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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: 10/16/2003 04:18 PM
Good Afternoon Philadelphia!
I'm glad to announce that these discussions will continue until at least the end of October.
The wind is still blowing pretty briskly out there, but with air sinking down from higher elevations out west, it is warming slightly keeping it from being really cold. The front is becoming stationary over the region as most of it's punch is heading off to the northeast into eastern Canada.
The Infrared view shows a band of clouds along and ahead of the front. The coldest air is up in Canada still.
You can see that cooler air up north(the boundary is quite evident with oranges (60's/70's) south of the front and 40's/50's up north.
Winds are still out of the west (but a bit weaker than yesterday).
At the moment, the thickest clouds are out west and north of the city. We have broken cumulus overhead right now.
We are on the right side of the GIANT ridge (hill-like flow of air moving north then south) over the western 2/3rds of the country. You expect non-stormy weather on the right side of a ridge (and storms on the right side of a trough, a southward dip in the flow at this level - which is about 18,000feet above sea level). The winds are moving parallel to the black lines from west to east across the country.
Rapidly (by Friday morning!) a NEW trough forms over the lakes reinvigorating our front and giving us a chance of rain tomorrow.
The GFS model shows the precipitation along the front intensifying at that time on the map below.
Our next chance of rain is next week. We shouldn't see any bad weather until next week (when a punch of cold air slams in).
More details tomorrow morning!
And I'll see you tomorrow morning!
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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