Strong storms and another record high are possible Wednesday in Philly

Following another run at a record high, strong thunderstorms, with gusts 60 to 70 mph, are possible late Wednesday afternoon or evening, the National Weather Service says, and an “isolated tornado” isn’t out of the question.

Storms are are expected sometime between 3 p.m. and 10 p.m., said Mike Silva, a meteorologist in the Mount Holly office, and their strength would be very much dependent on the timing and and intensity of daytime heating. Highs Wednesday are forecast to reach the mid- and upper-70s, exceeding the standing record for the date of 74 degrees.

This would happen the day after the official temperature at Philadelphia International Airport shot up surprisingly to 83 degrees, a record for the date, and the normal high for a June 15.

The National Oceanic and Atmospheric Administration’s Storm Prediction Center lists a 15% chance that storms will reach “severe” criterion — that is gusts of at least 58 mph — with a 2% chance of a tornado in the Philly region.

The severity would be closely related to the timing, said Silva’s colleague Alex Staarmann. If the storms arrive late in the day, they could get a boost from the solar heating. Late at night, things will have cooled down.

“The later it comes in, the lower the severe chances will be,” he said. “If it comes in a little earlier, we could have more problems.”

The warmth Wednesday is not expected to rival Tuesday’s. That’s assuming the forecast holds.

Tuesday’s warmth was borne on winds from the southwest that gusted to near 25 mph late in the afternoon.

The forecast whiff — the highs were supposed to have been in the mid-70s — was borne on computer hiccups that are common this time of year, said Staarmann.

“The models in the spring when we get these really warm patterns are notoriously low for temperatures,“ Staarmann said, ”so we kind of expected it would over-perform significantly."

It wouldn’t take an over-performance for a record to fall Wednesday. The forecast high would beat the standing record for a March 11 set five years ago.

The previous record for a March 10 was 82. (The differences between the old March 10 and 11 records are quirks of the 150-year-old climate record period.)

This is the third-earliest that Philadelphia has recorded an 80-degree reading: It reach 80 on March 8, 2000, and 82 on March 9, 2016.

But faux summer is about to end, possibly dramatically.

Thursday’s high is expected to be around 60 degrees, but that might happen at 12:01 a.m. Temperatures are due to fall through the day and may reach freezing early Friday.

Highs are expected to be mostly in the 50s during the weekend, but another strong front is due to crash temperatures early next week, with lows possibly in the upper 20s Tuesday morning.

This is known as March.