There is a twitter ombudsman on tumblr.
Hurricane Sandy approaching New York. twitter.com/efitz6/status/…— Eamonn Fitzmaurice (@efitz6) October 29, 2012
It’s actually a picture from 2011, of a thunderstorm over Manhattan during a tornado alert (which turned out to be uneventful in the end, although the US and other countries were struck with an unusually high number of tornados that year). The original source appears to be this Wall Street Journal article, and the picture was taken through a tinted window by a finance professional called Charles Menjivar (from his workplace, most likely - his current employers are situated pretty much where this picture looks to be taken from).
It is traditional, when the US is menaced by a weather event, for people to tweet pictures of things that aren’t it. Generally they’re pictures of supercell thunderstorms, because they look way cool and a lot more threatening than actual hurricanes, which mostly just look sort of grey and wet and blurry unless you’re looking at them from above. Here are some of the more usual supercell picture suspects, which have previously been claimed to be hurricanes Isaac, Irene and (from the pre-Twitter days) Isabel, but weren’t. Keep a weather eye out for them.
UPDATE: Oh look, another one:
That, as Elliot Bentley points out, is actually a stock picture of the George Washington Bridge from 2009.
UPDATE UPDATE: Hey, you know who might want to stop tweeting pictures of “Sandy” without checking them? BuzzFeed’s Andrew Kaczynski (who’s normally a bit more reliable than this):
That second one is so fake (not just misattributed, it’s actually a Photoshopped picture of - naturally - a supercell thunderstorm) that it’s even on Snopes. (In his defence, he has corrected the latter one.)
UPDATE UPDATE UPDATE: Another one getting retweeted all over the place (and even written up by The Washington Post, although they’ve since killed the link) is this one of soldiers standing guard over the Tomb of the Unkowns even as Sandy rages around them:
Amazing soldiers standing at the Tomb of the Unknown Soldier during hurricane Sandy. twitter.com/OMGFacts/statu…— OMG Facts (@OMGFacts) October 29, 2012
It’s also not entirely true - the picture is from September, as the 3rd US Infantry Regiment (aka The Old Guard), the regiment that keeps watch over the Tomb, themselves tweeted:
This, at least, has some truth to it: the Old Guard are still maintaining their vigil at the Tomb, as the pictures they posted on Facebook show.