40/70 Benchmark

This pressure/SST dipole that you see in the MEI schematic above is what has retarded the development of this el Nino and epitomizes the disfunction of the warm ENSO paradigm to date. The weaker dipole resulted in less prominent WWB in much the same manner that an east coast storm lacking a strong pressure gradient will have less wind and meager baroclinicity...thus a weaker system. The issue has been alleviated to an extent, but its never going to catch up the the SST anomalies.

I mentioned in my work that since the forcing has been so far west, that phase 6 will be an issue during periods of thawing....2006-2007 also had this issue, but that winter was much different near the pole due to solar considerations.

Introducing the Relative Ocean Nino Index Oldenborgh et al have observed that the crux of the issue is that the traditional Nino 3.4, from which the ONI is derived, "not only describes ENSO but also has a trend due to global warming, which has very different impacts from that of el Nino" (Oldenborgh et al, 2021). The piece goes onto assert that this is problematic because the "spacial pattern of the observed SST trend over the past century does not resemble the ENSO pattern" (Oldenborgh et al, 2021). The suggested solution is to use the Relative Ocean Nino Index (RONI), which is a value derived from the difference of the original index with the contemporaneous tropical mean SST anomalies. According to Oldenborgh et al, subtracting the tropical mean SST anomaly not only removes the trend, but also results in an SST anomaly (RONI) that is of more direct relevance to changes in tropical convection driven by SST anomalies. Removing the trend in order to distinguish between ENSO related warming and climate change attributed background warming is important because tropical convection is more sensitive to the warming of ENSO relative to the rest of the tropics. Thus convection will concentrate in areas that warm the most relative to the tropical mean background warming. This is why the current generally warm Pacific basin is reducing the ability of ENSO to assert itself in the hemisphere to a level commensurate with the current 1.5 ONI value, as reflected by the ASO tri-monthly RONI value of 1.05, which is weak-moderate and somewhat more in line with the current 0.3 MEI value. This explains why el Nino has thus far failed to redistribute the tropical convection denoted by the negative velocity potential away from the central Pacific to the eastern Pacific, co-located with the strongest ENSO anomalies in regions 1.2 and 3, as was the case in 1997 and 2015. In comparison, the ASO RONI values were 2.15 and 1.87, which explains why the tropical forcing was much more co-located with the greatest anomalies to the east. The ocean-atmosphere coupling was much stronger. This is reflected by the AS bi-monthly MEI values of 2.2 and 2.1 as compared to the current value of 0.3. Theoretically speaking, should the el Nino become intense enough and the warmest anomalies remain strongly biased to the east, at some point the convective forcing should realign itself with the strongest positive ENSO anomalies to the east and away from the residual warmest absolute SSTs to the west. The key is what is this critical threshold and will it be reached.

The bi-monthly Multivariate El Niño/Southern Oscillation (ENSO) index (MEI.v2) is the time series of the leading combined Empirical Orthogonal Function (EOF) of five different variables (sea level pressure (SLP), sea surface temperature (SST), zonal and meridional components of the surface wind, and outgoing longwave radiation (OLR)) over the tropical Pacific basin (30°S-30°N and 100°E-70°W). The EOFs are calculated for 12 overlapping bi-monthly "seasons" (Dec-Jan, Jan-Feb, Feb-Mar,..., Nov-Dec) in order to take into account ENSO's seasonality, and reduce effects of higher frequency intraseasonal variability. During the typical height of ENSO during late Fall/early Winter, the canonical features of atmosphere and ocean anomalies are shown schematically below based on a composite of 11 historical El Niño and La Niña events. Key features of composite positive MEI events (warm, El Niño) include (1) anomalously warm SSTs across the east-central equatorial Pacific, (2) anomalously high SLP over Indonesia and the western tropical Pacific and low SLP over the eastern tropical Pacific, (3) reduction or reversal of tropical Pacific easterly winds (trade winds), (4) suppressed tropical convection (positive OLR) over Indonesia and Western Pacific and enhanced convection (negative OLR) over the central Pacific (Fig. 1a). Key features of composite negative MEI events (cold, La Niña, Fig. 1b) are of mostly opposite phase. For any single El Niño or La Niña situation, the atmospheric articulations may depart from this canonical view. Fig. 1: Schematic diagram showing the physical mechanisms by which the SST (shaded), OLR (contours), surface zonal and meridional winds (vectors), and sea level pressure (represented by "H" and "L" which indicate the high and low pressure center, respectively) determine the wintertime Multivariate ENSO Index (MEI) during (a) El Niño and (b) La Niña events. The schematic is based on the composite anomalies for November-December (ND) drawn from 11 warm events and 11 cold events during 1980-2016.

We didn't need the overwhelming canonical response that produced the powerful Pac jet that eviscerated the entire month of December. I'm sorry, I just do not agree with you. We'll see how it plays out...I am not concerned about the winter being dominated by Maritime forcing.....during thaw periods, I can see some phase 6...sure.

The other caveat being that this el Nino isn't half as coupled with the atmosphere as that one was. People need to stop comparing this to the most intense el Nino events in history because this is orders of magnitude less expressed in the hemisphere, regardless of the SST anomalies.

Greenline is down, I think.

Eh, we're all getting old.

Yea, just about time....firing up my model perscriptions.

"As I get colder, I don't mind the torches so much"....you have said something to that effect on several different occasions.

Says the guy who cries about the cold every winter for the past 10 years.

I can't stand driving in town, but I'll probably be there....no issues with the venue.

I need a Miller C.

Cool. Same

I would think at least 8 based on the poll....

Its not dropping....these folks were the minority that voted for other dates.

2pm. I am going to leave the date 12/2... I don't see anyone who originally went 12/2 now saying that they can't make it, which would be cause for change....I know that confuses the more feeble minded, but it is what it is.

Safe to assume @CoastalWxis out because I don't think he has ever ended up coming once he expressed doubt lol Would 12/9 be easier for you?

So it seems like you are out. Which date did you vote for?

I have yet to see anyone explicitly say that they can make 12/9 and not 12/2....Jerry maybe, but he also said he can try to show up during the PM and he normally doesn't stay late, anyway. Scott may have a sitter issue, but he didn't say the next week would be any better. What I do see is 7 votes for 12/2 and 3 votes for 12/9.

I think this timing is perfect TBH.....the only season that I can recall to have early December snow not rot is 1995....every other large early December snowfall was skunked and nearly gone by the holidays. I am talking e MA coastal plane...obviously this is probably different in the ORH hills.

Why would we move it to a date where less people will show per the poll? Are there any folks who would like to change their vote?

You have a point about the PV, but no one expected this season to be frigid...all the more reason to be leery of the early threats until climo catches up.

I am confident that this season will provide enough high latitude blocking for that not to be a major issue for the majority of the season. Perhaps I will be wrong, but the passage of the MJO through the maritime continent in early December is not a sign of that.