Another winter storm, and the Tri-State is again right on the line between areas that may see some snow in the morning and areas that will just have rain. In developing the forecast for today, I've been trying to figure out how strong the cold air advection will be around the back of the low. You can see on the satellite/radar pic that the low has full matured and is wound up pretty tight.
These deep lows can make it difficult to forecast an accurate snowfall amount, because as they wind up tighter, they tend to choke off the moisture supply, especially to the south and east of the low track. You have probably heard me talk about the "dry slot"…this is where the low pulls a plume of dry air up from the southwest as it intensifies. Sometimes, we'll have storms along the warm front and then the sun will break out as skies clear ahead of the the cold front and more storms. That clear interval is the dry slot.
This wind chart clearly shows the position of the low by 7:00 Wednesday morning…you can see how the wind streamline arrows all converge around the center over northern Indiana. I believe that the strong winds will trump the moisture supply, so we'll wind up with very light—if any snowfall on Wednesday morning. The areas most likely to see anything on the ground will be generally north of the Ohio River. Warm, wet ground conditions and temperatures near freezing will minimize the travel impact from any snow that manages to fall.
I ran the 12z accumulated snow models and came up with very light snowfalls across the Tri-State. The bottom line here is that tonight's event will not have much impact, and temperatures will quickly rise into the 40's tomorrow afternoon, aided by strong southwest wind.
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