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Meteorology (Weather)/Philadelphia and Thunderstorms


Hello Donald,
I've lived in South Philadelphia for 23 years.  I do know the weather and how it works.  Something is puzzling to me.  Not always, but most of the time, Thunderstorms that approach the city of Philadelphia, especially South Philadelphia, seem to fall apart as they get right over the city.  I was under the impression that cities had a heat island effect that actually “created” thunderstorms?  If this were true, wouldn’t storms actually intensify as they meet the hotter air that is associated with urban/concrete areas?
In the last 23 years of living here, I can recall only two or three times that have formed thunderstorms directly overhead and then proceeded to move into New Jersey.  The hills west of the city do tend to produce much more activity.  I have also seen storms approach from the western suburbs of Philly, fall apart as they get over the city and then rebuild as they get east of the city.  It’s as though the city and the dry heat is dissipating the storms.   Is it me or is this observation correct?  Sorry for being long-winded.  Thank you.  Russell

Hi Russell

You're correct that "heat islands" can add to differential up-flow of air which help create/enhance thunderstorms.

In the situation of Philadelphia, the ocean is about 40 miles to the east and ocean sea-breezes typically act as a stabilizer to the atmosphere thus creating a diminishment to thunderstorms favorable environment.  

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Donald Rosenfeld


Any questions (except private) answered from the 1st grade level on up pertaining to any aspect of Weather. I am a 20 year member of the American Meteorological society and a long time forecaster of eastern United States snow storms and Hurricanes.

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