Model guidance is finally starting to get a better handle on the evolution of how the next several days play out across the Midwest, including here in Illinois. With better model agreement over the last 24 hours, we can say that the likelihood of widespread snow accumulations across portions of the state is on the increase. The latest information and thoughts follow below...
This afternoon, our main upper level low is slowly progressing its way through the Four Corners region with the heart of the ridge over the Midwest and our area, aiding in these above normal temperatures and really spring like warmth across portions of Illinois today. What happens from here and over the next 36 hours remains a bit complicated with several moving parts/smaller weather disturbances as everything as a whole pushes east into the plains.
As the trough and upper level low slowly nose out into the southern plains, low pressure will develop across northern Mexico and southern Texas and eventually come northeast Tuesday evening and through the day on Wednesday with the track shown below. It will then end up across the eastern Midwest/Ohio Valley by Wednesday night and Thursday morning. With the high pressure centered across the northern plains and northern Midwest as shown below, low level cold air will be able to be advected into portions of Illinois ahead of this system, setting the state for it to be cold enough for snow.
The animated loop below runs from 9pm tomorrow night through noon on Thursday, showing one models take and evolution of this main system as it progresses through the region. As you can see, a fairly large area of snow exists on the north and northwest side, affecting a large portion of Illinois on Wednesday and Wednesday night. There could be a mixing zone of sleet and freezing rain further downstate.
Updates will continue with another one set for later this evening and our first TAM showing expected snowfall totals from this main system will be out with tonight's update or tomorrow morning. Either way, confidence is increasing for widespread snow accumulations across portions of the state.
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