Ingredients of an Ice Storm

Good Saturday morning bloggers,

The snow from Friday night is long gone, but there are slick spots left over.  These will melt by noon.

The weather this weekend will be rather tame with highs jumping to the 50s Sunday.  A storm system will be tracking west to east across the USA Monday-Tuesday.  It will get its act together east of our area Monday, but we may still see a brief period of rain as it moves by.  More importantly, a cold blast will follow the storm system.  See maps 1-3










This cold air will settle into the Plains and Midwest Tuesday and Wednesday as a storm system moves into the southwest USA.  This storm system looks rather strong as it tracks northeast into the Plains Wednesday night-Thursday.   The storm will try to replace the cold air with warm/moist air.  However, cold air is dense and does not like to move out fast.  So, the warm air will  run up and over the existing cold air.  This rise of the warm/moist air creates clouds and precipitation.  At cloud level, the precipitation will be in the form of snow.  When it begins to fall to the ground through a layer below 32 degrees, it stays snow.  If it falls through a layer above 32° it melts to rain drops.  If it encounters a low level, thicker cold layer the rain drops can freeze and become sleet.  If the low level cold layer is shallow, then the liquid rain drops do not freeze until they reach the ground, an ice storm.  See the diagram below.




So, given this diagram where does our area lie.  Below I will show to maps from the 6Z GFS at 129 hours.  This is valid at 9 AM Wednesday.

MAP #5:  The first thing we look at is where is the rain-snow line, also known as the 540 thickness.  Cold air is dense, and when the thickness of the atmosphere from 1000 to 500 mb is 540 decameters or less, then it is below 32 through the layer.  So, this means along and north of the 540 thickness you have snow, most of the time unless the surface temperature is warm.  Our area is in the 546 thickness line.  This means there is a layer above 32° between 1000 and 500 mb.  So, any snowflakes will melt on the way down.  If the temperature around 5000 feet, the 850 level, is 32° or higher then the rain drops stay liquid as they reach the ground.  If the ground temperature is below 32° then the rain drop freezes on the surface, creating a glaze.  If the surface temperature is above 32° then it is rain reaching the ground.  Sleet will occur if the thickness is above 540, but the 5000 foot temperatures is below 32° by a few degrees.  This means the snowflakes are melting on the way down, but re-freezing around 5000 feet into ice pellets.  So, this is what would reach the ground.

So, again our thickness is around 546.  This means the snowflakes will melt on the way down.



MAP #6: THE 850 TEMPERATURE IS AROUND 32°.  So, this is likely not cold enough for the raindrops to re-freeze.  They stay liquid.



MAP #7:  THE SURFACE TEMPERATURE IS BELOW 32°, LIKELY MID 20S .  The rain drops would freeze on contact with the surface.  UH OH!  AN ICE STORM.  Not only does this show below 32° the surface, but in the 6 hour period from 3 AM to 9 AM Wednesday we receive .55″!  This is just the 6 hour period.  Total rainfall may come close to 1.00″.



Now, all of this being said it is 5 days away and can change.  If the main storm tracks farther south, we are in the deeper cold air and snow is what we have.  If the storm goes farther north, then the warm air gets forced in and our temperature will rise above 32° and we have rain.  But, if it changes little we have freezing rain.  It could start as sleet/snow if the precipitation races in before the deeper cold air exits.  This kind of forecast is always complex.  We will be discussing this the next several days.

Have a great weekend and enjoy the 50s on Sunday!

Jeff Penner




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  1. So what seems most likely, snow changing into rain? Jeff, what do you see as the most likely scenario?

  2. Still 5 days out and the models have been shifting north and northwestward. Past experience says this shift will continue a bit further. I think the storm will pass to the northwest and we will mainly have rain and possibly some thunder then be dry slotted. Look for the WAA to get us above freezing quickly by early Thursday AM with just a brief period of ice (advisory type event at best along I-70). I wouldn’t be surprised to see the heavy snow track end up in Western Nebraska into the Dakotas.

    This will be like most storms this winter that look promising early then miss us by a large margin. I would be very happy to be wrong and get a decent snowstorm for once…we’ll see…

  3. LoL..Mike you have absolutely no idea what will happen that far out. Even the experts are saying it’s way to early to make a call.

    • LOL…HeatMiser, you hurt my feelings by saying I have ‘no idea’. ;)

      I would put my scenario at about 70% likely right now. I have tracked storms and the models in our area for years. This scenario has happened quite a bit over the years. The models tend to under estimate the WAA in these situations. A weaker storm may well stay on a more southerly course.

      I think the storm is supposed to come ashore Tuesday night. We will then have a better idea when it is better sampled by the models.

      Still, unlike the ‘experts’, I am willing to put it out there 5 days ahead. :)

      • LoL Mike! 70 percent based on what? LoL I say it’s a roll of the dice, thus the best you can do is guess 50-50. LoL

  4. Like the 12Z GFS. Looks like more snow for KC, but again the cutoff is pretty sharp.


    • It seems like it’ll depend on whether the arctic high over Canada or the WAA has the greater influence over the storm. If it’s the latter, it’ll shift north and give us mostly rain. Something that everyone can say with good confidence is there will be some good moisture to help with the drought, which is much worse off to the west and northwest. :)

  5. Very good blog Jeff! One of the best and most informative write ups, showing the different scenarios.

  6. Good blog today Jeff. Happy to see my interpretation of yesterday’s data agrees pretty closely with yours today, as the 6z didn’t appear to change much from yesterday’s GFS runs.

  7. Only four days after Gary posed the question, “Will we have more accumulating snow this winter” on the blog, we have our answer and it is yes. 0.2 inches of snow officially measured at KCI last night, bringing seasonal total to 4.9 inches. I also had .2 inches at my house in KC North.

    • pathetic. We are in such dire snow straights that we call .2 inches accumulating snowfall. By the way, I measured this morning and we got every bit of 2 inches in Lawrence last night.

  8. That 12z GFS run is an eye-opener. Snow to ice and back to accumulating snow with no changeover to plain rain and liquid totals near 1 inch to 1.25 inches. Still too far away time-wise to be highly concerned. If models still look like this after the storm comes onshore then it will be time to start preparing for a major winter storm in the vicinity.

  9. By the way…go away ice storm, nobody likes you. As for a snow storm…welcome my friend, come on down!

  10. Amazing how the consistent the models have been concerning this storm for almost a week. The precip type has been a question, obviously, but what doesn’t seem to vary from run to run is the strength and relative position. Still a ways to go but impressive so far.

    • Forgot the link to the 12z GFS meteogram:


      and “”

  11. Regardless of the type, I am just hoping for the precipitation. However, please no ice. Bring on the rain or snow!!!

    • I need 6 or 7 inches to be happy minimum at this point, you know, considering old man winter has been pathetically incompetent these last two winters around here.

  12. Jeff, your post was great. I really enjoy your presentation and posts and you will probably not like what I’m going to say but I hope you continue to be the weekend forcaster. Not to say anything bad about George Waldenburger but you are much better.
    I and am sure I speak for a lot of vewers thanks for your hard work as we all appreciate it.
    I will be in Florida by next Thursday and I hope KC get a major snowstorm and not an ice storm.

  13. Latest GFS suggests ULL comes ashore in N California around noon Tuesday. New data not quite out far enough to see how this GFS run models the storm for us.

  14. GFS suggests precip begins around KC metro between 9 pm and midnight Wed. night as snow or snow/sleet mix. I have to run out on an errand in a few minutes so someone else pls finish interpreting this run.

  15. I’m only looking at the 850mb layer right now, but at least there the GFS is showing even a bit more cooler than the 12z run.

  16. Only concern I have is track of ULL is not favorable for much snow here unless we get snow in the WAA regime.

    • The GFS is hinting we will get some snow in the WAA regime, but heaviest period of precip would probably be ice for KC according to this GFS run.

      • Seds,

        All sleet and snow storm maybe??? Canadian model has a lot of snow for KC. Euro, not as much, but still a fair amount??

        The month of Feb. has a good chance of finishing above normal precip.and below normal on temps should these parade of Pacific storms pan out. Wild finish to winter is near…..

        • I hope it’s all sleet and snow, I hate freezing rain. But I realistically think there will be a liquid water component to the precip at some times. I doubt it is all sold ice forms.

  17. The only thing worse than a drought is getting the wrong kind of moisture. That would be a freezing rain that falls as liquid and freezes on contact. Why is that worse than no rain at all? Because when it falls and freezes, it breaks branches off of trees and shrubs, and sometimes brings down healthy trees. Even when it doesn’t break them, it BENDS the branches and subjects the tree to stress. Stressed trees are vulnerable to critters that primarily attack weakened trees.

    The last big ice storm we had cost us two destroyed full sized apple trees, and damaged a host of other apple trees and other trees. We couldn’t even walk through the woods for nearly a year because of randomly falling broken branches and the amount of wood lying pick-up-stick fashion on the forest floor. Such damage also impairs habitat for the wild creatures.

    If you want to hear a chilling sound, a deeply depressing sound? Stand in a sheltered doorway near a forest/deep woods while freezing rain is falling with no wind. You’ll hear a ominously quiet hissing sound… then a tinkling noise as a branch sloughs off some of the ice. Then you’ll hear loud CRRRRACKS as branches break. If the branch breaks off and falls, you get the crrrack then a tinkling as the branch falls through the lower branches knocking off the ice. And the worst sound is a deep hollow sounding really loud crack and then a crashing sound as a large tree gives up and falls.

    And when the ice melts, most of the moisture either evaporates, or runs off instead of soaking in.

    Freezing rain is bad.

  18. “″

    I think we are all interpreting this data a little different. The NWS GFS and IWM shows a decent track with good moisture. Also I’m not completely buying the 800-500 lines. We will be below freezing ground and at the 0 line in the 500 up to 800 with good lift. That’s my interpretation.

    • The 500 vort track is bullseye towards KC then lifts north at border towards Iowa. The 18z shows this drawing up lots of moisture from the south side of the storm and bringing it right over our area. There is a slight 3 hour period of time where the 800 line draws farther north basically right over KC but the 500 to surface stays at 0 line throughout. The cold air stays in place.

      This will be an all snow event according to this run. That’s my uneducated interpretation.

  19. Considering the surprising consistence I imagine us here in the metro will at least see snowflakes.

  20. Hey Jeff,

    are you going to update the blog after the new data rolls in at 6pm tonight. just wondering.


  21. Looking better the last few runs of the GFS. Like it. Updated snowfall map from IWM.


  22. I am saying this whole thing blows up and we get sprinkles at best and maybe clouds. Virtually no chance of WAA snow. How often does that occur here in KC? Almost never! Playing the percentages. Mizzou has a better chance of winning a road game against a decent opponent and that isn’t good! The chances of us getting WAA snow is about the same as the Royals winning 95 games! Which will happen first in KC from today? Can we post this on air Gary?

    A) Officially a 6″ snowfall
    B) Royals win 95 games
    C) Chiefs win a playoff game

    • Two and three winters ago, WAA snows here were common. That’s part of why we got so much snow those winters. But yes, generally they are rare here.

      • Do the royals get more than one year to get B’s 95 wins? I think they can do it in 2 (or 3…).

  23. Well of course A. No way Royals win 95 games in not three years. 80-83 games at best. Rotation is still awful. Chiefs, well they don’t have a QB won’t for at least a year. Better chance if 6″ snow in next two years.

    • I think A too, but not because the Royals rotation is still awful. I disagree with that. Major upgrade there.

      • An upgrade, yes. Still not capable of staying healthy or pitching past the fourth or fifth inning. Bullpen gets run down fast. The bats are decent if they can start better than last year, especially at home, them there may be hope for a decent season. Still think starting rotation won’t stay healthy even thru spring training.

  24. when is the new blog update going to come, is Jeff penner slacking on this major storm or leaving us out of the details of what he showed us on the 6pm newscast.


    • I think Jeff said at the end of his blog this morning enjoy your weekend and have a great day Sunday. I think that is his way of putting himself off the hook for any more comments this weekend. Lazy with a storm on the way.

  25. Those who think the Royals pitching staff still isn’t good has probably been reading too much material from Rany. Read what you see about the Royals on the Internet with a grain of salt, and keep in mind Moore was hired by Booby Cox as talent evaluator. Moore has made our offense the main concern which I’m happy to say is a good thing. Last year was not a true indicator of how good our offense is. Pitching putting us out of the game before we bat and underage hitters was the cause. Expect. 85 wins.

  26. “″

    IWM looks good for the ULL track. Moisture and temps. NOAA NWS is not as nice as last run for us.

    We are still in the wait and see game

  27. Just for those who love snow, this model is your friend :)


    I can’t say it’s realistic though.

  28. Can’t help but wonder. In looking at the 500 Mb chart, there is a pretty significant area of low pressure that exists near Nova Scotia around the same time that the ULL is projected to pass through the middle part of the country on Wednesday/Thursday. I wonder how much of a factor, if any, that area of low pressure will be on what happens around here. It seems to me that it will be a factor. Thoughts?

    • Just speculating here, but it seems like the stronger and slower that low is in moving off to the east, the more it will block this low from advancing off to the east, and thus forcing it to turn to the north more quickly and definitively. If this happens, it obviously increases our chances of ice/rain, and decreases our chances of significant snowfall.

      Again, I’m only speculating, and for all I know, it could have the exact opposite effect on the storm that will be passing through our part of the country, or perhaps it won’t have any effect at all upon our storm, but to me it seems as though our storm would stand a better chance of pushing further eastward before turning northward if the northeastern low pressure is weaker and faster moving.

      Any input on this from someone with knowledge of what potential impact the eastern storm could have is appreciated.

  29. I have always liked Canada. Here is their 500 MB chart from the 00Z run. Sign me up for this one!


  30. Matt the 540 line is way north on that model… Wouldn’t that mean more of a freezing rain event? With the low passing right through the metro?

  31. Wow never mind lol….. I was looking at the wrong line. This would mean quite a bit of snow if it were to verify!

  32. “”

    This has been trending towards more snow for us, and it’s indicating a very heavy band of snow.