I wasn’t going to blog today…but then Mother Nature is showing me a path to potentially get some snow flakes here before the weekend…after a more Spring-like weather for the next couple of days. So now I have to write about it…it’s what I do.
The good news is that this is just a blip in a mild to warm pattern that will continue into the weekend…so we’ll focus the blog on this questionable blip.
Today: Sunny and pleasant with highs in the mid 60s
Tonight: Fair and cool with lows in the 30s
Tomorrow: Increasingly breezy and warmer with highs in the mid 70s
Thursday: Showers developing later in the afternoon. I think we’re OK for the parade. Turning windy and cooler as well in the afternoon. Highs near 60° early in the afternoon but falling into the 50s later in the afternoon. Rain chances increase especially in the evening.
This Sunday marks the Spring equinox. Equinox is Latin for “equal night.” But the equinox, the actual day when the Sun is above the horizon for the closest to 12 hours, varies by latitude. For the KC area…it will be actually on St Patrick’s Day, the 17th.
Spring though starts on Sunday at 10:33 AM…I think we may be in the 70s!
Before that though…there is an issue. Last night during the late newscasts I alluded to the risk of seeing some wet snowflakes IF certain things happened with the next storm system coming through the Plains. This is still a needle in the haystack type scenario but it could happen and the model data overnight is a bit more bullish on this potential.
How can this come together? We need to get surface temperatures below 38°…really 37°. We need to get our storm system to develop it’s own cold air through the atmosphere. We need the storm to be close enough to us for this to happen. We need to have precipitation going when all this happens. There are probably a few other things as well.
Can the snow stick? Only if it’s coming down hard enough to overcome the warmer ground temperatures. IF this happens during the day on Friday…it will be tough to get non-grassy accumulations. Not impossible…just tough. That March sun angle thing is a thing, especially on the pavement.
So what about the storm itself? It doesn’t exist. Yup still not there. See the clouds southwest of San Francisco into the Pacific Ocean? That is going to turn into our storm.
Let’s go up to about 18,000 feet or so and show you the evolution of the future disturbance. For timing purposes… 0Z is 7PM…6Z is 1AM…12Z is 7AM and 18Z is 1PM
You can see how the storm comes into the Plains.
As the storm comes into the Plains…it starts chilling the air down in the atmosphere. This happens from the top downwards toward the surface. You can see that playing out in the data from early this morning up around 5,000 feet. The maps below are the temperatures at that approx. altitude in Celsius. 0°C is 32°F.
That’s at 5,000 feet though.
Below that the air is marginally cold to support flakes making it to the ground…but it is close. Let me show you the overnight temperature profile of how the atmosphere is reacting.
This is from the NAM model and look to the far right side. The areas in white or gray show the atmosphere 32° or below. That would support snow or frozen precipitation. On the far left side are the pressure levels which we convert to altitude.
So notice how the air supports snowflakes to about 3,000 feet and then those snowflakes come into air that is above 32° closest to the ground.
Model data typically has trouble resolving this small areas. IF the snow is heavy enough…it will cool things down enough and the flakes will make it to the ground. IF the snow is light enough…the flakes will melt.
In these situations you get those big dinner plate snowflakes. It’s not unusual for mid to late March and April to have this type of “big” snowflake events.
The approx. timing of this would be near or after 12AM on Friday morning. The overnight NAM model actually targets the I-35 corridor with accumulating snow. It would have to snow hard and fast for this to happen. The EURO sort of gives us some minor accumulations and the GFS does as well from here northward.
It’s interesting to watch. Again EVERYTHING would have to come together for this to happen…but it is on the table hence the blog for the day.
Just part of the March Madness of weather.
The feature photo is from Vicki Jim Voelk. Her Crocus are popping!