According to the US mainstream media, it's all because of Hurricane Sandy (CNN, LA Times, or Fox News, for example).
According to not-so-mainstream media, the largest increase in jobless claims was seen NOT in the states battered by Hurricane Sandy but in Ohio and Pennsylvania.
From Breitbart (11/15/2012; emphasis is mine):
The Department of Labor has announced that new jobless claims rose by a staggering 78,000 in the first week after the election, reaching a seasonally-adjusted total of 439,000. Over the past year, and in the weeks leading up to the election, jobless claims were said to be declining, dipping as low as 339,000, with the media proclaiming that they had reached the "lowest level in more than four years." Now, suddenly, the news seems far less rosy.
From the Department of Labor press release this morning:
In the week ending November 10, the advance figure for seasonally adjusted initial claims was 439,000, an increase of 78,000 from the previous week's revised figure of 361,000. The 4-week moving average was 383,750, an increase of 11,750 from the previous week's revised average of 372,000.
Some of the new claims, especially in New Jersey, were due to Hurricane Sandy--but these were offset by a decline in claims filed in New York. The highest numbers of new filings came from Pennsylvania and Ohio, where there were thousands of layoffs in the construction, manufacturing, and automobile industries.
Both states had been targeted by the presidential campaigns. President Obama highlighted his record of job creation in Ohio in particular, focusing on the automobile industry. The state reported 6,450 new jobless claims in the week after the election--second-highest after Pennsylvania, which recorded 7,766 new claims.