An advancing frontal system has brought heavy rains to the Mississippi Valleyregion and the northern Gulf Coast. Low pressure over the central plainstapped into abundant gulf moisture from the Gulf of Mexico to produce numerousstorms ahead of an advancing cold front. Deep-layer southerly winds in front ofthe low transported warm, moist air up from the Gulf northward into theMississippi Valley. Storms that formed within this moist air ahead of thecold front deposited significant amounts of rain from eastern Texas up throughthe Mississippi Valley and over to the Florida panhandle. The continuousregeneration of storms all the way down into the Gulf of Mexico combined withtheir movement to the north led to an effect known as “training” wherebyseveral different storms pass over the same area. This can lead to significantrainfall accumulations.
The Tropical Rainfall Measuring Mission (TRMM) satellite took this imageof a cluster of storms as they were approaching the Houston area. The imagewas taken at 15:50 UTC (9:50 am CST) on 17 November 2003, and it shows rainfallrates from the TRMM Precipitation Radar (PR) in the inner swath and the TRMMMicrowave Imager (TMI) in the outer swath overlaid on visible data from theTRMM Visible Infrared Scanner (VIRS) in white. Areas of heavy rainfall (redareas) associated with convective storms are embedded within areas of moderate(green areas) to light rain (blue areas). These storms spawned up to 21 tornadoes and flooded the Houston area, causing 25 to 30 million dollars worth of damage, according to news reports. One person drowned in the high waters.
TRMM is a joint mission between NASA and the Japanese space agency NASDA.
References & Resources
Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC)
