NASA’s Aqua satellite tv for pc analyzed the cloud high temperatures and water vapor content material in Hurricane Sally because it crawls towards landfall, and located the potential for big quantities of rainfall, which, coupled with sluggish motion, can result in catastrophic flooding. Two devices supplied three views of Sally’s temperatures and water vapor that exposed the soaking functionality of the slow-moving hurricane.
At eight a.m. EDT on September 15, NOAA’s Nationwide Hurricane Middle (NHC) cautioned, “Historic flooding is feasible from Sally with excessive life-threatening flash flooding probably by way of Wednesday [September 16] alongside parts of the northern Gulf Coast.” Forecasters are utilizing NASA’s infrared and water vapor knowledge to investigate the rainfall potential from Sally.
Warnings and Watches in Impact on September 15
NHC issued a Storm Surge Warning for the mouth of the Mississippi River to the Okaloosa/Walton County Line, Florida and for Cell Bay. A Hurricane Warning is in impact for east of the Mouth of the Pearl River to Navarre, Florida. A Tropical Storm Warning is in impact for east of Navarre, Florida to Indian Go, Florida and from the mouth of the Pearl River westward to Grand Isle, Louisiana, together with Lake Pontchartrain and Lake Maurepas and metropolitan New Orleans.
NASA’s Infrared Knowledge Reveals Heavy Rainmakers
Tropical cyclones include a whole lot of thunderstorms, and infrared knowledge can present the place the strongest storms are situated. That’s as a result of infrared knowledge offers temperature data, and the strongest thunderstorms that attain highest into the environment have the coldest cloud high temperatures. Two devices aboard NASA’s Aqua satellite tv for pc supplied infrared knowledge on Sally’s cloud tops.
On September 15 at three:25 a.m. EDT (0725 UTC), the Reasonable Decision Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Aqua satellite tv for pc revealed probably the most highly effective thunderstorms have been round Hurricane Sally’s middle and within the northeastern quadrant. In these areas, cloud high temperatures have been as chilly as or colder than minus 80 levels Fahrenheit (minus 62.2 Celsius). They have been situated over the Gulf of Mexico and simply offshore from coastal Alabama, Mississippi and the Florida Panhandle. Robust storms with cloud high temperatures as chilly as minus 70 levels Fahrenheit (minus 56.6. levels Celsius) surrounded each areas and have been producing massive quantities of rain.
4 minutes later, one other instrument aboard NASA’s Aqua satellite tv for pc analyzed Sally’s cloud high temperatures to confirm the information from MODIS. The Atmospheric Infrared Sounder or AIRS instrument or AIRS instrument confirmed the strongest storms have been offshore within the northern Gulf of Mexico the place they have been as chilly as or colder than 210 Kelvin (minus 81 levels Fahrenheit (minus 63.1 levels Celsius). NASA analysis has proven that cloud high temperatures that chilly point out robust storms which have the potential to create heavy rain.
Water Vapor Content material
Water vapor evaluation of tropical cyclones tells forecasters how a lot potential a storm has to develop. Water vapor releases latent warmth because it condenses into liquid. That liquid turns into clouds and thunderstorms that make up a tropical cyclone. Temperature is vital when attempting to grasp how robust storms may be. The upper the cloud tops, the colder and stronger the storms.
On September 15 at three:25 a.m. EDT (0725 UTC) Aqua’s MODIS instrument additionally gathered water vapor content material and temperature data on Sally. The MODIS picture confirmed the best concentrations of water vapor and coldest cloud high temperatures have been across the middle of circulation and within the northeastern quadrant of the storm. The water vapor knowledge confirmed the coldest cloud high temperatures have been as chilly as or colder than minus 70 levels Fahrenheit (minus 56.6 levels Celsius) in these storms. Storms with cloud high temperatures that chilly have the potential to provide heavy rainfall.
Sally’s Rainfall Forecast from NHC
The NHC warns, “Sally is anticipated to be a sluggish transferring system because it approaches land producing 10 to 20 inches of rainfall with remoted quantities of 30 inches alongside and simply inland of the central Gulf Coast from the western Florida Panhandle to far southeastern Mississippi. Historic flooding is feasible with excessive life-threatening flash flooding probably by way of Wednesday. As well as, this rainfall will result in widespread reasonable to main flooding on space rivers.
Sally is forecast to maneuver inland early Wednesday and transfer throughout the Southeast producing rainfall of four to eight inches, with remoted most quantities of 12 inches, throughout parts of southeastern Mississippi, southern and central Alabama, northern Georgia, and the western Carolinas. Important flash and concrete flooding is probably going, in addition to widespread minor to reasonable flooding on some rivers.”
Sally’s Standing on September 15
At eight a.m. EDT (1200 UTC) on September 15, the Nationwide Hurricane Middle famous the middle of Hurricane Sally was situated close to latitude 29.1 levels north and longitude 88.zero levels west. That’s about 65 miles (110 km) east of the mouth of the Mississippi River.
Sally is transferring towards the northwest close to 2 mph (four kph), and this basic movement is anticipated to proceed this morning. A northward flip is anticipated this afternoon, adopted by a sluggish north-northeastward to northeastward movement tonight and persevering with by way of Wednesday evening. Most sustained winds are close to 85 mph (140 kph) with larger gusts. The estimated minimal central strain based mostly on knowledge from the Air Drive Hurricane Hunter plane is 982 millibars.
Sally’s Forecast Monitor
NHC stated, “Though little change in power is forecast till landfall happens, Sally continues to be anticipated to be a harmful hurricane when it strikes onshore alongside the north-central Gulf coast. On the forecast monitor, the middle of Sally will go close to the coast of southeastern Louisiana at present, and make landfall within the hurricane warning space tonight or Wednesday morning.”
NASA Researches Tropical Cyclones
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NASA’s Aqua satellite tv for pc is one in a fleet of NASA satellites that present knowledge for hurricane analysis.
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