Now that nature is done doing its worst (let’s hope!) we’ll be catching a relative break on the majority of days over the next 2 weeks. Temperatures will run below average through Friday, with some weekend moderation. Readings will drop back early next week for a couple of days before rebounding midweek. Lake effect will be strictly limited in supply with no indications of moderate or heavy accumulations into next week. In general, the upper level flow will allow some ridging in the east–in the mean–though there will be ups and downs within this pattern. So, anyone looking at smoothed temperature anomalies on CPC maps as being the whole story will be disappointed from time to time. Near the end of the 2 week period, Arctic Oscillation ensemble members have a tendency toward becoming Negative/Cold, but there is still quite a bit of spread at the end of the run–as there usually is. And the PNA seems to be taking on a Positive phase late in the period as well. Model ensemble means hint at the rebuilding of western heights late in the run, with the GEM being the strongest on that ridging. However, it can’t be foreseen if this a temporary ridging in a progressive pattern of ups and downs, or if it is going to be the beginning of a new western ridge/eastern trough amplification. Having seen the 2 links on the previous thread (http://www.cpc.ncep.noaa.gov/products/intraseasonal/temp10anim.shtml) and (https://www.aer.com/science-research/climate-weather/arctic-oscillation) posted by Dave from Rochester and Ayuud, I’m inclined to think if the end of those runs isn’t yet indicative of a return to colder conditions, it might follow shortly beyond the 14-16 day range.
As for ENSO, we still can’t say an el nino event is now occurring because the standard calls for 3 consecutive months of el nino conditions to have occurred. However, warming has continued across most of the tropical Pacific east of the dateline, and key Nino region 3.4 is now at .9 degrees above climatology. So, it’s not an event, and CPC by definition says we still have a neutral ENSO in place for now. Nonetheless, we have el nino conditions in place. This warming was in place during the recent extreme pattern, so no one should jump to conclusions that this el nino condition is bound to be a match for the probable Sudden Stratospheric Warming which seems to have taken shape. We just have no evidence at this point such would be the case. Most ENSO models still indicate a weak el nino is taking shape, but there are now a couple more members (out of more than 20) which point to a short period of moderate el nino conditions than there were a few weeks ago. An interesting note: the CFS v.2 is an outlier for next year, showing a weak el nino weakening by spring and then redeveloping more strongly toward next summer. That time range is far beyond the window of known reliability for predicting ENSO phases in the first place, but it’s also the only model showing that redevelopment.