As history, weather is prone to a certain degree of pattern repitition. But, as history, weather never replicates itself.
The chances of a repeat of the damage from Thursday's storms, which took out power to 350,000 customers in southeastern Pennsylvania and South Jersey, are remote.
That said, the National Weather Service has posted a severe-thunderstorm watch, in effect until 8 p.m. Some are starting pop up already in North Jersey, Maryland and Virginia.
As noted in Peter Mucha's online story, the atmosphere would be hard-pressed to duplicate Thursday's conditions, which produced the third-strongest wind gust in Philadelphia history -- 75 m.p.h.
No. 1 on that list, by the way, is 94 m.p.h., which occurred during Hurricane Hazel in 1954, one of the nation's superstar tropical storms and one blamed for 369,511 outages just in the PECO service territory.
A few conditions today are similar to Thursday's. It is quite hot. Already the official temperature has reached 95; on Thursday, it was 97.
Once again, however, some drier air is keeping down the heat index, which stood at 97 at 1 p.m. Meteorologists suspect that dry air gave the Thursday storms a jump start.
Some of the rain falling into the the dry air set off mass evaporation, which has a cooling effect and would have given an extra kick to the winds.
Once the storms are gone, it should turn quite comfortable by tomorrow afternoon, and that comfort is due to last through Thursday.
But right now it looks as though another heat wave is on the horizon for the holiday weekend.