In the United States tornadoes develop most often in the spring when warm moist unstable air accompanies strong fronts and fluctuating upper-air systems. There is a also a slight increase in tornado activity in late October and November. Tornadoes form least often in December and January so the tornadoes that occurred yesterday over the south-eastern United States were unusual. The TRMM satellite was flying over on December 10, 2012 at 1743 UTC (12:43 PM EST) and captured data showing tornado spawning thunderstorms within a frontal system moving through Louisiana, Mississippi, Alabama, Georgia

The TRMM satellite has now been making highly accurate measurements of rainfall from space for fifteen years. TRMM can be used to calibrate rainfall estimates from other additional satellites. Those Rainfall data (3B42) are routinely created and stored at the Goddard Space Flight Center. The TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA) at the NASA Goddard Space Flight Center can be used to analyze rainfall over a wide portion of the globe. The TMPA analysis above shows the estimated amount of rain contributed by named tropical cyclones over the western Atlantic in

The TRMM satellite flew above tropical storm Bofa on November 27, 2012 at 1601 UTC and collected data used in the image above. TRMM showed that tropical storm Bofa had an area of very intense convective storms near the center of circulation. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) data revealed that rain was falling at a rate of over 70mm/hr (~1.75 inches) in that area. TRMM's Precipitation Radar (PR) also showed that powerful storms in the area of the developing eye wall were reaching to heights of about 17km (~10.6 miles). Click here to see a simulated flyby above Bofa