Bob Tisdale reports in his Weekly ENSO Index Drops Below The La Niña Threshold at Watts Up With That.
NINO3.4 SST anomalies (a commonly used El Niño-Southern Oscillation Index) have dropped significantly below the -0.5 deg C threshold of a La Niña Event. They are presently at approximately -0.74 deg C.
NINO3.4 SST Anomalies
Weekly Global SST anomalies rose since the last mid-month update, but made a minor dip last week. Global SST anomalies usually lag NINO3.4 SST anomalies by a few months so the global SST anomalies should be nearing their seasonal peak for this year, before they start to respond to the depressed NINO3.4 SST anomalies. For the week centered on August 17, 2011, Global SST anomalies are +0.169 deg C. I’ve also included a shorter-term graph so that the most recent wiggles are visible.
La Niña has been a major factor in the drought in the Texas and the US South East and our large snow pack in the Sierra this last winter. We may have another large snow pack and the droughts may continue. More on this latest weather event, when is is clear if the La Niña strengthens or if this reversal was temporary.