The Philly weather might be a turkey on Thanksgiving, and then expect a major chill

After an all-time dry spell, the region should have reason to be thankful that more rain is in the forecast this week.

But does it have to happen on Thanksgiving?

On the brighter side, Wednesday, traditionally one of the busiest travel days of the year, should be ideal for those planning to leave town.

Unfortunately, computer models are indicating strongly that nature is going to serve up a turkey for Thursday with a chilly, soaking rain throughout the region, and perhaps some snow mixed in as nearby as the Lehigh Valley.

“It looks like a damp Thanksgiving,” said AccuWeather meteorologist Matt Greene. And it appears it might rain on the parade: The morning weather, he said, is “not looking great.”

It’s not a done deal. The system that is expected to cause the rain was not expected to make landfall on the West Coast until Monday or Tuesday, when it would be in sight of ground-based instruments that, theoretically at least, would improve forecasts as the storm moved across the country.

Forecasters are more confident that in the aftermath of the storm, the coldest weather of the season is likely to send low temperatures into the 20s later in the weekend or early next week — even at freeze-resistant Philadelphia International Airport, which hosts the official thermometer and rain gauge.

“It will be January-like,” said Alex Staarmann, a meteorologist in the National Weather Service’s Mount Holly office.

Droughts have tended not to end precipitously, and it is likely going to take a while to recharge the groundwater and fill the reservoirs this time also.

A horrific drought that began in May 1964 that was followed by a bone-dry July and August — months when humans and vegetation are thirsty and swimming pools need filling — continued through 1965. Both years were among the driest ever in Philly in records dating to 1872.

But last week the winds of seasonal change were evident as upper-air patterns altered dramatically, Staarmann said.

After the first rainless October ever, it was just a week ago that Philly appeared poised to break a record for the driest meteorological autumn — Sept. 1 through Nov. 30 — now held by the fall of 1922, when 2.37 inches was measured officially.

However, after four consecutive calendar days of rain — which hadn’t happened since August — the total since Sept. 1 bumped up to 2.20 inches. That’s not the stuff of floods: Through Friday, Philly’s rain total was less than a fifth of what it should be normally, according to the National Oceanic and Atmospheric Administration’s Middle Atlantic River Forecast Center.

The interagency U.S. Drought Monitor has the immediate Philly area and all of South Jersey in “extreme drought” conditions. The Delaware River Basin Commission said last week that Delaware River levels were down 60%.

Drought advisories are in effect in both Pennsylvania and New Jersey.

Don’t expect them to go away, no matter how much rain falls on Thanksgiving.

NOAA’s Climate Prediction Center has an 80% to 90% likelihood of below-normal temperatures the first week in December.

But it also has the odds favoring below-normal precipitation.