Matt Makens

With La Niña in control, we enter most of our forecasts with a drier and warmer
than average bias – unless the PNA and NAO combine to offer a trough-favored
pattern, which isn't the case through much of the next month.

October was interesting in that we had enough significant cold over the plains
for the eastern half of Colorado to have had near and colder than average
conditions.

Precipitation was just as expected... lacking in most areas: 

Going forward, we believe that there may be some relief for some of the mountain
areas of Colorado – as seen in the most recent snow event, but areas east of the
mountains will likely continue to struggle to receive much meaningful moisture. 

We will also continue to see periods of strong wind, which will only add insult
to injury in terms of soil moisture depletion.

The Next Two Weeks:
The PNA and NAO oscillate a bit during the next two weeks but neither offer much
of a significant negative trend, which would be an indicator of a slower flow
regime and time for deeper trough development over the Western US.

On the contrary, the GFS points to a rather strong ridge to develop early next
week, allowing warmer than average and dry conditions to return to the state.

The maps below are computer model forecasts from the EURO and GFS models, and
show the general precipitation pattern during the next two weeks. Brown areas
indicate drier than average conditions, while green areas indicate wetter than
average conditions.

The temperature forecast will generally remain average to above average.

The next month:
The MJO will take a more favorable phase for mountain moisture approaching
Thanksgiving, and we may see enough help from the PNA to allow some troughing,
too. This combination implies the chance of colder and wetter weather for the
back-end of November and into early December.

The end result of this may be to see the drier than average conditions shift
east as the mountains may benefit from the change.

Temperature anomalies may shift a bit too.


The bottom line, La Niña's impact on Colorado remains quite "classic" going
forward with only occasional cold snaps and moisture.

October results are in, a look ahead through early December