FinViz
That 10:30 EST tumble is a pretty quick reaction to the weaker than expected withdrawal from storage.
Here's the rest of the story from ZereHedge:
Today's Nat Gas (News) Leak In 3-D Action
Via Nanex,
On January 31, 2013, approximately 400 milliseconds before the official release of the EIA Natural Gas Report, trading activity exploded in Natural Gas Futures and ETFs such as UGZ, UNG and BOIL. Now that the Feds have stated that they don't think there is merit in prosecuting people who get news information earlier than others by milliseconds, is it any wonder?
1. Natural Gas Futures - March 2013 (NG.H13) showing trades and depth of book.
1. UNG showing trades color coded by exchange between 10:29:59 and 10:30:04.
This resolution clearly shows trading activity starting about 400 milliseconds before the official news release time of 10:30. Note the spike at 10:30 - which is when everyone else received the information.

2. Natural Gas Futures - March 2013 (NG.H13) showing trades and depth of book.
Click for animation of this chart.

3. Natural Gas Futures - March 2013 (NG.H13) showing trades and depth of book.
Click for animation of this chart.
...MUCH MORE