Just when you thought you might not need to remember the Spanish meteorological word "derecho" and the nastiness that came with it last June at the AT&T National, think again.
Conditions are ripe for a derecho to form on a path from the Midwest of the United States through the East Coast on Thursday, including a possible track through the Philadelphia area, site of Merion Golf Club and the 2013 U.S. Open.
A derecho is a long-lasting storm that extends at least 240 miles, bringing with it sustained straight-line winds of 57+ mph as well as the possibility of severe, damaging rain.
While the odds of a derecho forming are unclear, forecasters are tipping several inches of rain for Merion during the day on Thursday. A flood watch is in effect from 10 a.m. on Thursday until 6 a.m. on Friday.
Nearly 6 inches of rain have already fallen on Merion since last Friday, when Tropical Storm Andrea rolled through the area, dumping 4+ inches of rain. The additional Monday rain prompted the closure of the 11th hole on the East course, the lowest point of the property but the planned first hole for half the field during the opening two rounds using split starting tees.
For a look at the derecho which struck Congressional C.C. and the AT&T National last June, click here. Also check out our report on the eerie third round that took shape that Saturday.