C210 PLT ENCOUNTERS WX-TURB AND DIVERTS FOR LNDG.

Narrative

I WAS ON AN ANGEL FLT/COMPASSION FLT TRANSPORTING A 6 YR OLD PATIENT FROM HPN TO AGC. FLT STARTED AT 9G0; MY HOME BASE AND WAS WATCHING A SLOW MOVING FRONT SW TO NE ACROSS RTE OF FLT IN BOTH DIRECTIONS. PASSED THROUGH FRONT ON THE WAY TO PICK UP THE PATIENT AND WAS ANALYZING THE STRENGTH OF RADAR RETURNS FROM DOWNLINK WX 'WORX' AS WE PASSED THROUGH IT ON THE FIRST LEG. YELLOW RETURNS WERE MILD TURB ON THIS LEG. AFTER PICK UP OF PATIENT WE HAD TO RETURN THROUGH THE FRONT TO DROP OFF THE PATIENT IN PITTSBURGH. WE WERE ABLE TO AVOID STORM CELL BY FLYING N OF COURSE (STORM CELL TRAVELING NE) AND WAS IN AN OPEN AREA AND A LARGER BAND OF SHOWERS WAS BTWN US AND DEST. THERE WAS YELLOW ON DOWNLINK THROUGHOUT THE FRONT AND A COUPLE OF MORE INTENSE RAINFALL AREAS IN THE YELLOW. I THOUGHT WE WOULD BE ABLE TO AVOID THE HEAVIER RAIN AND THEREFORE TURB BY AVOIDING THE DARKER AREAS OF PRECIP. WE VERY QUICKLY ENTERED SEVERE TURB AND IMMEDIATELY DID A 180 DEG TO EXIT THE PRECIP. PRIOR TO ENTERING THE PRECIP WE INFORMED ATC THAT WE WERE GOING TO DEVIATE TO AVOID THE HEAVIER RAIN. THEY APPROVED DEV INITIALLY AND ALSO WARNED US OF HVY AREAS OF PRECIP. AFTER WE REVERSED COURSE; WE CALLED ATC AND INFORMED THEM THAT WE WERE DOING A 180 DEGS WITH NO RESPONSE. AFTER GETTING KNOCKED AROUND IN THE TURB I DECIDED TO GET DOWN TO THE NEAREST ARPT WITH AN IFR APCH AND LAND AND WAIT OUT THE WX ON THE GND. I CALLED ATC AND INFORMED OF DEV TO ALTOONA AND AGAIN NO RESPONSE. ATC THEN STARTED CALLING AND WE KEPT ON TRYING TO COMMUNICATE AND NEITHER WAS GETTING THROUGH TO THE OTHER. WHEN THEY FINALLY RESPONDED TO OUR CALL WE WERE CHEWED OUT FOR DEVIATING ALT AND HDG WITHOUT CLRNC. I WAS ON APCH TO THE ALTOONA ARPT AT THIS POINT AND QUICKLY BROKE OUT OF CLOUDS AND CANCELED IFR SO AS TO KEEP OUT OF ARGUMENT WITH ATC. MY REASON FOR QUICKLY STARTING THE APCH WAS THE PREVIOUS BAND OF WX WAS CLOSING OUR BACK DOOR AND AT 8000 FT WE HAD TO GET DOWN IN A HURRY TO MAKE THE APCH BEFORE THE OTHER STORM MOVED IN ON US. I DID NOT HAVE ANY ROOM TO WAIT FOR ATC TO RESPOND. IN RETROSPECT I AM NOT SURE WHAT I COULD HAVE DONE DIFFERENTLY ONCE WE ENTERED THE SEVERE TURB. I REALIZE CONFLICTS WITH OTHER ACFT WERE POSSIBLE BUT DIDN'T SEE AN OPTION WITH ATC NOT RESPONDING. IN THE FUTURE I WILL LAND BEFORE THE PRECIP AND TREAT ALL YELLOW PRECIP AS NO GO AREAS. THE DOWNLINK MIGHT HAVE GIVEN ME TOO MUCH CONFIDENCE. I HAD LOOKED AT CLOUD TOPS; MOVEMENT OF CELLS; STRIKE FINDER DATA AND DOWNLINK SPHERIC DATA AND SATELLITE DATA WHEN I MADE MY DECISIONS. WITH ALL THAT I STILL MADE THE WRONG DECISION ON HOW TO NAV THE WX.