NUEVO LAREDO, Mexico -- Mexican authorities urged people to move to shelters while officials in Texas distributed sandbags and warned of flash floods as Tropical Storm Hermine strengthened and headed toward the northwestern Gulf Coast on Monday.

Hermine will probably make landfall around midnight just south of the U.S.-Mexico border, threatening to bring as much as one foot of rainfall to some areas battered by Hurricane Alex in June. Remnant rains from Alex killed at least 12 people in flooding in Mexico.

Hermine "will briefly be over Mexico, and then we're expecting it to produce very heavy rainfall over south Texas," said Eric Blake, a hurricane specialist at the U.S. National Hurricane Center. "We're expecting widespread rainfall totals of 4 to 8 inches with isolated amounts of a foot possible. Especially in the hilly and mountainous terrain that could cause life-threatening flash flooding."

The storm's winds strengthened to about 60 mph, and by Monday afternoon it was located about 100 miles south-southeast of Brownsville, Texas. Tropical storm force winds extended out up to 105 miles from the storm's center.

WASHINGTON -- The Food and Drug Administration is poised to approve the first genetically modified animal for human consumption, a highly anticipated decision that is stirring controversy and could mark a turning point in the way American food is produced.

FDA scientists gave a boost last week to the Massachusetts company that wants federal approval to market a genetically engineered salmon.

"Food from AquAdvantage Salmon ... is as safe to eat as food from other Atlantic salmon," the FDA staff wrote in a briefing document. Those findings will be presented Sept. 19 to a panel of experts that will advise top FDA officials whether to approve the altered salmon.

AquAdvantage is an Atlantic salmon that has been given a gene from the ocean pout, an eel-like fish, which allows the salmon to grow twice as fast as a traditional Atlantic salmon. It also contains a growth hormone from a Chinook salmon.

WASHINGTON -- People's emotional well-being -- happiness -- increases along with their income up to about $75,000, researchers report in today's edition of Proceedings of the National Academy of Sciences.

For folks making less than that, said Angus Deaton, an economist at the Center for Health and Wellbeing at Princeton University, "Stuff is so in your face it's hard to be happy. It interferes with your enjoyment."

Dr. Deaton and Daniel Kahneman reviewed surveys of 450,000 Americans conducted in 2008 and 2009 for the Gallup-Healthways Well-Being Index that included questions on people's day-to-day happiness and their overall life satisfaction.

Happiness got better as income rose but the effect leveled out at $75,000, Dr. Deaton said. On the other hand, their overall sense of success or well-being continued to rise as their earnings grew beyond that point.

HENDERSON, Nev. -- A small plane crashed and burst into flames on a street in a southern Nevada residential neighborhood Monday, killing one person and badly injuring three others, authorities said.

Las Vegas Metropolitan Police Sgt. John Sheahan said two males and two females were aboard the single-engine Piper Cherokee when it crashed in Henderson, just south of Las Vegas.

Washington correspondent Daniel Malloy writes the "Pittsburgh On The Potomac" blog exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.