The stock market exploded in a near-record first hour buying rush today and ended the day with broad gains, except for the select group of blue-chip industrials for which the Dow Jones industrial average is a barometer.

The New York Stock Exchange index of composite prices rose .13 to 62.72 and Standard & Poor's 500-stock composite index gained .10 to 109.05. At the American Stock Exchange, the market value index rose .87 to 251.75 -- the second consecutive new high.

Advancing issues outnumbered declining stocks in all markets by a 2-1 edge and over-the -counter stocks, as measured by the NASDAQ composite index gained .92 to 151.60.

In addition, all Dow Jones averages except for the 30 industrials also advanced. The Dow index of industrials was down 1.62 to 850.09 but had been ahead 7 points earlier in the day. The relatively weak gains of the Dow averages last year masked a substantial overall market gain in 1979.

New York Stock Exchange volume rose to 65.26 million shares from 53.39 million Tuesday in the third-busiest day in Big Board history.

Wednesday's NYSE volume was the heaviest since 81.61 million shares changed hands last Oct. 10, and close behind the second-busiest day, Aug. 3, 1978, when 66.37 million shares were traded.

Opening-hour volume of 20.22 million shares was just below the record of 20.73 million set last Oct. 10. "But you could see from the intensity" of the first-hour surge that the rally "was just not going to last," said Monte Gordon of Dreyfus Corp.

Nationwide turnover in NYSE-listed issues, including trades in those stocks on regional exchanges and in the over-the-counter market, came to 73.71 million shares.

IBM, up by more than 4 Tuesday, slipped 2 to 65 3/8 and Texas Instruments lost 1 3/4 to 94. LTV led the NYSE most-actives and was off 1 1/8 at 11 1/2 while U.S. fell 1 3/8 to 19 7/8.

Exxon was off 1/2 at 52 5/8 but Getty rose 1 to 76 1/2, Eastman Kodak fell 1 1/8 to 47 1/8 after boosting film prieces, and Du Pont dropped 1 1/4 to 40 3/8.Among areospace issues Boeing was off 1 1/2 at 56 1/2 and Lockheed was down 2 7/8 at 40 7/8.

The early rally was sparked by Tuesday's commerce Department estimate the economy grew at an unexpectedly strong 2-3 percent annual rate in last year's fourth quarter.

Forest products issues were higher despite the report, with Boise Cascade up 1 1/2 at 34 1/2. Metals issues were mixed, with copper producer Asarco off 2 at 40 1/2 and an actively-traded Alcan Aluminum up 2 1/8 at 52 3/4.

American Telephone & Telegraph fell 1/8 to 52 1/4 after the Federal Communications Commission and competition in the telephone industry has had beneficial effects for consumers.

Standard & Poor's index of 400 industrials was up .06 at 122.30; the SIP 500-stock composite index rose .10 to 109.05. The NYSE's composite common-stock index rose .13 to 62.72 and the American Stock Exchange's market value index added .87 to 251.75.

The NASDAQ composite index of the over-the-counter market rose .92 to 151.0.