Joe’s Weather Blog: What I feel confident about heading towards Christmas (MON-12/18)

One week from today Jolly Old St Nick will have visited all the good boys and girls out there…and hopefully one of the items that the kids will be getting is cold weather clothes. It’s going to get cold…and potentially VERY cold. That is one of the things I’m most confident in when looking at the pattern upcoming. We’ve had starts and stops this month so far in regards to the cold weather…and this month is running more than 6° above average and that number may go a bit higher through Thursday before it comes crashes down. It’ll be interesting to see how the last 10 days of the month average out…also of note is the snow threats that may develop as well…



Forecast:

Today: Becoming sunny and mild with highs well into the 50s

Tonight: Fair and cool but still not too bad for mid December…lows in the 30s

Tuesday: Mostly sunny and mild again with highs well into the 50s

Wednesday: The concern is lower clouds invading the area…lets again shoot for highs into the 50-55° range.



Discussion:

Last night I had a bit of fun reminiscing about what happened last year at this time…on the 17th we had about 1-4″ of snow in the area…with plunging temperatures and sub-zero wind chills. Then on today’s date (last December) we were getting prepared for one of the, if not the, coldest Chiefs football game in modern history…with a gametime temperature of 1°. Here is the blog I wrote on that day!

You’re saying…wait a second…it really never snowed last winter…well it did…and sadly it was one of the “bigger” snows that winter in KC…setting the stage for those nasty temperatures.

This is from LAST DECEMBER…2016!

The high on the 18th (today’s date) was 6°. It was our coldest morning as we tanked to -9° with some areas down to almost -20°

Then on the 19th we started to dig out…the low was -3° and the high was 25°.

Snowcover is a BIG deal when it comes to overnight lows…and the maintenance of cold air masses.

Onwards…

I really don’t want to get involved much in the day to day weather through Wednesday…so let’s just skip to the more interesting stuff.

Starting on Thursday some rather interesting weather will be coming into the Plains. This will feature another big warm-up with temperatures surging to near 60°, and depending on the timing of the next shot of Canadian air later Thursday and whether or not we get sunshine through the low clouds on Thursday…highs may be into the 60s. It’s worth noting that the record high on Thursday is 63° set in 1893 (one of those weird lower high records compared to days before and after)…one of our oldest records too! Just putting that out there. Another tidbit…

It’s NOT out of the question we can get there…the set-up is favorable…it will be a matter of how much low level cloud over in the region…

Moisture will be coming northwards later Wednesday…that moisture is ahead of a rather stout surface storm that will be coming into the Plains on Thursday. As that process occurs…colder Canadian air will be dumping into the northern Plains and flowing southwards…so that you get roughly this surface set-up later Thursday afternoon/evening…

The front is still just barely to the west of here at 6PM…that puts us just ahead of the cold front…in an area favorable for warmth…but a caveat.

Lower clouds will be coming northwards…dew points will be increasing at the surface…and the winds will help bring in the moisture ahead of the front. That moisture though should be relatively “shallow”…not overly thick through the atmosphere. As a matter of fact only about 2-3000 feet thick. This “shallow” moisture layer could easily get chewed up by the dry air above it…considering the winds should be blowing pretty good during the day ahead of the front. IF we can get enough wind…and enough sunshine that 120+ year old record may be in jeopardy. 

So with all that said…the front will sweep through the region later Thursday and push the warmth all the way towards FL…in it’s wake…Canadian air moves in. So that is the forecast for FRI/SAT…colder…not brutal…but colder…closer to 32° for highs.

Then it starts getting more interesting heading towards Christmas Eve…perhaps as early as Saturday night. This is also the part that confidence in what the play out is going to be goes downhill. We know it’s going to get cold…then it’s going to get colder! That I’m guaranteeing. Ironically last Christmas was the 3rd warmest Christmas (65°) in KC weather history…and yet this Christmas may be one of the colder ones…or at least Top 15. a lot will be determined by whether or not there is snow on the ground

Coldest Christmas Day highs…OH MY to 1983!

Now that I have your attention regarding the “S” word…there continues to be the threat of “something” somewhere out there before Christmas. There though are MANY issues with this. The model data, as expected is back and forth…the GFS had it for a run or two yesterday then lost it. The EURO model after not having anything…got the snow back into it yesterday and last night.

The way the EURO is creating the snow is interesting…and really this is going to come down to the way this big digging trough (dip in the jet stream) orients itself. Let me try and show you what I mean. Let’s go up to about 18,000 feet or so…what we refer to as the 500 mb level in the atmosphere.

Using the slider bar below…push it to the far right…that shows the EURO model for noon on Sunday. Notice the way the trough (big dip or U) in the jet stream is shaped and the axis of that dip…

Now slide the slider to the left…this shows the GFS model…again for noon on Sunday. Notice the BIG difference in the “dip” or U in the jet stream…notice how it’s more centrally located in the Plains?

That difference in the orientation of the jet stream is vital to our snow chances. IF the EURO is right…this pattern would allow a rather decent string of winds aloft to come through the Plains…this jetstreak would create enough lift to generate snow. There might be a time that we’re fighting dry cold air and trying to saturate the atmosphere initially, but in time…it would snow(!). With the cold air in place…this would be a high ratio snow.

What does that mean? Well typically we talk about how 1″ of rain would = 10″ of snow…or there abouts. When the atmosphere is barely supportive of snow (just barely cold enough)…this ratio drops. When the opposite occurs…and the atmosphere is VERY cold (which it will be on Sunday) more snow can be created by the same amount of moisture. we used to get those types of snows back in the big winters of 09=10 and ’10-11 if you remember. That fluffy and easier to shovel type snows.

As a matter of fact the EURO model yesterday at least was a classic set up for this type of event…and to a large extent so was last nights run.

The GFS says otherwise. With the orientation of that U or dip in the jet stream…that wave coming out of the SW can’t really play out for us…it would be shunted more towards the I-44 corridor.

The rub is which is right…and again it’s just too early to say. As you know I preach using the ensembles to help with confidence from 5-10 days away from an event…which still applies. The ensembles off the EURO model are cranking out about .15″ of liquid for Christmas Eve with slightly higher “liquid” totals just south of KC proper (I mean just south)…again remember the higher snow ratio issue that will unfold that day.

Which model is typically more accurate? Well history says the EURO…and there is proof that many don’t like to look at…just because the GFS model is run 4 x’s per day means squat. Notice the blue line below…notice (mostly) it’s on top of the other models…notice the black line (GFS skill)…not as good.

That actual data…and it’s not subjective interpretation…though still doesn’t mean the EURO model is right for Sunday.

The ensemble data is showing the razor closeness of this possible snow. The GFS model isn’t to optimistic BUT it’s own ensemble runs are more optimistic BUT the placement of whatever may happen is all over the place…so the ensembles say something could happen closer to home (as opposed to the “operational”model that is viewed more widely.

OK…if you’re not totally confused yet…let’s recap…because I’m approaching 1500 words again and the internet may break ;)…

While my weather geekness is very interested in the EURO scenario…when a model shows a near perfect set-up some 6+ days out from an event…with an almost perfectly located snow bulls-eye max…color me somewhat skeptical. IF the EURO is just a bit off with regard to the trough shape or orientation that I highlighted above…then the results here on the ground will be different! Please remember this!!!!!!!! Please remember this when you see on FB various snow models posted and shared a bizzilion times. 

Also of note..again to reiterate…what MAY happen will be a high ratio snow event…that means less moisture creates extra snow compared to average. So those common model snow maps that most may post will likely underdo the potential somewhat.

Right now I can’t budge off my White Christmas forecast. There is a 20% chance of a White Christmas in KC in my opinion. I will think harder about this tomorrow…I won’t be going down…regardless of the model data…but I could go up.

It all depends on the “shape” of the letter U in the weather world….amazing!

Last nugget before I wrap this VERY long blog up…the last 10 days of the month may be one of the coldest last 10 days of December we’ve seen in KC…it won’t be 1983…and IF there is snow on the ground it will be colder…but this is another #evergreen piece of data.

Our feature photo comes from Kevin Short…it was taken at the WW 1 Memorial.

Joe

 

 

 

 

 

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6 comments

  • Richard

    Thank you for your thoughts with this comprehensive blog Joe. You put a lot of thought and work into it.
    I especially like the maps that you put out. The automated maps on Saturday that we could look in on and see what was unfolding at any given time. And todays slider map ! Very nice.
    So, no doubt it will be a cold Christmas Eve and day. The ups and downs/back and forths of the models predicting snow can make them crazy to follow, which I don’t ! 😊
    At any rate it will be nice even if we have just enough to make it a white Christmas, which we rarely see here.
    Again, thanks for the blog Joe

  • Lance Eberhardt

    Another great blog. Thanks for the candid & honest approach. Too many “what if’s” out there to go all in and I like how you keep it real. One of the many things I’ve learned from reading your blog is the fact of how difficult is it to forecast beyond 5 days. Keep doing what you’re doing!

  • Mike Beckner

    Joe, this blog is an example of why, in my estimation, you are the finest communicating meterologist in this market. Nothing against any of your team mates, mind you, but the extent to which you research and present your hypotheses is not only enlightening, it demonstrates your knowledge of your science, and the pitfalls of weather forecasting. Thanks so much for all you do!