(Updates to U.S. morning trade)

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U.S. stocks rally on tech strength

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European stocks little changed

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Fed's economic projections; dot plot eyed

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Turkish assets drop after arrest of Erdogan rival

By Stephen Culp

NEW YORK, March 19 (Reuters) - U.S. stocks advanced and bitcoin rebounded on Wednesday as markets awaited the rate decision from the U.S. Federal Reserve, which could provide insight regarding the state of the economy and the central bank's next monetary policy moves.

Megacap tech-related momentum stocks rebounded in a risk-on revival that put the Nasdaq out front, strengthened the dollar and put gold on the defensive.

Turkey detained President Tayyip Erdogan's main political rival in what the main opposition party called "a coup against our next president," battering Turkish stocks and sending the lira plunging as much as 14.5% against the dollar before it pared those losses.

The Federal Reserve is expected to conclude its two-day monetary policy meeting with a decision later on Wednesday to let its key interest rate stand in the 4.25% to 4.50% range.

But the accompanying statement, Chair Jerome Powell's press conference and the central bank's Summary of Economic Projections - including the dot plot - will be parsed for clues regarding the timing of the Fed's next rate move.

(The Fed has) dialed rate cut expectations back down to two this year," said Matthew Keator, managing partner in the Keator Group, a wealth management firm in Lenox, Massachusetts. "With the uncertainty surrounding the new administration and some of their policies I just think it behoves them to kind of take a wait and see approach at this point."

"I would be surprised if there was anything that deviated from that," Keator added.

Ukrainian President Volodymyr Zelenskiy was set to speak with U.S. President Donald Trump on Wednesday and said the United States should be in charge of monitoring any ceasefire in the Ukraine war.

"We live in such a global society there's always going to be something happening out there in the world," Keator said. "But long-term investors, I believe, have the ability to kind of look through some of that day-to-day noise."

The Dow Jones Industrial Average rose 246.54 points, or 0.60%, to 41,829.45, the S&P 500 rose 36.30 points, or 0.65%, to 5,650.99 and the Nasdaq Composite rose 159.22 points, or 0.90%, to 17,661.27.

European stocks struggled for gains, edging back from the previous session's robust gains ahead of the Fed decision.

Europe's broad FTSEurofirst 300 index fell 0.38 points, or 0.02%.

MSCI's gauge of stocks across the globe rose 3.29 points, or 0.39%, to 842.82.

The pan-European STOXX 600 index was flat, while Emerging market stocks fell 2.12 points, or 0.19%, to 1,143.05. MSCI's broadest index of Asia-Pacific shares outside Japan closed lower by 0.18%, to 593.97, while Japan's Nikkei fell 93.54 points, or 0.25%, to 37,751.88.

The dollar rallied ahead of the central bank's decision, but backed down from the day's highs as markets digested the shock of Turkey's arrest of Istanbul mayor Ekrem Imamoglu, Erdogan's main political rival.

The dollar index, which measures the greenback against a basket of currencies including the yen and the euro, rose 0.34% to 103.65, with the euro down 0.43% at $1.0896.

Against the Japanese yen, the dollar strengthened 0.42% to 149.89.

The Turkish lira was last trading down 3.55% at 37.987 per dollar.

Cryptocurrencies benefited from risk-on investor sentiment.

Bitcoin gained 2.65% to $84,190.58. Ethereum rose 6.52% to $2,029.63.

U.S. Treasury yields gained on Wednesday and two-year yields hit a three-week high ahead of the U.S. central bank's rate decision.

The yield on benchmark U.S. 10-year notes rose 1.7 basis points to 4.298%, from 4.281% late on Tuesday. The 30-year bond yield rose 0.7 basis points to 4.5861% from 4.579% late on Tuesday.

The 2-year note yield, which typically moves in step with interest rate expectations for the Federal Reserve, rose 3.6 basis points to 4.078%, from 4.042% late on Tuesday.

Crude prices seesawed. Russia and Ukraine accused each other on Wednesday of violating a new agreement for a 30-day halt to attacks on energy targets hours after it was agreed by Trump and Russian President Vladimir Putin.

U.S. crude rose 0.33% to $67.12 a barrel and Brent rose to $70.81 per barrel, up 0.35% on the day.

Gold prices held steady about the $3,000 per ounce mark, continuing to benefit from safe-haven demand.

Spot gold fell 0.1% to $3,030.87 an ounce. U.S. gold futures fell 0.13% to $3,031.10 an ounce.

(Reporting by Stephen Culp Additional reporting by Harry Robertson in London and Ankur Banerjee in Singapore Editing by Frances Kerry)