It really is going to rain in Philly Wednesday night, forecasters say, and snowflakes are even possible Friday

What may well become the region’s heftiest rainfall in over three months is a virtual certainty Wednesday night into Thursday, forecasters are saying.

As you likely will be hearing again during the next several weeks, it won’t come close to washing out rain deficits and drought anxieties, but the atmosphere is hinting that it may be ready to behave very differently.

It’s even possible that accumulating snow falls upon the parched Poconos, and some areas north and west of the city could see wet snowflakes on Friday.

“A pattern change is definitely on the way,” said Joe DeSilva, a meteorologist with the National Weather Service office in Mount Holly.

In its Tuesday outlook, the National Oceanic and Atmospheric Administration’s Climate Prediction Center had the odds favoring above-normal precipitation in the East for the Nov. 27-to-Dec. 3 period, referencing changes in the upper-air flow that favor moisture from the Gulf of Mexico to stream northward.

In ordinary times, that’s a question reserved for snow, but after having broken a 150-year-old record for consecutive days without measurable rain during what is likely to be a record-dry fall, ordinary rain has become extraordinary.

The forecasts are calling for 0.5 to 0.8 inches of rain, with up to an inch just to the north of Philadelphia, beginning late Wednesday night into Thursday morning.

“We’re getting excited about a half inch to an inch,” said Dave Dombek, senior meteorologist with AccuWeather Inc. “In a normal situation, this would a yawner.”

Since Aug. 18, Philadelphia has received 0.88 inches of rain, according to NOAA’s Middle Atlantic River Forecast Center, which uses a sampling of county stations. That’s about 11 inches below long-term averages, or 7% of normal.

The figures for the surrounding counties are pathetically similar. The interagency U.S. Drought Monitor has the entire region in “severe drought” and parts of southeastern New Jersey in “extreme drought.”

Both New Jersey and Pennsylvania have posted drought advisories.

The weather service is calling for up to 4 inches of snow to fall upon the Poconos, with the potential for more from the potent storm due to settle across the Northeast and Mid-Atlantic.

The storm will generate wintry northwest and west winds Thursday and Friday, perhaps gusting to 40 mph, with temperatures in the region no higher than the mid-40s Friday. Rain and snow showers are possible north and west of the city, the weather service says, but accumulating snow is not expected.

“It’s not like we’re flipping into a wet pattern,” said Dombek, but the colder weather is sharpening the temperature contrasts that energize the storm-moving winds.

”It’s finally happening,” he said. “We’re not just talking drought, drought, drought. We’re actually talking about some other stuff going on.”