New data Monday night suggests a significant winter storm will impact much of my area Tuesday and Tuesday night. This is a challenging forecast due to the fact the storm is still digging at the time of this post. Due to the increased phasing and development of a closed 500mb low, models have come in stronger, wetter, and further south.
It's my belief that winter storm warnings will eventually be extended further south Tuesday morning than they are tonight. The icing potential should be more focused south of I-80. North of here, snow should be the dominate form of precipitation. Rain or mixed precipitation is likely in far SE Iowa and WC Illinois, especially near and south of HWY 34 before a final transition to snow.
There's some really complex interactions with this system which is likely to make this a difficult and challenging forecast, even as the event is unfolding. Confidence in solutions is still lower than I would like this late in the game. That said, I do have some snowfall forecasts off the models Monday night. This is just to give you an idea of what the snowfall ranges are at this stage of development. It's this and (fresh model output Tuesday) that snowfall forecasts will be based on
The EURO. Better known as the king and the money maker. Again I defer to its winning ways.
Here's the 10:1 ratio on the EURO. It's a bit less than the Kuchera method above. It should end up somewhere in the middle of the two.
The regional perspective of the EURO.
The 3k NAM NEST
The GEM (Canadian)
As you can see there are some pretty robust solutions with subtle but important differences in track. This has big implications on how far south and east the heavy snow band extends. We will have a much better grasp on the situation early Tuesday. Until then, roll weather...TS