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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 02:38 PM
Good Morning Philadelphia!
The server this page resides on continues to be down today... so no one will be able to see it live either. I'll, again, quickly recap what is happening, and wait for the big diagnosis to return when the power is back on!
The front is still to our west and is now labeled as a stationary front. It's motion will be very slow over the next day or so. The heaviest moisture/rainfall is off the coast to our east, but showers should redevelop around here (Philadelphia) once daytime heating takes hold.
Clouds are still quite thick over the state this morning. The increased cloudiness could inhibit heating of the ground, and that would decrease the coverage and severity of the thunderstorms we could get.
The radar image shows much less rainfall this morning, but some sites have approached the 12" mark. Just in the last 12 hours, Columbia NJ has received 3.90", Lincoln Park NJ 2.14 inches and Leavitt Falls PA 1.89 inches. This is a very wet pattern again!
Temperatures behind the front (over Ohio and W. Virginia) are cooler by about 10 degrees than they are where we sit ahead of the front.
Winds are lighter but still out of the south west and south east over the state.
The upper air map (the winds blow west to east (primarily) parallel to the black lines) showing winds at 18,000 feet or so, shows the big trough still in the eastern 1/3rd of the US (marked in red). Smaller short waves (marked in blue) are rotating around it. As the smaller waves rotate around, they can kick off showers and thunderstorms. There are PLENTY of them to do so.
The Jet stream (colored in blue) follows this large trough pattern. We have strong north winds over Indiana and south winds over us through much of the upper atmosphere.
With this pattern in place, we will continue to have a chance of showers as long as the trough sits to our west...
Tuesday? Still showery, even if the rain becomes more widely scattered (only chance rain amounts, not huge swaths of heavy rain).
By Friday morning, the upper air map shows the trough hasn't really changed much...so...
The possibility of rain remains in the forecast.
And on into Saturday...
Monday morning and the trough, though a bit more on top of us, is still pretty much in place.
So the rain and chances of rain will stay with us. Sorry. At least this is keeping the August heat at bay!
Hopefully the servers will be working on Tuesday and I'll be able to post live again.
Until then, keep looking up and stay dry!
Meteorologist John Ensworth
Surface Station sky cover color key:
Flight category definitions:| Category | Ceiling | Visibility | |
|---|---|---|---|
| Low Instrument Flight Rules LIFR* (magenta circle) |
below 500 feet AGL | and/or | less than 1 mile |
| Instrument Flight Rules IFR (red circle) |
500 to below 1,000 feet AGL | and/or | 1 mile to less than 3 miles |
| Marginal Visual Flight Rules MVFR (blue circle) |
1,000 to 3,000 feet AGL | and/or | 3 to 5 miles |
| Visual Flight Rules VFR+ (green circle) |
greater than 3,000 feet AGL | and | greater than 5 miles |
| *By definition, IFR is ceiling less than 1,000 feet
AGL and/or visibility less than 3 miles while LIFR
is a sub-category of IFR. +By definition, VFR is ceiling greater than or equal to 1,000 feet AGL and visibility greater than or equal to 3 miles while MVFR is a sub-category of VFR. |
|||