Accumulating Snow Possible on Monday

Just as spring is starting to settle into the Stateline, winter will make an abrupt return with the likelihood of accumulating snowfall for this upcoming Monday.

As far as high temperatures are concerned, this has been the third warmest start to March (through the 13^th) on record for the city of Rockford with an average high temperature of 52°. This stretch featured 11 days with high temperatures at, or above, the daily normal including five days in the 60’s. But, in typical northern Illinois fashion, winter has not given up just yet.

Saturday was a very active weather day in the Plains. A strong system of low pressure vertically stacked to the top of the troposphere provided everything from blizzard conditions to tornadoes. Heavy snowfall and strong winds prompted a blizzard warning to be issued for parts of Wyoming, Nebraska, and South Dakota with places like Cheyenne, WY expecting upwards of 36” of snow through the weekend. Meanwhile, a strong cold front sitting atop a potent dryline across western Texas brought severe thunderstorms, including multiple tornadoes, to the Texas Panhandle. It’s this same system that will be bringing this late-season snowfall to the Stateline.

This storm will be pushing across the Plains very slowly leaving the Stateline dry on Sunday. Although, as winds shift to the northeast to chase this storm, cold air will be pulled into the Stateline likely keeping highs in the upper 40’s across most of the area. As the pressure gradient quickly tightens, winds will pick up as well gusting as high as 30mph through the day. The center of this storm system will remain in the Plains well into Monday, but precipitation will extend further and further eastward thanks to a growing occluded front. Arriving in the predawn hours of Monday morning, the precipitation will likely start out as snowfall and continue as such through the morning. As the low levels of the atmosphere heat up slightly heading into the afternoon, rain will begin to mix in with the snow. Snow could continue to fall as late as around midnight. The greatest deal of uncertainty associated with this system is its temperature profile which will have a great influence on the precipitation type and the snow’s liquid equivalency which adds up to a great influence on how much snow will pile up. The snow is forecast to be a rather wet and heavy snowfall which promotes lots of compaction. Further compaction will be brought on by the rain that is expected to mix in for a time. In addition, the warmer weather has warmed the surface above freezing which will provide some melting before the snow begins to accumulate. While most computer models are forecasting anywhere from 4-6” of snow accumulation, these previously mentioned factors are not accounted for and therefore these numbers are likely an overshoot. A couple of inches is more likely with localized amounts up to a few inches possible.