INADEQUATE RWY TOUCHDOWN AND CTRLINE MARKINGS.

Narrative

WE COMPLETED AN ILS DOWN TO 500 FT ABOVE FIELD ELEVATION AT MDT ON RWY 31 BEFORE BREAKING OUT OF THE LOWEST CLOUD DECK AND SEEING THE RWY. I BELIEVE THE CURRENT VISIBILITY WAS 1 1/2 MI IN HVY RAIN. THERE HAD BEEN SNOW IN MDT EARLIER AND THERE WAS SLUSH ON THE RWY ALTHOUGH THE RWY WAS PLOWED EITHER 50 FT OR 90 FT EITHER SIDE OF THE CTRLINE (I CAN'T REMEMBER WHICH). FROM 100 FT AGL TO TOUCHDOWN; IT WAS VERY DIFFICULT (IMPOSSIBLE?) TO DISCERN THE RWY CTRLINE MARKINGS AND TOUCHDOWN ZONE MARKINGS. MUCH OF THIS CAN BE ATTRIBUTED TO THE HVY RAIN AND THE SLUSH ON THE RWY. HOWEVER; WHEN WE LEFT THE NEXT MORNING; WITH THE RWY FULLY PLOWED AND DRY; I NOTICED EVEN THEN THAT IT WAS DIFFICULT TO SEE THE RWY CTRLINE AND SOME TOUCHDOWN ZONE MARKINGS BECAUSE AN ASPHALT PATCH HAD BEEN APPLIED TO THE RWY; LENGTH-WISE; CENTERED AROUND THE RWY CTRLINE. COMBINED WITH THE RUBBER LEFT ON THE RWY BY LNDG ACFT; THE CTRLINE IS DIFFICULT TO SEE DURING THE DAY AND WAS ESSENTIALLY INVISIBLE UNDER THE CONDITIONS WE EXPERIENCED THE NIGHT BEFORE. THE ALL WX MARKINGS ARE NEXT TO USELESS AT NIGHT; WITH RWY CLUTTER AND LOWER VISIBILITY; THE VERY CONDITIONS UNDER WHICH THEY ARE MOST NEEDED! I WOULD MOST CERTAINLY RECOMMEND REPAINTING THE CTRLINE MARKINGS AND TOUCHDOWN ZONE MARKINGS ON THE ENTIRE RWY. CTRLINE LIGHTS WOULD BE EVEN BETTER.