Joe’s Weather Blog: We’ve been down this snow road before (WED-1/12)

Weather Blog

KANSAS CITY, Mo. — I’ve been thinking and thinking about this storm and trying to think about any past systems that were sort of similar. There is actually a website sort of devoted to taking current model data and then comparing its output to previous real storms (remember at this point all we have is eye candy on the models for the region and for the storm track) and even using that information, it’s struggling to find something that cuts a path and intensifies through the Plains as this one does.

There are shades to previous storms: a storm in late January/early February in 2015 is sort of similar, but trying to find something that really lines up has been tough.

One complication of several that this poses to me: Some good data has been ingested into the models overnight thanks to a recon mission investigating the moisture content of the atmosphere off the western US. So that may be helpful, and isn’t a routine thing.

There are lots of what ifs with this and will continue to be into Friday. There is a wrinkle to this, too, including the potential of precipitation-type issues for at least part of the State Line area… really remarkable when looking at the higher-res data available.

Anyway, let’s enjoy the 50s for a couple of more days.

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Forecast:

Today: Filtered sunshine and less windy than yesterday with highs in the mid-50s.

Tonight: Fair and not too bad with lows near 32 degrees.

Tomorrow: More sunshine and pleasant with highs in the mid-50s.

Friday: Increasing clouds with some light rain possible in the evening moving in from the north. Highs in the 40s.

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Discussion:

Our first 60-degree day happened yesterday thanks to strong winds gusting to 37 mph for a couple of hours in the afternoon. That proved the mixing that I talk about often to stir the air up and allow it to warm up despite the low sun angle we have in the middle of the winter season. The only thing holding us back today is the lack of wind to again stir the air up and the cirrus clouds filtering out the sunshine for awhile at least, but overall this is a nice run of days around the Plains.

The main item of the blog is this thing off the western U.S. coast.

It’s the big comma shaped cloud off the western U.S. There are actually three: one in the lower right, another in the top middle (our system), and another on the far left.

How that system fares as it comes ashore and where it ends up going is the driver to our snow and rain risks here as well.

Ahead of the storm, the air is rather mild and that isn’t going away anytime soon (the next 48 hours or so).

Temperature anomalies today and tomorrow are wonderful for January standards:

Tomorrow:

That’s a lot of red and orange on the maps above. That’s mild, hence the 50s when average highs are in the upper 30s for mid-January.

Because of clouds, we should see a drop into the 40s Friday. That will be in response to our system.

The storm in question comes ashore tomorrow and then the wave in the atmosphere sort of goes through various iterations as it moves through the northern Rockies where it then starts to merge with another fast-moving wave coming out of British Columbia. So we have a couple of things trying to happen.

The end result is an intensifying upper-level storm developing near the region. Take a look at how the EURO is portraying the unfolding events above us around 18,000 feet up:

See that developing circle in Kansas… that’s our maturing storm dropping west of the area.

That track is important to us for several reasons: One is that it means it’s less likely we get dry slotted, two it means that colder air on the north side of the system towards the Interstate 80 corridor and northwards will create a large area of accumulating snow. That in time will be dropping southwards and that is the crux of our potential accumulation locally.

With us being on the east side of this uniquely tracked storm, there is an issue and the models are starting to sniff it out. A layer of air above 32 degrees closer to the surface that may take a bit of time to get rid of on Friday night. Let me show you what I mean. Take a look at the EURO and the GFS side by side. The numbers represent the temperatures at around 3,000 feet or so. They’re in degrees Celsius so anything above zero is above freezing. No bueno for snowflakes to make it to the ground.

These maps are for midnight Saturday.

Slide right for the EURO and left for the GFS

See that “tongue” of 32-plus degree air for a bit right along the State Line? That is something to watch. That would slow down the transition to snow for a few hours.

The newest NAM model that just came out this morning though doesn’t have this “tongue” of “warmth” at 3,000 feet or so at midnight Saturday. It’s ready for snow! To be fair, the NAM is also trying to overcome some dry air in the bottom 5,000 feet of the the atmosphere, which I also think is realistic for a time on Friday evening. What I’m trying to say is that it may take a bit of time Friday evening/night to get things to come together.

OK, let’s drill down towards the surface and follow what the NAM does in terms of when things get going. These maps start at 6 a.m. Friday. For timing, 18Z is noon, 21Z is 3 p.m., 0Z is 6 p.m., 3Z is 9 p.m., 6Z is midnight, and 9Z is 3 a.m. That blue shading is snow.

The biggest key for us to get accumulating snows around here is how well doesthe east-to-west band of snow develop towards and north of the I-80 corridor. What happens there will be dropping southwards down the State Line, and perhaps a bit east-southeast as well. If it’s a fully developed band, several inches of snow are possible on the assumption that we get rid of the “warm” layer when it gets here, we should.

Now the issue is how much precip this thing cranks out as it intensifies into the Plains. The new data this morning has roughly 4/10ths of an inch of liquid equivalent. Now this is good for snow lovers, but we’ve seen time and time again this winter how the models are too generous with the liquid outputs only to back off within 24 hours (or less) of the main event, and that is VERY much in the back of my mind.

OK so let’s say the model does back off on the totals. Let’s generously cut that number by 1/3 or even 1/2(?). That is still roughly 1/4 inch of liquid. The ratios should be pretty standard with this, close to 10:1. The raw output would get you here, without me cutting the possible biased high liquid amounts.

Via Weathernerds.org

Let’s just sort of massage those numbers down a bit and you more or less get roughly a 2 to 4-inch swath of snow for the metro, higher up north. That is sort of where my headspace is right now.

Another way of portraying the range of possibilities is to use the ensembles. Basically it allows us to get data using small variations of initial conditions, model physics, etc. There are some 95-100 model solutions that I can look at each day, two to four times per day… a lot of models.

When there are a lot of the ensemble members agreeing with the main model that most look at, it gives you more confidence in a solution. When the ensemble members are all over the place, you may have less confidence in what could happen.

So let’s share that with you. These are from the EURO, GFS and Canadian. I’ve shown these before.

EURO…
GFS
Canadian

The first shade of blue in the members represents 2 inches of snow. Of the 93 models (I included the other data that I looked at), 68% have at least 2 inches of snow.

So let’s try and make this simpler. This is just from the EURO model. The probability in % of at least 1, 3, and 6 inches of snow.

% chance of 1 inch of snow. For Kansas City, that’s roughly more than 60%
3 inches of snow. For Kansas City, that’s roughly 30% and wow that is a gradient developing!
The risk of 6 inches of snow. Northern Missouri barely in that

The GFS not shown is sort of about the same too.

So there is confidence in at least 1 inch, decent thoughts for 3 inches, and little thought at this point for 6 inches.

Again, these are just the model outputs.

There is one other issue that may develop with the snow band coming through near or after daybreak Saturday: Winds. The winds above us really crank up by 9 a.m. several thousand feet above us:

30-40 mph winds above the surface

Some of these winds may work their way to the surface so we could have a wind-whipped snow as well Saturday morning before lunch, blowing the snow all over the place from east to west.

So many things to think about. We’ll continue to watch things unfold. It does appear though that the heaviest snow from this is more towards Iowa than towards the State Line near Kansas City.

Oh and Saturday will likely feature some sort of midnight high with PM temperatures likely only in the 20s.

My goodness!

Ben got his drone up this morning and it was spectacular.

Joe

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