Brian Bledsoe

La Niña is still alive and well. The sea surface temperature anomaly animation
for the past 90 days not only shows La Niña being maintained, but it is actually
getting a bit stronger.

While the North Pacific has warmed from late this spring, the central/equatorial
Pacific has remained quite cool. The animation below shows what is happening
beneath the surface across the equatorial Pacific: 

Simply put, the graphic shows ocean depth down to 450 meters across the
equatorial Pacific Ocean. Those last few frames show cooler than average water
dominating all the way down to 150 meters, until you get to the Western Pacific
Ocean (left side), where warmer than average water dominates. Could this change?
Not right now... Easterly trade winds continue to rip across the equatorial
Pacific Ocean. The forecast graphic below shows exactly that.

The blue/green represents strong easterly trade winds blowing across
central/equatorial Pacific, essentially in the western ENSO regions. These
strong trade winds allow for the upwelling of cool water beneath the ocean
surface. That keeps the sea surface temperature anomalies quite cool. The
orange/red shaded areas are westerly wind bursts. They basically converge over
Indonesia, which causes a lot of thunderstorm activity, that can be tied to the
MJO (Madden-Julian Oscillation) Remember, the MJO is very important when it
comes to our weather variability. 

With this setup, the MJO cannot fully cycle and many times fades in "region 4 or
5". The graphic below shows what the MJO has been up to, since late May...

You can see that it had a pretty good bump into regions 6, 7, and 8, before it
has essentially stayed in null space (very weak), or cycled from regions 1
through 4. 

Now, the MJO usually isn't the dominant longer range forecast feature during the
summer. This tends to change as we enter into fall and winter. As of today, it
shows the same persistent trend that prevailed last fall and winter. This is a
trend that concerns me, because I think it may occur this fall and winter. If La
Niña would weaken and go away, the trade winds would weaken and the MJO would
cycle. This would likely lead to more frequent storms to cycle through, and
prevent the weather pattern from getting stuck in a rut. Do I see that that
happening? No, not for awhile anyway. 

The graphic below shows a high likelihood for La Niña to hang around, until late
winter.

This takes into account several different computer models, and most of them are
fully on board with La Niña hanging around. The one silver lining to this? It
could POSSIBLY weaken late this winter, which would allow for better snow
potential in February through April. If this weakening trend occurs sooner, then
it is possible our chances for better snow will occur sooner. As of right now, I
don't see much changing until at least January.

Does that mean no snow? Of course not. However, FOR SOME OF US the likelihood
for less frequent snow producing storms is higher. The computer model forecasts
shown below, show that trend too.

EURO Seasonal Model Precipitation Forecast
October 

November

December

January

February

The EURO Seasonal Model doesn't show a complete shutout for snow for us. In
fact, one could argue that the Northern Front Range and possibly Northeast
Plains could see average to above average snowfall as we move into the winter
months. Kind of similar to what happened last winter, AFTER it finally did start
snowing in January and February. However, we might have to get through a dry
fall and part of the early winter.

NMME Model Precipitation Forecast 
October

November

December

January

February

The NMME Model is pretty much on board with that kind of thinking too. Likely
drier than average October and November, before we start to see better
opportunities for some snow. I would also say this: The farther north you live,
the better your chances will likely be. Areas south of I-70 (aside from the
Palmer Divide) will usually struggle to see much snow. That is reflected with
the models, as they both show the tendency for a storm track that favors
northern areas. This is consistent with what La Niña is usually about.

I know it is quite early, and I didn't address any possible analog years to
match up with the next several months, but I know you are thinking about what
lies ahead. For that reason, I wanted to share my thoughts. I'll provide another
update, in a few weeks and start talking analogs.

La Niña update and early fall/winter outlook