PA28 PILOT REPORTS DEPARTING UNINTENTIONALLY FROM CLOSED RWY AFTER MISSING NOTAM DESCRIBING CLOSURE.

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I DEPARTED ZZZ WHILE THE ARPT WAS CLOSED BY A NOTAM. I SELF-BRIEFED ON DUATS EARLIER IN THE DAY; 3-4 HRS PRIOR TO THE FLT. I OVERLOOKED THE AERODROME NOTAM THAT INDICATED THE ARPT WAS CLOSED. PART OF THE REASON THAT I DID NOT FIND THE NOTAM CLOSING THE ARPT IS THE NEW NOTAM FORMAT THAT HAS GONE INTO EFFECT SINCE MY LAST FLT IN JANUARY. I READ A BRIEF STATEMENT ABOUT THE CHANGES TO THE NOTAM FORMATS IN JANUARY BUT DID NOT RESEARCH THE CHANGES. AFTER I DEPARTED THE ARPT I WAS MONITORING APCH CTL AND HEARD THE CTLR ADVISE ANOTHER ACFT THAT THE ARPT I JUST DEPARTED WAS CLOSED BY NOTAM. I CALLED THE CTLR AND ADVISED HIM THAT I HAD JUST DEPARTED THE ARPT AND THAT I WOULD LAND AT A NEARBY ARPT AND PHONE THE ARPT AT ZZZ TO DETERMINE THE STATUS OF THE ARPT. THE ARPT MGR INFORMED ME THAT THE ARPT WAS NOTAMED CLOSED DUE TO WATER ON THE RWY 400-500 FT FROM THE APCH END OF RWY X. THE FLOODED AREA IS NOT VISIBLE FROM THE OTHER END OF THE RWY WHERE I STARTED MY DEP ROLL AND THERE WERE NO MARKINGS ON THE RWY INDICATING THE CLOSURE. I WAS AIRBORNE AND IN A CLB ATTITUDE PRIOR TO THE POINT ON THE RWY WHERE THE WATER WOULD HAVE BEEN VISIBLE. I ASKED IF I COULD RETURN TO THE ARPT SO THAT I COULD RETURN THE ACFT TO THE HANGAR. THE ARPT MGR TOLD ME THAT I COULD LAND AT MY OWN RISK. I OVERFLEW THE ARPT TO VISUALLY INSPECT THE UNUSABLE PORTION AND DETERMINED THAT THERE WAS AT LEAST 2000 FT OF USABLE RWY WHEN LNDG ON RWY Y. THE AVAILABLE RWY WAS MORE THAN SUFFICIENT FOR SAFELY LNDG THE PA28 I WAS FLYING; SO I PROCEEDED TO LAND AND PARK THE ACFT. I WILL REVIEW THE REVISED NOTAM TERMINOLOGY AND ACRONYMS SO THAT I WILL NOT OVERLOOK ANY NOTAM IN THE FUTURE AND WILL CALL THE FLT SVC WX BRIEF NUMBER FOR A NOTAM CHK PRIOR TO FLYING IN THE FUTURE. I HAVE GOTTEN OUT OF THE HABIT OF CALLING FSS DUE TO LONG PHONE DELAYS SINCE THE SYS WAS PRIVATIZED. I HOPE THAT THE CALL RESPONSE TIME HAS IMPROVED.