Saturday, March 7, 2015

Long Range Climate Models Forecast El Nino Development in Summer, Fall

After a failed El Nino prediction for this winter, despite the NOAA declaration of the phenomenon in the last few days, model guidance is once again forecasting an El Nino developing in the summer and fall.

The above image shows the sea surface temperature deviation from normal, centered over the central Equatorial Pacific, forecasted until late 2015. The red line shows observed anomalies to date, while the yellow boxes portray the range of SST anomalies in the forecast period. This particular forecast sees water temperatures warming steadily from late spring into the fall, when the average of the boxes reaches 1.0ยบ C at the very end of the forecast period.

The next forecast, from the Australian Bureau of Meteorology, shows temperatures quickly warming up from mid-spring onwards, solidly in El Nino territory by the early winter of 2015-2016. This was another model that consistently forecasted an El Nino this past winter, but never verified. It's quite possible we see this happen again this summer and fall.

The atmosphere is, right now, quite conditioned for an El Nino to develop. We have been seeing sustained negative values from the Southern Oscillation Index (SOI), an indicator of El Nino conditions in the atmosphere. This winter, it didn't come out as expected. However, if we keep a similar SST set-up across the Pacific, as well as our pre-conditioned environment for the El Nino, we could see that develop. I remain pretty skeptical, however.

To summarize:

- Model guidance is projecting an El Nino to form for the summer and fall months.
- Because the majority of model guidance was incorrect in their forecasts this past winter, uncertainty is extremely high.



Anonymous said...

Hello Andrew. Thank you for your updates. Quick question regarding potential development of El Nino. What does this typically translate to for the plains and central Midwest in terms of temps and moisture for summer, fall and early winter?

Perhaps you can provide some graphics on this?


Anonymous said...

Andrew, you are the long-range forecasting machine! given the failed el-nino from this winter, what caused the ridge of high pressure to form over the west coast... thought that this was due to at least a partial el--nino piling warmer h20 into the west coast. does this next el-nino forecast bring an even colder winter to the eastern half of the us of a next year??? hope you have a moment to post on this... i'll need to call a real estate agent, or pre-buy even more propane for next season. thanks for being out there with the prognostications. much appreciated.

Anonymous said...

I second the first posters request for a graphic. As someone who likes to visaulize things, I find that I am often uncertain about your written explanations. When you do include the graphics to match it helps me to gain knowledge by matching your written prognostications to the graphical version.