A weak cold front is sinking southward out of Minnesota getting set to stall over central Iowa this evening. A wave (clipper like disturbance) will quickly slide east/southeast along the boundary overnight. That will provide a brief period of forcing that will generate some light snow or rain and snow mixed after midnight. The current track suggests most of the precipitation would be north of I-80 and most focused in a west to east band between HWY 30 and HWY 20.
Moisture is meager and temperatures marginal so the overall impacts will be minimal and confined to the north. That means where there are accumulations they are most likely to be found in the corridor between HWY 30 to just north of HWY 20. That area has the potential for 1/2" to 1 inch of snow. A few high resolution models show up to 2" in pockets of narrow banding but that is likely to be the exception and isolated in nature. Some of these models are also a a bit further south closer to I-80 but I'm not sold on that yet. I still think most of what sticks will be on grassy and elevated surfaces. The majority of the snow falls between midnight and 5 or 6am.
Temperatures never get much lower than 30-32 even during the period of snow and then pop back to 40 by mid to late morning Wednesday so what does stick should be pretty much gone by mid-day.
Below you can see what the models are putting out for accumulations. I wonder though just how much of this actually accumulates with melting and settling going on.
The 12k NAM
The 3k NAM
The bottom line is this thing will be in and out in a hurry, I doubt anything more than a trace of snow gets much further south than HWY 30. Looks like just enough to be a nuisance.
On a positive note the weekend is going to be a beauty and I'll have more on that in my next post. Roll weather...TS