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Weekly Weather Event -Week of Feb. 24

February 28, 2020

In a highly unusual event even for forecasters, a narrow band of snow dumped between 6 to 13 inches of snow on western Nebraska and northern Kansas on Tuesday February 25th. This especially strong snowfall measured only 7 to 15 miles wide, with little snow fall measured outside of the narrow band. The contrast between the deep snowpack and surrounding areas was strong enough to be seen by satellite images and from flights over Kansas.

A band of snow like this is formed on the mesoscale level, which describes weather events that happen on a more local scale as opposed to larger scale storms that can be modeled days in advance. These smaller storms are responsible for things such as lake effect snow in the Great Lakes region, and snowbands such as these are known for having highly concentrated snowfalls that quickly taper off.

Forecasting snow has always been a challenge for meteorologists. While raindrops are typically spherical, snowflakes can take on several different shapes depending on the temperature at which the water freezes and the relative humidity. Some snowflakes are shaped like the classic six-pointed hexagon, but they can also take the form of flat plates, needles, or thin columns. This shape often how snowflakes will clump together as they fall to the ground, and more importantly, how much air is trapped between those clumped-up snowflakes. All these factors combined make determining the actual depth of a snowfall difficult.

In addition to the challenge of determining just how much snow will fall, small changes in the atmosphere can drastically alter the outcome of a winter storm. Faulty or incomplete data can skew predictions, unexpected warmer layers in the atmosphere can melt snow and cause it to melt into rain or re-freeze into sleet or freezing rain, and models are only as accurate as the data being entered into them. Even so, predictions are more accurate today than they were even 20 years ago, and innovations in the field are helping researchers better forecast weather events around the globe.