FLT CREW OF A320 ENCOUNTER TURB AND OVER-REACTIVE AUTOTHROTTLES INPUT ON APCH TO IAD. POSSIBLE BREACH OF UNSTABILIZED APCH CRITERIA ENSUED.

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MODERATE TURB FROM DOCCS INTXN THROUGH LNDG. INTERCEPTING GS ON THE ILS TO RWY 19L AT IAD. OUTSIDE THE OM WE SELECTED MANAGED SPD; AFTER VERIFYING ACTIVATED AND CONFIRMED. AUTOTHROTTLES SURGED CAUSING INDICATED AIRSPD TO INCREASE ALTHOUGH MAGENTA MANAGED SPD INDICATOR SHOWED SLOWER. I BELIEVE THAT ACFT SENSED A LOSS OF ENERGY DUE TO TURB AND DECIDED TO INCREASE PWR. CAPT DISCONNECTED AUTOTHROTTLES AND HAND-FLEW ACFT TO A SAFE LNDG ON RWY 19L AT IAD. VERY HVY RAIN ON FINAL WITH GUSTY WINDS AT 3000 FT FROM 220 DEGS/65 KTS DIMINISHING TO ABOUT 210 DEGS/10 KTS AT 20 FT. WE FELT THE APCH WAS CONDUCTED IN A SAFE MANNER (IT TOOK A FEW MOMENTS TO GET BACK ON GS AFTER PWR SURGE); BUT IT MAY NOT HAVE MET STABILIZED CRITERIA AT 500 FT DUE TO THE GUSTY WX CONDITIONS. FROM OM INBOUND CONDITIONS WERE OFFICIALLY VFR ALTHOUGH HVY RAIN CAUSED DIMINISHED VISIBILITY THROUGH WINDSHIELD EVEN WITH WIPERS ON FAST. OUR FOCUS FOR THE LAST 800 FT OR SO WAS OUTSIDE TO MAINTAIN VISUAL ALIGNMENT WITH RWY. LNDG WAS UNEVENTFUL AND WITHIN TOUCHDOWN ZONE.