Brian Bledsoe

We have talked at length about how we thought the monsoon would fail again this
year, and wanted to update you on whether out thoughts have changed. 

The answer in short is no.

While some areas have received some rain lately, it has been quite spotty
overall, and not nearly enough to erase the ongoing drought for much of the area
[https://www.weather5280.com/blog/2020/07/09/drought-update-the-outlook-july-9th-2020/]
. 

Here is a look at precipitation anomalies over the last 90 days: 

You can see the deficit in inches for most of the Southwest US. Especially hard
hit...Southern Colorado, New Mexico, Southwest Kansas, and the Panhandle Region. 

This deficit has lead to this: 

Many of you are familiar with the Drought Monitor, but the Short-Term Indicator
is many times a better representation of who has been seeing rain lately and who
has not. Notice how many areas in the Rockies and in the lee of the Rockies are
struggling. 

So, why don't we think this pattern will break? It has everything to do with the
positioning of the high pressure cell over the south/southwest part of the
country. Here is the Euro Model 500mb forecast for the next 15 days:

While a trough tries to squash the ridge during the middle of next week, and it
does, the ridge reappears in a rather strong fashion in the same area that it
has been positioned. This is due to the ongoing drought, and the positive
feedback that exists with drought. Dry soil heats up more/faster than wet soil.
Each day it heats up more/faster, the more it dries out. This allows the
atmosphere to mix more easily, promoting breezy to windy conditions almost each
day. On top of that, the ridge position over the Four Corners states,
effectively keeps the monsoon moisture shunted well to our south, and will not
allow it to come north. So again, the more the pattern persists, the harder it
is for it to break. Drought positive feedback is one of the hardest things to
break in weather. It takes a full on pattern shift for this to happen, and we
are running out of monsoon time. The Euro Model ensemble mean 15 day
precipitation forecast, also shows this trend.

Notice all the brown (drier than average) over the same areas that are being hit
by the drought? That's no coincidence. The Euro Model Weeklies precipitation
forecast for the next month shows basically the same:

Also note the red over parts of Arizona, New Mexico, and Northern Mexico? This
indicates much drier than average conditions. Essentially, if areas to our
south, which are closer the monsoon plume are much drier than average, then why
would we be any different being farther away from the monsoon plume? Good
question, we don't think we will be. 

One caveat to this setup is IF we can sneak a few weak cold fronts through our
area, and develop some upslope (thunderstorm fuel increase) behind those fronts,
we will see occasional thunderstorm action. However, without the sustained
monsoon plume coming up from the south, the rain will likely remain pretty
spotty, and the drought will persist and or intensify. 

One such cold front may swing through by early/mid next week, and with that you
can see below an uptick in potential precipitation probabilities for Eastern
Colorado: 

This is all obviously not good news, especially with the ongoing/intensifying La
Niña episode. La Niña usually portends drier than average conditions for the
fall, for those same areas being hit hardest by the drought. The Euro Season
Model precipitation forecast for the rest of summer and early fall concurs with
our thinking: 

August-October

The Euro Seasonal Model does show a little more optimism in the mountains and
along the northern Front Range for August, but that is about it. Doesn't really
change the fact that areas experiencing extreme drought right now, likely won't
get any sustained relief by the fall.

Updated monsoon outlook