Back To Home
The Story Behind the Weather - By Forecaster John
Ensworth M.S. -
The Discussion of Weather Events Daily for Philadelphia and Pennsylvania
Last updated: 04/07/2004 09:36 AM
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: Clearer skies, but cooler air filtering in ahead of the next round of precipitation.
In long: The 500mb map, showing winds blowing mainly west to east parallel to the black lines across the nation at about 18,000 feet above sea level, shows the trough we had hanging tough over the region for the last week, finally moving off. There are small ripples in the flow out over Oklahoma and Arizona, and another trough in central Canada. All these will make a mish-mash of weather for us over the next few days.
Currently, though, there are no system directly hitting Philadelphia. The closest low in western New York and it's cold front IS heading towards us.
The cloudiness is spotty except up with the low and front. (This visible satellite view shows bright, reflective surfaces as white and dark, absorptive surfaces as dark).
the Infrared View shows the cooler air (in yellows) up with the front and Low and the very warm Gulf Stream flow (darker red marked by blue arrows) flowing down to our southeast. Neat? No?
So as those ripples in the upper air flow head our way, the front to our north slides just to the south of the state and starts to stall out. The low in Tennessee and in the Great Lakes bear watching...
Because you can see that precipitation is building and moving east and north towards us by Thursday morning.
They combine to make more rain for us by Thursday night.
As that front comes down, it brings some polar air with it. Today's highs are in the very mild mid 60's F today...
But drop to the upper 50's F for Thursday.
Look for a cold rain to return Thursday afternoon/night. Sorry, but look at how GREEN all the plants will be this spring!
I'll see you again Thursday.
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. |
|||