Good afternoon everyone! The beginnings of our incoming winter storm is impacting the western portions of NE as of 12:45pm CST. Currently the precipitation is more in the form of a mixed bag of snow and rain but as we work into the evening and overnight hours, temperatures will cool and allow for a greater coverage of snow. Also given some dry air this system has to overcome initially, not all of the precipitation shown on radar below is reaching the ground, especially along its eastern periphery. Dynamic cooling (saturating the lower levels of the atmosphere and hence cooling them) will allow for more precipitation to reach the ground with time.
A significant winter storm will traverse the region this evening through Sunday evening bringing several inches of snow to many locations. If you weren’t able to check out this morning’s update, Winter Storm Warnings remain hoisted by the National Weather Service for portions of northern MO, southern/southeastern IA, far southeastern/northwestern NE and far northeastern KS. The cancellation times for these weather bulletins are shown below as well. Winter Weather Advisories are in effect for the remainder of NE, northern KS and along the northern/southern periphery of the Winter Storm Warnings in IA/MO.
There will be plenty of frontogenesis (development of a boundary that aids in lift) with this winter storm as it works through the region tonight into Sunday. circled below is the corridor we believe has the best potential for a deformation (snow) band to set up that leads to several inches of accumulating snow. Accumulating snows are likely outside of this corridor, but the significant frontogenesis in the dendritic growth zone aids in snow development. Slight fluctuations in track are going to remain as the newest NAM3km has ever-so-slightly shifted this region south which will have ramifications on snow totals.
Simulated radar through 12am CST Monday: The mixed bag of precipitation in western NE continues to work eastward through the day with light rain showers working into eastern NE as the afternoon and evening progresses. Snow coverage will increase this evening in northern/western NE as the low pressure system lifts out of the Rockies. This system will slowly work ESE through the nighttime hours, bringing a mixed bag of rain/snow/freezing rain to the southern two-thirds of IA and rain showers to northern KS. A decent swath of moderate-heavy snow will develop across NE overnight with the southern periphery of the snows working into northwestern KS. Sunday morning, rains slowly change over to snow across the southern two-thirds of IA and the rest of northern KS while northern MO initially works in a mixed bag of precipitation before also transitioning to snow. During the day Sunday, the snows work eastward, gradually lifting out of central NE and north-central KS. The deformation band that sets up across southern IA, northern MO and far northeastern KS late Sunday morning/early afternoon will push eastward with all snow out of NE and KS ~4-5pm CST Sunday and eventually IA and MO around 12am CST Monday. The European model continues to hold onto the snows in southeastern IA and northeastern MO a tad longer than high-resolution guidance, which is something to note.
The threat for patchy dense fog remains late tonight into Sunday morning across southeastern MO. Winds will remain fairly light during this timeframe and given the recent rains, plenty of moisture will be lift over. Warm air advection will also promote the development of this fog, which could very well continue through a good portion of the morning before gradually fading. Another pocket of patchy fog may develop in southeastern KS.
As this system progresses across the Central Plains Sunday, it will undergo strengthening which will result in stronger winds. Wind gusts approaching 40mph at times will lead to blowing and drifting snow, especially in areas harder hit. Near-blizzard conditions are possible given the snows and strong winds, so significant reductions in visibility should be expected.
Updated total snowfall this evening through Sunday evening: We continue to highlight an axis of 3-5″ of snow stretching from northwestern NE through southeastern NE/northwestern MO into southeastern IA. Given the frontogenesis previously discussed and the ample lift in the dendritic growth zone, a corridor of 5-8″+ of snow is likely from St. Joseph through Davenport, IA. Snow accumulations will decline as you head north and south of this axis. Roads are expected to become snow covered and slick, so if you are traveling through these areas during this timeframe, definitely be mindful of the weather. Travel will be extremely difficult due to slick/snow covered roads and near-blizzard conditions. As previously mentioned, models have trended slightly further south, which you will find noted in this updated graphic.
If you have any questions do not hesitate to reach out! Have a great rest of your day!