Brendan Heberton

We are nearly a week into October now and inching closer to the average snowfall
for many locations across Colorado and the High Plains. Plenty of anticipation
on when we can expect the first snow to fly this season at lower elevations,
with the backdrop of El Niño (and some historical support for early season
snows), but also we are coming off the hottest September on record globally, a
stat that hardly screams "snow". 

> ERA5 September 2023 monthly data are out.

I'm still struggling to comprehend how a single year can jump so much compared
to previous years.

Just by adding the latest data point, the linear warming trend since 1979
increased by 10%. pic.twitter.com/AnNAbyUQwY [https://t.co/AnNAbyUQwY]

— Mika Rantanen (@mikarantane) October 3, 2023
[https://twitter.com/mikarantane/status/1709141665762492512?ref_src=twsrc%5Etfw]
Across the CONUS we've seen a rather high-contrast start to the month with
regard to temperature anomalies – the western U.S. running much colder than
average to start the month, and the central plains and upper midwest running
grossly above average over the last 5 days. 

This, however, will shift in a big way for the second week of the month. That
is, the cold will move into the central and eastern half of the country this
weekend and into next week, with anomalous heat building across the west. 

For Colorado, the transition initially may not change much. We have been on the
eastern edge of the cold to start the month, and will find ourselves on the
western edge of the cold over the next week. 

That said, after the ridge builds in this weekend and early next week across the
west it looks like it'll let a system through by the middle to latter half of
next week which could deliver some meaningful precipitation and snowfall to
parts of Colorado somewhere in the Wednesday to Friday timeframe. 

A system of some variety looks increasingly likely, but the details will take
some time to work out. Front and center will be if there will be enough cold air
for snow at lower elevations or if the snow will be confined to higher
elevations across the region. The chance for precipitation across the region
however has growing confidence. 

Here are the latest probabilities for east-central Colorado: 

With the European ensemble showing a good signal for some weather moving through
for the middle to latter half of next week: 

For those in the Denver area, specifically, the chance for snow looks largely
dependent on if we can piece together some cold air. Right now, guidance isn't
all that impressive on that front, but certainly a cool off by Thursday. Still,
lows near 40°F Thursday morning when we may see our best chance of precipitation
would suggest snow would be favored at higher elevations up outside of the city. 

If we take an early look at snowfall probabilities for 1" of snow or more
through next Saturday the 14th. Good odds for the central Rockies, but some
signs that some model guidance wants to pull that snow line down a bit over
lower elevations of the adjacent plains... so something to watch. 

And finally, snow or no snow, we are hopeful for some precipitation later next
week. Through Wednesday morning, pretty quiet across the region: 

If we pull those totals through next Friday night, we see guidance pulling some
beneficial moisture across the northern Rockies, and ultimately the northern and
central High Plains: 

Plenty more to come as we get into next week, but something to watch as we head
into the weekend! 

While we wait, don't forget to enter your chance to win this year's snowfall
prediction contest. The window for submit entries comes to a close on the 10th! 

Weather5280 First Snowfall Prediction Contest 2023Predict the first measurable
snowfall at Denver International Airport and win!
[https://www.weather5280.com/contests/first-snowfall-prediction-contest-denver]

Weather5280 Insider: Will system next week deliver season's first snow to the Front Range of Colorado?