So Long...+ENSO

This winter/s +ENSO...oft a convenient scapegoat for the abnormally warm temperatures across much of the CONUS...appears to be fading...and fast.

NOAA/s ENSO definition...based solely on SSTAs in region 3.4...holds that if the anomaly is at least +0.5°C...it/s el Nino. If the anomaly is less than or equal to -0.5°C...then it/s la Nina. The Australians consider the Southern Oscillation Index (SOI)...Outgoing Long wave Radiation (OLR)...trade winds...sub-sea surface temperature anomalies...as well as SSTAs.

There are significant signals...using the Australian criteria...that +ENSO is on-goin..but in its last throes.

ENSO signals...week ending January 21:



1) SOI stands @ -5.5...doubling down from December/s end-of-month value of -2.4. +ENSO is indicated when the SOI is negative.



2) ENSO region 3.4 SSTA 0.57°C...barely above the 0.5°C threshold.

3) Trade winds weaken and reverse direction during +ENSO. Trade winds are currently normal to above normal in the ern portion of region 3.4 and anomalous near the International Dateline. Some have suggested the west wind comes courtesy the MJO...but MJO is still largely voo-doo...so who can say for sure what it means.



4) Above normal sub-sea surface temperarture...such as those shown during November...are supportive of +ENSO conditions. Below normal sub-sea surface temperatures are now reaching well into the ern PAC.



5) OLR has been negative since early January...indicating widespread active convection in the region...and a sign that el Nino is on-going.

Recap
SOI 30-day moving average still weakly negative. SSTAs still above +ENSO threshold but falling fast. OLR negative. Trade winds in flux. Sub-sea surface anomalies trending negative.

+ENSO doesn't usually end during the srn HEMI/s summer...so it probably has some life left...but it/s getting about time to say...'so long.'