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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: 09/20/2003 09:00 AM
Good Morning Philadelphia!
After all that craziness with Isabel, and with a front passing at present, things are going to be nice and quiet. The next chance of rain comes Monday (and you can handle a bit of rain - no?)- so I'll talk about that on Monday...
Let's look at the totals/normals for Philadelphia:
Our normal high is 76 and low is 60. So, with the hint of a ridge overhead and copious amounts of water around--- we are staying warmer than one would expect.
We also are only about an inch above normal for the month (Isabel missed us as far as flooding rains go). And for the year we are about 3 inches above normal. BUT we are 12" above last year's total to this point. That may be why it feels so wet.
Philadelphia, Pennsylvania (KPHL)
| Actual | Normal | Record | Last year | |
|---|---|---|---|---|
| Today | ||||
| High temperature | -- | 76° | 90° (1983) | -- |
| Low temperature | -- | 60° | 45° (1956) | -- |
| Yesterday | ||||
| High temperature | 82° | 77° | 92° (1983) | 81° |
| Low temperature | 67° | 61° | 43° (1959) | 62° |
| Precipitation | 0.35 " | 0.13 " | 1.95 " ( 1938 ) | 0.00 " |
| Month-to-date precip. | 3.65 " | 2.54 " | -- | 1.48 " |
| Year-to-date precip. | 34.40 " | 31.49 " | -- | 22.55 " |
The next front is stalling in our vicinity (so we'll have a chance of clouds through the weekend.
You can see these clouds stretched overhead giving us an interesting sky this morning.
The radar is absolutely clear and quiet.
And the winds are dying down to near nothing over Philadelphia. You can still see the circulation around the remains of Isabel at the top of the picture in Canada.
The 500mb map (the winds at 18,000 feet) show a very broad trough across the US (or a zonal --> which means straight west to east flow <-- flow between a west coast ridge and an east coast ridge). This will keep the nation cool and push a new front quickly towards in a couple of days.
So today is clear and calm.
The next front is organizing in the Plains Sunday and beginning it's march eastward.
The rains ahead of the front is almost on our doorstep Monday...
Then it too pulls north (like the last front) but leaves us with a chance of some rain.
Once the east coast ridge breaks down a bit, we'll see fall return. For now, enjoy this nice (if a bit warm) weather.
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. |
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