No more jokes about guess who's not coming to the cherry blossom festival: In pinkish regal splendor, the buds of 5,000 Yoshino trees peaked in full bloom yesterday, lining the Tidal Basin and East and West Potomac Park with wafting blossomy lace that drew the largest crowd of nature-loving onlookers Park Police say they've ever seen on a single day.

Park Service officials estimated the crowd size shortly after noon at 100,000 picnicking, Frisbee-throwing, kite-flying, nature-hiking people, not to mention the hundreds of office workers who took a little extra lunch-hour time to lose themselves in 85-degree temperatures and tree clouds of blossoms.

But numbers don't tell the story of bumper-to-bumper traffic snarls 2 1/2 miles long down Ohio Drive, from the Lincoln Memorial past the Jefferson Memorial to 14th Street NW.At times, it took 40 minutes to go two blocks between Constitution Avenue and Ohio Drive. Cars stalled, some of them out of gas, ad an influx of visitors for the week-long festival helped jam downtown Washington streets. Weekend traffic is expected to be even worse, and police have asked the public to use public transportation whenever possible.

Touch-and-go, a fifty-fifty chance -- these were phrases used by those who predict whether the blossoms will arrive in time for the festival. James Lindsay, chief horticulturalist for the National Park Service here changed his predictions with the changing weather. In the end, though, he said we can all thank the weather for this year's timely cherry blossom arrival.

"People start in January asking me when the cherry blossoms are going to bloom," said Lindsay, who noted his 95 percent accuracy. "But the calls increased Feb. 14, the start of a string of days of good warm weather, eight or nine days of 60 degrees and higher. The trees need cold fall and winter temperatures and a number of days of weather in the 60s before the blossoms will appear.

"It's like when you're wearing winter clothes all winter long, you're not going to take them off until you're sure it's going to be warm, a time when the guys wear T-shirts and the girls scanty things," Lindsay said. "On Feb. 18, the temperature hit 73 degrees."

That was when Lindsay predicted the trees would be in full bloom as early as March 20. Weather forecasters said all but six days in February were above normal in temperature highs. On Feb. 25, a few days after Lindsay's early prediction, the temperature dipped into the low 40s and 50s and stayed there until March 25, Lindsay said, putting the blossoms "on hold, like putting them into the refrigerator." Thereafter, the temperature rose to the 60s and has been rising incrementally ever since.

Yesterday was a near record temperature day; the high of 85 degrees recorded at 3 p.m. was just two degrees short of the record set in 1963. Forecasters with the National Weather Service predicted cooler temperatures in the low 80s for today and Sunday, the result of a stormy weather system advancing into the area and bringing intermittent showers and thundershowers. The rain will be good news for gardeners but could be disastrous for the Yoshino cherry blossoms, which, in the absence of driving wind or heavy rain, were expected to last until the middle of next week.