Issued when severe weather is likely to occur. Stay tuned to NOAA Weather Radio, commercial radio or television for information.
Issued when severe weather has been reported by spotters or indicated by radar. Warnings indicate imminent danger to life and property to those in the path of the storm.
Why are some weather reports for western Chester County different from eastern Chester County?
From National Weather Service, Mt Holly, NJ Weather Field Office:
The climatology in western Chester County is quite different compared to the eastern part of the county, which means the weather can be a lot different too. For instance, during the winter months, the western portions of the county can receive a lot more snow than the eastern sections. When this situation arises, we can now issue a warning just for the western portion of the county if we think snow will be heavier there than in the east. This holds true for other types of hazardous weather as well, such as excessive heat, where the more urban areas in the eastern section of the county experience higher temperatures than in the west Population density also plays a role because the effects of hazardous weather become more problematic as the number of people affected increases.