The macro view: There are a number of reasons to expect the Dow Jones Industrial Average (DJINDICES:^DJI) and the broader S&P 500 Index (SNPINDEX:^GSPC) to be volatile tomorrow:

One, equity markets are reopening after their longest closure since September 2001. For the New York Stock Exchange, this is the longest weather-related closure since 1888.

Two, accountants and analysts will be busy trying to tally the direct costs and the knock-on economic impact of Hurricane Sandy. Expect a wide range of estimates, with greater media focus on top-of-the-range forecasts.

Three, tomorrow is the last day of October; some money managers may want to make end-of-month adjustments to their funds. At least we can be thankful that the reopening doesn't coincide with the end of a calendar quarter.

Four, although we're more than halfway through a (middling) earnings season, tomorrow will be a full day in terms of information, particularly as some companies that were meant to report during the first half of the week have had to postpone their announcements.

The micro view: Speaking of earnings announcements, two economic bellwether stocks will report earnings tomorrow: General Motors (NYSE:GM) and Visa (NYSE:V). GM reports before the opening; Visa, after the close. In the wake of Hurricane Sandy, analysts will no doubt be especially eager to hear from executives at one of the largest property and casualty insurers, Allstate (NYSE:ALL) which is also reporting tomorrow.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.