.

The Gulf of Mexico Low Pressure Area

The other area of strong storms seen on the Suomi NPP infrared image area is associated with a large area low pressure located just offshore of the coast of southern Mexico, in the Bay of Campeche. That low pressure area is producing disorganized showers and thunderstorms.  NHC said that gradual development is possible, and a tropical or subtropical cyclone could form late this week over the western or central Gulf of Mexico while the system is moving generally northeastward.  Regardless of development, this system could produce gusty winds, rainfall, and rough surf along portions of the northern Gulf Coast Friday and Saturday.

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.

For updated forecasts. Visit: www.nhc.noaa.gov

By Rob Gutro 
NASA’s Goddard Space Flight Center

TD15 – Atlantic Ocean

Oct. 16, 2019 – NASA’s Terra Satellite Catches End of Atlantic Tropical Depression 15

Tropical Depression Fifteen or TD15, developed off the west coast of Africa on Oct. 14 by 5 p.m. EDT. The depression never strengthened into a tropical storm before it reached the end of its life. NASA’s Terra satellite provided an image of  TD15 after stretched out and ceased being a tropical cyclone.

Terra image of TD15
NASA’s Terra satellite passed over TD 15 at 1:30 p.m. local time on Oct. 16 and the MODIS instrument aboard captured a visible image. The image showed the surface circulation had become elongated from north to south. There were also just a few weak swirls in the circulation envelope, and has degenerated into a trough (elongated area) of low pressure Credit: NASA Worldview

At 5 a.m. EDT (0900 UTC) on Oct. 16 the remnants of Fifteen were located near latitude 17.3 degrees north and longitude 24.1 degrees west. That is about 90 miles (145 km) north of the Cabo Verde Islands.  The remnants were moving toward the northwest near 8 mph (13 kph), and that motion should continue today. Maximum sustained winds were near 30 mph (45 kph) with higher gusts. The estimated minimum central pressure is 1009 millibars.

When NASA’s Terra satellite passed overhead at 1:30 p.m. local time, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard captured a visible image of TD15.

Visible imagery provides a look at the shape of the storm. A storm’s shape 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.

The image showed the surface circulation had become elongated from north to south. There were also just a few weak swirls in the circulation envelope, and has degenerated into a trough (elongated area) of low pressure. As a result, it is no longer a tropical cyclone. The system should weaken further today.

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.

By Rob Gutro
NASA’s Goddard Space Flight Center

Hagibis – Northwestern Pacific Ocean

Oct. 16, 2019 – Typhoon Hagibis Leaves Destruction in Its Wake

Typhoon Hagibis, one of the most destructive storms to hit Japan in decades, made landfall on Saturday, Oct. 12, 2019 southwest of Tokyo with wind speeds equivalent to a Category 3 hurricane. The damage it left in its wake is visible from space.

ARIA image of destruction from Hagibis
NASA’s ARIA team, along with the Earth Observatory of Singapore, created this map showing damage from Typhoon Hagibis, which struck southwest of Tokyo on Oct. 12, 2019. Credit: Contains modified Copernicus Sentinel data (2019) processed by ESA, the ARIA team at NASA-JPL and Caltech, and EOS in Singapore

NASA’s Advance Rapid Imaging and Analysis (ARIA) team, in collaboration with the Earth Observatory of Singapore (EOS), used satellite data to create this map showing areas in Japan that are likely damaged as a result of Typhoon Hagibis. The color variation from yellow to red indicates increasingly more significant ground surface change, or damage.

The map was produced using synthetic aperture radar (SAR) data from the Copernicus Sentinel-1 satellites operated by the European Space Agency (ESA). The pre-event images were taken on Oct. 7, 2019, and the post-event image was acquired about 12 hours after the typhoon’s landfall. The map covers an area of 155 miles by 220 miles (250 kilometers by 350 kilometers) indicated by the red polygon.

The map was delivered to Sentinel Asia, a consortium that supports disaster management across the Asia-Pacific region using space-based technologies. Maps like this one can be used as guidance to help responders identify damaged areas and to allocate resources accordingly. The map may be less reliable over vegetated or badly flooded areas.

This map contains modified Copernicus Sentinel data processed by ESA, the ARIA team at NASA’s Jet Propulsion Laboratory and Caltech, both in Pasadena California, and EOS in Singapore. Its production was funded by NASA’s Disasters Program.

More information about ARIA and NASA’s Disasters Program is available here:

https://aria.jpl.nasa.gov/
https://disasters.nasa.gov/

By Esprit Smith
NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

Hagibis – Northwestern Pacific Ocean

Oct. 15, 2019 – NASA’s Aqua Satellite Reveals Flooding in Japan from Typhoon Hagibis

Typhoon Hagibis made landfall in Japan over the weekend of October 12 and 13, bringing damaging winds, rough surf and flooding rains. NASA’s Aqua satellite provided a visible image of the flooding caused by the torrential rainfall.

Flooding in Japan as seen by Aqua
These two visible images of east central Japan were taken before and after the arrival of Typhoon Hagibis. The image of the left reveals dry land. The image on the right, after Hagibis made landfall and moved away from Japan, shows the extent of flooding in the central region around Toyko. Credit: NASA Worldview

Hagibis made landfall just before 6 a.m. EDT (7 p.m. local time, Japan) on Oct. 12, on the Izu Peninsula, located southwest of Tokyo.

On Oct. 12 at 5 p.m. EDT (2100 UTC), the Joint Typhoon Warning Center issued their final bulletin on Tropical Cyclone Hagibis. The storm has moved off Japan and re-emerged in the Northwestern Pacific Ocean where it is becoming extra-tropical. On Oct. 12 at 5 p.m. EDT, Hagibis was located near 28.6 north latitude and 141.9 east longitude, about 113 nautical miles south-southeast of Misawa, Japan. Hagibis was speeding to the northeast at 36 knots (41 mph/67 kph) and had maximum sustained winds 65 knots (75 mph/120 kph), still at hurricane-strength.

In its wake, Hagibis dropped large amounts of rainfall that flooded neighborhoods and cut power to thousands of people. There were also landslides from the heavy rainfall. Rainfall totals in Hakone were the highest at 994 mm (39.1 inches). Izu City received 760 mm (27.7 inches) and Chichibu received 683 mm (26.8 inches).

On Oct. 15, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument provided a visible view of Japan, where Typhoon Hagibis made landfall and dropped huge rain totals. The image was compared to a visible image taken of the same region before the typhoon and showed a marked difference and many flooded areas.

On Oct. 13, Japanese public broadcaster NHK reported at least 31 deaths had occurred and there were still over 186 people missing. The storm was becoming extra-tropical as it moved east toward Alaska.

On Oct. 15, Hagibis’ remnants reached Alaska. The Southcentral and Southwest Alaska Forecast Discussion from the National Weather Service Anchorage Alaska on Oct. 15 cited “A strong 958 millibar low [pressure area] (remnants of Hagibis) centered west of St. Matthew Island continues to slowly move northward. This low has brought hurricane force gusts and high seas to the Bering waters overnight.”

For updated Alaska forecasts, visit:
https://forecast.weather.gov/MapClick.php?lat=53.6733&lon=-166.6483

By Rob Gutro
NASA’s Goddard Space Flight Center

Ema – Central Pacific Ocean

Oct. 15, 2019 – NASA’s Terra Satellite Catches a Glimpse of a Fleeting Ema

Tropical Storm Ema had a very short life, but NASA’s Terra satellite caught a glimpse of the storm before it dissipated in the Central Pacific Ocean.

Worldview image of Ema
On Oct. 13 NASA’s Terra satellite passed over Ema when it was still a tropical storm, but weakening. Strong convection was limited to the area north of the center of circulation due to southwesterly wind shear. The storm appears shallow other than that area of strong thunderstorms. Credit: NASA Worldview

The newest tropical storm of the Central Pacific Ocean hurricane season formed to the northwest of the Hawaiian Islands late on Oct. 12. Although there was no threat to Hawaii, there was a Tropical Storm Watch is in effect on Oct. 12 for portions of the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals to Maro Reef.

At 2 a.m. HST/8 a.m. EDT (1200 UTC) on Oct. 13 the center of Tropical Storm Ema was located near latitude 22.1 North, longitude 165.9 West. Ema was moving toward the west-northwest near 10 mph (17 kph), and maximum sustained winds were near 40 mph (65 kph).

NASA’s Terra satellite passed over Ema on Oct. 13 when it was still a tropical storm. After Terra passed over Ema, the storm weakened to a depression. The MODIS or Moderate Resolution Imaging Spectroradiometer instrument visible image showed strong convection (rising air that forms the thunderstorms that make up a tropical cyclone) was limited to the area north of the center of circulation. That’s because of strong southwesterly wind shear affecting the storm that’s pushing the bulk of clouds and showers to the north. The National Hurricane Center also said that the storm appears shallow other than that area of strong thunderstorms.

By 11 a.m. HST/5 p.m. EDT on Oct. 13, the Tropical Storm Watch for portions of the Papahanaumokuakea Marine National Monument from French Frigate Shoals to Maro Reef has been canceled as Ema weakened to a depression.

On Monday, Oct. 14 at 5 a.m. EDT (0900 UTC), Ema, a post-tropical cyclone by that time, had dissipated near 25.4 degrees north latitude and 168.3 degrees west longitude.

By Rob Gutro
NASA’s Goddard Space Flight Center

Melissa – Northern Atlantic Ocean

Oct. 15, 2019 – NASA Provides a Farewell Infrared View of Extra-Tropical Storm Melissa

NASA’s Suomi NPP satellite passed over North Atlantic Ocean on Oct. 14 and provided forecasters with an infrared view of Tropical Storm Melissa that revealed wind shear was tearing the storm apart as it was becoming extra-tropical.

Suomi NPP image of Melissa
On Oct. 14, 2019 at 1:30 a.m. EDT (0530 UTC), the MODIS instrument that flies aboard NASA-NOAA’s Suomi satellite revealed that Melissa was being adversely affected by wind shear that was pushing all storms northeast of the center. In that area, cloud top temperatures were as cold as minus 70 degrees Fahrenheit (minus 56.6 Celsius). Credit: NASA/NRL

NASA’s Suomi NPP satellite used infrared light to analyze the strength of storms in Tropical Storm Melissa. Infrared data provides temperature information and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

Melissa became an extra-tropical cyclone on Monday, Oct. 14. The only thunderstorms and precipitation associated with the circulation were displaced up to 100 miles east of the center in this infrared image from NASA-NOAA’s Suomi NPP satellite on Oct. 14, 2019 at 1:30 a.m. EDT (0530 UTC). That area had cloud top temperatures as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 Celsius). Cloud top temperatures that cold indicate strong storms with the potential to generate heavy rainfall and that area was being pushed northeast by southwesterly 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.

The Suomi NPP satellite image also revealed that the inner-core consisted of a swirl of low clouds. NOAA’s National Hurricane Center (NHC) said the imagery also showed “a large amount of cool post-frontal stratocumulus wrapping into the northern and western portions of the circulation.”

What is Extra-tropical?

Extratropical 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.

Melissa’s Last Advisory

At 11 a.m. EDT (1500 UTC), on Oct. 14, the NHC or National Hurricane Center issued the final advisory on the system. The center of Post-Tropical Cyclone Melissa was located near latitude 41.0 degrees north and longitude 51.4 degrees west. Melissa was moving toward the east near 23 mph (37 kph) and this general motion is expected to continue through Tuesday. Maximum sustained winds were near 40 mph (65 kph) with higher gusts. NHC said, “Swells generated by Melissa are gradually subsiding along much of the U.S. east coast, portions of the Bahamas, Bermuda, and Atlantic Canada.”

The cyclone should gradually weaken before it dissipates today, Tuesday, Oct. 15.

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.

By Rob Gutro
NASA’s Goddard Space Flight Center

Melissa – Northern Atlantic

Oct. 11, 2019 – NASA Sees Atlantic Subtropical Storm Melissa Form off New England Coast

Satellite data has confirmed the formation of Subtropical Storm Melissa. NASA’s Terra Satellite provided a visible image the former Nor’easter turned subtropical storm off the coast of New England.

The National Hurricane Center or NHC noted that the Nor’easter centered southeast of New England (in the northeastern U.S.) becomes a subtropical storm, and that the change in storm status does not change expected impacts from wind and coastal flooding along portions of the mid-Atlantic coast and Southeastern New England.

On Oct. 11, the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite provided a visible image of the newly developed Melissa. Forecasters at the National Hurricane Center noted on Oct.11 at 11 a.m. EDT, “Convection increased near the center of the nor’easter centered southeast of New England overnight. First-light visible satellite imagery briefly showed an eye-like feature before the convection around the immediate center began to weaken. However, a large convective band still persists over the northern semicircle, and this structure indicated the system has transitioned to a subtropical cyclone.”

satellite image of Melissa
On Oct. 11, the MODIS instrument that flies aboard NASA’s Terra provided a visible image of Subtropical Storm Melissa off the New England coast. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).

At 11 a.m. EDT (1500 UTC), on Oct. 11, the center of Subtropical Storm Melissa was located near latitude 38.5 degrees North and longitude degrees 69.6 West. That is about 190 miles (300 km) south of Nantucket, Massachusetts. Melissa is moving toward the south-southwest near 3 mph (6 kph), but little net motion is expected today. A turn toward the east-northeast with an increase in forward speed is forecast tonight and this motion will continue through the weekend. On the forecast track, the center of Melissa will move away from the east coast of the United States.

Maximum sustained winds are near 65 mph (100 kph) with higher gusts. Gradual weakening is expected over the next couple of days, and Melissa is forecast to lose its subtropical characteristics by Saturday night. Winds of 40 mph extend outward up to 345 miles (555 km) from the center, primarily over waters. The estimated minimum central pressure is 995 millibars.

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.

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

Rob Gutro
NASA’s Goddard Space Flight Center, Greenbelt, Md.