The challenge of late winter storms

March is here! The thought of spring is in the air, the days are getting longer, and you just dug out your green sweater and leprechaun hat to wear on the 17th. But hold the phone, winter isn’t over just yet. March still deals us a fair share of snow and when it falls, the forecast can get very tricky and change at the last second.

Every snowfall has its variables that a meteorologist must calculate. How much moisture is in the atmosphere? At what altitude is the snow forming? What type of ice crystals are forming there? Will there be a lake effect component to the totals? How warm is the ground? And so on, and so on…  As we’ve said so many times this winter, the atmosphere is fluid. Those variables are always changing. When they change the forecast changes, sometimes a little, and sometimes a lot.

But late winter and early spring systems add in a few more twists. Often times these massive systems reach all the way to the Gulf states and feed off the ample moisture. However, that moisture, riding the low level jetstream (airflow around 5,000 ft. moving 40-80 mph) can get cut off if thunderstorms form along the way. Just imagine coasting along that low level jetstream. You have an unobstructed path into Wisconsin until all of a sudden, towering supercell thunderstorms pop up over Missouri and Illinois. The highway of warm, moist air is forced on an off ramp by those storms while the winter storm over Wisconsin is choked for moisture and fizzles.

Even if the low level jetstream has a clear path to our region, the flow of warm air itself can change the composition of the storm system. Here’s how it plays out: The snow begins with temps cool enough for accumulation. But as the low level jet wraps into the storm, temps begin to rise. The new blanket of snow quickly melts as the precipitation turns to rain. Yet only 30 miles north the snow is still falling. The result is something that could play out tomorrow (3/2/12). Thunder and rain come down in Kenosha and blinding snow piles up in West Bend (that’s hypothetical and NOT the actual forecast). Eventually the cold air wins out and all of us see snow. But usually by the time we’re at the back edge of the storm there isn’t much moisture left and all the heavy snow pushes east.

These days meteorologists have great tools and technology to keep up with the changing forecasts. But those updates are only good if viewer is willing to listen. At FOX6 Skyvision Plus gives us a new look at the atmosphere every three hours. This allows our predictions to keep up with every new move Mother Nature makes, but also requires the viewer to walk stride for stride when keeping an eye on a never static, and sometimes chaotic atmosphere.