 Welcome to the weather forecast for the week beginning Wednesday, February 10th, 2021. I'm Chief Meteorologist John Ennsworth for Longmont Public Media. We start this week with a new moon, and if you take a look at the skies over Colorado video also on this channel, you'll see that many of the planets in the night sky are near the sun or behind the sun at this time as well. So not a lot of things to see in the sky but stars, and this week, those have been covered by clouds most of the time. Taking a look at our drought from last week to this week, you can see we have not so bad along I-25, still bad out west, but we've had some release on the eastern plains there and down the southern parts of the state from the rainfall and snow that has occurred. The snowpack is really fantastic. We have a lot of snow building up, so much so that the avalanche danger is even elevated. So once that starts to melt in the spring, we'll see this change quite rapidly, but right now it's not affecting the soil hydrology much. The avalanche danger, I think I heard that the number of avalanche deaths is a record this year in the United States and some of that's due to the really good snowpack and some of it's probably due to people not being able to get reservations at ski resorts and having to go back country where things are not cared for or as safe. So be careful out there. Looking nationally, there's our drought conditions from last week and you'll see some rains in the west and in the eastern margins of this, gave a little bit of release so some of the colors are less severe. We're hoping that as we go into the spring, we'll get more moisture into the continent, we'll see a lot of this start to pair back. As far as we can get it knocked back before summer, the better. Speaking of that precipitation, out on the plains not much, southern mountains not much, but the northern and central mountains got a lot. Some of these areas are an inch, two inches, even three inches of liquid precipitation equivalent. So melt the snow down, see how much water fell, and that's continuing. It's going on as we continue to get moisture from the Pacific upsloping onto the western side of the Rockies. So the big story is this broad trough over the nation. We have a little ridge out west, a little ridge out east, but this big trough is going to be reinforced and see other troughs dig down in short-wave troughs bringing much colder air down into the nation. This will broaden and deepen, we are really going into the icebox. Some of that is because of what you're going to hear on the news, polar vortex. Polar vortexes are not weird, they happen every year. There's always cold air that can break off from the Arctic, and travel down to the lower latitudes, and that's what's about to happen. The water vapor satellite image showing dry air and the reds down here, moist air and the grays through here and the white colors. The pink are very cold ice crystals in the upper atmosphere at the top of this moisture. So those are the cloudy skies that they have there and out east of us. But this purpley color up here is probably under clear skies. The air is so cold at the surface and in the lower column of the atmosphere that is cold as these high clouds are. So that's the polar vortex. You can see even the swirl around the low right there, and some of that's going to be breaking off and coming down into the west eventually. So what we have right now is a train of moisture from the west up sloping into the mountains, you have snow in Utah and Western Colorado. If you take a look at the Rockies, you can see they look about twice as tall as normal, and that's the eastern side of this moisture. As it tops of the mountain, it's dropped a lot of its water load in the form of snow. That air sinks back down and warms up and the clouds evaporate. So you just have this end of the moisture off to our west. What we've been seeing in the mornings, the last couple of mornings and we'll probably get for another morning or two is the edge of this Arctic front being draped right down I-25. Last weekend, we were expecting it to be very cold, and that didn't materialize because the really cold air being dense stays close to the earth, and it was only about 4,000 feet deep above sea level. So Sterling and Kansas and Nebraska had the cold. Up here, I-25 and into the mountains remain pretty nice. It wasn't bad at all this weekend. But by bit, the cold air is getting reinforced and a little deeper. It's now about 6,000 feet deep. So we're seeing temperatures in the teens in the morning and lingering in the teens and 20s throughout the day. If you go to Estes Park, they only got down to the 20s, and they climbed almost to 40 today. They're above that cold air. Then deeper part of the cold air up by Sterling had them in single digits much of the day. So you can get the weather you want just driving east and west through Colorado right now. Eventually, the cold air is going to come and overrun that and we'll see that in just a moment. So here's our 10-day GFS ensemble. Here's our normal high temperature of 45. We're raising all the way to 47 over the next 10 days, and normal low 18 rising to 20. So we get a couple degrees expected warmth. That's not what's going to happen. Our forecasted temperatures are right in that normal area, but because that Arctic front, just a few miles from Lyons to Estes Park you get a big change in weather. The models don't pick up that detail very well. So it thinks we're in that air that Estes Park is enjoying more than the cold that we really have. But here on Thursday, the cold front arrives. Here's a really good agreement among the model runs that there's snow coming and snow continuing on into the next week, but the temperatures plunge far below normal. You'll see in my seven-day forecast, I'm calling for really serious cold, single digits for highs one day. So let's put this into motion and watch what this polar vortex does. Here it is rotating around up here. Here comes a lobe of cold air down. I have a little trough in the southern branch of the jet stream. It'll help pull this down. There's a closed circulation right there, super cold air and there's that big trough digging it down to the west, and here's the weekend energy. This is what's going to help lift moisture up and pull the cold air down. You can see going into next week, there's still a trough over Colorado, and it isn't until later in the week, we start to see a ridge build on the west coast again. So we've got seven to 10 days of this ahead of us. Let's take a look at that cold air. The purples in the pinks are below normal, really below normal temperatures. You can see the above normal and red here. You can see this outline of the mountains very carefully here. It's all caused by altitude alone. But then as that trough comes down, the cold air just floods down into the west, much deeper than the Iraqis are tall, and the entire Western US, even down to Arizona, southern California, gets amazing cold air. This will probably kick off a period of Santa Ana winds in California. So I'll keep an eye open for that in the news because the air has got to go someplace. And then finally, at the end of that sequence there, I can't back it up, sorry, you did see some of that warm air start to come back into the west. So let's take a look at our storm in the future. You see a very tight gradient here with that cold air out in the plains and warm in the west. Then the storm starts to gather as we came into the weekend. This low helps organize all that, and we get a pretty extended period of upslope snow, pretty heavy at times, especially in the mountains before it pulls out in the plains, probably causes a newsworthy blizzard up in the New England states in Michigan. So the snow over the next five days, says 10 days, sorry about that, is pretty significant. Not all models agree with this, but this has this in the four to six inch range out here on I-25 in two foot, three foot amounts from the mountains. Then you go out to 10 days, you can see the state maybe picks up another two, three, five inches with the places in the mountains reaching 36 inches of snow and the yellows there, there and down through here. So this is really gonna bring in the snow pack. It's gonna be significant. So here comes the cold looking at 30s, Wednesday into Thursday, the cold front comes Thursday night, the snow chances start picking up right away and we plunge to the teens and then single digits for Saturday. Valentine's Day will be in the teens but sub zero temperatures at night. So cover up the pipes inside your house. Everything else should probably be pretty hardy and ready for the winter, but those need to be protected still and we don't see 40s again until the beginning of next week. For frequent weather updates and local news, check out longmontleader.com. I've been chief meteorologist John Insworth. Keep looking up.