* WHAT...Heat index values up to 104 expected.
* WHERE...In Maryland, Central and Eastern Allegany County. In Virginia, Augusta, Eastern Highland, and Rockingham Counties. In West Virginia, Eastern Grant, Eastern Mineral, and Eastern Pendleton Counties.
* WHEN...Until 8 PM EDT this evening.
* IMPACTS...Hot temperatures and high humidity may cause heat illnesses.
* ADDITIONAL DETAILS...Prolonged excessive heat may impact power, water, and transportation systems. Heat index values of 95 to 100 are possible again Sunday afternoon.