Heat still in retreat

Lasting only three days each, the two “heat waves” this season in Philadelphia barely met the government’s technical definition of three consecutive days with an official high of 90 or better.

A puff of heat is due to return the next couple of days, but this one isn’t even going to clear the minimum threshold for a heat wave.

But for Thursday, Friday, and Saturday the forecasts call for temperatures stunningly comfortable for late July in Philadelphia, with no serious heat on the horizon.

The 6- to 10-day outlook issued this afternoon by the government’s Climate Prediction Center sees the odds favoring below-normal temperatures around here.

The 8- to 14-day outlook, which would cover the period through Aug. 4, is similar.

Once again, an upper-air trough, which favors cooler air, is due to prevail in the East. The government forecasters sound fairly certain of it the scenario, giving the 6- to 10-day forecast a 5 out of 5 on the confidence scale.

Meanwhile, the Commodity Weather Group, in Washington, issued the first winter outlook we’ve seen, and it calls for below-normal temperatures in much of the nation, including the Midatlantic region.

The company, which provides forecasts to energy and agricultural interests, is looking for developments in the Pacific to drive the winter.

In its weekly update, the climate center says it still is calling for an 80 percent chance of an El Nino – an anomalous warming in the tropical Pacific – to take hold in the fall.

Sea-surface temperatures in the key El Nino zone remain above normal, but are shy of El Nino conditions.

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