Heat Advisory

* WHAT...Heat index values of 100 to 104.

* WHERE...In Maryland, Extreme Western Allegany County. In West Virginia, Western Mineral County.

* WHEN...Until 8 PM EDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat illnesses.

* ADDITIONAL DETAILS...Early morning low temperatures around 70 combined with oppressive humidity will result in little to no overnight relief. Prolonged excessive heat may impact power, water, and transportation systems.