Why does snow melt so quickly in March?

 Recent snowfall has been quick to begin melting away especially with Wednesday's sunshine and afternoon highs pushing the upper 30s. But sunshine is not the only way to decrease the snow depth on the ground! Three main ways to melt away snow is through sunshine, sublimation, or latent heat release through higher humidity.

Heat from the sun is the most commonly thought of way to melt away snow, but this is especially true for later spring months. In December and January, the angle of the afternoon sun is much lower in the sky. While March and April feature a much higher sun angle, focusing more of the sun's radiation directly to the surface, which melts the snow faster even if the temperature were the same in March compared to January.

That was certainly evident Wednesday afternoon in the Stateline, with sunshine promoting rapid snow melt in Rochelle. Another way snow can disappear even when temperatures are not above freezing is through sublimation. That is when water molecules go straight from a solid state (snow and ice) into gaseous state (water vapor). This process is most common with ice cubes that you leave in the freezer for a long time. Even though the temperature in the freezer is never above freezing, the ice cubes can get smaller as individual water molecules turn straight into vapor and dissipate into the air.

Another way to melt snow is through latent heat release. That is when moisture from the air condenses onto snow, similar to how a cup of ice water "sweats" in the summertime. That process of condensation onto the icy surface leads to a release of latent heat, which cools the air around the snow but works to heat up the snowpack itself, only further melting it away. This is the main reason why snow can melt effectively even at night! When dew point temperatures are above freezing, the moisture in the air condenses onto the snow, melting it further!

We will have both the sunshine's radiation and a moist air mass over the next few days, so expect that recent snowpack to melt away rather quickly through the course of the weekend