Date: 201812
Local time of day: 0601-1200
Location: CO15.Airport, CO
Weather elements / visibility: Snow; 10
Aircraft: Sail Plane
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Mission: Personal
Flight phase: Descent
ATC / advisory: CTAF CO15
Reporter organization: Personal
Reporter function: Single Pilot; Pilot Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Flight Instructor
Human factors: Situational Awareness; Time Pressure
Anomaly: Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued Advisory / Alert; Air Traffic Control Provided Assistance; Flight Crew Returned To Departure Airport; Flight Crew Took Evasive Action
Contributing factors: Weather; Procedure; Human Factors
Primary problem: Human Factors

Narrative: Weather report indicated clear skies and visibility >10 miles using local soaring BLIP (Boundary Layer Information Prediction) maps. I did not get the TAF for APA which was 22 miles north as I was planning to fly glider local within 5 miles of CO15.  AWOS on field indicated Skies clear; winds from south at 10 kts; ceiling unlimited; Temp/DewPt 38/10 when I took off. There was a frontal type cloud approximately 10 miles to the north at takeoff.  Field elevation 7040. Tow pilot took glider to south of field approximately 4 miles to 12;000 MSL. I released from tow and did several maneuvers taking about 5 minutes and losing 1;000 feet. I noted a cloud coming above me and that the frontal type cloud had come much closer approaching from the NNW. I did several further maneuvers to lose altitude to the south of the airfield. I turned to the AWOS frequency which was reporting winds from the north and ceilings of 3100 feet. A call to the tow pilot who was returning to the field indicated that visibility and ceilings were deteriorating to the north. I turned to the north back to the field at high speed (130 kts) with the intent of coming in under the clouds and entering the pattern at 1000 ft AGL to arrive in 2 minutes. As I proceeded north; forward visibility deteriorated significantly so that I could not see the field although I could ground references. I descended at high speed 130 kts to 500 feet AGL toward the field following power lines which ran toward the field. There was now visible snow or ice on my wings but I wanted to keep the airspeed high in case there was unnoticed accumulation. I went through the Before Landing Checklist and briefed the passenger to tighten seat belts as we may have to land off the air field. A call from the Ground Operations Director to me stated they did not have me in sight and the field conditions had deteriorated with a snow squall over the field coming from the north. I stated I did not have the field insight and I estimated my position as 1/2 mile south of the field at 500 ft AGL. At that time; I had slowed to about 100 kts holding at an altitude where I could still see ground references trading airspeed for altitude. I did identify a potential off-field landing site known to me from a previous successful outlanding by another pilot. Seconds later; I identified a road and landmark used as the entry point for patterns landing to the south at our airfield although I did not see the runway (no lighting). I turned to the east with planning to do an extended base leg to the runway or the airfield landing north since the snow squall had moved from the north. Immediately after turning east; I saw the runway through the snow squall and called a base leg for the north runway. I was at 300 feet AGL about 80 kts. I pulled out the spoilers and slowed to 70 kts for possible icing with my calculated normal landing speed of 54 kts. I was till at 300 feet AGL and turned final with reduced forward visibility due to snow; but adequate ground and slant angle visibility to see the end of the runway. I could not see more than 1000 feet down the runway however. Snow was blowing over the runway; but there still no snow or ice on my wings. As I crossed the approach end of the runway at 100 feet AGL; I slowed to 54 kts. The flare; touchdown and rollout were normal. I saw people coming to the edge of the runway on a taxiway (my planned stopping point) to help retrieve the sailplane when I was about 500 feet from the taxiway. The rollout and stop were normal with normal braking. Upon exiting the sailplane after it came to a stop; about 1/4' of snow had accumulated on the wings in 30 seconds; but there was no ice. The snow was light; dry and fluffy. Upon landing; the ground crew informed me the AWOS had a 7 minute delay in broadcasting and that another pilot had looked at the TAF for APA 20 miles to the NNW at that time and forecast snow flurries about the time of my takeoff.Lessons learned -1) Delay or stop takeoff if visible unexpected weather is apparent; even if AWOS reports winds blowing the opposite direction2) Even when flying local; obtain TAF of fields in 30 mile radius3) Recognize a delay in the AWOS broadcast and use trend information accounting for the delay. I did listen to the AWOS at least 4 times during the flight; but did not account for the delay4) Land off field in clear weather is probably a better option than proceeding to an airfield with compromised visibility.5) Postpone a flight if weather appears marginal.6) Communicate with ground personnel to augment AWOS information in deteriorating weather conditions - this is key for single pilot resource management.




Synopsis: Glider pilot reported encountering IFR conditions during VFR flight due to sudden weather deterioration.