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The Story Behind the Weather - By Forecaster John Ensworth M.S. - 

The Discussion of Weather Events Daily for Philadelphia and Pennsylvania

 Last updated: 09/14/2003 02:32 PM

Good morning again!  Well, the much advertised changes are on their way!  Did you finally begin to get a bit tired of the heat/haze/and humidity?  Here comes a break from the heat and haze part! 

This morning, we have very light showers and very isolated thunderstorms way out west with nothing nearby Philadelphia at present. 

The heat is still quite amazing... we have mid 80's air temperatures by 10am already!!  Yikes.  But if you look out west, you see temperatures (in red, upper left on each station) only in the 60's and 70's.  Bring it on.  [the key to station code sky conditions can be found at the very bottom of this page]. 

The heat advisories we've lived under all week and through the 4th weekend has been canceled, and with wind speeds picking up as the next system approaches, we have no pollution alerts today.  The extreme heat has been broken by the cloud cover you can see on the visible satellite picture below.  Other than a brief break just to our west, the thickening clouds are what we will see over the next day. 

At present, the cold front is draped just through the northern counties and will kick off some showers as it moves through the very moist air (see the 70's (green) dew points on the surface observation map up above).  But the real big player is that low forming and deepening over Nebraska. 

Over the next day and a half, that low will begin to approach us.  The front will stall just to our south and the green arrows (on the water vapor satellite picture below) show the ample flow of tropical moisture roaring up from the equator into the east. The red circled area of extreme high moisture, uplifting air and high cold clouds is the big wave in the atmosphere that is making the low in Nebraska deepen. 

So, once again, here is your meteorological future!  By 2pm today, we'll have the front stalling just to our south with showers possible much of the day across the entire state. 

By 2am Thursday, we see the atmosphere briefly calming down, but the low is on the move in our direction and is over NE Iowa gathering strength. 

By 8am Thursday, it is pulling in more moisture and becoming a very mature storm system with a warm front again approaching us from the SW and a big cold front sweeping unusually far south towards Texas and Oklahoma. 

Then the warm front, low pressure rain spreads across the state by Thursday evening 8pm. 

One more distant concern that will be fun to watch will be Tropical Storm (or soon Hurricane?) Claudette that you can see at the very bottom of the last map (below the blue H - high pressure center in the Gulf of Mexico).   It could make a US landfall and the moisture may arc to the northeast (like Bill) towards us by the start of middle of next week.  There just isn't anything boring about the weather; is there?!

Meteorologist  John Ensworth

Surface Station sky cover color key: