A very strong early-season storm will move across Colorado later this week, bringing a very large temperature drop, the first snow of the season and a hard freeze Friday morning that will end the growing season in southern Colorado.
The best days to be outside will be Monday and Tuesday, as the wind will pick up Wednesday with the approach of the cold front and a strengthening jet stream.
The cold air will move in prior to waking up on Thursday and will drop temps from the 70s and 80s on Wednesday into the 30s and 40s for Thursday. It’ll be a shock to the system and windy Wednesday night and early Thursday as the colder air arrives.
So, what about the snow? Four days out I look for agreement in computer models between the upper air pattern, the cold front timing and strength, and the pattern of precipitation that the models are pumping out. The more agreement there is between these different aspects of the storm, the more confidence I have in how things will work out.
As you can see in the image above, showing the forecasted snow between the European long-term model and the Global Forecast System model of the United States, you can see a couple noticeable similarities:
– A bulleseye over the continental divide north of Highway 50
– Accumulating snow over the higher terrain of the Pikes Peak Region
– Indications of at least some snow over the eastern plains
– A minimum along the Arkansas River from Pueblo eastward
While the models differ a little in terms of magnitude, the similar pattern gives me confidence to tell you at this point Monday morning that many of us will get our first snow of the season later this week. We’ll start nailing down specific expected amounts in the next day or two.
Another thing we’re certain about at this point is that the coldest air of the season will bring a hard freeze to everyone that hasn’t had it yet. Some mountain areas may drop into the single digits early Friday. A spot or two in the high mountains could drop below zero if the sky clears fast enough. There are some indications that if there is enough snow on the ground, a couple spots on the Palmer Divide could start the day below 10 degrees too.