The stock market is, for now at least, expected to have a normal trading session on Monday despite the arrival of Hurricane Irene in New York.

The New York Stock Exchange, the Nasdaq Stock Market and the alternative BATS venue said they expected to open trading for the week as usual. But with the New York subway system closed down and commuter rail service into the city suspended, the question remains: who will staff Wall Street?

A final decision is expected later on Sunday after regulators, exchange officials and others meet to discuss the storm and market operations. The decision hinges on whether subways are running, the extent of flooding in downtown Manhattan, and power outages, sources familiar with the plan said on Sunday.

The NYSE and broader U.S. marketplace are mostly automated, quietly running out of powerful data centers in New Jersey and elsewhere. Electronic trading is expected to function normally on Monday.

At this point, though like everybody else we don't have a hotline into the mayor's office, we're a lot more comfortable than we were yesterday when the strength of the storm was an unknown, said Mike Shea, a managing partner and trader with Direct Access Partners LLC in New York.

Shea's firm has a presence on the NYSE floor, and in Boston and Miami. He said that virtually all of his firm's traders could function from home.

Hurricane Irene battered New York with heavy winds and driving rain on Sunday, knocking out power and flooding some of Manhattan's deserted streets, including in the Wall Street district.

Irene was downgraded to a tropical storm on Sunday morning but was still sending waves crashing onto shorelines and flooding coastal areas.

There was about a foot of water in the streets of the South Street Seaport in downtown Manhattan, although there was less damage than many had feared.

The New York Mercantile Exchange (NYMEX), a few blocks from the NYSE, also plans at this time to open on Monday, parent CME Group Inc said on Sunday.

Any decision to halt U.S. equity trading, or even a portion of it such as the NYSE floor, would involve the U.S. Securities and Exchange Commission and major market operators NYSE Euronext and Nasdaq OMX Group .

The NYSE trading floor now handles a fraction of the buy and sell orders that it did five years ago, when about 3,000 brokers, specialists and others worked there.

There are now about 1,000 on the floor, and Lou Pastina, executive vice president of NYSE operations, has estimated the Big Board would need half of them to safely open on Monday. Floor specialists are still important, particularly at the open and close of markets, when orders pile up.

(Writing by Chris Sanders; Reporting by Jonathan Spicer; Additional reporting by Ryan Vlastelica and David Sheppard)