Tag: Omar 2020

Sep. 04, 2020 – NASA’s Aqua Satellite Finds Wind Shear Not Letting Up on Omar  

Tropical Depression Omar is one stubborn storm. Since it developed early in the week, it was being affected by wind shear. That wind shear has not let up by the week’s end, and NASA satellite imagery showed the bulk of storms were being pushed to the southeast of the center. Yet, he persists.

NASA’s Aqua Satellite Reveals Effects of Wind Shear 

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 Sept. 4 at 2:05 a.m. EDT (0605 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite gathered infrared data on Omar that confirmed wind shear was still adversely affecting the storm. The center of circulation appears to be a swirl of clouds devoid of precipitation. In addition, satellite data reveals that some dry air is also being drawn into the circulation, which is further inhibiting the development of thunderstorms.

The only precipitation was in an area of fragmented storms pushed to the southeast of the center, as a result of strong north-northwesterly vertical wind shear. 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.

Wind Shear Affecting Omar

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.

Omar’s Status on Friday, September 4, 2020

At 5 a.m. EDT (0900 UTC) on Sept. 4, the center of Tropical Depression Omar was located near latitude 35.3 degrees north and longitude 58.5 degrees west. That is about 415 miles (670 km) east-northeast of Bermuda. The depression is moving toward the east near 7 mph (11 km/h) and a turn toward the northeast with an increase in forward speed is expected over the next couple of days. Maximum sustained winds are near 30 mph (45 km/h) with higher gusts.

Forecast for Omar

The National Hurricane Center noted if the lack of convection continues, Omar will be declared a remnant low-pressure system later today, Sept. 4. The cyclone is expected to become absorbed by a frontal trough (elongated area of low pressure) within a couple of days.

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

Sep. 03, 2020 – NASA’s Terra Satellite Provides Clear Picture of Wind Shear Battering Omar

NASA’s Terra satellite provided a visible image that showed Tropical Storm Omar had weakened to a depression as it continued to be battered by strong upper level winds.

NASA Satellite View

The Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite captured a visible image of Tropical Storm Omar on Sept. 2 at 1:30 p.m. EDT that showed outside winds pushing the bulk of clouds and storms east of the center. Using visible imagery, like this image from Terra, in addition to microwave and infrared satellite imagery, forecasters downgraded Omar from a tropical storm to a depression.

Satellite imagery was created using NASA’s Worldview product at NASA’s Goddard Space Flight Center in Greenbelt, Md.

In the next National Hurricane Center (NHC) advisory at 5 p.m. EDT, Omar was downgraded to a depression. This image and other imagery “showed the system remains sheared with a bursting pattern on satellite, occasionally exposing the center, and a large area of curved bands in the southeastern quadrant of the circulation,” said Eric Blake, Senior Hurricane Specialist at NOAA’s National Hurricane Center in Miami, Fla.

About 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. In the case of Omar, strong outside winds from the north-northwest were pushing clouds to the south-southeast of the center of circulation.

Omar on Sept. 3

Despite the strong wind shear, Omar continued to hold onto depression status on Sept. 3. At 5 a.m. EDT (0900 UTC), the center of Tropical Depression Omar was located near latitude 36.3 degrees north and longitude 62.4 degrees west. That is about 310 miles (495 km) north-northeast of Bermuda.

Omar is moving toward the east near 14 mph (22 kph), and this general motion is expected to continue through tonight, accompanied by a decrease in forward speed.  A turn toward the east-northeast and northeast is expected Friday and Friday night. Maximum sustained winds are near 35 mph (55 kph) with higher gusts. The estimated minimum central pressure is 1005 millibars.

NHC Hurricane Specialist Robbie Berg noted, “Amazingly, 50 knots of north-northwesterly shear has not been enough to prevent deep convection from developing, likely because Omar remains in an unstable thermodynamic environment and over [warm] sea surface temperatures of 27-28 degrees Celsius [80.6 to 82.4 degrees Fahrenheit].” Tropical cyclones require sea surface temperatures as warm as 26.6C (80F) to maintain strength. Warmer sea surface temperatures can help intensify a storm.

NHC forecasters expect dissipation by Sunday, Sept. 6 since all global computer forecast models indicate that the remnant low’s circulation should open up into a trough [elongated area of low pressure] by then.

About NASA’s Worldview and Terra Satellite

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.”

NASA’s Terra satellite is one in a fleet of NASA satellites that provide data for hurricane research.

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

Sep. 02, 2020 – NASA Catches Formation of Atlantic’s Record-breaking 15th Tropical Storm

Tropical Depression 15 strengthened into a tropical storm late on Sept. 1 and was renamed Omar. Visible imagery from NASA-NOAA’s Suomi NPP satellite was compiled into an animation that showed the system’s formation and strengthening. NASA’s Terra satellite also provided temperature data on Omar that revealed wind shear was affecting the storm.

Another Record-Breaker

Omar is the 15th named storm of the 2020 Atlantic hurricane season, and is the earliest 15th storm on record, besting the previous mark by about a week from Ophelia of 2005.

NASA Animates Omar’s Development

At NASA’s Goddard Space Flight Center in Greenbelt, Md. using the NASA Worldview platform an animation of satellite imagery was created to show Omar over three days. Using visible imagery from the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite, an animation shows the development, organization and movement of Tropical Depression 15 from Aug. 30 to Sept. 1 off the coast of North Carolina. On Sept. 2, it became Tropical Storm Omar.

This animation of visible imagery from the VIIRS instrument aboard NASA-NOAA’s Suomi NPP satellite shows the organization and movement of Tropical Depression 15 from Aug. 30 to Sept. 1 off the coast of North Carolina. On Sept. 2, it became Tropical Storm Omar. Courtesy: NASA Worldview, Earth Observing System Data and Information System (EOSDIS).

Infrared Data Reveals Wind Shear Battering Omar

Strong upper-level winds are battering Omar and pushing the strongest storms to the southeastern quadrant. Those northwesterly winds are not expected to let up, putting Omar on a weakening trend. NASA’s infrared data showed how those outside winds were displacing the strongest storms in Omar’s circulation.

On Sept. 1 at 10 p.m. EDT (Sept. 2 at 0200 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Terra satellite gathered temperature information about Tropical Storm Omar’s cloud tops. MODIS found the most powerful thunderstorms were on the southeastern side of the storm, 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.

“Satellite images show that the system remains sheared with a bursting pattern on satellite, occasionally exposing the center, and a large area of curved bands in the southeastern quadrant of the circulation,” Eric Blake wrote in the 5 a.m. EDT Omar Discussion. Blake is a senior hurricane specialist at NOAA’s National Hurricane Center (NHC) in Miami, Florida.

Omar’s Status on Sept. 2

At 5 a.m. EDT (0900 UTC), NOAA’s NHC noted the center of Tropical Storm Omar was located near latitude 36.2 degrees north and longitude 68.7 degrees west. Omar was centered about 350 miles (560 km) northwest of Bermuda. The storm is moving toward the east-northeast near 14 mph (22 kph), and this general motion is expected to continue through this afternoon.  Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Little change in strength is expected through tonight.  The estimated minimum central pressure is 1003 millibars.

Omar’s Bleak Forecast

The NHC forecast calls for Omar to turn toward the east during the evening hours on Sept. 2, with a reduction in forward speed occurring through Friday, Sept. 4. Weakening should begin by Thursday, Sept. 3, with Omar likely to become a remnant low-pressure area by Thursday night.

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