WX AVOIDANCE MANEUVER PLACES M20 PLT IN PROX OF ARR TFC ACFT. POTENTIAL CONFLICT.

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DEPARTED TEB ON VFR TRIP TO ACK. WX BRIEFING INDICATED CIG'S 2000 FT TO 5000 FT ALONG RTE WITH POSSIBLE ICE IN CLOUDS. VISIBILITY WAS GENERALLY 5 MI OR BETTER. NO INDICATION OF SNOWSHOWERS AT RPTING STATIONS ALONG RTE. I DECIDED VFR AT 1500 FT WAS BETTER THAN IFR IN CLOUDS WHERE ICE MIGHT BE ENCOUNTERED AND WAS RPTED. HAD FLT FOLLOWING WITH NY TRACON UNTIL BDR CLASS D. CONTACTED BDR TWR. RPTED 'CLR E' AND WAS ADVISED TO CONTACT HVN TWR -- STILL IN GOOD VMC. ABOUT 7 MI W OF HVN ENCOUNTERED HVY SNOWSHOWERS. CONTACTED HVN TWR AND WAS TOLD 'FIELD IS IFR; 800 FT OVCST.' AT THIS TIME I EXECUTED A 180 DEG TURN TOWARDS THE S AND WAS ADVISED BY HVN TWR; 'APCH HAS ADVISED OF A CONFLICT WITH AN ACFT ON RWY 2 APCH COURSE.' I ELECTED TO TURN L APPROX 260 DEGS FROM A HDG OF 170 DEGS BACK THROUGH N TO 270 DEGS. THIS PROLONGED MY TIME IN IMC; BUT TURNED ME AWAY FROM THE RWY 02 APCH COURSE. AS SOON AS I ESTABLISHED THE 270 DEG HDG VMC CONDITIONS RESUMED. THE PROB AROSE BECAUSE I HAD GOOD VISIBILITY INITIALLY IN THE SNOWSHOWERS AND ASSUMED THEY WERE A LCL PHENOMENA. THE GENERAL POOR VISIBILITY OVER LONG ISLAND SOUND AT NIGHT MASKED THE TRUE SIZE OF THE SNOWSHOWER ACTIVITY. I FEEL MY CORRECTIVE ACTION WAS SWIFT; ALTHOUGH I DID NOT IDENT THE IMC CONDITION IN A TIMELY ENOUGH MANNER. THE GOOD WX AT BDR LED ME TO CONCLUDE THAT HVN WAS OKAY; VMC. THIS WAS ALSO SUPPORTED BY THE EARLIER WX BRIEFING. I AM REALLY ANGRY WITH MYSELF FOR NOT LISTENING TO THE HVN ATIS PRIOR TO CONTACTING THE TWR. THIS WAS AN INEXCUSABLE; LAZY; AND UNNECESSARY OVERSIGHT. NEVER AGAIN. ALTHOUGH THIS EVENT IS A VMC INTO IMC INCIDENT; IT HAS MADE ME RE-EVALUATE MY GENERAL OPERATING GUIDELINES FOR VFR VERSUS IFR. I CONTINUED THE FLT SUCCESSFULLY IN GOOD VFR AT 9500 FT. AS A SINGLE ENG; NO ICE AIRPLANE DRIVER; I HAVE OFTEN OPTED FOR THE 'SCUDDY' FLT OVER FILING IFR. IN THIS CASE; THIS WAS A TRULY POOR CHOICE. TEB AND ACK AND MOST OF THE RTE HAD IMPROVING VFR. IT WAS CERTAINLY POSSIBLE TO FILE IFR AND CLB VMC TO TOP ANY SNOWSHOWER ACTIVITY IN THE AREA. BUT AS SOON AS THE WX BRIEFING RPTED 'ICE' I DISCOUNTED IFR AS A POSSIBLE CHOICE. FURTHERMORE; I REMEMBER THINKING OVER BDR THAT I COULD SEE THE 'STARS ABOVE' IN MOST DIRECTIONS. I DON'T KNOW WHY I CONTINUED INTO THE SNOWSHOWER ACTIVITY WHEN IT WOULD HAVE BEEN QUITE EASY TO CLB VFR TO SEE HOW HIGH THE SNOW PRODUCING CLOUDS WERE. AT THAT POINT; A GO-NO-GO DECISION COULD HAVE BEEN MADE WITHOUT PRESSURE. THE CLASSIC HUMAN FACTORS WERE AT WORK HERE. I WAS LATE FOR A PLANNED DINNER AND MY 'GET-THERE-ITIS' MADE IT TOO EASY TO CONVINCE MYSELF THAT I COULD SEE THE EDGE OF THE SNOWSHOWERS. THIS ALSO DISTRACTED ME; AND CAUSED ME TO 'FORGET' TO LISTEN TO THE HVN ATIS. NIGHT AND FATIGUE WERE INSIDIOUS CONTRIBUTORS.