Narrative:

Flying on V23 at 10000 ft; the MEA; to stay below the freezing level. It was +2 degrees C at 10000 ft MSL. Briefing had airmet for occasional light to moderate turbulence. Ride from ZZZ to south of shasta was uneventful with an occasional very light bump. A couple of mi south of fjs we encountered severe turbulence; hitting heads a few times and throwing the plane. We lost close to 2000 ft before gaining control of the plane -- 60 degrees off course and still losing altitude. As I brought the nose up to arrest the descent we 'popped' out of the clouds and I saw scott valley below. I pointed the plane to A30 and finally communicated with ZOA through another plane and then canceling with ZSE before landing at A30. WX/winds were worse than forecast and hindsight says I should not have made that trip below 14000 ft. Seems like we hit a mountain wave coming off the 7000-8000 ft peaks to the west. Being only 2000 ft above that terrain in IMC was not a good idea. I was trying to remain below the freezing level to stay out of ice although we did have a tks deice system. A better choice would have to been 90 degrees at 16000 ft or 14000 ft and if ice was found do a 180 degrees. Callback conversation with reporter revealed the following information: reporter stated that he felt lucky to come out of the clouds over A30. The plane remained at A30 until he could retrieve it a week later. The reporter feels that more information should be available about the potential for severe turbulence in this area.

Related reports:

Google
 

Original NASA ASRS Text

Title: MOONEY 20 PLT ENCOUNTERS SEVERE TURB NEAR FJS AND LOSES 2000 FT.

Narrative: FLYING ON V23 AT 10000 FT; THE MEA; TO STAY BELOW THE FREEZING LEVEL. IT WAS +2 DEGS C AT 10000 FT MSL. BRIEFING HAD AIRMET FOR OCCASIONAL LIGHT TO MODERATE TURB. RIDE FROM ZZZ TO S OF SHASTA WAS UNEVENTFUL WITH AN OCCASIONAL VERY LIGHT BUMP. A COUPLE OF MI S OF FJS WE ENCOUNTERED SEVERE TURB; HITTING HEADS A FEW TIMES AND THROWING THE PLANE. WE LOST CLOSE TO 2000 FT BEFORE GAINING CTL OF THE PLANE -- 60 DEGS OFF COURSE AND STILL LOSING ALT. AS I BROUGHT THE NOSE UP TO ARREST THE DSCNT WE 'POPPED' OUT OF THE CLOUDS AND I SAW SCOTT VALLEY BELOW. I POINTED THE PLANE TO A30 AND FINALLY COMMUNICATED WITH ZOA THROUGH ANOTHER PLANE AND THEN CANCELING WITH ZSE BEFORE LNDG AT A30. WX/WINDS WERE WORSE THAN FORECAST AND HINDSIGHT SAYS I SHOULD NOT HAVE MADE THAT TRIP BELOW 14000 FT. SEEMS LIKE WE HIT A MOUNTAIN WAVE COMING OFF THE 7000-8000 FT PEAKS TO THE W. BEING ONLY 2000 FT ABOVE THAT TERRAIN IN IMC WAS NOT A GOOD IDEA. I WAS TRYING TO REMAIN BELOW THE FREEZING LEVEL TO STAY OUT OF ICE ALTHOUGH WE DID HAVE A TKS DEICE SYS. A BETTER CHOICE WOULD HAVE TO BEEN 90 DEGS AT 16000 FT OR 14000 FT AND IF ICE WAS FOUND DO A 180 DEGS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT HE FELT LUCKY TO COME OUT OF THE CLOUDS OVER A30. THE PLANE REMAINED AT A30 UNTIL HE COULD RETRIEVE IT A WK LATER. THE RPTR FEELS THAT MORE INFO SHOULD BE AVAILABLE ABOUT THE POTENTIAL FOR SEVERE TURB IN THIS AREA.

Data retrieved from NASA's ASRS site as of January 2009 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.