bluewave

Maybe upwelling from the frequent frontal passages.

The subsurface has cooled quite a bit in the eastern regions this summer. So there will need to be another kelvin wave in order to maintain those levels. Absent a new kelvin wave, we are set for an unusually early peak in Nino 1+2 and 3. Which would probably lead to a peak in 3.4 about 4-6 weeks after that. So not the usual El Niño timing if the subsurface counties to cool. None of the very strong El Niño events of the past had a subsurface cooling trend during the summer. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/wkxzteq.shtml

Yeah, I also think 29.7 is near a record in Nino 4 for this time of year. While it won’t average this high for the whole month due to the steep incline, getting close to +30C is impressive.

This El Niño continues to do its own thing.

NOAA maintains an IOD index which they call DMI. The fall of 2019 was the strongest positive on record. But it faded by the winter as record SSTs returned north of Australia with the very strong MJO 4-6 that winter. https://stateoftheocean.osmc.noaa.gov/sur/ind/dmi.php

Yeah, it has been pretty unusual to get a trough this deep over the area with the Atlantic at these record SST levels. Winter troughs have been tough to come by since 15-16 with only shorter intervals until the WAR or SE Ridge returned. But even a mild winter with a ridge nearby can produce a decent snowstorm or two with some blocking and more favorable Pacific periods.

It was one of those seasons when the RMM index MJO 4-6 was a more reliable indicator than the weak forcing near the Dateline. Just a classic La Niña pattern with the ridge north of Hawaii and SE Ridge over the US. The RMM is usually more in line with where the VP anomalies show up. But for some reason that wasn’t the case in 19-20.

Yeah, the impressive +IOD lead to the very strong SPV and +NAO which muted the weak El Niño signal. https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/asl.1005 Northern Europe and the UK experienced an exceptionally warm and wet winter in 2019/20, driven by an anomalously positive North Atlantic Oscillation (NAO). This positive NAO was well forecast by several seasonal forecast systems, suggesting that this winter the NAO was highly predictable at seasonal lead times. A very strong positive Indian Ocean dipole (IOD) event was also observed at the start of winter. Here we use composite analysis and model experiments, to show that the IOD was a key driver of the observed positive NAO. Using model experiments that perturb the Indian Ocean initial conditions, two teleconnection pathways of the IOD to the north Atlantic emerge: a tropospheric teleconnection pathway via a Rossby wave train travelling from the Indian Ocean over the Pacific and Atlantic, and a stratospheric teleconnection pathway via the Aleutian region and the stratospheric polar vortex. These pathways are similar to those for the El Niño Southern Oscillation link to the north Atlantic which are already well documented. The anomalies in the north Atlantic jet stream location and strength, and the associated precipitation anomalies over the UK and northern Europe, as simulated by the model IOD experiments, show remarkable agreement with those forecast and observed.

This was actually the 2nd strongest trough near the region during the summer behind 2009. But since we have warmed up so much since then, it wasn’t as cool as that year was. Still very impressive in the age of the persistent WAR and SE Ridge patterns.

This looks like it’s going to be the strongest 500mb ridge on record for the Midwest. Most of the times this region has approached 600 dm in the past resulted in 95-100° temperatures in our area. Goes to show how strong the Greenland blocking is.

I should have mentioned 20-21 also. Was looking at the wrong column for 22-23. Just weary of fully believing these super El Niño forecasts when the subsurface is much cooler than 16 and 97 and the models have been verifying too warm in 3.4. Plus the general warm bias of these model forecasts in recent years.

I didn’t take it that way. These extreme rainfall events are becoming the new normal. It’s just something to be aware of for citizens and government agencies.

This is a highly anomalous upper air pattern that will help to maintain the record moisture plume much further from the Baja than we typically see. This type of jet stream and trough assist more commonly happens in the East allowing flooding rains well inland from the coastal plain.

We have seen some pretty big errors made by the JMA during recent Augusts. While the ENSO state was different, it was off by about +0.6 last winter and around +1.1 too warm for DJF 21-22. Many times the ENSO models in recent years didn’t get the correct Nino 3.4 temperature for the winter until already into SON. So these ENSO models are often repeater models that just carry forward and build off of what ever month they were initialized in.

There have been so many in the last decade that they probably have to dramatically shorten the recurrence intervals for our warmer atmosphere that can hold much more moisture. They forgot to add the The Death Valley event last summer to the official list below. The most recent one was near West Point back in July. Several last summer also weren’t added to the list. https://www.weather.gov/owp/hdsc_aep

The 15-16 super El Nino was the only warm ENSO event in the last decade that the models didn’t have a warm bias for. So that’s why I like to take a wait and see approach as to how strong this event gets. Looks like after the current WWB coming through we go back to some weaker trades again. This current WWB was also displaced closer to 1+2 and 3 and less impressive near the Dateline like we have been seeing.

My main concern with the model forecasts from July was the only models showing a super El Niño had August above +1.5. August is set to come in under +1.5 on OISST which I believe has been running a little warmer than the official ERSST. I know other models have warmed in August. But we don’t have the September verification yet to judge them by. July models showing super El Niño and their August forecast AUS…………..1.93 ECMWF……..1.67 Metfrance….1.95

We have been past the spring forecast barrier several times over the last decade and the actual pattern has gone against what the ENSO models were showing as late as August or the early fall. The ENSO models haven’t been doing too well this summer with 3.4. The SSTs have come in much cooler than the forecasts from June and July were indicating. But Nino 1+2 has stayed warmer longer than the model forecasts. Plus the forcing forecasts verified further west than most of the guidance. So it’s not unreasonable to think that there will be more errors of some type with model forecasts going forward. I am not doubting the super El Niño forecasts because of any attachment to a cold winter. We haven’t had a cold winter since 14-15 in the Northeast. So I have gotten used to milder winters over the years. But we have seen many incorrect model ENSO forecasts since 2012-2013 which needs to be taken into account when viewing these model outputs.

My only hesitancy in buying the models showing a super El Niño is how much cooler the subsurface is than at this point than in August 2015 and 1997. So not sure if several of the ENSO SST forecasts are still showing excessive momentum. The present heat values are less than half what they were in 1997 and 2015. I know we have a small sample size of super El Niño so there could be more variation in subsurface patterns than we have seen in the past.

Yeah, we can see how serious the flash flooding was in Death Valley last summer when they had their historic rainfall which was lower than is being projected with Hillary.

Several locations in the Northeast have had their wettest summer so far from June into Mid-August.

It will be their version of a Harvey or Florence with a year of rainfall for those areas in just a few days.

Yeah, I am hoping we get some piece of the summer to winter blocking carryover even if we have warmed quite a bit from several of the past years. A warmer version could still produce better snowfall than last winter. Just cold enough has worked for us with a raging STJ and even a small amount of blocking. Many would accept another mild winter if we can get a decent snowstorm or two.

February 2015 was probably the biggest fluke since 2000. Some of the papers I read pinned the 13-14 and 14-15 mega NE PAC Ridge on the warmer waters near 15N in the WPAC. It’s interesting that the forcing emanating from just 15 degrees further south along the equator in the WPAC creates such a warmer response for us with the frequent MJO 4-6 transits over the last 8 winters.