Matt Makens

June is upon us and is off to a wet start across parts of the plains and
mountain west where scattered to numerous thunderstorms impacted day-to-day
operations. As of Friday June 2nd, a number of flood alerts paint the map from
Montana to Wyoming and Nebraska, and from New Mexico through Texas into
Oklahoma.

This is following a month of wet weather in the same zones. May 2023 was an
impressive month for precipitation along the Rockies and adjacent plains.

Sadly, however, deficits grew for much of the Midwest, Corn Belt, and Pacific
Northwest. 

The trend for June is much the same as May, but precipitation likely spreads out
a bit for the mountainous west and Great Basin. 

The precipitation for Colorado, Kansas, Oklahoma, and Texas likely will favor
the early month before a shift to the northwest. 

If this orientation should strike us in one way, it is a similarity to an El
Niño "look" for summer. I ran this analysis of El Niño summers since 1990 to
show the precipitation orientation. Granted the sample of years is low using
that time frame, but the climate variations during the entire period of record
are not representative of the most recent 30 years (AMO and PDO phases, which we
will not get into today).

I included any variety of El Niño for this product, but strength of El Niño does
have an impact. Other research shows the difference between strong versus weak
phases.

El Niño has not been declared. The ocean temperatures in the ENSO region are
near the threshold, but three-consecutive months of 0.5°C+ warmer than average
temperatures are needed from the sea surface for NOAA to declare it officially.

 Other agencies, including Australia's, want the atmosphere to correspond to the
oceans. We did begin to see the atmosphere appear more Niño-like in May, but
this is a transitional phase and we have not "locked" into a pattern yet.

I discuss this in a rather nerdy video on the topic:

The ultimate growth of this Niño and duration are to be seen. Surface and
low-level trade winds near the Equator that sustain and grow an El Niño haven't
robustly changed but are gradually moving into an El Niño condition. 

Although there is an impact from the MJO (wave pattern impacting tropical
weather) to help drive the ENSO conditions, there is some research done in the
past decade to show that the MJO has a relatively weak impact on sustaining an
El Niño. 

That research suggests until we establish trade winds that alone are more
westerly, the El Niño conditions will remain as they are now through a weak
phase. The cause of this wind environment isn't well understood, but is a
notable factor in El Niño events of the past. 

A well developed wind and ocean configuration drove the strong '97-'98 event,
but was very weak in '14-'15 (a false alarm El Niño in 2014 that ultimately
later developed).

Data into mid-late May suggest to me we are in an environment stronger than that
of '14 but a far cry from '97. Time will tell...

Again, though, this El Niño event appears to be well on the road to establishing
itself, we are seeing the transition now and will this month. An official El
Niño declaration looks quite likely by the time we hit Autumn.

June 2023 weather outlook: Wet signal continues early on