PRCP
USE modern ratio 1.084 annually. Monthly factors range 0.87-1.21. Physical basis confirmed both eras. CIs overlap 11/12 months. No trend in combined record. Most defensible variable.
TMIN
USE warm-season factors (May-Oct): +0.7 to +1.1°F. MDT warmer overnight — consistent across eras. Winter months uncertain (sign reversal between eras). Seasonal application required.
MaxDP
USE modern factors: +0.6 to +1.5°F. Modern era perfectly stable (p=0.981). Drought 1962-65 excludable. Susquehanna moisture signature is the most physically robust finding in this analysis.
AvgRH
USE modern factors: +2 to +4%. Corroborates dewpoint. Consistent direction all 12 months both eras. No modern trend. Use with confidence as secondary humidity metric.
TMAX
CAUTION — significant trend p=0.000. MDT cooling progressively vs CXY both eras. Do NOT apply a fixed TMAX offset for homogenization. Era-specific factors only; acknowledge instrumentation uncertainty.