On the high plateaus and ridge summits of the Central Appalachians, mean annual precipitation often exceeds 1270 mm (50 in) due to orographic uplift effects. To the east of these higher elevations, rain shadow areas in the Great Valley section of the Ridge and Valley Province receive less than 860 mm (<34 in) of mean annual precipitation. Soil survey activities, including the development of soil series and catena concepts across these landscapes have only recognized Udic soil moisture regimes (Soil Survey Staff, 1994). Using the Newhall Simulation Model to calculate monthly water balances and soil biological windows from long-term climate records and individual years, perudic soil moisture conditions occur more frequently than previously recognized on soil landscapes that are dominantly Udic. They become the dominant condition at the higher elevations of the Central Appalachians, in Pennsylvania, Maryland, West Virginia, and Virginia. The Udic soil moisture regime has been broadly defined in which the soil moisture control section is not dry in all parts for as long as 45 consecutive days, following the summer solstice, where the mean annual soil temperature is less than 22 degrees C; or dry in any part for as long as 90 cumulative days in normal years (Soil Survey Staff, 2003). Additional subdivisions of the Udic soil moisture regime were developed to separate these high elevation “wet” Udic environments that are marginally perudic from the drier Udic conditions. Perudic soil moisture regimes occur where precipitation exceeds evapotranspiration in all months, with only very brief periods when stored moisture is used and when moisture tension is < 100 kPa (<1 bar). Perudic soil moisture regimes correlate to Thornthwaite's (1948) concept of perhumid climates. In the Central Appalachians, these soil landscapes are associated with a moisture index >100 and >95 days when precipitation is measurable (>2.5 mm; 0.1 in). Key to the concept of a perudic moisture regime is the relative absence of a drying period during the summer months and the implications for processes of podzolization, clay translocation and deposition, the windthrow of trees, and the development of Umbric epipedons. A terrain modeling approach was coupled with the Newhall Simulation Model (NSM) to approximate regions of perudic and near-perudic soil moisture regimes. As inputs to the NSM, monthly average air temperatures and total precipitation from long-term (>60 y) weather stations in the Central Appalachians were used to derive the occurrence of perudic events and draw relationships to the presence and absence of argillic and cambic horizons. In the perudic and near-perudic regions, the expression of argillic horizons in soils on the high plateau summits on gentle, broad stable slopes is limited and dominated by soils with cambic B horizons. Pit and mound microrelief and high elevation bogs and swamps are associated with these areas of near-perudic and perudic environments. Our research has led to the following outcomes: 1) ad hoc subdivisions of the Udic soil moisture regime to better reflect these high moisture surplus environments (“near-perudic”), 2) connections between the high moisture surplus environments, pedological processes operating in the unglaciated Central Appalachians, and their impact upon soil development, and 3) recognition of perudic environments at high elevations for the establishment of new soil series.