Winter weather is taking aim on Minnesota and Iowa once again. And just like our Thanksgiving system, we're riding the "Mix Zone". A little dose of everything is possible stretching across our area. Here's the scenario.
Winter Storm Warnings are in place along and west of I35. To the east, a Winter Weather Advisory is in place. The pink area remains the target for heaviest snowfall totals. Further east, in the yellow, the warmer components are at play, meaning a mixed precipitation before changing to snow.
Tonight, a light batch of that mixed bag slides into the area. This is the leading edge of our storm, which will largely go towards saturating the atmosphere. Eventually some precip will reach the ground. A light glaze of ice is possible on untreated surfaces with this activity, so take notice out the door Monday morning.
But bigger impacts are ahead. The heart of the storm is still well to our southwest. Over Kansas tonight, another, more potent shield of precip will expand and push towards the area. This will be our big player.
So who see's what? Like I mentioned, that mix area is clipping the area once again. That will set up especially for our southeastern counties, like Floyd, Howard and Fillmore counties on Monday. These are the local areas that stand to see the warmest temperatures in the atmosphere. In this pink area, a light glaze of ice, up to 1/10" is possible from freezing rain.
Moving further west, the colder component wins out and it should be snow only west of I35. Mixed precip no longer becomes an issue after 6 PM on Monday.
The mixed precip will eat away at snowfall numbers in this area. I fully expect to see a sharp gradient between areas with little snow (east) and areas with a lot of it (west). That middle ground will lay right across the area.
Here's the timing. We have a little bit of activity tonight, like I mentioned. But the heaviest mix/snow will fall beginning around 10 AM Monday in northern Iowa, spreading northward and ending around 3 AM Tuesday morning. This is the period where we will pick up the bulk of our accumulations. We won't be completely done for Tuesday though. Snow showers will continue on and off throughout the day, tacking on the last little bit to our totals.
Expect a very heavy, dense snow that may reduce visibility under 1/2 mile at times during the heaviest band Monday afternoon/evening. Monday evening and Tuesday morning's commute will be significantly impacted, especially to the west.
Thankfully, the storm threats don't include much wind or a cold blast of air following the snow. In fact, I expect temperatures to rise for the rest of the week, slowly melting the snow pack that we do receive!
Here's what the Storm Tracker 6 Weather team is watching very closely: The freezing point in the lowest levels of our atmosphere. This will be key between big snow totals and not so much. Totals will quickly ramp up from a dusting to 6" across this line, in what looks like as little as 60 miles or so. Any subtle shift warmer or colder would mean a BIG impact to the going forecast.
The heaviest precip axis. The consistent trend has been to put the heaviest precipitation (whether it be rain and/or snow) across NW Iowa and SW Minnesota. But there are some computer model runs shifting that axis closer to the I35 corridor.
The dry slot. This is a dry layer of air above the surface that takes away the ice crystals from the atmosphere. No Ice, no snow. This is what shuts off the snow at 3 AM on Tuesday. There is still a sign of ample moisture down low. This could potentially bring a little freezing drizzle, but the bigger impact will be from the snow that has already fallen. So I'm not so concerned about this. What I will be watching for closely, is the timing of the dry slot, ie: the end of the heavy snow band.
That's what's on my mind. Given the complexity of the situation, there will likely be some subtle (hopefully just subtle) changes between now and the onset. Storm Tracker 6 Meteorologist Cindy Morgan is in Monday morning to get you out the door. I'll continue updates through the evening.
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Storm Tracker 6 Chief Meteorologist