SNOW MEASUREMENT REMINDERS
24 Hour Precipitation - (SHEF Code PP) 24 Hour Precipitation is just that - the routine 24 hour precipitation report, usually taken at around 700am. It may be regular rainfall, snow, sleet, freezing rain, or freezing drizzle. It is the water content of that precipitation. This measurement is easy in the summer, as it is simply the rainfall in your precipitation gage. In the winter, it is USUALLY the melted snowfall from your rain gage. Melted precipitation is measured to the nearest 0.01 inch, just like rainfall using the NWS provided measuring stick and the smaller inner measuring tube. Do not measure the melted precipitation directly in the larger 8 inch outer cylinder, it must be poured into the smaller inner measuring tube to be measured.
Occasionally, especially during windy conditions, you may have a significant snowfall, yet your gage remains nearly empty. It will then be necessary to take a core sample of just the newly fallen snow from the previous 24 hours. During windy conditions when it is determined that the amount of snow caught in the gage is not representative the observer will have to measure the snow at several points to try to come up with a representative amount of newly fallen snow and this is the amount to be melted for the water content and this is the figure that is reported in the observation as the 24 Hour Precipitation. It is reported to the nearest 0.01 inch.
Snow Depth - (SHEF Code SD). This is the total depth of the snow on the ground. It is reported to the nearest whole inch...2.4 inches is reported as 2 inches and 2.5 inches is reported as 3 inches.
24 Hour Snowfall - (SHEF Code SF). This is the amount of newly fallen snow in the past 24 hours. It is reported to the nearest 0.1 inch. It is not the total depth of snow on the ground, but the additional accumulation in the past 24 hours. If the ground was bare on the previous days observation, then of course, it would be the total snow on the ground.
Snow Water Equivalent - (SHEF Code SW). This is the water content of ALL snow on the ground...old and new. It is reported at designated times during late Winter and early Spring (time of year when the Snow Pack melts) usually about February 1 to the end of the Snow Season. The Snow Water Equivalent is obtained by inverting the 8 inch rain gage can and pushing it through the entire depth of snow on the ground that represents the average snow depth. Make sure that snow does not fall out of the 8 inch can when you remove the snow core. It is very helpful to have a firm, thin sheet of metal to slide between the surface of the ground and the rim of the 8 inch can to cleanly gather the entire sample of snow. The snow is melted and the liquid is measured by pouring it into the smaller inner measuring tube and using the NWS provided measuring stick. This is reported to the nearest tenth of an inch.
24 hour precipitation is reported to the nearest..........0.01 inch.
24 Hour Snowfall is reported to the nearest................0.1 inch.
Snow Water Equivalent is reported to the nearest.......0.1 inch.
Snow Depth is reported to the nearest..........................1 inch.