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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: 02/18/2004 12:37 PM
 

Good Afternoon Philadelphia!   

    I'm glad to announce that these discussions will continue until at least the end of February (it's a short month)! 
    I have the necessary server space (especially with missed days!).  

In short: The low sliding up the east coast stayed further east than expected and didn't hit Philadelphia as hard as expected.  What a break!  Our next storm moves in at the start of the weekend, with rain. 

In the Long: You can see the surface low to our east out to sea kicking up some good rain and snows around it, but not for us. All's quite on the western front.  

The visible satellite view shows the bright white clouds all off the cosat and some bare ocean visible.  Over Pennsylvania, we have some old snows (and new snows) visible in the higher terrain to our west, but not much even close to Philadelphia. And with north winds blowing with 43F air, the snow flurries that fell are gone now. 

We've warmed up enough for the infrared satellite view to be more than just a green color.  Remember, this view shows color coded temperatures over the region with reds being warm (usually warm ground or ocean) and greens to blues being very cold higher altitude clouds.  We have been so cold this winter that the ground was at the temperature the green colored clouds are now.  Hurray for warm temperatures!

The 500mb map (which is the flow aloft at about 18,000 feet above sea level with winds traveling west to east over the continent parallel to the dark black lines and tends to 'steer' surface storm features) shows the ridge that is kicking the Low away from us and the broad ridge over the central US that is responsible for so much nice warm quiet weather.

Thursday morning the low out east pulls to the northeast further away.  A mostly dry front slides down the Plains brining a small shot of cooler air into the Central US, not much changes here. 

By Thursday night, that front is hard to pick out and a new system is forming over the Colorado, Kansas, New Mexico, Texas, Oklahoma region.  We continue with moderate north winds as our most recent Low keeps moving away. 

By Friday morning, the low in the Oklahoma region heads eastward on the right side of the trough you can see in the 500mb map below for Friday morning.  Here comes our next shot of rain!

Saturday morning, 7am, the trough is further east and the Southern Plains low is brining us rain with snow a state north of Philadelphia. 

Just for fun, here is a glimpse DEEP into the future. Tuesday night next week shows the northern US a bit cooler than normal with the jet stream doing something new... it is racing across the southern tier of states.  What interesting weather will come of this new look to the atmosphere's flow?  We'll watch it as time goes on... 

I'll return tomorrow- Thursday.. see ya then! 

Meteorologist  John Ensworth

Surface Station sky cover color key: