Monday, December 1, 2014

Winter '14 / '15 - ENSO Takes A Second Step Toward el Niño Event

Is it el Niño or is it el Noño?

DEFINE the BEGUINE
One definition holds the Oceanic Niño Index (ONI) has to:
... met +0.5°C threshold for five straight months of a 3-month running mean.  For historical purposes warm 'episodes' are defined when the threshold is met for a minimum of 5 consecutive over-lapping seasons.
Another holds North America's operational definitions for El Niño, based on the ONI index is:        
El Niño: A phenomenon in the equatorial Pacific Ocean characterized by a positive sea surface temperature departure from normal (for the 1971-2000 base period) in the Niño 3.4 region greater than or equal in magnitude to 0.5 degrees C (0.9 degrees Fahrenheit), averaged over three consecutive months.
WHAT'S THE EVIDENCE?
The latest SST anomaly (SSTa) for ENSO Region 3.4 from NOAA's Climate Prediction Center (CPC) is +1.0°C (26-NOV-14).  This brings the 13-week (i.e., three months) moving SSTa average in ENSO Region 3.4 to 0.58°C.

Last week/s 13-week ENSO Region 3.4 moving SSTa average of 0.54°C breached the 0.5°C threshold for North America's operational definition for El Niño.  The week previous:  +0.492°C.

ENSO Region 3.4 SSTa (BLUE) and 13-week SSTa Moving AVG (ORANGE)
JAN-10 to Present
WTF?
In spite of these developments ... what's the hold-up in recognizing the beginning of el Niño 2014?  It is b/c of how a 'month' is defined?

A month starts on the 1st and ends on the 30th or 31st (piss off FEB). 
Anyone think there's a Gregorian calendar hanging over ENSO Region 3.4?

 Just b/c the ENSO Region 3.4 SSTa havn't been above the +0.5°C threshold for three consecutive calendar months doesn't mean +ENSO hasn't started.  The 13-week moving average (i.e., 3-month) ENSO Region 3.4 average SSTa exceeded the el Nino threshold during the week of 19-NOV-14.


CPC/s foot-dragger report
ENSO: Recent Evolution, Current Status and Predictions (01-DEC-14)

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