Matt Makens

January starts off with a bang across the West with a steady supply of moisture
hitting California and then fanning out to surrounding states, Colorado
included.

We recently wrote about the next wave of moisture adding to flooding issues for
California, and the latest snowpack numbers there: 

Atmospheric River delivering torrential rain, snow, and wind to California;
significant flooding possible this weekOne storm is not a drought buster,
however, the current extended pattern in
place over California could make a significant dent in the ongoing drought
there
– but at a cost. Precipitation totals along coastal California (northern
California in
particular) have been significant over the last 14 day…Brendan HebertonJan 03,
2023Weather5280
[https://www.weather5280.com/2023/01/03/atmospheric-river-delivering-torrential-rain-snow-and-wind-to-california-significant-flooding-possible-this-week]
For Colorado, the supply of moisture gave our snowpack a boost as a whole (126%
of median as of January 4th), but we have a lot of water needed across the
Arkansas basin to get us back to average there: 

Although it appears the mountains will remain above normal for January, the
plains may not without some luck later in the cycle. 

In this post we will discuss teleconnections first, then discuss the next two
weeks and the monthly averages.

For a time the atmosphere began to weaken its La Niña grip. At the same time we
saw dramatically strong ridging over Alaska, now gone, and a Greenland blocking
ridge. The combination of all the above led to the dramatic cold we felt as a
country leading into and through Christmas and the development of this
atmospheric river of moisture for the West.

Going forward, the atmospheric strength of La Niña is rebounding, we see
troughing return near/over Alaska and Greenland. With that said, it appears we
will be shifting moisture back to the Pacific Northwest and Northern/Central
Rockies more so than the Southwest. Plus, the atmosphere will be building up a
reserve of cold air to the north which will ultimately dip into the U.S. The
timing of these things will increase late January into February. That may be
neither here nor there as what moisture is falling in early January likely makes
up for any shortfalls later in the month, and the warmth east of the Rockies
probably trumps the impact of the cold for the Northern Plains later this month,
too. 

What's controlling the weather in January as La Niña shifts back to the leading
connection? Let's take a look at a series of teleconnections and what they can
tell us about the upcoming weeks. 

The MJO
[https://www.climate.gov/news-features/blogs/enso/what-mjo-and-why-do-we-care],
may weaken anyway but will shift from phase 7 to 8 which is a drying impact on
the Western US. and a cooling impact on all areas east of the Rockies. 

The PNA, NAO, and AO all trend back toward relative neutrality during the month.

Those teleconnections do lead me to believe there will be a build up of cold air
to the north this month which has the potential to drop south into the states
very late in the month or early February.

The next two weeks
The moisture supply out West, and the precipitation with associated (potentially
severe) thunderstorms over the South are likely the biggest headlines for the
first half of the month.

For Colorado's mountains, it is looking likely for a wet month but I feel it
will be close in the end for many of our local SNOTEL sites. You can see the
real surplus is over California for the next couple of weeks.

Let's zoom in. Here's an example for precipitation and snowfall on the way to
Steamboat Springs.

Meanwhile, east of the mountains a milder and drier than average forecast are
seeming more likely until the tail end of our two week period. Denver used here:

We do have an eye on that 11th/12th system, it's the next best chance for
moisture and hopefully it improves by bringing more moisture to us than what is
currently projected, but we shall see.

That uptick in precipitation for the Denver area toward January 19th will be fun
to watch. GFS (I know I know, don't go there) shows a great looking storm two
weeks out ;-) that would help the back-half of the month: 

January averages
In the end, it appears the remainder of the month will average out to be
something like this for precipitation (wetter than average is the green shades,
drier than average in the browns):

And, the temperature outlook for the month along these lines:

From a teleconnection and analog based approach the results are similar,
however, teleconnections do suggest the development of cold over Canada that
will move into the U.S. This may not develop until February, as modeling
suggests.

Bottom line
In the near term the moisture certainly favors California and what's left of
that moisture will try to fan out toward Colorado, particularly across the
western half of the state. There appears to be reasonable likelihood that the
mountains will do okay this month but those of us east of the mountains return
to a quieter phase relative to the second half of December and very early start
to January. 

If the metro areas and Plains have a chance at good moisture it'll come after
mid-month as it appears in all data as of this posting.

January's weather outlook across Colorado and the region