I haven't heard of anything in the upper river of note. I'd say, wait for the first significant cool front (at least several days in a row in the 70s with nights in the 50s) before the Rock really start to stack up that way. In the meantime, I wouldn't be suprised if a few stray Rock make it well into the river with the upcoming "cooler front" (day temps in the low 80s, low 60s at night).
"Don't talk to me about naval tradition. It's nothing but rum, sodomy, and the lash." - Sir Winston Churchill