C182 PLT WAS UNABLE TO MAINTAIN ALT DUE TO MOUNTAIN WAVE IN ZDV AIRSPACE.

Narrative

WHILE NBOUND APPROX 30 NM FROM CIMARRON VOR; ON V-19; IN CRUISE FLT; I ENCOUNTERED A STRONG DOWNDRAFT. I WAS FORCED TO CONFIGURE THE ACFT TO VX TO MAINTAIN ALT BUT EVENTUALLY THIS FAILED AND AFTER APPROX 8 NM I WAS UNABLE TO MAINTAIN ALT. I REQUESTED A BLOCK ASSIGNMENT OF 11000- 12000 FT BUT WAS UNABLE TO MAINTAIN THIS. I REQUESTED A DEV TOWARDS LOWER TERRAIN AT TRINIDAD; CO. I WAS ABLE TO HALT THE DSCNT AT 9700 FT MSL WHICH IS BELOW MEA/MOCA FOR THIS SEGMENT. I WAS ABLE TO INITIATE A CLB AT VY APPROX 12 MI SW OF TRINIDAD AND EVENTUALLY WAS ABLE TO RETURN TO MY ASSIGNED ALT. I ESTIMATE THE DOWNWARD PORTION OF THIS WAVE WAS APPROX 30 MI N TO S AND 15 MI E TO W. AT THE TIME OF THE INCIDENT THE ACFT WAS IN THE FORWARD THIRD OF THE WT/BAL ENVELOPE AND APPROX 500 LBS BELOW GROSS WT. WINDS ALOFT AT MY ALT WERE APPROX 240 DEGS AT 15 KTS WHICH WAS CLOSE TO FORECAST. THERE WERE NO AIRMETS IN EFFECT FOR THIS RTE AND ONLY THE USUAL LIGHT TURB HAD BEEN ENCOUNTERED. FORECAST WINDS OVER THE MOUNTAIN PEAKS WAS 20-22 KTS FOR NORTHERN NEW MEXICO AND SOUTHERN COLORADO. RATE OF SINK AT VX AVERAGED -150 FPM WITH RANGE OF 0 TO -600 FPM.