Ground Controller described a taxiway excursion by an Air Carrier taxiing for departure; the reporting noting no taxiway braking action reports were available at the time of the incident.

Narrative

Aircraft was issued detailed taxi instructions to Runway 26L; pilot checked on with current ATIS. Weather (snow; low visibility) at time of incident was such that aircraft was barely visible from tower. Pilot called and asked if he could make a right 270 degree turn; apparently to rejoin his assigned taxi route. I approved his unusual request; as it appeared that he may have missed his turn I immediately offered alternative taxi instructions to eliminate the need for a 270 degree turn at the intersection. Pilot reported that braking action on the taxiway was poor. He then reported something to the effect that he was unable to comply with my alternate instructions. He then reported that he was in the grass. There had been no previous braking action reports regarding taxiways. I immediately informed the Supervisor of the situation. Normally the airport authority is meticulous about reporting field conditions; it seems like they may have been behind the power curve today. A braking action report regarding taxiways would have been beneficial to alert users to the conditions experienced. The airport had just plowed the runway and airport crews were just in the vicinity of the incident minutes earlier.