A C182 TURBO ENCOUNTERED IMC AND ICING. AFTER IFR CLRNC WAS UNABLE TO MAINT ALT DUE TO ICE AND DIVERTED TO A NEARBY ARPT.

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I WAS ENRTE FROM ZZZ1 TO ZZZ2 IN A 182 TURBO AT NIGHT IN VFR CONDITIONS. ABOUT ARRIVING AT THE BORDER; I SAW THAT THERE WAS WX AHEAD. I NOTED THE FREEZING LEVEL VIA THE G1000 XM RADIO WX SVC WAS 12000 FT IN THE LCL AREA. I SAW THAT I WOULD BE HDG INTO CLOUDS AHEAD AND WAS ON FLT FOLLOWING WITH APCH SO I ASKED FOR AN IFR CLRNC. I WAS ISSUED 'CLRED TO ZZZ3.' I WAS GLANCING AT THE ZZZ3 ON THE G1000 EVERY ONCE IN AWHILE AND NOTICED A STORM CELL IN MY PATH. I NOTIFIED ATC. THEY SAID THEY DID NOT HAVE ANYTHING ON RADAR. APPROX 3 MINS AFTER THAT XMISSION; I BEGAN TO NOTICE ICE (RIME) BUILDING UP ON MY WING. CONCERNED; I ASKED ATC TO DIVERT ME TO THE W; OUT OF THE TRAILING EDGE OF THE CELL I WAS ABOUT TO FLY INTO. THEY TOLD ME THAT DUE TO TERRAIN; I WOULD HAVE TO WAIT 8 MINS BEFORE THEY COULD DIVERT ME. IN THE NEXT FEW MINS; I SAW ACCUMULATIONS OF APPROX 2-3 INCHES OF MIXED ICE ON THE WING AND INCHES(?) OF CLR ICE ON THE TAIL (BOTH HORIZ AND VERT STABILIZERS). I PREVIOUSLY HAD THE AUTOPLT ON; AND THE PLANE WAS BANKING TO THE L AND PITCHING UP. I DISCONNECTED AUTOPLT; MADE SURE THE PITOT AND PROP HEAT WERE ON AND TOOK CTL OF THE PLANE. I NEEDED QUITE A BIT OF FORWARD PRESSURE TO KEEP THE AIRPLANE FROM LOSING AIRSPD. I WAS IN IMC AND MADE SURE THE PLANE WAS STRAIGHT AND LEVEL. I WAS UNABLE TO HOLD ALT AND THUS HAD TO DSND BELOW MEA. I NOTIFIED ATC AND THEN TOLD ME TO TRY AND CLB TO 10000 FT FOR TERRAIN AVOIDANCE. I TOLD THEM THAT I WOULD NOT AND WOULD BE ABLE TO AVOID TERRAIN VIA TAWS-B. THEY VECTORED ME TO THE ILS FOR ZZZ3. AFTER I HAD BEEN BELOW THE MEA FOR A FEW MINS; THE ICE HAD ALL COME OFF THE AIRFRAME. THERE WAS MODERATE TURB IN THE AREA AND I NOTED 60 KT XWIND WHICH TURNED INTO A HEADWIND AS I APCHED THE INBOUND ILS COURSE. I FLEW PAST THE COURSE ONCE; BEING DISORIENTED BY THE TURB; BUT THEN INTERRUPTED AND FLEW THE ILS DOWN TO APPROX 200 FT ABOVE MINIMUMS WHEN I SAW THE ARPT. I WAS CLRED TO LAND VIA L DOWNWIND AND NOTICED IT WAS RAINING WHEN I WAS ON FINAL. PROB AROSE: I BELIEVE I SHOULD HAVE DELAYED OR POSTPONED THE FLT AS THERE WERE MANY AIRMETS OUT FOR TURB AND ICING (ABOVE 12000 FT). I FLEW INTO A CLOUD AND THE TEMP DROPPED AND ICE STARTED FORMING. CONTRIBUTING FACTORS: PRECIP IN CLOUDS. FORECASTED FREEZING LEVEL WAS NOT ACTUAL. BAD DECISION MAKING BY PIC. DISCOVERED: I USED A FLASHLIGHT TO CHK SURFACES AFTER ENTERING IMC. CORRECTIVE ACTION: ASKED FOR DIVERSION. DSNDED TO ABOVE FREEZING TEMPS. HUMAN PERFORMANCE CONSIDERATIONS: WX CHKING -- AIRMETS SHOULD HAVE TOLD ME TO STAY PUT; BUT I DECIDED TO CONTINUE. AFTER WEIGHING DECISION OF CLBING TO POSSIBLE NON-ICING CONDITIONS OR DSNDING TO ABOVE FREEZING TEMPS; I CHOSE THE LATTER; BUT IT PUSHED ME BELOW THE MEA FOR THE RTE.