Narrative:

Planning to ferry the airplane from trk to another airport at a lower altitude in anticipation of IMC and extensive snow accumulation the next day; I checked weather and conditions at trk (cavok) and in the sacramento area (broken 3;000) I decided to attempt to fly VFR westbound along highway 80. After departure trk; I leveled off at 7;000 feet (>1;000 feet AGL) and followed highway 80. After a few minutes of flight; the cloud layer on the other side of donner pass came into view. I decided to attempt fly underneath the clouds and descended to an altitude below the clouds. Approaching the highest elevation point of highway 80; I determined there was not enough clearance over the pass and turned around. After turning around; I noticed a higher ceiling and better visibility over the old donner pass road and proceeded in that direction. After crossing donner pass at low altitude AGL; but clear of clouds; I started to realize that the ceiling was decreasing rapidly on the west side of the pass and I needed to take evasive action. Faced with the option of turning around at low altitude and cross the pass again in climb eastbound or climbing through the relatively thin layer of clouds; I elected to execute a maximum performance climb straight ahead in direction of the road and highway through the clouds to a safe altitude and VMC where I contacted ATC and requested a clearance to complete the ferry flight IFR. My mistake was decision-making that relied on interpolating weather conditions in between two points that are too far apart and with too many weather-influencing factors. I was surprised by the sudden onset of low and descending ceiling after taking off in cavok minutes earlier. I should have never attempted to execute the flight VFR. Easily accessible additional real-time weather information for geographic locations between airports would have been helpful and could have resulted in better decision-making.

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Original NASA ASRS Text

Title: C340 pilot reported departing TRK in VFR conditions headed across Donner Pass westbound and encountered IMC conditions. Pilot climbed to VFR conditions and contacted ATC to complete the flight IFR.

Narrative: Planning to ferry the airplane from TRK to another airport at a lower altitude in anticipation of IMC and extensive snow accumulation the next day; I checked weather and conditions at TRK (CAVOK) and in the Sacramento area (broken 3;000) I decided to attempt to fly VFR westbound along HWY 80. After departure TRK; I leveled off at 7;000 feet (>1;000 feet AGL) and followed HWY 80. After a few minutes of flight; the cloud layer on the other side of Donner Pass came into view. I decided to attempt fly underneath the clouds and descended to an altitude below the clouds. Approaching the highest elevation point of HWY 80; I determined there was not enough clearance over the pass and turned around. After turning around; I noticed a higher ceiling and better visibility over the old Donner Pass road and proceeded in that direction. After crossing Donner Pass at low altitude AGL; but clear of clouds; I started to realize that the ceiling was decreasing rapidly on the west side of the pass and I needed to take evasive action. Faced with the option of turning around at low altitude and cross the pass again in climb eastbound or climbing through the relatively thin layer of clouds; I elected to execute a maximum performance climb straight ahead in direction of the road and HWY through the clouds to a safe altitude and VMC where I contacted ATC and requested a clearance to complete the ferry flight IFR. My mistake was decision-making that relied on interpolating weather conditions in between two points that are too far apart and with too many weather-influencing factors. I was surprised by the sudden onset of low and descending ceiling after taking off in CAVOK minutes earlier. I should have never attempted to execute the flight VFR. Easily accessible additional real-time weather information for geographic locations between airports would have been helpful and could have resulted in better decision-making.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.