WASHINGTON (AP) - Scientists studying weather records have made an electrifying discovery that many Gulf Coast residents probably already knew - the days with lightning storms doubled in the 1997-98 El Nino. The number of days with lightning during that December through February was more than twice that of other recent winters. There were 33 lightning days recorded during that winter in the northern Gulf of Mexico compared with 15 days during other winters, the researchers said in a paper appearing in the Feb. 15 issue of Geophysical Research Letters. During those 33 days the network of ground sensors and satellites counted 138 hours of lightning, compared to 50 hours in other recent winters.