Snowmelt parameters are climatic variables that apply across the entire study area when simulating snowfall and snowmelt.

The Snowmelt page of the Climatology Editor dialog is used to supply values for the following parameters related to snowmelt calculations:

• Dividing Temperature Between Snow and Rain: Enter the temperature below which precipitation falls as snow instead of rain.
• Antecedent Temperature Index Weight: This parameter reflects to what degree heat transfer within a snow pack during non-melt periods is affected by prior air temperatures. Smaller values reflect a thicker surface layer of snow which result in reduced rates of heat transfer. Values must be between 0 and 1, and the default is 0.5.
• Negative Melt Ratio: This is the ratio of the heat transfer coefficient of a snow pack during non-melt conditions to the coefficient during melt conditions. It must be a number between 0 and 1. The default value is 0.6.
• Elevation Above Mean Sea Level: Enter the average elevation above mean sea level for the study area, in feet or meters. This value is used to provide a more accurate estimate of atmospheric pressure. The default is 0.0, which results in a pressure of 29.9 inches Hg. The effect of wind on snow melt rates during rainfall periods is greater at higher pressures, which occur at lower elevations.
• Latitude: Enter the latitude, in degrees North, of the study area. This number is used when computing the hours of sunrise and sunset, which in turn are used to extend min/max daily temperatures into continuous values. It is also used to compute daily evaporation rates from daily temperatures. The default is 50 degrees North.
• Longitude Correction: This is a correction, in minutes of time, between true solar time and the standard clock time. It depends on a location's longitude (
  
  ) and the standard meridian of its time zone (SM) through the expression 4 (
  
  -SM). This correction is used to adjust the hours of sunrise and sunset when extending daily min/max temperatures into continuous values. The default value is 0.