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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 02:39 PM
 

Good Evening Philadelphia!   

    Here's a late brief update, but there isn't much to say except here comes the remains of Henri as predicted for more than a week in this set of discussions. 

The radar to our south shows showers off the coast. The immediate story is the remains of Henri, and there it is. 

We have high cirrus streaming in a band over us (just like you'd expect from a tropical system) as the moisture begins to pull to the north/northwest. 

The surface map shows the low as an extended double lobed low (there are two centers marked as two L's). The northern one will dominate and swing to the northwest towards us. 

As this approaches, the counterclockwise flow around the lows brings onshore flow to or coasts and increases coastal erosion (see the red circled area for the places where the onshore winds will increase over the next 48 hours). 

To see where the Low(s) will go, we can look at the 500mb map (the upper level winds at about 18,000 feet) and you can see a small upside down trough marked with an "X".  This is the direction the low will want to go.  It is ON OUR HEADS in Philadelphia. 

Friday at 8am we have the rain and low still to our south, but winds will increase out of the east in Philadelphia and clouds will begin to thicken. 

By Saturday AM, we have rain and storms spreading in as the Low (remains of Henri) finally arrive. 

Sunday 8am, and the rain begins to taper off as the low moves north and the heaviest rains stay on the east side of the low center. 

After that, the front from the Great Plains will begin to approach bringing the continued chance of rain into the start of next week. 

Even further out is Hurricane Isabel that is now a Cat 5 (maximum on the 1-5 scale) hurricane heading toward the eastern US. 

It is projected to hit (most probably) the Carolinas (but anywhere from the Gulf to Maine is under the gun still).  Eventually it's moisture will pour over Philadelphia - if it hits straight on (not too likely), hits somewhere else on the coast to the south (and then curves northeast to us) or if it hits in the Gulf of Mexico and recurves towards across the eastern US.  We will PROBABLY see water from it by the end of next week. 

Stay tuned!

We'll keep an eye on all this together!  Until tomorrow... enjoy the dryth.  (I know it's not a word.)

Meteorologist  John Ensworth

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