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MODEL MAYHEM, MAKE THAT MARCH MADNESS...

Before we get to the late weekend storm and what that means for snow or no snow, just another reminder of what an exceptional period of weather we went through in February. 10,127 record low mins and maxes were observed, 703 monthly record low maxes and mins and 200 all time record low maxes and mins (year-to-date). Note also the 3,514 record snow reports too this year to date. Holy cow Batman!

February temperatures over all the Midwest averaged 10-12 degrees below normal. For most of the region the month ended up somewhere in the top 3-6 coldest of all time.

During the peak of the outbreak, 30 percent of the country established record cold highs. That is an astounding figure.

SO WHAT ABOUT THE LATE WEEKEND STORM?

In my last post I left you in a quandary regarding the potential for accumulating snow Sunday night and Monday. Two models said yes, the other (the EURO) made a major shift north and said no. Today, the GFS shifted north, while the EURO made a correction back to the south. The only model that's been consistent is the Canadian GEM remaining stationary.


Clearly models are having a devil of a time handling the thermal profiles which is creating mayhem right over my area. Let me show you the latest snow projections from each model verses its previous run 24 hours earlier The latest is on the left, the previous run on the right. I'm especially surprised at the EURO which was on, off, and now on again in my northern counties.


The EURO, notice its push south.

The GFS is now furthest north missing my area after dumping on it yesterday.

The GEM remains consistent but it may be too far south.

One benefit of todays data is that I can now get another opinion thanks to the 12K NAM. It only goes out 84 hours which is 6:00AM Monday meaning the storm is still in progress. Based on what I can see through that period it is plenty cold enough for snow and it's aimed at my area. Interpolating another 6-12 hours I think it would show significant snow over much of my area. The 12K has been pretty reliable this winter so that is a plus on the side of snow, but not a guarantee.

THE VERDICT

So what's the verdict? I wish I knew! Earlier today I was leaning towards the idea most of the snow would stay near and north of HWY 20 (my far northern counties). Now with the latest evidence from the 12K and the EURO bringing the snow back south I think much of my area near and north of I-80 is still very much in play for a switch from rain to snow Sunday night. Further south, you're not out of the woods either as the 12K and GEM are focused on delivering snow there as well.


Here's how the southern part of my area would get the snow the GEM and 12K advertise. 850 temperatures of 0, which approximate the rain/snow line at 5,000 feet are above freezing (as are surface temperatures) Sunday evening. Just warm enough for rain to kick things off.

The key to what happens next is tied to the strength of a powerful cut-off low that emerges from the central Plains overnight. By Monday morning as the associated trowel pivots overhead, heavier precipitation develops initiating evaporative cooling. Notice how the 12K is showing 850 temperatures collapsing as top down cooling takes place. This cooling is likely to spread east as the system moves in that direction.

Monday morning at 6:00AM you can also see that surface temperatures north of I-80 are below freezing and are at or near 32 even in the far south. This could mean a period of freezing rain or sleet before any transition to snow.

The 12K does indicate that by daybreak Monday showing freezing rain in the pink areas.

In the precipitation "type" depiction below, you can see the sleet and freezing rain preceding the advancing snow in blue.

Needless to say this is a super tough forecast and it is going to take some time before this is resolved, especially with all the range in various solutions. I'm very anxious to see where we stand Friday night. By then data will be better sampled on the west coast and hopefully models will start to lock in on trends. I wish I had the answers to the puzzle but the pieces keep moving. That said, the latest trends lead me to believe much of my area north of HWY 34, especially near and north of I-80 stand a good chance of seeing rain changing to a wet snow (possibly preceded by sleet and freezing rain) late Sunday night or early Monday. Stay tuned and as always roll weather...TS

ONLY 24 COPIES LEFT:

I will take this opportunity to mention that I only have 24 copies left of my book on the most expensive thunderstorm in United States history (11 billion dollars in estimated damage). This will be the final printing. If you are interested in having the most authoritative account of this extreme event I would suggest you act now. Don't miss this opportunity to own the weather story of a generation. You can order yours at derechobook.com

BOOK ENDORSEMENT.

*This book has been quite the talk with the Iowa State Library promoting it. I have never seen the State Library promote any books like this unless it was an award winner of particular interest to libraries. Hopefully your sales are through the roof!

Jolene Kronschnabel-Director of Hawkins Memorial Library, La Porte City, Iowa

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