Brian Bledsoe

As we head deeper into July we thought it time to give an update on the progress
of the monsoon. If you've been frequenting the site, you know that we not only
expected the monsoon to be a late arrival, but also a diminished one. So far,
there has not been any real monsoon signal. The graphic below shows is a
precipitable water forecast, for the next two weeks. 

Basically, brown means a drier atmosphere, and green means a moist atmosphere.
The green that shows up across Colorado and the surrounding area is not tied to
the monsoon. We would want to see a plume of green extending northward out of
Mexico into Arizona and New Mexico, signaling a push of monsoonal moisture. We
really don't see this occurring in the forecast animation. There is a little
push over the Baja of California into Arizona, but nothing significant. 

However, there is a signal that lies beyond the next two weeks, that does show
some potential. The graphic below is a zonal wind anomaly forecast for the next
two weeks. Notice the forecast period on the left side of the graphic... The
region of interest is from west to east across the equatorial Pacific and Indian
Ocean. Blue shading means easterly trade winds, while yellow/red means
westerlies. 

Notice that there are some easterly trade winds occurring in ENSO regions 4 and
3.4, through July 11th. This is really not consistent with what you would expect
from a developing El Niño. However, this anomaly can sometimes happen before the
true push from El Niño occurs, which should be later this summer and fall. 

From July 13th through July 19th, notice what starts to show up? A westerly wind
burst (yellow/orange) shading near Niño 4, between the Dateline and 120 E. That
westerly wind burst looks to have some staying power, and could likely cause a
rather stout MJO signal to develop. The graphics below are MJO forecasts (EURO
and GFS) through the 19th of July.

Pretty crazy, but they both have the same idea of the MJO signal potentially
popping out of the null space later this month, between the 18th and 20th. The
EURO models is less aggressive with the signal, but still has a wide range of
possibilities. The models are also pretty wild with the actual forecast strength
of this POTENTIAL event, but that will likely become more clear in the coming
days. 

Having an MJO event show up this time of year, as we head into the heart of
monsoon season, is a good thing. It would likely give the monsoon a little kick
in the butt, even if for a relatively short time. I am not wildly optimistic
that this will have a lot of staying power and erase our diminished monsoon
forecast. In fact, the latest EURO seasonal model forecast (shown below) for
July/August/September, continues to show drier than average for much of the Four
Corners region. We shall see. 

The western half of Colorado is MUCH drier than the eastern half, and fire
danger continues to grow each and every day. So even if this were to only
materialize for a short time, it would at least put in check the growing dryness
on the Western Slope. 

The latest forecast from the NMME model comes out in the next few days. When
that happens, we'll be revisiting this subject. All for now!

2023 North American Monsoon forecast update