NASA satellites offered a take a look at the rains possible in Hurricane Sally prior to and after it made landfall in southern Alabama. NASA’s Aqua satellite and IMERG analysis were utilized to evaluate the storm’s flooding capacity.
Sally came ashore on Wednesday, September 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 continual winds near 105 miles per hour (169 kph). As a slow-moving storm, Sally produced a great deal of rains, left flooded streets and knocked out power to numerous thousands on the U.S. Gulf Coast.
NASA’s Infrared View of Sally
Cloud leading temperature levels supply details to forecasters about where the greatest storms lie within a cyclone. Tropical cyclones do not constantly have consistent strength, and some sides are more powerful than others. The more powerful the storms, the greater they extend into the troposphere, and the chillier the cloud leading temperature levels. NASA offers that information to forecasters at NOAA’s National Hurricane Center or NHC so they can include it in their forecasting.
On September 16 at 3: 11 p.m. EDT (1911 UTC) NASA’s Aqua satellite examined Sally utilizing the Atmospheric Infrared Sounder or AIRS instrument. AIRS discovered coldest cloud leading temperature levels as cold as or chillier than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) around the center of flow and to the northeast and east of the center. NASA research study has actually revealed that cloud leading temperature levels that cold suggest strong storms that have the ability to produce heavy rain.
At that time, the AIRS image revealed those strong storms over the Florida Panhandle, much of Alabama, Georgia and extending into western South Carolina.
On September 16 at 3: 11 p.m. EDT (1911 UTC) NASA’s Aqua satellite examined Sally utilizing the Atmospheric Infrared Sounder or AIRS instrument. AIRS discovered the coldest cloud leading temperature levels as cold as or chillier than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) around the center of flow and to the northeast and east of the center. NASA research study has actually revealed that cloud leading temperature levels that cold suggest strong storms that have the ability to produce heavy rain. Credit: NASA JPL/Heidar Thrastarson
NASA Calculates Sally’s Rainfall
NASA integrated information from several satellites to approximate the rains from Hurricane Sally in near-real time at half-hourly periods from September 11-16, 2020. Rainfall rates and rains build-ups are approximated utilizing NASA’s Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm. IMERG integrates observations from a fleet of satellites, in near-real time, to supply near-global quotes of rainfall every 30 minutes.
NASA IMERG integrated information from several satellites to approximate the rains from Hurricane Sally in near-real time at half-hourly periods from September 11 to 16, 2020. This animation reveals rains rates (blue/yellow shading) and rains build-ups (green shading) from NASA’s IMERG algorithm, overlaid on tones of white/gray cloud information from NOAA infrared satellite instruments. The multi-colored line programs Sally’s track based upon National Hurricane Center advisories, with orange showing typhoon strength winds. Credit: NASA/Jason West
Rain rates along Sally’s track occasionally surpassed 1 inch/hour near its core and integrated with its sluggish speed, caused high build-ups along the Gulf Coast. By 5: 00 a.m. CDT (1000 UTC) on Sep. 16, IMERG had actually approximated overall build-ups along the southern Alabama shoreline and western Florida Panhandle going beyond 16 inches in some areas. NOAA rain gauge observations were broadly constant with the IMERG build-ups.
Sally Breaks a Pensacola Rainfall Record
The National Weather Service at the Pensacola Regional Airport in Florida reported 18.17 inches of rains from Sally on September 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 essential message has to do with the rains from Sally: Widespread flooding is anticipated from main Georgia through southeastern Virginia. Along the main Gulf Coast, most extensive moderate to significant river flooding from the historical rains occasion will crest by the weekend, however rivers will stay raised well into next week.
NHC Rainfall amounts to anticipated as Sally crosses the Southeast U.S. through Friday:
- Central Georgia: Sally will produce extra rains overalls of 3 to 6 inches, with localized greater quantities, on top of 3 to 6 inches, which has actually currently fallen. Widespread flash flooding and small to moderate river flooding is most likely.
- Central to upstate South Carolina: 3 to 6 inches, with separated quantities of 10 inches. Widespread flash flooding and small to moderate river flooding is most likely.
- Western to main North Carolina into south-central and southeast Virginia: 4 to 6 inches, separated quantities approximately 8 inches. Flash flooding and extensive small river flooding is most likely.
Sally’s Status on September 17
At 5 a.m. EDT (0900 UTC), the center of Tropical Depression Sally lay near latitude 31.8 degrees north and longitude 85.7 degrees west. The center had to do with 50 miles (80 km) southeast of Montgomery, Alabama. The anxiety is approaching the northeast near 12 miles per hour (19 kph) and a northeastward to east-northeastward movement is anticipated into Friday.
Maximum continual winds have actually reduced to near 30 miles per hour (45 kph) with greater gusts.
The approximated minimum main pressure based upon neighboring surface area observations is 1000 millibars.
Senior Hurricane Specialist Stacy Stewart of NOAA’s National Hurricane Center in Miami, Fla. kept in mind, “Although the general convective cloud and rain guard in satellite and radar images continues to deteriorate, Tropical Depression Sally is still producing substantial rains throughout east-main Alabama and west-central and central Georgia. Surface observations and Doppler radar information suggest that Sally has actually damaged to a 25 knots [29 mph/46 kph] anxiety over southeastern Alabama.”
Sally’s Forecast Track
NHC states that extra weakening is anticipated throughout the next number of days, and Sally is anticipated to end up being a residue low by tonight or Friday early morning. On the projection track, the center of Sally will cross southeastern Alabama today, over main Georgia this afternoon and night, and relocation over South Carolina late tonight into Friday, September 18.
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