bluewave

The IOD influence is pretty far west of the main WPAC warm pool from the Dateline back to north of Australia. Notice the vast expanse of +30C SSTs in that region. So Nino 4 is currently the warmest of the ENSO regions. This is where the forcing has been focusing all summer. The subsurface in the Nino 3 and 1+2 areas has been getting less over the summer. So there isn’t much warming left in the pipeline beyond the current levels absent another kelvin wave for the eastern regions. But there is a lag in 3.4 which can run up further following the eventual 1+2 peak. So 3.4 usually peaks after. Need a new kelvin wave to warm the subsurface since it’s dipping to around 0.9 which isn’t in line with past super events. Those were going +1.5 to +2.0 or higher during the past super events since 1980 from August into September. So need a steady rise in upper ocean heat in order for some of the stronger model forecast for 3.4 to verify. We’ll see if we finally get some stronger WWBs in the CPAC leading to a new kelvin wave and upper ocean heat increase going into the fall. https://psl.noaa.gov/map/clim/sst.shtml

Nino 1+2 can be very noisy since it’s such a small geographic area. But the subsurface has been gradually cooling over the summer from the Dateline to the South American coast. None of the super El Niño’s showed a decline in upper ocean heat content to near +1.00 from June into August. But we only have a small sample size of 3 years since the data became available in 1979. The El Niño experts on twitter haven’t mentioned much about these declining values. They mostly are talking about what the models show in regard to the SSTs. But we know how the models have had errors with their forecasts even from late summer into early fall. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt

It was only in reference to the Topeka sounding which set a new record for that upper air station. https://forecast.weather.gov/product.php?site=TOP&issuedby=TOP&product=AFD&format=CI&version=1&glossary=1 Our H5 height yesterday evening was 603 dm, the highest legitimate value ever observed in a sounding here at TOP.)

Areas to our north will have only the 2nd time on record with the warmest temperature of the year occurring in April. There were a few ties. But our area didn’t get warm enough back in April to pull it off. Monthly Highest Max Temperature for Hartford Area, CT (ThreadEx) Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Season 2023 96 88 94 93 88 M 96 1976 96 86 93 92 93 88 96 2002 95 87 94 98 99 91 99 2009 94 89 86 88 94 84 94 1990 94 81 91 95 93 87 95 1962 94 94 91 94 90 86 94 Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Year Apr May Jun Jul Aug Sep Season 2002 97 90 96 100 100 91 100 1990 94 83 92 98 93 91 98 2023 93 90 91 96 90 M 96 2009 93 87 89 91 95 86 95 1976 93 83 93 91 93 89 93

New record with plenty of flooding.

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.