WX RPTING EQUIP ASOS INACCURATE WX RPTED ACR MISSED APCH.

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ASOS IS NOT REPRESENTATIVE OF THE TRUE CONDITIONS OVER THE ARPT. ASOS WX WAS RPTING 36 SCATTERED; 60 SCATTERED; 10 PLUS MI VISIBILITY AT XX56Z OB. AT APPROX XY20Z THE BE99 ATTEMPTED AND ILS APCH AND AT 2 MI FINAL; RPTED MISSED APCH. AS THE ACFT PASSED OVER THE ARPT AT 1600 FT; I COULD NOT SEE THE ACFT. I RPTED THE CONDITION TO MY SUPVR WHO IN TURN RPTED THE INACCURACY TO THE NWS AND THE TRACON SUPVR. NWS ISSUED A SPECIAL WX RPT A FEW MINS LATER. THE BE99 PLT MADE ANOTHER APCH AND UPON LNDG; ADVISED ME THE BASES OF THE LOWER LAYER WERE DEFINITELY BROKEN AND ON FINAL HE BROKE OUT AT 1200 FT. A LR35 PLT RPTED THE SAME CONDITION A FEW MINS LATER. OTHER PLTS IN THE PATTERN CONFIRMED THE BROKEN LAYER PLUS THE SUPVR AND OTHER CTLS OBSERVED IT. ASOS WAS NOT RPTING THE TRUE WX CONDITION. I UNDERSTAND ASOS ONLY RPTS WHAT IS DIRECTLY ABOVE THE CELLOMETER. HOWEVER IN THIS INSTANCE; IT NEVER DID RPT THE TRUE CONDITION. THE BROKEN LAYER WAS OVER THE ARPT FOR AT LEAST 50 MINS BUT WAS NEVER RPTED BY ASOS. THE ONLY CORRECTABLE ACTION AS I SEE IT IS TO HAVE QUALIFIED PERSONNEL DO THE OBSERVATIONS OR SOMEHOW IMPROVE THE ASOS EQUIP ACCURACY.