CL65 TAXIING FOR DEP AT BWI CROSSED RWY HOLD LINE.

Narrative

AFTER GIVEN TAXI INSTRUCTIONS FROM THE GATE TO THE DEP RWY AT BWI; I CONFIRMED THE TAXI RTE WITH THE CAPT. AT THAT POINT THE CAPT CALLED FOR THE TAXI CHKLIST. WHILE I WAS PERFORMING THE CHKLIST WE MADE A WRONG TURN ON THE TXWY AND THE NOSE OF THE ACFT WAS ACCIDENTALLY TAXIED ACROSS THE HOLD SHORT LINE OF A RWY. THE ACFT WAS IMMEDIATELY STOPPED; WITH THE NOSE PROTRUDING ACROSS THE HOLD SHORT LINE. CORRECTIVE INSTRUCTIONS FROM GND CTL WERE GIVEN AND IMMEDIATELY FOLLOWED. NO ACFT CONFLICTS OCCURRED. THERE WERE MANY CONTRIBUTING FACTORS TO THE EVENT. FIRST; WE WERE WORKING THE LAST LEG OF A CONTINUOUS DUTY TRIP WITH A LIMITED AMOUNT OF REST IN A HOTEL. SECOND; THE FACT THAT WE WERE RUNNING CHKLISTS DURING ACFT MOVEMENT ALSO CONTRIBUTED. THIRD; BALTIMORE; MD; JUST HAD A SEVERE SNOW STORM AND THE RWY AND TXWY SIGNS WERE OBSTRUCTED WITH SNOW AND ICE. TO PREVENT ALL OCCURRENCES SUCH AS THIS ONE; MANY FACTORS MUST BE CONSIDERED. I FEEL THAT CREW FATIGUE; CHKLIST USAGE DURING ACFT MOVEMENT; AND ARPT MARKINGS AND SIGNS ARE GOOD PLACES TO START.