Tag: Douglas 2020

July 30, 2020 – NASA Finds Post-Tropical Low Douglas Crossing a Line   

The strong wind shear that weakened Douglas to a tropical storm early on July 29 has further weakened it to a post-tropical low-pressure area. NASA’s Aqua satellite provided an infrared view of those remnants, headed across the International Date Line in the Pacific Ocean.

NASA’s Aqua Satellite Shows a Post-tropical System 

NASA’s Aqua satellite uses infrared light to analyze the strength of storms by providing temperature information about the system’s clouds. The strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

On July 30 at  0105 UTC  (July 29 at 9:05 p.m. EDT), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite gathered infrared data on Douglas that confirmed wind shear had reduced the storm to a post-tropical low pressure area. The wind shear pushed the coldest cloud tops northeast of the center. Those storms had cloud top temperatures as cold as minus 50 degrees Fahrenheit (minus 45.5 Celsius).

What is a Post-tropical Cyclone?

NOAA’s National Hurricane Center defines a post-tropical cyclone as a former tropical cyclone. This generic term describes a cyclone that no longer possesses sufficient tropical characteristics to be considered a tropical cyclone. Post-tropical cyclones can continue carrying heavy rains and high winds. Note that former tropical cyclones that have become fully extratropical… as well as remnant lows…are two classes of post-tropical cyclones.

Douglas Ready to Cross a Line

NOAA’s Central Pacific Hurricane Center (CPHC) issued the final advisory on Douglas on July 29 at 11 a.m. EDT (5 a.m. HST/1500 UTC). Douglas had degenerated into a post-tropical low-pressure area about 1,135 miles (1,830 km) west-northwest of Honolulu, Hawaii. It was centered near latitude 24.7 degrees north and longitude 175.4 degrees west. The post-tropical cyclone is moving toward the west near 23 mph (37 kph). Maximum sustained winds are near 35 mph (55 kph) with higher gusts.

Douglas’ remnants were expected to cross the International Date Line early on July 30, and it is expected to dissipate shortly after the crossing.

Established in 1884, the International Date Line passes through the mid-Pacific Ocean and generally follows a 180 degrees longitude north-south line on the Earth. East of the Date Line lies the central Pacific Ocean. West of the dateline is the western Pacific Ocean.

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events 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 more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

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

By Rob Gutro
NASA’s Goddard Space Flight Center

July 29, 2020 – NASA’s Terra Satellite Finds No Strong Storms Left in Tropical Storm Douglas  

Strong wind shear has been the undoing of Tropical Storm Douglas. NASA’s Terra satellite provided infrared data revealed the tropical cyclone was devoid of strong storms, indicating wind shear has weakened it.

One Warning Remains for Douglas

On July 29, a Tropical Storm Warning is in effect for portions of the Papahanaumokuakea Marine National Monument from Maro Reef to Lisianski.

NASA’s Terra Satellite Reveals Effects of Wind Shear 

NASA’s Terra satellite uses infrared light to analyze the strength of storms by providing temperature information about the system’s clouds. The strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures. However, cloud tops in Douglas showed no very cold cloud tops on July 29 at 5:45 a.m. EDT (0945 UTC) when they were imaged by the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite.

Wind shear had sapped the strength of the storm and prevented strong thunderstorms from forming. Tropical cyclones are made up of hundreds of thunderstorms, and when there are no strong storms present in satellite imagery, it is a sure sign of weakening.

At 5 a.m. EDT (0900 UTC) on July 29/11 p.m. HST on July 28, NOAA’s Central Pacific Hurricane Center (CPHC) in Honolulu, Hawaii noted, “Due to persistent southerly vertical wind shear, Douglas has been devoid of deep convection for nearly 24 hours, and it appears that it will soon be a post-tropical remnant low.”

About Wind Shear  

The shape of a tropical cyclone provides forecasters with an idea of its organization and strength. Wind shear occurs when outside winds batter a storm and change the storm’s shape pusing much of the associated clouds and rain to one side of it.

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. Southwesterly wind shear was pushing the bulk of Douglas’ clouds to the north-northeast of the center.

Status of Tropical Storm Douglas on July 29, 2020

At 8 a.m. EDT (2 a.m. HST/1200 UTC), the center of Tropical Storm Douglas was located near latitude 24.7 degrees north and longitude 174.3 degrees west. Douglas is about 320 miles (515 km) southeast of Midway Island. Douglas was moving toward the west near 23 mph (37 km/h), and this general motion is expected to continue until Douglas crosses the International Date Line in about 24 hours. Maximum sustained winds were near 40 mph (65 kph) with higher gusts. The estimated minimum central pressure is 1010 millibars.

Forecast for Douglas

NOAA’s CPHC said, “Large seas and swells generated by Douglas will impact portions of the Papahanaumokuakea Marine National Monument west of Maro Reef through Wednesday. These swells may produce large breaking waves that could inundate some of the lower-lying atolls. Rainfall associated with Douglas will impact portions of the Papahanaumokuakea Marine National Monument west of Maro Reef through Wednesday.”

Weakening is forecast during the next two days, and Douglas is expected to dissipate shortly after crossing the Date Line.

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events 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 more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

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

By Rob Gutro
NASA’s Goddard Space Flight Center

July 28, 2020 – NASA’s Terra Satellite Finds Wind Shear Weakening Tropical Storm Douglas  

Former Hurricane Douglas has encountered strong wind shear after passing the Hawaiian Islands and has now weakened to a tropical storm. NASA’s Terra satellite provided infrared data to find that the strongest storms were displaced from the center as the storm weakens.

Warnings in Effect for Douglas on July 28

On July 28, NOAA’s Central Pacific Hurricane Center (CPHC) continued posting warnings and watches. A Tropical Storm Warning is in effect for portions of the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals to Maro Reef. A Tropical Storm Watch is in effect for portions of the Papahanaumokuakea National Marine Monument from Maro Reef to Lisianski.

NASA’s Terra Satellite Reveals Effects of Wind Shear 

NASA’s Terra satellite uses infrared light to analyze the strength of storms by providing temperature information about the system’s clouds. The strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

On July 28 at 5 a.m. EDT (0900 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite gathered infrared data on Douglas that confirmed wind shear was adversely affecting the storm. Persistent south to southwest vertical wind shear showed strongest storms were pushed north and northeast of the center. Those storms had cloud top temperatures as cold as minus 50 degrees Fahrenheit (minus 45.5 Celsius). Satellite imagery also shows the low-level circulation center became exposed.

The wind shear and displacement of storms has led to a rapid weakening trend over the past 24 hours.

Wind Shear Affecting Douglas

The shape of a tropical cyclone provides forecasters with an idea of its organization and strength. When outside winds batter a storm, it can change the storm’s shape and push much of the associated clouds and rain to one side of it. That is what wind shear does.

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.

Status of Tropical Storm Douglas on July 28, 2020

At 8 a.m. EDT (2 a.m. HST/1200 UTC), the center of Tropical Storm Douglas was located near latitude 23.8 degrees north and longitude 165.7 degrees west. That is about 40 miles (60 km) east of French Frigate Shoals, and about 525 miles (845 km) west-northwest of Honolulu, Hawaii.

Douglas was moving toward the west-northwest near 18 mph (30 kph), and this general motion is expected to continue the next couple of days. Maximum sustained winds were near 50 mph (85 kph) with higher gusts. The estimated minimum central pressure was 1001 millibars.

Forecast for Douglas

NOAA’s CPHC said weakening is forecast over the next couple of days, and Douglas is expected to dissipate by Thursday, July 29. Interests elsewhere in the Papahanaumokuakea Marine National Monument should monitor the progress of this system.

NASA Researches Tropical Cyclones

Hurricanes/tropical cyclones are the most powerful weather events 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 more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

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

By Rob Gutro
NASA’s Goddard Space Flight Center

July 27, 2020 – NASA Sees Hurricane Douglas Brush Hawaii

Imagery from NASA’s Terra satellite was used to create an animation showing Douglas’ movement past the Hawaiian Islands.

Although the Hawaiian Islands missed a landfall from Hurricane Douglas, the storm was certainly close enough to bring strong surf, heavy rains and gusty winds to the islands. NASA’s Terra satellite imagery showed the storm’s track as it moved just north of the islands.

Visible imagery of Hurricane Douglas from July 25 to 26, taken from the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Terra satellite was compiled and made into an animation using NASA’s Worldview application. The imagery showed Douglas’ center staying just off shore from the Hawaiian Islands.

NASA’s Earth Observing System Data and Information System (EOSDIS) Worldview application provides the capability to interactively browse over 700 global, full-resolution satellite imagery layers and then download the underlying data. Many of the available imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks “right now.”

Warnings in Effect on July 27

NOAA’s Central Pacific Hurricane Center (CPHC) posted several updates to the warnings on July 27. A Hurricane Warning is in effect for portions of the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals. A Tropical Storm Warning is in effect for portions of the Papahanaumokuakea Marine National Monument from French Frigate Shoals to Maro Reef. A Hurricane Watch is in effect for portions of the Papahanaumokuakea Marine National Monument from French Frigate Shoals to Maro Reef, and a Tropical Storm Watch is in effect for portions of the Papahanaumokuakea Marine National Monument from Maro Reef to Lisianski.

Douglas’ Status on July 27, 2020

NOAA’s CPHC noted at 11 a.m. EDT (5 a.m. HST/1500 UTC), the center of Hurricane Douglas was located near latitude 22.9 degrees north and longitude 160.4 degrees west. Douglas is moving toward the west-northwest near 17 mph (28 kph), and this general motion will continue the next couple of days, with a slight turn toward the west. Maximum sustained winds are near 90 mph (150 kph) with higher gusts. The estimated minimum central pressure is 987 millibars.

In Hawaii, rainfall associated with Douglas is expected to affect portions of the main Hawaiian Islands today. Total rain accumulations of 3 to 6 inches with locally higher amounts are possible, with the greatest rainfall in elevated terrain on Kauai. Heavy rainfall will also affect portions of the Papahanaumokuakea Marine National Monument the next couple of days.

Douglas’ Forecast

NOAA’s CPHC noted, “Hurricane force winds are expected over portions of the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals later today and tonight. Tropical storm conditions are expected from French Frigate Shoals to Maro Reef Tuesday and Tuesday night, with hurricane conditions possible.

Tropical storm conditions are possible from Maro Reef to Lisianski Tuesday night and Wednesday.

Large swells generated by Douglas will affect a large swath of the Papahanaumokuakea Marine National Monument the next couple of days. Weakening is forecast during the next couple of days.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

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

By Rob Gutro
NASA’s Goddard Space Flight Center

July 26, 2020 – NASA-NOAA’s Suomi NPP Provides Night-Time Analysis of Hurricane Douglas

NASA-NOAA’s Suomi NPP satellite provided forecasters with various nighttime views of Hurricane Douglas as it approaches Hawaii. The various imagery provided valuable data on the storm’s structure and strength.

On July 26, NOAA’s Central Pacific Hurricane Center or CPHC warned that “Dangerous Hurricane Douglas is closing in on the Hawaiian Islands.”

Many Warnings in Place for Hawaii

On Sunday, July 26, 2020 warnings and watches pepper Hawaii as Hurricane Douglas approaches. A Hurricane Warning is in effect for Oahu, Kauai County, including the islands of Kauai and Niihau. A Tropical Storm Warning is in effect for Hawaii County, Maui County, including the islands of Maui, Lanai, Molokai and Kahoolawe. In addition, a Hurricane Watch is in effect for Hawaii County, Maui County, including the islands of Maui, Lanai, Molokai and Kahoolawe. A Tropical Storm Watch is in effect for portions of the Papahanaumokuakea Marine National Monument from Nihoa to French Frigate Shoals.

What NASA-NOAA’s Suomi NPP Satellite Showed

On July 25 at 5 a.m. EDT (0900 UTC) Hurricane Douglas was a strong Category 2 storm with winds near 110 mph. NOAA’s CPHC mentioned that Douglas had a degraded satellite presentation. Two and one half hours later, NASA-NOAA’s Suomi NPP satellite passed over Douglas and provided a nighttime view of the storm as well as an infrared view.

In the nighttime view, the waxing crescent moon (27% illumination) was still low enough with the features in the Suomi NPP Day Night Band were illuminated by airglow. “There continued to be no mesospheric waves, which is not surprising given the gradual degradation of the storm,” said William Straka III, Researcher at the University of Wisconsin – Madison, Space Science and Engineering Center (SSEC), Cooperative Institute for Meteorological Satellite Studies (CIMSS). Straka provided the nighttime and infrared images.

The high-resolution infrared imagery from Suomi NPPs Visible Infrared Imaging Radiometer Suite (VIIRS) instrument showed a closed circulation and a relatively compact storm. The VIIRS instrument cloud top temperatures around the eye were as cold as 210 Kelvin (minus 81.6 degrees Fahrenheit (minus 63.1 Celsius), indicating powerful storms.

Straka noted, “Satellite imagery also seemed to indicate some warmer air being pulled in to the storm. This was supported by the Advanced Microwave Scanning Radiometer 2 (AMSR2) instrument (that also flies aboard Suomi NPP) data taken roughly 20 minutes earlier, which also seemed to show an exposed circulation on the southeast side.”

Satellite Imagery on July 26, 2020

CPHC Hurricane forecaster Thomas Birchard said in the July 26 discussion, “Worth noting is that the data also indicate that the low-level center is south of the center that is seen in conventional satellite imagery. Recent microwave images confirm that the cyclone is tilted to the north with height, due to southerly vertical wind shear. Despite the vertical wind shear, Douglas is expected to only slowly weaken as it comes dangerously close to the Hawaiian Islands.”

Hurricane Douglas’ Status on Sunday, July 26, 2020

NOAA’s CPHC noted at 8 a.m. EDT (2 a.m. HST/1200 UTC) on July 26, the center of Hurricane Douglas was located by Hurricane Hunter aircraft near latitude 20.5 north, longitude 153.6 west. That puts Douglas’ center about 190 miles (300 km) east of Kahului, Hawaii and 285 miles (460 km) east of Honolulu, Hawaii.

Douglas is moving toward the west-northwest near 16 mph (26 kph), and this general motion is expected to continue for the next couple of days. The estimated minimum central pressure is 983 millibars. Maximum sustained winds are near 90 mph (150 kph) with higher gusts.

 Forecast for Douglas

NOAA’s CPHC forecast calls for “Some slow weakening is forecast during the next 48 hours, but Douglas is expected to remain near hurricane intensity as it passes near, or over, the islands. On the forecast track, Hurricane Douglas will pass dangerously close to the main Hawaiian Islands later today.”

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

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

By Rob Gutro
NASA’s Goddard Space Flight Center

July 25, 2020 – NASA’s Aqua Satellite Examines Hurricane Douglas as it Nears Hawaii

NASA’s Aqua satellite provided a visible image of Hurricane Douglas is it continued on its track toward Hawaii. The storm is now a Category 2 hurricane and warnings were posted on July 25, 2020 as the storm approaches.

Warnings Up for Hawaii

The Central Pacific Hurricane Center has posted warnings for Douglas.

A Tropical Storm Warning is in effect for Hawaii County, Maui County, including the islands of Maui, Lanai, Molokai and Kahoolawe. A Hurricane Watch is in effect for Hawaii County, Maui County, including the islands of Maui, Lanai, Molokai and Kahoolawe and Oahu.

On July 24 at 1:30 p.m. EDT, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite provided a visible image of Douglas. Hurricane Douglas maintained its eye and structure as it continued moving west through the Central Pacific Ocean and toward Hawaii.

Status of Hurricane Douglas on July 25

At 8 a.m. EDT (2 a.m.’s/1200 UTC), on July 25, NOAA’s Central Pacific Hurricane Center said the center of Hurricane Douglas was located near latitude 18.7 degrees north and longitude 147.7 degrees west. That is about 485 miles (780 km) east of Hilo, Hawaii.

Douglas is moving toward the west-northwest near 18 mph (30 km/h). This motion is expected to continue through Saturday, followed by a slight decrease in forward speed and a turn toward the west. The estimated minimum central pressure is 973 millibars. Maximum sustained winds are near 110 mph (175 kph) with higher gusts. Douglas is a category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale.

Douglas’ Forecast Track

Gradual weakening is expected to continue through the weekend. However, Douglas is still forecast to be near hurricane strength when it nears the islands. On the forecast track, Douglas will be near the main Hawaiian Islands Saturday night through Sunday night.

For more than five decades, NASA has used the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. NASA brings together technology, science, and unique global Earth observations to provide societal benefits and strengthen our nation. Advancing knowledge of our home planet contributes directly to America’s leadership in space and scientific exploration.

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

For past NASA updates on Douglas visit: https://blogs.nasa.gov/hurricanes/tag/douglas-2020/

July 24, 2020 -NASA’s Tracking Hawaii-bound Major Hurricane Douglas

Hurricane Douglas is a major hurricane tracking through the Central Pacific Ocean on a forecast track to Hawaii. NASA’s Aqua satellite used infrared light to identify strongest storms and coldest cloud top temperatures and found them surrounding the eyewall of the powerful hurricane. In addition, images from NASA-NOAA’s Suomi NPP satellite were used to generate an animated track of Douglas’ movement and intensification over four days.

Infrared Data Reveals Powerful Storms

On July 24 at 6:30 a.m. EDT (1030 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite gathered temperature information about Hurricane Douglas’ cloud tops. Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

MODIS found the most powerful thunderstorms were in the eyewall, where temperatures were 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.

Andrew Latto, hurricane specialist at NOAA’s National Hurricane Center noted, “Douglas continues to look impressive in satellite images, with a clear eye and symmetric convection in all quadrants.”

NASA Animates Douglas Through Time

At NASA’s Goddard Space Flight Center in Greenbelt, Md. using the NASA Worldview platform, an animation was created to show Douglas over four days. Using visible imagery from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite, an animation shows the intensification and movement of Hurricane Douglas from July 20 to July 24 in the Eastern Pacific Ocean. Douglas was a Category 4 hurricane on July 24.

Douglas’ Status on Friday, July 24, 2020

At 5 a.m. EDT (0900 UTC), the center of Hurricane Douglas was located near latitude 15.7 degrees north and longitude 140.3 degrees west. That is about 1,010 miles (1,630 km) east-southeast of Hilo, Hawaii.

Douglas is moving toward the west-northwest near 18 mph (30 kph), and this motion is expected to continue for the next few days with a gradual decrease in forward speed and a slight turn toward the west.

Maximum sustained winds are near 130 mph (215 kph) with higher gusts.  Douglas is a category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale.  Hurricane-force winds extend outward up to 30 miles (45 km) from the center and tropical-storm-force winds extend outward up to 90 miles (150 km). The estimated minimum central pressure is 954 millibars.

Gradual weakening is expected to begin today, July 24, and continue through the weekend.

NHC Key Messages

The National Hurricane Center’s key about Douglas is that the storm is expected to move near or over portions of the Hawaiian Islands this weekend, and there is an increasing chance that strong winds, dangerous surf, and heavy rainfall could affect portions of the state beginning Saturday night or Sunday.

About NASA’s Worldview

NASA’s Earth Observing System Data and Information System (EOSDIS) Worldview application provides the capability to interactively browse over 700 global, full-resolution satellite imagery layers and then download the underlying data. Many of the available imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks “right now.”

Tropical cyclones/hurricanes are the most powerful weather events 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

July 23, 2020  – NASA Sees Compact Douglas Strengthening to a Major Hurricane

Although a compact storm, hurricane Douglas in the Eastern Pacific is mighty, as it has become the season’s first major hurricane. NASA-NOAA’s Suomi NPP satellite provided forecasters with an image of Douglas that showed development of an eye as it quickly intensified.

Early on July 22, Douglas was still a tropical storm. By 11 a.m. EDT (1500 UTC) it had strengthened into a hurricane. At 5:54 p.m. EDT (2154 UTC), the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard Suomi NPP revealed that the storm developed an eye. VIIRS showed that powerful bands of thunderstorms had circled the eye. Bands of thunderstorms were spiraling into the low-level center from the northern and southern quadrants. There was an indication that only a little dry air that earlier affected the storm, remained. What little dry air there was, stretched across the northern portion of the circulation, which was limiting the amount of deep convection wrapping around that part of the eye.

By July 23 at 5 a.m. EDT (0900 UTC), Douglas had rapidly intensified into a major hurricane. Maximum sustained winds have increased to near 120 mph (195 kph) with higher gusts.  Douglas is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Hurricane-force winds extend outward up to 25 miles (35 km) from the center and tropical-storm-force winds extend outward up to 105 miles (165 km).

The center of Hurricane Douglas was located near latitude 13.1 degrees north and longitude 134.0 degrees west. That is about 1,470 miles (2,365 km) east-southeast of Hilo, Hawaii. Douglas was moving toward the west-northwest near 17 mph (28 kph) and this general motion is expected to continue through Saturday. The estimated minimum central pressure was 967 millibars.

Satellite data on July 23 at 5 a.m. EDT showed Douglas had a ragged but nearly clear eye surrounded by cold cloud tops of minus 70 degrees Celsius (minus 94 degrees Fahrenheit), indicating very powerful thunderstorms.

NHC forecasters note that some additional strengthening is possible on Thursday.  Gradual weakening is forecast to begin by early Friday. Interests in the Hawaiian Islands should monitor the progress of Douglas.

Tropical cyclones/hurricanes are the most powerful weather events 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

July 22, 2020 – NASA Infrared Confirms Douglas Still a Tropical Storm

Infrared data from NASA’s Terra satellite showed that dry air around Tropical Storm Douglas has been inhibiting it from strengthening into a hurricane.

On July 22 at 2:15 a.m. EDT (0615 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Terra satellite gathered temperature information about Tropical Storm Douglas’ cloud tops. Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

MODIS found powerful thunderstorms where temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 Celsius) around the center and in a thick band of thunderstorms north of the center. Cloud top temperatures that cold indicate strong storms with the potential to generate heavy rainfall.

Forecasters noted that Douglas’ overall appearance has changed little over the early morning hours on July 22. Douglas has not intensified to hurricane status because dry air is affecting the eastern portion of the cyclone’s circulation and preventing thunderstorm development. A tropical cyclone consists of hundreds of thunderstorms.

At 5 a.m. EDT (0900 UTC) on July 22, the National Hurricane Center (NHC) noted the center of Tropical Storm Douglas was located near latitude 11.9 degrees north and longitude 128.0 degrees west. Douglas is centered about 1,875 miles (3,020 km) east-southeast of Hilo, Hawaii.

Douglas is moving toward the west near 15 mph (24 km/h).  A turn toward the west-northwest along with an increase in forward speed is forecast to occur by late Wednesday.  The west-northwestward motion is forecast to continue at least through Saturday. Maximum sustained winds are near 65 mph (100 km/h) with higher gusts. The estimated minimum central pressure is 998 millibars.

Strengthening is forecast during the next couple of days, and Douglas is expected to become a hurricane on Wednesday, July 23. NHC forecaster Andrew Latto noted in the morning discussion, “The system is forecast to remain in a favorable environment for intensification for the next day or so. Beyond 36 hours, the combination of cooler SSTs and dry air should cause Douglas to slowly weaken.”

Tropical cyclones/hurricanes are the most powerful weather events 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

July 21, 2020 – Tropical Storm Douglas Organizing in NASA Infrared Imagery

Tropical Depression 8E developed on July 20 and quickly organized into a tropical storm. Infrared NASA satellite imagery revealed that Tropical Storm Douglas contained strong storms and showed banding of thunderstorms around its center.

Tropical Depression 8E formed about 905 miles (1,460 km) southwest of the southern tip of Baja California, Mexico by 11 a.m. EDT on July 20. Within 12 hours, 8E had strengthened into a tropical storm and was renamed Douglas.

On July 21 at 6 a.m. a.m. EDT (1000 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite analyzed Douglas’ cloud tops in infrared light. Infrared data provides temperature information, and the strongest thunderstorms that reach high into the atmosphere have the coldest cloud top temperatures.

The National Hurricane Center (NHC) noted that Douglas’ center is also now embedded beneath a central dense overcast (a large central area of thunderstorms surrounding its circulation center) in infrared imagery, near an area of cold overshooting cloud tops.  Aqua found several areas of strong storms around the center of Douglas’ circulation and in broken bands of thunderstorms wrapping into that low-level center. In those areas, temperatures were 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.

At 10 a.m. EDT (1500 UTC), the center of Tropical Storm Douglas was located near latitude 12.4 degrees north and longitude 124.2 degrees west. About 2,110 miles (3,390 km) east of Hilo, Hawaii.

Maximum sustained winds have increased to near 65 mph (100 kph) with higher gusts.

The estimated minimum central pressure is 998 millibars. Douglas is moving toward the west-southwest near 15 mph (24 kph). A turn toward the west at a similar forward speed is expected later today, followed by a turn toward the west-northwest Wednesday night (July 22).

NHC forecaster Robbie Berg said, “The low-[wind]shear, warm sea surface temperature environment within which Douglas is moving is a recipe for continued strengthening, potentially at a rapid rate, for the next 48 hours.”

Additional strengthening is forecast during the next several days, and Douglas could become a hurricane later today.

Tropical cyclones/hurricanes are the most powerful weather events 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