NASA observes rainfall from tornado-spawning storms in the southern US
For two days in mid-April, severe storms raced through the southern U.S. and NASA created an animation using satellite data to show the movement and strength of those storms.
From Sunday, April 12 into Monday, April 13, 2020, a series of powerful thunderstorms developed across the southern U.S., bringing heavy rainfall and spawning several destructive tornadoes.
At NASA's Goddard Space Flight Center in Greenbelt, Md. an animation was created that shows rainfall estimates for the region from April 11 to 13, derived from NASA's Integrated Multi-satellite Retrievals for GPM (IMERG) data product. The GPM or the Global Precipitation Measurement mission is a constellation of satellites provide the data for NASA's IMERG. The animation showed several storms that dropped more than 0.6 inches/16 mm of rainfall per hour.
On April 12, two sets of storms with those rainfall rates almost blanketed the state of Arkansas and then moved into the Tennessee Valley. Storms also generated tornadoes as they moved through Alabama, Mississippi, northern Georgia, and the Carolinas. The tornadoes in the animation were confirmed with reports from the National Oceanic and Atmospheric Administration or NOAA.
What is IMERG?
The near-realtime rain estimate comes from the NASA's Integrated Multi-satellitE Retrievals for GPM (IMERG) algorithm, which combines observations from a fleet of satellites, in near-realtime, to provide near-global estimates of precipitation every 30 minutes. By combining NASA precipitation estimates with other data sources, we can gain a greater understanding of major storms that affect our planet.
IMERG fills in the "blanks" between weather observation stations. IMERG satellite-based rain estimates can be compared to that from a National Weather Service ground radar. Such good detection of large rain features in real time would be impossible if the IMERG algorithm merely reported the precipitation observed by the periodic overflights of various agencies' satellites. Instead, what the IMERG algorithm does is "morph" high-quality satellite observations along the direction of the steering winds to deliver information about rain at times and places where such satellite overflights did not occur. Information morphing is particularly important over the majority of the world's surface that lacks ground-radar coverage.