I decided on one more update before I head back to Iowa for the remainder of the week, seeing as with such nice weather today there was only the upcoming two storm systems to look forward too. Models are beginning to show some agreement, or at least a few models are coming to the same agreement with this mornings' and afternoon model runs. Essentially the confidence is building that we will see a rain/snow event mainly over areas of Kansas and Missouri for both Friday and Sunday.
Friday: Both the 12z and 18z NAM showed consistency in their solution, which had been the outlier when compared to other model runs yesterday. However, this morning the runs of both the Canadian GEM and European ECMWF trended to a stronger solution. Still not as strong as the operational NAM, but is something to think about in regards to the strength of the upper level wave that will be moving across the area on Friday. For this reason, expect precipitation amounts to be higher than the GFS, but not as strong as the NAM. The other large question will be regarding temperatures, as with a stronger solution should come better warm air advection just ahead of the trough. This would likely lead to a rain/snow mix near/along I70, with snowfall likely just north and all rain further south. This is shown fairly well in the NAM, with a tight gradient of no snow to heavy snow essentially focused over Kansas City and other areas along I70. The most likely scenario will have a true mix of rain and snow for the Kansas City area, with ~1" of a heavy wet snow likely across the area. Areas just north of the KC Metro may see up to 2" of snow, while just south may only see a dusting. This will be a tricky forecast, thus even any subtle changes in the track/strength of the system could drastically change the snowfall forecast.
Sunday: Models are beginning to creep towards a consensus in allowing the pacific wave to come onshore and across the Rockies without much inhibition by the emerging blocking pattern. This would lead to a stronger system, and with ample moisture available may lead to some significant snowfall amounts over some portion of the central Plains. This is another system that will feature a tight gradient of no snow to heavy snow, as the thermal gradient along the surface and lower levels will be quite dramatic. The 18z GFS left this gradient nearly along I70 in Missouri and along I35 in Kansas, with areas north seeing mainly snow (perhaps heavy at times) and areas south seeing mainly rain. That does leave a small area that will be along the transition line that would see a mix of rain/snow and perhaps even some sleet or freezing rain dependent upon localized thermal profiles. The 12z Canadian has a similar solution in regards to strength and only slightly slower in timing, location-wise it is approximately 50-100 miles further south than the GFS. The ECMWF has been the outlier in regards to timing and strength with this system, and continues to be so. However, it has trended a little faster and stronger in the latest 12z run thus increasing the likelihood that a solution similar to the GFS/GEM can be expected. With this in mind, it does appear likely that some portions of Kansas/Missouri will have the potential of significant snowfall for Sunday. The band of heaviest snow would appear to have the potential for greater than 8" of snowfall, with this band being quite narrow it is going to be difficult to forecast for at this time. However, expect forecasts from local sources to begin more discussion on this event as the weekend nears.
