Summer 2017 Outlook Update 6 years ago
March 30, 2017
- New El Niño emerging.
- Playing field very warm to start.
- Cooler zone pulled back to the west.
- Heavy spring rains in Texas and into the Plains.
The previous forecast looked like this:
The actual analog package looks like this:
The JAMSTEC model forecast has changed. It was this:
Now it has more cool in the north-central states and more warmth in the Southeast:
The CFSv2 was this:
It remains quite similar but it's warmer:
Discussion
The current SST map shows a cold eastern Indian Ocean, an emerging El Niño and a cooler look to the AMO (a less warm or cooler eastern and southern North Atlantic).
This is the coldest we have seen the water to the west of Australia since 1986 and 1982, the former was a moderate El Niño and the latter a strong one. So, an El Niño is likely coming on and the consensus among the forecast team ranges from very weak to moderate.
The JMA in February:
In March, it's quite strong all the way and briefly touching +1.5°C:
It is important to note that dynamical models have a hard time forecasting SSTs in the spring. This is known to meteorologists as the "spring predictability barrier," so expect some fluctuations in the forecasts until we get into the summer. From what we see, this may evolve into a "Modoki" event, more in Nino3.4 than Nino1+2 as the summer evolves. This may have implications for next winter, but likely not yet for the summer.
There is a big jump, though, on warmth, and the two closest El Niño summer patterns to this one are 2002 and 2006. Again, using the older normals to create the warmer look:
What we did though is pull the cool back westward to adjust for where we think the heaviest precipitation will occur, and the idea that the Gulf of Mexico is warm and ready to supply moisture into Texas and the eastern Plains, perhaps not through blazing daytime highs, but instead higher nighttime lows. We can't really use 2002 and 2006 all the way, because in both of those years the Gulf of Mexico was cool, not like it is now. The record early season western Gulf of Mexico warmth is going to play a role, and that is why we have changed the forecast a bit.
Note on Precipitation
We may find this to be a case of wet and warm, as the SSTs surrounding the eastern and southern U.S. are well above normal. As the El Niño evolves, there is a tendency for more troughiness to try to develop over the nation's midsection, which would set up a clash.
The last 10 runs of the CFSv2 have this:
This leaves the Southeast the driest, but it also shows enhanced moisture over the southern Rockies, which would back the CFSv2's attempt at being less warm there. This does not appear to be in the same league as some of the hot and dry summers we have had with La Niñas that responded to the 2009-10 El Niño and the soil moisture configurations. Instead, it appears to be a warmer and wetter looking summer.
There is also the very important matter of spring soil moisture feedback, which we cannot yet tell if and when that could be an influence on the early summer pattern. We have long term drought in the Southeast and from the northern Mid-Atlantic to southern New England:
The short term drought blends have dryness in the Southeast and along the Mississippi Valley. but heavy precipitation with the bowling balls will take that out soon:
We will have to watch this evolve through April, as a lot of times a heat ridge can establish itself where drought feedback is strongest - many times where the short term and long term drought coincide (in this case the Southeast).
The Verdict
There are arguments as to where it's going to be warmest, but the loudest message is that an above normal summer is on the way. However, we feel this will be more front-loaded than last year, which had a sputtering start before really hitting the endless summer stride in July-September. A widespread warm, more classically centered summer is the call. The place to look for cooling to develop first relative to averages is in the Plains.