Tag: Sally 2020

Sep. 17, 2020 – NASA Analyzes Rainfall and Rainmaking Capability in Hurricane Sally

NASA satellites provided a look at the rainfall potential in Hurricane Sally before and after it made landfall in southern Alabama. NASA’s Aqua satellite and IMERG analysis were used to analyze the storm’s flooding potential.

Sally came ashore on Wednesday, Sept. 16 around 5:45 a.m. EDT near Gulf Shores, Alabama. It was a Category 2 storm on the Saffir-Simpson Hurricane Wind scale with sustained winds near 105 mph (169 kph). As a slow-moving storm, Sally generated a lot of rainfall, left behind flooded streets and knocked out power to hundreds of thousands on the U.S. Gulf Coast.

NASA’s Infrared View of Sally

Cloud top temperatures provide information to forecasters about where the strongest storms are located within a tropical cyclone. Tropical cyclones do not always have uniform strength, and some sides are stronger than others. The stronger the storms, the higher they extend into the troposphere, and the colder the cloud top temperatures. NASA provides that data to forecasters at NOAA’s National Hurricane Center or NHC so they can incorporate it in their forecasting.

On Sept. 16 at 3:11 p.m. EDT (1911 UTC) NASA’s Aqua satellite analyzed Sally using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) around the center of circulation and to the northeast and east of the center. NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

At that time, the AIRS image showed those strong storms over the Florida Panhandle, much of Alabama, Georgia and extending into western South Carolina.

On Sept. 16 at 3:11 p.m. EDT (1911 UTC) NASA’s Aqua satellite analyzed Sally using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found the coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) around the center of circulation and to the northeast and east of the center. NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain. Credit: NASA JPL/Heidar ThrastarsonNASA Calculates Sally’s Rainfall

NASA combined data from multiple satellites to estimate the rainfall from Hurricane Sally in near-real time at half-hourly intervals from September 11-16, 2020. Rainfall rates and rainfall accumulations are estimated using NASA’s Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm. IMERG combines observations from a fleet of satellites, in near-real time, to provide near-global estimates of precipitation every 30 minutes.

NASA IMERG combined data from multiple satellites to estimate the rainfall from Hurricane Sally in near-real time at half-hourly intervals from September 11 to 16, 2020.  This animation shows rainfall rates (blue/yellow shading) and rainfall accumulations (green shading) from NASA’s IMERG algorithm, overlaid on shades of white/gray cloud data from NOAA infrared satellite instruments. The multi-colored line shows Sally’s track based on National Hurricane Center advisories, with orange indicating hurricane strength winds. Credit: NASA/Jason West

Rain rates along Sally’s track periodically exceeded 1 inch/hour near its core and combined with its slow speed, led to high accumulations along the Gulf Coast. By 5:00 a.m. CDT (1000 UTC) on Sep. 16, IMERG had estimated total accumulations along the southern Alabama coastline and western Florida Panhandle exceeding 16 inches in some locations. NOAA rain gauge observations were broadly consistent with the IMERG accumulations.

Sally Breaks a Pensacola Rainfall Record

The National Weather Service at the Pensacola Regional Airport in Florida reported 18.17 inches of rainfall from Sally on Sept. 16. That broke the previous record of 5.28 inches on that date in 1979.

Forecast for Excessive Rainfall Over the U.S. Southeast

NHC’s key message is about the rainfall from Sally: Widespread flooding is expected from central Georgia through southeastern Virginia.  Along the central Gulf Coast, most widespread moderate to major river flooding from the historic rainfall event will crest by the weekend, but rivers will remain elevated well into next week.

NHC Rainfall totals expected as Sally moves across the Southeast U.S. through Friday:

• Central Georgia: Sally will produce additional rainfall totals of 3 to 6 inches, with localized higher amounts, on top of 3 to 6 inches, which has already fallen. Widespread flash flooding and minor to moderate river flooding is likely.
• Central to upstate South Carolina: 3 to 6 inches, with isolated amounts of 10 inches. Widespread flash flooding and minor to moderate river flooding is likely.
• Western to central North Carolina into south-central and southeast Virginia: 4 to 6 inches, isolated amounts up to 8 inches. Flash flooding and widespread minor river flooding is likely.

Sally’s Status on Sept. 17

At 5 a.m. EDT (0900 UTC), the center of Tropical Depression Sally was located near latitude 31.8 degrees north and longitude 85.7 degrees west. The center was about 50 miles (80 km) southeast of Montgomery, Alabama. The depression is moving toward the northeast near 12 mph (19 kph) and a northeastward to east-northeastward motion is expected into Friday.

Maximum sustained winds have decreased to near 30 mph (45 kph) with higher gusts.

The estimated minimum central pressure based on nearby surface observations is 1000 millibars.

Senior Hurricane Specialist Stacy Stewart of NOAA’s National Hurricane Center in Miami, Fla. noted, “Although the overall convective cloud and rain shield in satellite and radar imagery continues to erode, Tropical Depression Sally is still producing significant rainfall across east-central Alabama and west-central and central Georgia.  Surface observations and Doppler radar data indicate that Sally has weakened to a 25 knots [29 mph/46 kph] depression over southeastern Alabama.”

Sally’s Forecast Track

NHC says that additional weakening is forecast during the next couple of days, and Sally is expected to become a remnant low by tonight or Friday morning. On the forecast track, the center of Sally will move across southeastern Alabama this morning, over central Georgia this afternoon and evening, and move over South Carolina late tonight into Friday, Sept. 18.

NASA Researches Earth from Space

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. 16, 2020 – NASA Observes Hurricane Sally Making Early Morning Landfall in Alabama    

NASA’s Aqua satellite and the NASA-NOAA Suomi NPP satellite provided views of the strength, extent and rainfall potential as Hurricane Sally was making landfall during the morning hours of Sept. 16.

Watches and Warnings  

NOAA’s National Hurricane Center has many warnings and watches in place today, Sept. 16. A Storm Surge Warning is in effect from Dauphin Island, Alabama to the Walton/Bay County Line, Florida. A Hurricane Warning is in effect for the Mississippi/Alabama border to the Okaloosa/Walton County line, Florida.

A Tropical Storm Warning is in effect for east of the Okaloosa/Walton County line, Florida to Indian Pass, Florida and from the Mississippi/Alabama border to the Mouth of the Pearl River.

NASA’s Infrared Data Reveals Heavy Rainmakers

Tropical cyclones and hurricanes are made up of hundreds of thunderstorms, and infrared data can show where the strongest storms are located. That is because infrared data provides temperature information, and the strongest thunderstorms that reach highest into the atmosphere have the coldest cloud top temperatures.

On Sept. 16 at 4:10 a.m. EDT (0810 UTC) the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite used infrared light to analyze the strength of storms within Sally. MODIS found the most powerful thunderstorms were north of the eye where cloud top temperatures were as cold as minus 80 degrees Fahrenheit (minus 62.2 Celsius).

Strong storms with cloud top temperatures as cold as minus 70 degrees Fahrenheit (minus 56.6. degrees Celsius) circled the most powerful storms. NASA research has found that cloud top temperatures that cold indicate strong storms with the potential to generate heavy rainfall.

NASA’s Night-Time View of Sally’s Landfall Approach

On Sept. 16 at 4:15 a.m. EDT (0815 UTC), the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NOAA-NASA’s Suomi NPP satellite captured an early morning image of Hurricane Sally approaching landfall near Gulf Shores, Alabama as a Category 2 Hurricane. This nighttime image shows the extent of Sally’s clouds blotting out the city lights from southern Mississippi to the northwestern coast and panhandle of Florida.

Sally’s Official Landfall

NOAA’s National Hurricane Center reported that Hurricane Sally made landfall at 5:45 a.m. EDT (4:45 a.m. EDT/0945) near Gulf Shores, Alabama as a as a Category 2 hurricane, with maximum sustained winds of 105 mph (165 kph) and a minimum central pressure of 965 millibars.

Sally’s Status at 8 a.m. EDT on Sept. 16

The NHC noted at 8 a.m. EDT (1200 UTC), the center of the eye of Hurricane Sally was located by NOAA Doppler weather radars near latitude 30.4 degrees north and longitude 87.6 degrees west. Sally’s eye was just 15 miles (25 km) north-northeast of Gulf Shores, Alabama and 25 miles (40 km) west-southwest of Pensacola, Florida.

Sally is moving toward the north-northeast near 3 mph (6 kph). A north-northeastward to northeastward motion at a slightly faster forward speed is expected later today and tonight, followed by a faster northeastward motion on Thursday. Doppler weather radar data indicate that the maximum sustained winds are near 100 mph (155 kph) with higher gusts.

Hurricane-force winds extend outward up to 40 miles (65 km) from the center and tropical-storm-force winds extend outward up to 125 miles (205 km). A sustained wind of 74 mph (119 kph) and a gust to 92 mph (148 kph) were recently reported at the Pensacola Naval Air Station in Pensacola, Florida. The estimated minimum central pressure based on surface observations is 967 millibars.

NHC Key Messages, Historic and catastrophic flooding is unfolding

The National Hurricane Center issued Key Messages about Rainfall, Wind, Tornadoes and Surf:

RAINFALL:  Through this afternoon, Sally will produce additional rainfall totals of 8 to 12 inches with localized higher amounts possible along and just inland of the central Gulf Coast from west of Tallahassee, Florida to Mobile Bay, Alabama. Storm totals of 10 to 20 inches to isolated amounts of 35 inches is expected.  In addition, this rainfall will lead to widespread moderate to major river flooding.

Sally is forecast to turn northeastward after making landfall today and move across the Southeast through Friday, producing the following rainfall totals:

Southern and central Alabama to central Georgia: 4 to 8 inches, with isolated maximum amounts of 12 inches. Significant flash and urban flooding is likely, as well as widespread minor to moderate flooding on some rivers.

Western South Carolina into western and central North Carolina: 4 to 6 inches, with isolated maximum amounts of 9 inches. Widespread flash and urban flooding is possible, as well as minor to moderate river flooding.

Southeast Virginia: 2 to 5 inches, with isolated maximum amounts of 7 inches. Scattered flash and urban flooding is possible, as well as scattered minor river flooding.

STORM SURGE:  The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline.  The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide.

• AL/FL Border to Okaloosa/Walton County Line, FL including Pensacola Bay and Choctawhatchee Bay, 4-7 ft
• Okaloosa/Walton County Line, FL to Walton Bay County Line, FL,  2-4 ft
• Dauphin Island, AL to AL/FL Border including Bon Secour Bay, 2-4 ft
• Walton Bay County Line, FL to Chassahowitzka, FL including Saint Andrew Bay,  1-3 ft

The deepest water will occur along the immediate coast in areas of onshore winds, where the surge will be accompanied by large and damaging waves.  Surge-related flooding depends on the relative timing of the surge and the tidal cycle, and can vary greatly over short distances.

WIND:  Hurricane conditions are spreading onshore within the hurricane warning area in Florida and Alabama.  Tropical storm conditions will continue in portions of the warning areas through tonight.

TORNADOES:  A few tornadoes may occur today and tonight across portions of the Florida Panhandle, southern Alabama, and southwestern Georgia.

SURF:  Swells from Sally will continue to affect the coast from the Florida Big Bend westward to southeastern Louisiana during the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions.

Sally’s Forecast from NHC

Weakening is expected as the center moves inland today and tonight. On the forecast track, the center of Sally will move across the extreme western Florida panhandle and southeastern Alabama through early Thursday, and move over central Georgia Thursday afternoon through Thursday night.

About NASA’s EOSDIS 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.”

NASA Researches Earth from Space

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. 15, 2020 – NASA Aqua Satellite Casts Three Eyes on Sally and Finds Heavy Rain Potential

NASA’s Aqua satellite analyzed the cloud top temperatures and water vapor content in Hurricane Sally as it crawls toward landfall, and found the potential for large amounts of rainfall, which, coupled with slow movement, can lead to catastrophic flooding. Two instruments provided three views of Sally’s temperatures and water vapor that revealed the soaking capability of the slow-moving hurricane.

At 8 a.m. EDT on Sept. 15, NOAA’s National Hurricane Center (NHC) cautioned, “Historic flooding is possible from Sally with extreme life-threatening flash flooding likely through Wednesday [Sept. 16] along portions of the northern Gulf Coast.” Forecasters are using NASA’s infrared and water vapor data to analyze the rainfall potential from Sally.

Warnings and Watches in Effect on Sept. 15

NHC issued a Storm Surge Warning for the mouth of the Mississippi River to the Okaloosa/Walton County Line, Florida and for Mobile Bay. A Hurricane Warning is in effect for east of the Mouth of the Pearl River to Navarre, Florida. A Tropical Storm Warning is in effect for east of Navarre, Florida to Indian Pass, Florida and from the mouth of the Pearl River westward to Grand Isle, Louisiana, including Lake Pontchartrain and Lake Maurepas and metropolitan New Orleans.

NASA’s Infrared Data Reveals Heavy Rainmakers

Tropical cyclones consist of hundreds of thunderstorms, and infrared data can show where the strongest storms are located. That is because infrared data provides temperature information, and the strongest thunderstorms that reach highest into the atmosphere have the coldest cloud top temperatures. Two instruments aboard NASA’s Aqua satellite provided infrared data on Sally’s cloud tops.

On Sept. 15 at 3:25 a.m. EDT (0725 UTC), the Moderate Resolution Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite revealed the most powerful thunderstorms were around Hurricane Sally’s center and in the northeastern quadrant. In those areas, cloud top temperatures were as cold as or colder than minus 80 degrees Fahrenheit (minus 62.2 Celsius). They were located over the Gulf of Mexico and just offshore from coastal Alabama, Mississippi and the Florida Panhandle. Strong storms with cloud top temperatures as cold as minus 70 degrees Fahrenheit (minus 56.6. degrees Celsius) surrounded both areas and were generating large amounts of rain.

Four minutes later, another instrument aboard NASA’s Aqua satellite analyzed Sally’s cloud top temperatures to verify the data from MODIS. The Atmospheric Infrared Sounder or AIRS instrument or AIRS instrument showed the strongest storms were offshore in the northern Gulf of Mexico where they were as cold as or colder than 210 Kelvin (minus 81 degrees Fahrenheit (minus 63.1 degrees Celsius). NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

Water Vapor Content

Water vapor analysis of tropical cyclones tells forecasters how much potential a storm has to develop. Water vapor releases latent heat as it condenses into liquid. That liquid becomes clouds and thunderstorms that make up a tropical cyclone. Temperature is important when trying to understand how strong storms can be. The higher the cloud tops, the colder and stronger the storms.

On Sept. 15 at 3:25 a.m. EDT (0725 UTC) Aqua’s MODIS instrument also gathered water vapor content and temperature information on Sally. The MODIS image showed the highest concentrations of water vapor and coldest cloud top temperatures were around the center of circulation and in the northeastern quadrant of the storm. The water vapor data showed the coldest cloud top temperatures were as cold as or colder than minus 70 degrees Fahrenheit (minus 56.6 degrees Celsius) in those storms. Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

Sally’s Rainfall Forecast from NHC

The NHC warns, “Sally is expected to be a slow moving system as it approaches land producing 10 to 20 inches of rainfall with isolated amounts of 30 inches along and just inland of the central Gulf Coast from the western Florida Panhandle to far southeastern Mississippi. Historic flooding is possible with extreme life-threatening flash flooding likely through Wednesday. In addition, this rainfall will lead to widespread moderate to major flooding on area rivers.

Sally is forecast to move inland early Wednesday and move across the Southeast producing rainfall of 4 to 8 inches, with isolated maximum amounts of 12 inches, across portions of southeastern Mississippi, southern and central Alabama, northern Georgia, and the western Carolinas. Significant flash and urban flooding is likely, as well as widespread minor to moderate flooding on some rivers.”

Sally’s Status on Sept. 15

At 8 a.m. EDT (1200 UTC) on Sept. 15, the National Hurricane Center noted the center of Hurricane Sally was located near latitude 29.1 degrees north and longitude 88.0 degrees west. That is about 65 miles (110 km) east of the mouth of the Mississippi River.

Sally is moving toward the northwest near 2 mph (4 kph), and this general motion is expected to continue this morning. A northward turn is expected this afternoon, followed by a slow north-northeastward to northeastward motion tonight and continuing through Wednesday night. Maximum sustained winds are near 85 mph (140 kph) with higher gusts. The estimated minimum central pressure based on data from the Air Force Hurricane Hunter aircraft is 982 millibars.

Sally’s Forecast Track

NHC said, “Although little change in strength is forecast until landfall occurs, Sally is still expected to be a dangerous hurricane when it moves onshore along the north-central Gulf coast. On the forecast track, the center of Sally will pass near the coast of southeastern Louisiana today, and make landfall in the hurricane warning area tonight or Wednesday morning.”

NASA Researches Tropical Cyclones

Hurricanes are the most powerful weather event on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

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

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.

By Rob Gutro
NASA’s Goddard Space Flight Center

Sep. 14, 2020 – NASA Satellite Imagery Catches Sally’s Development into a Hurricane

Tropical Storm Sally was deemed a hurricane on Sept. 14 just after NASA’s Aqua satellite provided data on the storm.

Infrared Imagery on Sally

On Sunday, Sept. 13, NASA analyzed Sally’s cloud top temperatures to gauge if the storm was strengthening. Cloud top temperatures provide information to forecasters about where the strongest storms are located within a tropical cyclone. The stronger the storms, the higher they extend into the troposphere, and the colder the cloud temperatures.

On Sept. 13 at 2:35 p.m. EDT (1835 UTC) NASA’s Aqua satellite analyzed Tropical Storm Sally using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) around the center and east of the center. NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain.

Visible Imagery Helps Confirm Hurricane Status

On Sept. 14 at 12:10 p.m. EDT (1610 UTC), the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra satellite provided a visible look at Hurricane Sally just as it reached hurricane status in the northern Gulf of Mexico. In the Terra image, the strongest storms appear to be around the center of circulation and the northern and eastern quadrants of the storm, which are skirting Florida’s west coast.

At 12:30 p.m. EDT, Daniel Brown, senior hurricane specialist and warning coordination meteorologist at NOAA’s National Hurricane Center in Miami, Fla. noted, “A NOAA Hurricane Hunter aircraft investigating Sally recently measured peak flight-level winds of 88 knot at 700 millibars and SFMR [Stepped Frequency Microwave Radiometer] winds of 78 knot north of the center, and an Air Force reconnaissance aircraft just measured 79 knot flight-level winds at 700 millibars.  These data indicate that Sally has rapidly strengthened into a hurricane with an intensity of around 80 knots. In addition, data from the KEVX WSR-88D [the radar at Eglin Air Force Base, Fla.] show an eye forming at around 16,000 foot altitude. This special advisory has been issued to increase the initial and forecast intensity.”

The Stepped Frequency Microwave Radiometer (SFMR) is the primary instrument used by the National Hurricane Center to determine hurricane intensity.

Watches and Warnings in Effect on Sept. 14

A Storm Surge Warning is in effect for Port Fourchon, Louisiana to the Alabama/Florida Border, Lake Pontchartrain, Lake Maurepas, and Lake Borgne and for Mobile Bay. A Hurricane Warning is in effect for Morgan City Louisiana to the Alabama/Florida Border, and for Lake Pontchartrain and Lake Maurepas including metropolitan New Orleans. A Tropical Storm Warning is in effect for the Alabama/Florida Border to Indian Pass, Florida and for Intracoastal City, Louisiana to west of Morgan City.

A Tropical Storm Watch is in effect for Indian Pass to Ochlockonee River, Florida.

Sally’s Status of Sept. 14

At 12:30 p.m. EDT (1630 UTC), the center of Hurricane Sally was located near latitude 28.7 degrees north and longitude 87.0 degrees west. That is 130 miles (210 km) east-southeast of the mouth of the Mississippi River. Sally is moving toward the west-northwest near 7 mph (11 kph). This general motion is expected to continue today, followed by a decrease in forward speed and a turn toward the northwest tonight and a northward turn sometime on Tuesday.

Data from NOAA and Air Force Reserve Hurricane Hunter aircraft indicate that Sally has rapidly strengthened. The maximum sustained winds are near 90 mph (150 kph) with higher gusts.  Additional strengthening is forecast during the next day or so. The latest minimum central pressure estimated from reconnaissance aircraft data is 986 millibars.

Sally’s Forecast

On the forecast track, the center of Sally will move over the north-central Gulf of Mexico today, approach southeastern Louisiana tonight, and make landfall in the hurricane warning area on Tuesday or Tuesday night. Afterward, Sally is expected to move slowly north-northeastward near the northern Gulf Coast through Wednesday.

The AIRS instrument is one of six instruments flying on board NASA’s Aqua satellite, launched on May 4, 2002.

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. 13, 2020 – NASA Satellite Confirms Tropical Storm Sally Strengthening, Threatens Gulf States

NASA’s Terra satellite passed over the Gulf of Mexico on Saturday, Sept. 12 and visible imagery helped confirm that the nineteenth tropical cyclone of the Atlantic Ocean hurricane season strengthened into a tropical storm.

Tropical Depression 19 formed late on Friday, Sept. 11, and by 2 p.m. EDT on Saturday, Sept. 12, it had strengthened into a tropical storm and was renamed Sally. Visible imagery from NASA’s Terra satellite helped confirm the organization of the storm.

On Sept. 12, the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard Terra provided a visible image newly developed tropical cyclone. The imagery showed better-defined banding features over the southern portion of the circulation than earlier in the day. Sally appeared more organized on satellite imagery, enough to be classified as a tropical storm.

As Sally strengthened and moved away from the Florida Peninsula during the morning hours of Sept. 13, the National Hurricane Center (NHC) posted many warnings and watches along the northern Gulf coast.

Warnings and Watches on Sept. 13

A Storm Surge Warning is in effect for Port Fourchon, Louisiana to the Mississippi/Alabama Border and for Lake Pontchartrain, Lake Maurepas, and Lake Borgne. A Hurricane Warning is in effect for Morgan City, Louisiana to Ocean Springs, Mississippi and for Lake Pontchartrain and Lake Maurepas including metropolitan New Orleans. A Tropical Storm Warning is in effect for east of Ocean Springs to Indian Pass and from Intracoastal City, Louisiana to west of Morgan City.

A Storm Surge Watch is in effect for the Mississippi/Alabama Border to the Alabama/Florida Border. A Hurricane Watch is in effect for east of Ocean Springs to the Alabama/Florida Border. A Tropical Storm Watch is in effect for Indian Pass to Ochlockonee River, Florida.

 Sally’s Status on Sept. 13, 2020

At 11 a.m. EDT (1500 UTC), NHC reported the center of Tropical Storm Sally was located near latitude 27.5 degrees north and longitude 84.9 degrees west. That is about 135 miles (225 km) west of St. Petersburg, Florida.

Sally is moving toward the west-northwest near 12 mph (19 km/h), and a west-northwestward or northwestward motion is expected through Monday. Data from an Air Force Reserve Hurricane Hunter aircraft indicate that the maximum sustained winds have increased to near 60 mph (95 kph) with higher gusts. Strengthening is expected over the next day or so, and Sally is forecast to become a hurricane on Monday with some additional strengthening possible before landfall Monday night.

Sally’s Forecast Track

A decrease in forward speed and a turn toward the north-northwest is forecast on Monday night, and slow north-northwestward motion is expected Tuesday. On the forecast track, the center of Sally will move over the eastern Gulf of Mexico today, move over the north-central Gulf of Mexico tonight and Monday, and approach the north-central Gulf Coast within the hurricane warning area late Monday and Monday night. Sally is expected to move farther inland over southeastern Louisiana on Tuesday and Tuesday night.

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

By Rob Gutro 
NASA’s Goddard Space Flight Center