CANCELING IFR AS REQUESTED ON THE ATIS AT PWK; A GV CREW ENCOUNTERS WX WORSE THAN REPORTED RESULTING IN ABANDONING THE APCH AND CLBING VFR THROUGH THE OVERCAST BEFORE BEING ISSUED A NEW CLRNC.

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WE WERE COMING INTO PWK. THEY WERE USING RWY 34 DUE TO WINDY CONDITIONS. IT IS NORMAL PROC AT THIS ARPT TO CANCEL IFR IN ORDER TO CIRCLE TO LAND FOR RWY 34. IT IS NOTED ON THE ATIS THIS ROUTINE IS IN PROGRESS AND ARRIVING ACFT UNABLE TO CANCEL IFR SHOULD INFORM THE APCH CTLR ON INITIAL CONTACT. THIS IS NOT AN IFR APCH FOLLOWED BY 'CLRED FOR THE VISUAL.' THE CEILING AND VISIBILITY ON ATIS WERE MORE THAN ADEQUATE ALLOWING CIRCLING IN GOOD VFR CONDITIONS. I BRIEFED THE OTHER PLT FOR A 1900 FT MSL PATTERN. WE HAD THE ARPT IN SIGHT; BUT EVENTUALLY I DECIDED WE NEEDED TO DESCEND TO MAINTAIN VFR. IN RETROSPECT I SHOULD HAVE TURNED AROUND AND HEADED N TO MAINTAIN VFR. I DIDN'T. I DESCENDED TO JUST ABOVE IFR CIRCLING MINIMUMS WITH THE ARPT IN SIGHT ON THE DOWNWIND LEG. THE WX WAS NOT GOOD ENOUGH TO CONTINUE THE VFR CIRCLE AND LAND. I SELECTED GAR AND PITCHED UP INTO THE OVERCAST IN A CLBING L TURN OVER THE ARPT TO 2000 FT MSL AND A N HEADING. 15 SECONDS LATER WE WERE AGAIN VMC AND PICKED UP AN IFR CLRNC FOR A STRAIGHT IN LNDG ON RWY 16. I COULD HAVE DRUG THE GV ACROSS THE ARPT AT 600 FT AGL; AND MAINTAINED VFR AS I TURNED N. LEGAL; BUT NOT AS SAFE AS ENTERING THE CEILING UP TO 2000 FT MSL AND GOING N IN TO VMC CONDITIONS. THE ARPT WAS OFFICIALLY VFR THE ENTIRE TIME. PARTICULARLY AT THIS ARPT YOU NEED A VFR MINDSET BECAUSE THEIR LOCAL PROCS DEMAND IT. I SHOULD HAVE TURNED AROUND AT THE FIRST SIGN OF LOWERING CONDITIONS AND WAITED UNTIL THEY COULD PROTECT THE AIRSPACE FOR AN IFR CIRCLE TO LAND WITH POSSIBLE MISSED APCH. NEXT TIME I WILL DO JUST THAT.