Winter Storm!

Well after months and months of pure boredom, a weather system of some significance is making its way towards the area, poised to drop the first decent accumulating snow of the season. While this particular system will fall well short of any "Storm of the Century" headline, it will certainly test drivers winter driving skills. At this point, surrounding weather service offices as well as local forecasters are going with a band of 4-7 inches of snow across the area, which certainly seems reasonable given the moisture available for this system to work with, and the fact that the system will move through at a decent clip. Below is a map of snowfall potential, as well as the current watch area, courtesy of the NWS office in La Crosse and Chanhassen. Again, overall this map looks good given what the models have shown at this point.



Current headline map (posted 12:46am Saturday)



The current storm track takes the low from northern Missouri to a near Madison, WI and off to the northeast. This low also looks like it will have a decent tap into the Gulf of Mexico, as shown in the 850mb moisture transport. Below is the GFS forecast map from the Penn State e-wall site.




Taking a look at Bufkit, both the NAM and GFS show an area of dry air that will have to be overcome before snowfall can begin. If this particular dry air can be overcome sooner than models show, amounts could potentially be higher. If it takes longer for it to saturate, then amounts will be trimmed. At this point, Bufkit data from the GFS and NAM both show full saturation for EAU sometime between 4 and 5pm Saturday evening, so I would expect the snow to begin in that time frame. Below are images from the 00z run of the NAM and GFS. You'll notice omega values around -10 overlapping the snow growth zone, so fairly good dynamics showing up with this. I would expect snow rates to be approaching at least an inch/hour for a few hours time, and this could be the bulk of our accumulation.

GFS:



NAM:



While a watch is up now for the area, I fully expect this to be upgraded to a warning, maybe not so much for snow totals, but the fact that it is the first system of the season, and the NWS hopes it will force more caution on people. I also expect perhaps a tier or two of counties surrounding the warning area to be given an advisory, again just to keep people aware of what's going on. This system should keep us in all snow here in Eau Claire, with areas further south near La Crosse will probably see more mixing potential. So again to summarize, it looks like a decent band of 4-7 inches of snow is possible for the area, but keep in mind if some convective bands can form, as was the case a few weeks ago near St. Cloud, there could be amounts higher than 7 inches. However, given the very isolated nature of these bands, they are near impossible to forecast right down to the city. Stay safe out there everyone!