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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: 02/16/2004 07:26 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: A low slipping through the south will scoot northward up the East Coast and slip some snow into our faces Tue/Wed.
In the Long: The surface map looks VERY quiet still, but energy is gathering behind the High over our head (giving us the chilly but clear skies currently).
Combining the surface map with the infrared satellite view, you can see clouds and lift ahead of the occluded (purple) front and the warm front (red) in the center of the nation. That energy will be moving east and southeast and join up with the energy making the clouds and drizzle in the deep south states. These will come together to make a low on the coast to our south and we'll be on the northwest snowy side.
Temperatures after Sundays shot of chilly air are still below freezing with very cold air moving off to the north and east.
Looking at the predicted low temperatures tonight, the cold air is sitting in the northern US and still over New England.
Due to the recent shot of cold air we had some snow out west, but Philadelphia is still snow free.
As the back edge of this bubble of cold air moves off tonight, we'll see mid teens F tonight with below zero temperatures as close as the northern tier of counties.
By Tuesday 1pm, the low(s) begin the off the Georgia and South Carolina coast. Say bye-bye to the High leaving Maine.
So breaking it down, the low drifts north and strengthens spreading moisture into the cool/cold air over us and snow begins to fall by Tuesday night a few hours after sundown.
By 1am, the snow is getting heavier.
You can see the low moving northward by 7am Wednesday and the snow keeps coming.
Wednesday 7am drive time sees more moderate snow coming down. Drive carefully Wednesday!
I'll be back Wednesday (Tuesdays are just a bit CRAZY right now so I can't do a discussion on those days).
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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