BEECH 1900 ATX CLRED TO RWY 14 VIA TXWY G. BLOWING SNOW AND SNOW PLOWING IN PROGRESS RESTRICTING VISIBILITY. MISSED THE TURN ON TXWY G AND ENDED NEAR RWY 14. TWR REQUESTED 180 DEGS AND WAS ABLE TO CLR RWY PRIOR TO INTERFERING WITH ACFT ON 4 MI FINAL.

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NIGHT WX; VISIBILITY 1 1/4 MI IN SNOW; MIST WITH WINDS RPTED AT 090 DEGS/08 KTS. SNOW PLOWING WAS IN PROGRESS AND ACFT WAS RUNNING 30 MINS BEHIND SCHEDULE. THE ITHACA RAMP WAS EXITED AT TXWY G VIA TXWY C ENRTE TO RWY 14. AT THE TXWYS G AND C INTXN WAS A SNOWPLOW S OF THAT INTXN WITH LIGHTS ON FACING N. AFTER BEING ALERTED BY THE TWR THE SNOWPLOW WAS NOTED BY THE CREW TO BE STATIONARY AND A WIDE L TURN WAS INITIATED. THIS WIDE TURN RESULTED IN MY BEING UNKNOWINGLY ALIGNED WITH TXWY C WHICH IS ALMOST IMMEDIATE ACCESS TO RWY 14. WITH THE REDUCED VISIBILITY IN BLOWING SNOW AND THE 2 INCHES OF UNPLOWED SNOW OBSCURING THE TAXI LINES; I DID NOT REALIZE I WAS ON TXWY C UNTIL SEEING THE HOLD SHORT AND RWY LIGHTING. I WAS THEN ABEAM THE HOLD SHORT WHEN TWR CALLED ADVISING I WAS ENTERING RWY 14. A 180 DEG TURN WAS EXECUTED TO CLR THE RWY INTXN. AN ACFT WAS ON THE VOR APCH TO RWY 14 AT APPROX 4 MI. THAT ACFT LANDED WITHOUT DEV AFTER I HAD EXITED AT TXWY C AND WAS NBOUND ON TXWY A; THE ORIGINALLY INTENDED TAXI RTE. CORRECTIVE ACTIONS: 1) RATHER THAN TAXI DURING REDUCED VISIBILITY WITH HEADING (EFIS) DISPLAY IN WIDE SECTOR; GO TO HSI PRESENTATION FOR ORIENTATION. 2) DELAY CHKLIST ACCOMPLISHMENT UNTIL MANEUVERING IS COMPLETE AND ORIENTATION DURING REDUCED VISIBILITY IS CERTAIN. 3) FOR TWR PERSONNEL; WHEN ACFT ARE OBSERVED IN CRITICAL AREAS AND HEADED THE WRONG DIRECTION; A 'STOP TAXI' BE ISSUED OR CREW ALERTED PRIOR TO ALLOWING THE CREW TO CROSS A 'HOLD SHORT' OR APCH RWY ENTRY. SUPPLEMENTAL INFO FROM ACN 360834: RECOMMENDATION: UNDER LOW VISUAL CONDITIONS; CONFIGURE HEADING SYS TO HSI TO ASSIST IN ORIENTATION AND HOLD CHKLIST ACCOMPLISHMENT UNTIL ESTABLISHED ON KNOWN (VISIBLE) TXWY ROUTING. NOTE: I FELT THE TWR COULD HAVE BEEN MUCH MORE AGGRESSIVE IN HELPING TO PROVIDE DIRECTION UNDER THESE TYPES OF CONDITIONS.