A rare Saturday blog for you today as the weather, as usual, dictates the blog update. We're starting the day with clouds and an atmosphere that is gradually saturating through the Plains. The scope of the storms impacts will be through a corridor along the I-70 region, roughly 100-200 miles on either side into the Ohio Valley. This morning the storm's core is moving through and north of the four corners area in the southwest part of the US. It will intensify through the central Plains tomorrow afternoon and, aloft at least, pass over the Lakes region south of the Metro. Ahead of the storm moisture in the atmosphere will be piling up in the southern Plains and then come up I-35 towards KC later today. As far as the snow scenario goes, there are likely going to be big totals with this, but as I've stressed all week in the blog and on the air, the snow winners in terms of totals (more) may cut the Metro in half. That's what makes this storm a very complicated one to figure out. Ice is a likely given, though farther south of KC in terms of accumulating on power lines etc, and strong winds are a given as well with a bad combination south of US 50 towards 54 Highway into central Missouri. Forecast: Today: Cloudy with light freezing mist/drizzle/ice pellets and/or mixed snowflakes developing this afternoon. The amounts look rather light. Just be aware of any very light glazing that could occur and watch for changing road conditions, especially on untreated roads. Blustery with highs in the mid-to-upper 20s Tonight: We should see an increase in the sleet, and for areas south of the Metro, more freezing rain. Breezy and cold with temperatures holding in the 20-25° range. Snow farther north of the Metro, roughly 36 highway northwards Tomorrow: The mixed precipitation in the Metro gradually, and perhaps slowly, evolves from a mix to snow during the morning. This remains a very critical part of the system as a whole as we may see a considerable amount of sleet before this transition. Areas on the north side of the Metro should transition over before 10 a.m., while the south side (let's approximate it on 435/470) may be waiting a couple of hours later. Winds gust to 40+ MPH. Near-blizzard conditions are possible, and perhaps true blizzard criteria will be met. Temperatures dropping into the teens. Tomorrow night: Snow gradually winds down towards midnight with clearing skies before daybreak. Lows in the 0-5° range with wind chills well below 0°. Blustery. Monday: Sunshine with some clouds, winds drop off but remaining cold with highs in the 10-15° range. Discussion: I keep pounding on this with the storm... this system should be a widespread blizzard for the KC Metro area... but we are still fighting this "warm" nose of air several thousand feet up that will melt the snowflakes as they fall through the "warm" layer. It's not overly warm but enough to melt things, and that is really the game changer regarding potential snow. The eradicated "warm" layer is the key to snow totals and is likely to put up a fight for a while tomorrow. Unfortunately, this fight will be right on top of the 435 loop, and that makes this a hot mess to figure out. Let me try to illustrate this better for you. Taking a cross-section through the atmosphere from KCI south to Olathe. Here is a look at what's happening at KCI. For reference, on the left are specific pressure levels of the atmosphere but for your purposes consider this information as altitude (an extreme simplification). 925 millibars is roughly 2500 feet up... 850 mb is roughly 5000 feet up and 700 mb is roughly 10,000 up. The main thing I want to draw your eyes to is the bullseye of blue-ish purple. That is the chunk of air that is 32° or above. So flakes fall but melt then likely refreeze into ice pellets before pinging on your windows. At the bottom of the graphic is timing. SUN 0Z is 6 p.m. tonight, SUN 3Z is 9 p.m. tonight, SUN 12Z is 6 a.m. tomorrow, etc. It goes every three hours with hourly increments in the graphic hatches. So in the graphic above, based on this morning's HRRR model, there is a "warm" nose from roughly 8 p.m. tonight to 10 a.m. tomorrow at KCI. Hence the wintry mix/sleet is expected. On the south side... here is Olathe. See the difference in scope, longevity, and likely a couple of extra degrees of warmth in the bullseye? This is an issue for snow production because solely based on this data, that warm layer continues through roughly noon tomorrow. This would likely be quite a bit of sleet with perhaps some freezing rain patches as well. So let's just say, we have KCI as this sleet mixes through 9 a.m. and then they switch to fast accumulating snows. The model data shows roughly .4-75" of an inch of liquid equivalent coming in the form of snow. Being generous with snow ratios, typically roughly 10:1, (1" of rain = 10" of snow) let's say that becomes 12:1. At best, that would yield 6-10" of snow up there. Impressive if correct and timed out to that conversion time (it could be earlier or later by a couple of hours). On the south side towards Olathe, this is even more problematic. Roughly 3-4/10" of moisture is likely after noon, but they're still fighting sleet on the south side till lunch. So let's say that is converted to snow that would yield roughly 3-6" of snow. So you can see the spread from north to south in terms of totals and the data this morning mostly confirms this. A pretty impressive swatch of snow in the end with much heavier totals Up towards KCI and less dramatic totals south of 435-470 on the south side. Amounts trail off even more farther south. Overall just a real pain to figure. For areas north...towards 36 highway, this region still seems primed for the heaviest snows. In excess of 8" appears most likely there. The maps I put in the PM update in yesterday's blog are still pretty decent overall I think. I'm not so sure that 12" high end will be that apparent but there may be some jackpots out there towards that number. I made sure I broke out the area south of I 435-470 yesterday with that 3-6" bracket and that still seems prudent at this point. Farther south, the concerns towards Sedalia/Clinton/Butler/Pleasanton/Garnett is ice accumulations, and as the blog yesterday pointed out, winds are a BIG factor with the storm and those winds really crank tomorrow morning into tomorrow afternoon as the surface storm passes well south of here. 30-40 MPH gusts are on the table and with 1/4" of ice potentially on the power lines...that could be really problematic farther south. Farther north with those winds blowing the falling snow around reducing visibilities...blizzard criteria may be approached and an upgrade to a blizzard warning for at least part of the region is being considered. As I've mentioned a 1000 times this week... just infuriating that this system has this warm layer entrained into it messing up what should be a relatively easy forecast. Another consideration is that this storm may still be producing at least some accumulating snow into the evening tomorrow and perhaps we can get another 1-2" of snow after sunset for the area as a whole. What I'm continuing to stress is that Sunday morning when you wake up, especially on the south side, there may be very little accumulation aside from sleet or ice. Again be patient for the mix>snow transition to move in, but south side folks may be waiting till lunch or so for that fully to happen. If the timing of this process is sped up or delayed 3 hours (and it WELL COULD BE) the snow totals will vary 1-3". There is an upside on the north side and perhaps a downside to some degree on the south side. IF EVERYONE converts by 9 a.m. south side will get a whopper too of snow. From a pure model standpoint, the newest snow outputs are along the lines of what we've talked about and shown on the air. I don't think they need massive changes at this point. I can tell I'm burning out because this seems more like a rambling blog today. So where is the storm? It's not overly organized right now but will once it comes east into the better southern Plains an central Plains moisture aloft. Aloft this looks like a great storm...again that is what I keep coming back to, it's just a great-looking storm up there... and dynamic. The SPC has actually nudged a marginal risk of storms towards the I-70 corridor tonight and especially tomorrow and there is instability out there above us at least tomorrow morning, hence the continued small but not 0 risk of some rumbles of thunder with whatever is falling. Especially from the Metro southwards. More tomorrow and if need be this evening on the blog. Alex and Jacob have you covered on the air. Joe