Wednesday, August 19, 2015

Chandra Asks About El Niño

Chandra asks:
Can you give your expert opinion, in 8th grade terms??? lol!!!! I lived in the mountains during the last real el nino and O boy!!! So this really interests me!!!

NOAA NWS Climate Prediction Center announces:

The latest ENSO diagnostic discussion was released last Thursday, and highlighted the unanimous forecaster consensus for a strong El Niño event continuing into the winter. The latest weekly OI SST anomaly value in Niño 3.4 is +2.0C!
Ha! I had to look things up (SST means 'sea surface temperature': OI means nothing at all, as far as I can tell, so no wonder it's confusing).

The Niño-3.4 region is a place; the closest strip of ocean water along the Equator most likely to affect us (southwest of us; southeast of Hawaii). Surface waters there are 2 degrees Centigrade warmer than usual, which is an unusual state of affairs that we haven't seen since 1997. There's also no indication El Niño will go away before winter. Warm water provides an unusually-rich source of atmospheric moisture. Whether the weather can tap that moisture for us is still unclear, since we are so far from the Equator. Usually it means lots of rain, but not always. The illustration shows results of the winters of 1982-3 on the left (wet) and 1965-6 on the right (dry), both strong El Niño years. The rest of the atmosphere will have to respond favorably to help us.

My own sense is that we've seen a strip of drought move west across the U.S. for the last eight years, first affecting the American South (2006-8), then Texas (2010-11), then the Southwest (2012-13), then California (2014-15). It's now incorporating the Pacific Northwest (2015-?) as it continues its march west. My guess is that the Pacific Northwest will continue to be dry this winter, but drought will end in southern California. The most well-known climatologist in southern California, Bill Patzert at JPL, worries there could be floods in SoCal and continued drought in NorCal. His nightmare is a possibility!

If rains are to come, something will have to kill the Really Resilient Ridge that has bedeviled California since January, 2013. Interestingly, long-range, 2-week weather forecasts show a combination of powerful storms in Alaska and the northwest Pacific will create an Aleutian low that will kick the ridge west starting on August 28th, opening the possibility of some rain in NorCal as soon as September 7th. If so, that would be really early! I'm hoping that we'll know what lies in store for us fairly early.

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