A LUSCOMBE 8 PLT RPTS ENCOUNTERING IMC WHILE AT 700 FT ON A VFR TRIP BETWEEN LOCAL ARPTS.

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I PLANNED TO FLY MY PERSONAL AIRPLANE FROM ZZZ; A CLASS D ARPT WITH A PART-TIME CONTRACT TWR; TO ZZZ1 WHERE THE ANNUAL INSPECTION WAS TO BE PERFORMED. THE DISTANCE BETWEEN IS 50 NM AND IS OVER MOSTLY UNPOPULATED AND SPARSELY POPULATED COUNTRYSIDE. ZZZ IS A ZZZ2 SATELLITE ARPT UNDER THE 4000 FT RING OF THE CLASS B AIRSPACE. THE FIRST 5-10 MI OF THE TRIP INVOLVES FLYING OVER THE POPULATED NORTHERN SUBURBS. IT IS A RTE I HAVE FLOWN DOZENS OF TIMES AND AM FAMILIAR WITH THE LANDMARKS; TERRAIN AND OBSTACLES. ON THIS DAY; THERE HAD BEEN AREAS OF IMC ASSOCIATED WITH RAIN SHOWERS REDUCING VISIBILITY; ALTHOUGH CEILINGS HAD REMAINED ABOVE 2500 FT. AROUND XA30 THE RAIN SHOWERS HAD MOSTLY DISSIPATED AND THE ARPTS ALONG MY RTE WERE CLRING WITH ZZZ1 RPTING CLR SKIES. AT XB00; I PREPARED TO DEPART ZZZ. ATIS INFO WAS RPTING 4 MI VISIBILITY IN MIST. ALL MORNING I HAD BEEN FOCUSED ON THE VISIBILITY AS CEILING HEIGHTS HAD NOT BEEN A CONCERN. THE LUSCOMBE IS A TWO PLACE VINTAGE TAIL WHEEL AIRPLANE THAT CRUISES AROUND 100 KTS; SO MOST FLTS ARE DONE AT 1000 FT AGL OR BELOW. SINCE I WOULD BE LEAVING THE CLASS D INTO CLASS G AIRSPACE THE CEILING WAS OF LITTLE CONCERN AS LONG AS I HAD BASIC VFR MINS; 1000 FT. ZZZ TWR CLRED ME FOR TKOF WITH A L TURN FOR A W DEP ON COURSE. AT ABOUT 700 FT AGL I BEGAN TO ENTER THE BASES OF A SCUD LAYER WHILE CLBING. AT THIS TIME I WAS ALREADY ON A W HDG ON COURSE. I ASSUMED THIS WAS JUST AN ISOLATED PATCH OF SCUD ASSOCIATED WITH A SHOWER; SO I LEVELED OFF BELOW THE BASES AT AROUND 600 FT AGL. KNOWING THAT CONDITIONS WERE BETTER TO THE W I CONTINUED; WHICH INVOLVED LESS THAN MINIMUM CLOUD CLRNC IN THE CLASS D AIRSPACE; RATHER THAN RETURN TO POOR CONDITIONS AT ZZZ. BY THE TIME I HAD REACHED THE VOR WHICH IS ALONG THE COURSE; CEILINGS HAD IMPROVED IN ADDITION TO ME NOW BEING OUT OF A POPULATED AREA. DURING THE SIX MI BETWEEN ZZZ AND THE VOR WHILE FLYING TO KNOWN BETTER CONDITIONS; I WAS FORCED TO STAY BELOW THE BASES WHICH MAY HAVE COMPROMISED THE MINIMUM HEIGHT ABOVE POPULATED AREAS. BEING FAMILIAR WITH THE AREA AND ANY OBSTACLES IN MY JUDGEMENT ENTERING THE SCUD LAYER WOULD HAVE BEEN MUCH MORE DANGEROUS THAN COMPROMISING MY ALT. THE REMAINING FLT WAS UNEVENTFUL. UPON LNDG IN ZZZ1; I CALLED ZZZ TWR AND SPOKE WITH THE TWR MGR FOR TWO REASONS. FIRST; TO DETERMINE IF I HAD DEPARTED INTO IFR CONDITIONS. SECONDLY; IF AND WHEN THE AUTOMATED WX OR ATIS HAD RPTED THE LOWER LAYER. HE ASSURED ME THAT IT HAD BEEN VFR AND THAT IS WASN'T UNTIL XB30 THAT AWOS HAD RPTED A 700 FT BROKEN; 1/2 HR AFTER MY DEP. THE TAF FOR THE TIME WAS TEMPO; XC00 TO XE00 800 BROKEN. IN RETROSPECT I WAS TOO FOCUSED ON THE VISIBILITY AT THE TIME AND FAILED TO PAY ATTENTION TO DETERIORATING CEILINGS. TAKING TIME TO REVIEW THE WHOLE WEATHER PICTURE AGAIN AFTER DELAYING WOULD PROBABLY HAVE REVEALED THE PROB. ALSO; IF THE TWR HAD NOTICED THE LOWER CLOUDS; THEIR PASSING THAT INFO ON TO ME EVEN IF THE AUTOMATED WX WAS NOT RPTING IT; WOULD HAVE MADE ME RETURN TO THE HANGAR. I BELIEVE THOUGH THAT I WAS THE FIRST ACFT TO OBSERVE THE CONDITIONS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR DID NOT HAVE ADDITIONAL INFO TO PROVIDE.