Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 3:22 PM GMT on November 06, 2007
While Hurricane Noel's deadly rampage through the Caribbean was making headlines last week, Mexico experienced one of the worst flooding disasters in its history. Rescue crews are still at work plucking thousands of stranded residents off of rooftops in the state of Tabasco. Over 80% of Tabasco was underwater, and flood waters reached up to residents' rooftops in the capital city of Villahermosa. Up to 900,000 people are homeless in the disaster, which Mexicans are calling their Hurricane Katrina. The number of people dead or missing now stands at 26, due to a new mudslide yesterday that overwhelmed a small village near Villahermosa.
The floods were spawned by heavy rains that fell from a cold front that stalled over the Gulf of Mexico between October 28 and November 1. Satellite estimates of the rainfall show that no more than 7 inches of rain fell over the region during the period, which seems like too little rain to cause the massive flooding observed. It is possible these satellite estimates are flawed. The official rain gauge in Villahermosa reported 2, 81, 7, 0, and 2 inches of rain during the days October 28-November 1, respectively. Presumably, the 81 inches of rain reported October 29 is due to floodwaters inundating the rain gauge. Villahermosa averages 13 inches of rain in a typical October. No new rains have fallen since November 1, and the flood waters are gradually receding.
Figure 1. Thick clouds cover Mexico's Tobasco state on October 29, 2007, due a cold front that stalled over the region. The area received up to 7 inches of rain over a 5-day period. Image credit: NASA.
Disturbance 92L in far eastern Atlantic not a threat
A non-tropical "cut-off" low pressure system near 31N 37W, a few hundred miles southwest of the Azores Islands, is showing signs of becoming more tropical. This system was designated "92L" by NHC this morning. Phase space diagrams from Bob Hart at Florida State University show that 92L started off as a classic extratropical storm that was asymmetrical with a cold core, but the storm has gotten more symmetrical and the core has warmed. Satellite loops show only limited thunderstorm activity near the center of circulation at present, though. Sea Surface Temperatures are about 24° C under 92L, and are considerably cooler than the 26.5° usually needed to get a tropical cyclone going. Wind shear is 30-40 knots, and is expected to stay above 30 knots for the next two days. These factors should keep the storm from developing. The system is expected to turn northeast and move through the Azores Islands Friday or Saturday.
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