IFR ENRTE PA28 ENCOUNTERS ADVERSE WX CONDITIONS; DECLARES AN EMER WITH ZOB; IS UNABLE TO MAKE A LNDG AT NEAREST ARPT DUE TO WX; HDOF TO PIT APCH WHERE BETTER WX CONDITIONS ALLOW A LNDG.

Narrative

I WAS FLYING FROM MDT TO FWA. THE FLT BEGAN IN VFR CONDITIONS OUT OF MDT. WHEN I DEPARTED; THE RPTED CEILING IN MDT WAS 7500 FT; VISIBILITY WAS 5-10 MI. I CLBED TO 6000 FT AND BEGAN MY WESTWARD FLT. AS THE FLT PROGRESSED; THE CEILING BEGAN TO COME DOWN AND VISIBILITY DECREASED. WHEN I GOT OVER THE ALLEGHENY MOUNTAINS; I BEGAN EXPERIENCING STEADY LIGHT SNOW. I RPTED THIS CONDITION TO CTR. THEY ASKED IF I WAS EXPERIENCING ANY ICE FORMATION ON THE PLANE. I RPTED THAT I WAS NOT. ABOUT 2 HRS INTO THE FLT; I BEGAN CONSIDERING RETURNING TO MDT. THE CONDITIONS WERE GETTING MORE MARGINAL AND THE WX ALONG THE RTE WAS RPTED AS LESS APPEALING THAN EARLIER FORECASTS INDICATED. I WAS ABOUT TO MAKE A 180 DEG TURN TO RETURN TO MDT WHEN THE ENG FALTERED AND THEN STOPPED. I IMMEDIATELY INFORMED CTR; TURNED ON THE FUEL PUMP; MADE THE MIXTURE RICH; AND ENGAGED ALTERNATE AIR. THE ENG RESTARTED. HOWEVER; SINCE I WAS UNSURE OF THE SOURCE OF THE PROB AND THE ENG SEEMED A LITTLE ROUGH; I CHOSE TO DECLARE AN EMER AND ASKED FOR VECTORS TO THE NEAREST ARPT WITH A PRECISION APCH; RATHER THAN TURN AROUND AND ATTEMPT A FLT ACROSS THE MOUNTAINS AGAIN TO MDT. CTR VECTORED ME TO THE ILS AT A NEARBY ARPT. FRANKLY; I HAVE FORGOTTEN THE NAME OF THE ARPT. VISIBILITY AT THE ARPT WAS ABOUT 1/2 MI. AS IT TURNED OUT; I MISSED THE APCH. I THEN REQUESTED VECTORS TO AN ARPT WITH BETTER VISIBILITY AND CEILING. CTR HANDED ME OFF TO PITTSBURGH APCH; WHO VECTORED ME TO ILS FOR RWY 28 AT ALLEGHENY COUNTY. I LANDED THERE SUCCESSFULLY. HOWEVER; IN THE DSCNT THROUGH THE CLOUDS; I PICKED UP ABOUT 1/4 INCH OF RIME ICE ON THE LEADING EDGE OF THE WINGS. ON THE GND; I HAD THE FBO CHK THE ENG. THEY FOUND THE AIR FILTER CLOGGED WITH ICE. I DIDN'T KNOW IF THAT CAUSED THE INITIAL PROB OR WAS PICKED UP ON THE DSCNT. THE NEXT DAY; I CONTINUED THE FLT IN VFR CONDITIONS TO FWA AND FROM THERE; ON TO MY HOME BASE. DURING THE RUN-UP AT FWA; THE L MAGNETO WAS ROUGH AND SHOWED A DECREASE IN RPM OF OVER 200 RPM. I RETURNED TO THE RAMP AND HAD MAINT CHK IT OUT. THEY PULLED; CLEANED; AND RE-GAPPED ALL THE PLUGS AND REMOVED SOME DEPOSITS ON THE LEADS. AFTER THAT; THE ENG RAN SMOOTHLY AND I COMPLETED THE FLT WITH NO FURTHER INCIDENTS.