My thoughts on Summer 2020

Spring 2020 has been cold.  The reason has been the MJO, and the warm pool in the northeast Pacific.  Before the very mild winter, November into December 2019 was quite cold, the reason again was the MJO and that warm pool.

One thing I want to point out, many times, cold Mays lead to early season tropical cyclone activity in the western Atlantic and/or Caribbean.  Historically years with cold Aprils and Mays see increased odds of landfalling systems on the Gulf and East Coast of the U.S. In my hurricane season outlook updates, I has been talking about how that could be a real problem for the Mid Atlantic and Northeast.

Summer solstice will get here in 40 days, on June 20th. So, with April and so far in May, the question is, will this Summer be cool as well?

Sea Surface Temperatures:

The SSTs have changed a lot from summer 2019 and even from winter 2019/2020. 

The El Nino Southern Oscillation (ENSO):

The ESNO is a major driver when it comes to our weather pattern. It’s based on fluctuations in the ocean and atmospheric temperatures in the equatorial Pacific.  The ENSO is neutral when the SST in the tropical Pacific are between -0.5C and +0.5C.  El Nino is when the 3-month running average is above +0.5C and La Nina is when the 3-month running average is below -0.5C

We’ve been in ENSO neutral conditions (neither El Nino nor La Nina) since early Spring. But, In the equatorial Pacific we’ve seen cooling developing. The SST anomalies show the cooling on the surface and the subsurface. 

Here is a graphic from the IRI/CPC showing the model predictions for the ENSO.

The Multivariate ENSO index (MEI)

The MEI has shifted to slightly negative.

Based on the look equatorial Pacific a La Nina is looking likely starting this summer. Other outlets are saying the ENSO is going to stay neutral through the summer. But based on my calculations and observations I think it will end up being a La Nina. Looking at the sub-surface water temperatures we can see the surface is cooling and the cool water rises. The surface SST should cool much more as cold-water up-welling continues west of South America to the Date Line.

Historically, Summers that experienced very warm temperatures, occurred during a shift toward La Nina.

Large parts of the Atlantic Basin are warmer than average

The warm SSTs in the Gulf of Mexico and in the western Atlantic should help keep our nighttime lows higher than average.

The seasonal models:

CFSv2:

EURO:

JAMSTEC:

  

Soil Moisture:

The Verdict:

Temperatures:

The Northeast and Mid-Atlantic region can generally expect above average temperatures from June through August. I think once the hot weather gets really started, it is going to have some staying power.

June overall temperatures should be average to slightly above average.

July will end up quite warm in the Northeast and Mid-Atlantic, with temperatures generally above average.

August will be quite warm for much of the CONUS, with temperature anomalies here in the Northeast and Middle Atlantic above average to well above average.

July and August will be at least as warm as last year, in fact they could average 1-2 degrees warmer than July and August 2019.

The above average temperatures will stick around for the end of Summer into Fall 2020.   

Precipitation:  

This time of year, much of our rain comes from thunderstorm activity. Later in the Summer there will also be the possibility for impacts from tropical cyclones and tropical rain. As has been the case for the last 5-7 years, this summer has a good chance of being average to drier than average. But, that will depend on tropical activity, with the increased risk to the Northeast, Summer 2020 could end up being wet. But even if we see a wetter than average summer, there is still going to be the possibility for dry or even drought conditions in parts of the Northeast and Mid-Atlantic. So, while some areas will see much less rainfall, others may not.

Remember, these warm temperatures should extend into Fall 2020.

That’s it from me…….