Here is what I found with some primary internet searches:
145.370 - 147.345 + 146.955 - 444.950 +
St. Clair, PA Delano, PA Joliett, PA Delano, PA
SARA, W3SC
Delaware County ,monitors
446.925- 173.8 & 224.220/R
www.delcoskywarn.net
In my area all Skywarn ops. are on two meter, some however are on linked systems that include other bands. Not all NWS offices have an amateur radio based skywarn program, some rely on the unlisted 800' number given to spotters and the online reporting process. The best thing to do is to search the two meter repeater band, approx. 145. to 147.5, and listen to the various repeaters that come up, it will be easy to tell which ones are running Skywarn nets and which ones are just hams ragchewing about the weather.