SEATTLE (Reuters) - Washington state made history on Thursday as the first in the nation to legalize marijuana possession for adult recreational use, an occasion celebrated by dozens of users near Seattle's famed Space Needle tower amid blaring reggae music and a haze of pot smoke.

The public gathering defied a key provision of the state's landmark marijuana law, which forbids users from lighting up outside the privacy of their homes. And it underscored mixed messages that law enforcement officials have conveyed about the new statute.

Hours earlier, Seattle's city attorney issued a stern warning that pot puffing in public would not be tolerated and that violators faced citations carrying $100 fines.

But the local prosecutor's admonition was contradicted by the Seattle Police Department's own instructions to its officers to limit their enforcement actions to warnings, at least for the time being.

Passed by voters last month as a ballot measure called Initiative 502, the new marijuana law removes criminal sanctions for anyone 21 or older possessing 1 ounce (28.5 grams) or less of pot for personal recreational use.

It also legalizes possession of up to 16 ounces (0.45 kg) of solid cannabis-infused goods - like brownies or cookies - and up to 72 ounces (2.4 kg) of weed in liquid form.

However, driving under the influence of cannabis, or imbibing in public places, where the consumption of alcohol already is banned, remains illegal.

"If you're smoking in plain public view, you're subject to a ticket," Seattle City Attorney Pete Holmes said at a news conference Wednesday. "Initiative 502 uses the alcohol model. If drinking in public is disallowed, so is smoking marijuana in public."

The new law ultimately will permit cannabis to be legally sold and taxed at state-licensed stores in a system to be modeled after those in many states for alcohol sales. The state Liquor Control Board, along with agriculture and public health officials, have until December 1, 2013, to set up such a system.

But for now, it remains a crime to sell, cultivate or even share one's own stash, even though the law allows individuals to purchase a limited amount for personal possession.

'VICTORY FOR HEMP'

Little if any of the law's fine points seemed to matter to the mellow and largely middle-aged gathering of about 100 people near the foot of the Space Needle as the statute took effect at midnight.

Low-key cries of "Yeah!" and "Smoke some weed" and "Anybody got a bong?" rose after a Portland, Oregon, radio personality, "Radical" Russ Belville, finished a 10-second countdown on a bullhorn.

Mike Momany, 61, wearing a black "Bad Pig" brand motorcycle jacket, said he was forming the Washington State Cannabis Tourism Association to promote pot tourism. Although he has smoked grass for 40 years, Momany said he had slowed his intake "because it makes me eat too much."

Another smoker, wearing sunglasses and calling himself "Professor Gizmo," 50, said: "Victory for hemp. If our forefathers could see us now."

No police were visible as the aroma of cannabis wafted through the air and recorded Bob Marley music blared from loudspeakers.

Appeals to keep pot smoke indoors were expected to go unheeded again at a larger celebration by marijuana advocates planned for Thursday evening at the Space Needle.

The laid-back, hands-off directive of the Seattle Police Department was publicized on its own "SPD Blotter" website on Wednesday, accompanied by a picture of actor Jeff Bridges as the bearded, dope-smoking slacker character "The Dude" from the Coen brothers' comedy film "The Big Lebowski."

THE DUDE ABIDES

Borrowing a catch phrase from the film to make its own light-hearted public appeal to keep pot-smoking private, the department's notice carried the caption: "The Dude abides, and says, 'take it inside!"

While asserting that public marijuana use is expressly prohibited under Initiative 502, the police department said officers lack clear enforcement authority under current laws, adding it would take at least 30 days for legislation to be crafted enabling officers to cite violators.

"In the meantime, in keeping with the spirit of I-502, the department's going to give you a generous grace period to help you adjust to this brave, new, and maybe kinda' stoned world we live in," the department's online message says.

Prosecutors in several counties announced last month they were dismissing scores of misdemeanor marijuana possession cases following voter passage Initiative 502.

Whether public or private, cannabis use contradicts federal law, which classifies marijuana as an illegal narcotic.

In a statement issued on Wednesday, U.S. Attorney Jenny Durkan in Seattle reiterated the U.S. Justice Department position that growing, selling or possessing any amount of marijuana remained a federal crime, regardless of any changes in state law.

Colorado voters approved their own ballot measure in November similar to Washington's, although it goes further by allowing individuals to grow small amounts for themselves. The effective date for Colorado's law is January 5. Both states are among 18 that already have removed criminal sanctions for medical use of marijuana.

Washington's Initiative 502 also sets a new standard for marijuana impairment while driving, similar to the blood-alcohol standard for drunken driving, and those provisions were to be enforced starting on Thursday.