The euro is smack in the middle of its recent range, and this strategist is waiting for a breakout.

Sometimes, when a currency is rangebound, it makes sense to sit tight and wait for the market to indicate where it's headed next.

That's the plan of Willie Williams, a director in global macro sales at Societe General.

"I think the euro is caught in between two opposing forces," he told CNBC's Melissa Lee. "On the one hand, the market is waiting to see if there will be a Greek holiday regarding them servicing their debt," and whether Spain will use money from the loan program to buy bonds.

"On the other side we have U.S. data outperforming the G-5 peers at the moment," he adds.

Williams notes that the euro has been trading between 1.2100 and 1.2500 for the past few weeks, and "we're pretty much dead smack in the middle of the range."

So Williams wants to wait for indications that investor sentiment is really changing, which he says could happen as soon as Federal Reserve Chairman Ben Bernanke's speech at Jackson Hole. If the euro breaks above 1.2500, he says, it would probably mean that there is action coming from the European Central Bank or the Spanish government - that "something has happened to make us say there's more room for appreciation in the euro. the euro to appreciate." A break below 1.2100, Williams says, would mean "we've been disappointed by the ECB, and the U.S. data and higher U.S. yields are leading the direction."

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MULTI CURRENCIES v The Dollar

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