* Matches under way after delay of more than four hours
* Overnight snow finally thaws out at Dove Mountain (Updates with resumption of play)
By Mark Lamport-Stokes
MARANA, Arizona, Feb 21 (Reuters) - Play finally got under way at the WGC-Accenture Match Play Championship on Thursday after the resumption of the snow delayed first-round matches was pushed back four-and-a-half hours.
Two more inches of snow fell overnight at Dove Mountain's Ritz-Carlton Golf Club, lifting the total to four inches in under 24 hours, and hopes for a quick melt were dashed by plunging temperatures and early morning frost.
Officials repeatedly altered restart times as the par-72 course remained blanketed in white but, after the snow had finally disappeared in the desert sunshine, first-round matches resumed at 1 p.m. local time (2000 GMT).
With parts of the layout still very wet, officials said players would be permitted to lift, clean and replace balls in the fairway.
Though morning frost has been forecast for the rest of the week at the elite World Golf Championships (WGC) event, being played at 2,800 feet above sea level, conditions are expected to warm up on Friday, Saturday and Sunday.
"We'll stay in the 50s (F) the next couple of days, back to the low 60s on Saturday, and then probably upper 50s again on Sunday as another little weak front goes by," the PGA Tour's on-site meteorologist Stewart Williams told reporters.
"But it doesn't look like it has any moisture with it, so it's just going to drop our temperature a few degrees. Unfortunately we'll have below normal temperatures for the rest of the week, but at least we'll have some sun."
Just over three-and-a-half hours of golf was possible on Wednesday because of driving rain, sleet and then snow after 23 of the 32 matches had started with none finishing.
Players and caddies were left stunned by the sudden change in conditions and many of them ended up throwing snowballs at one another while waiting for officials to abandon play for the day.
"One minute we're playing golf, albeit it's a little cool, and then within a space of 25 minutes, it turns from playable to cold drizzle to sleet and to snow," Ian Poulter, the 2010 champion, said. "It's just bizarre."
Among the early matches, Australian Jason Day was in full command against American Zach Johnson, four birdies in the first eight holes helping him go 6up after 10 while Poulter was 3up on fellow Briton Stephen Gallacher after 12.
American Bo Van Pelt was 5up on Australian John Senden after 12 holes, defending champion Hunter Mahan was 4up on Italy's Matteo Manassero after nine and American Matt Kuchar was 3up on Japan's Hiroyuki Fujita after 14.
Northern Ireland's world number one Rory McIlroy, beaten by Mahan 2&1 in last year's final, and three-times champion Tiger Woods were among those yet to start their first-round matches.
McIlroy has been drawn to play Irishman Shane Lowry in the opening round while Woods will face fellow American Charles Howell III. (Reporting by Mark Lamport-Stokes; Editing by Steve Ginsburg/Gene Cherry)