Outside of Center City, the freezing rain has left a white patent-leather sheen on what is still a substantial snow cover.

But if winter wonderland suits your taste, savor it. It's about to vanish.

At 10 a.m. the official temperature at Philadelphia International Airport climbed to 34, and it is not expected to visit freezing again until sometime Saturday afternoon, around kickoff time for the Eagles and Falcons.

On Thursday morning, in perhaps a more significant development, the dewpoint — that's the temperature at which water vapor condenses; think beads of water on a cold can of Coke on a hot summer afternoon — is due to nudge above freezing.

The dewpoint is due to rise into the 40s during Thursday afternoon, and that will go to town on the snowpack. It will have a much bigger impact on it than the 1 to 2 inches of rain expected late Thursday  into Saturday

When the warmer air comes in contact with the snow and ice, it condenses. When it does, as snow-melt expert Nolan Doesken has explained, the change of state gives up latent heat that melts the snow faster.

Doesken was the longtime state climatologist in Colorado, where the air tends to be way drier, the dewpoints lower, and the melting slower.

In Steamboat Springs, Colo., where the snowpack is deep and dewpoints low, gray jays are known to eat out the hands of skiers.
Annelise Gambardello
In Steamboat Springs, Colo., where the snowpack is deep and dewpoints low, gray jays are known to eat out the hands of skiers.

Here in the East, the air tends to be juicier.

By the time the rain starts around here on Thursday, it could well be falling on bare ground as the snow disappears.

"I would think that most of it will be gone," said Valerie Meola, meteorologist at the National Weather Service in Mount Holly.

The combination of melted snow and heavy rain likely will yield a harvest of mud.

Right now, no flood watches are up; the water content of that snow isn't all that impressive. But Meola said that given the icing on area waterways, some ice-jamming is possible.

What will be a prequel thaw will end later Saturday as a potent cold front plows through.

In its wake, strong winds from the northwest will slice across Lincoln Financial Field during the Eagles-Falcons playoff game.

After a cold start to next week, a real, live thaw will get underway, the government's Climate Prediction Center says the rest of the month should be mild.