Weekly avg WAFz & OLRa also show a clear wave source emanating from the NE Pacific where SSTs are record warm & fueling convection anomalies. This dynamical connection is not unlike the findings of some studies of the 2021 Pacific NW heatwave, including this one: www.nature.com/articles/s41...

The fingerprints of El Nino with a subseasonal boost from the MJO/BSISO & GLAAM are all over this highly anomalous wave pattern

Even utilizing the Relative Oceanic Nino Index (RONI), the NINO 3.4 region SSTa this year are only being rivaled by the 1997-98 "El Niño of the Century". Our developing "Super" El Niño has exhibited the most remarkable build-up of SSTa since the beginning of the year in the entire satellite era.

I've updated the Ensemble Oceanic Nino Index (ENS ONI) Apr-May-Jun (AMJ) ENS ONI value of +0.97C was the 9th highest in AMJ since 1850, indicative of a strong El Niño via ranks The latest monthly ENS ONI value of +1.45C is the highest on record for June www.webberweather.com/ensemble-oce...

Westerly wind anomalies deep into the Indo-Pacific during the fall before El Niño play a *very* underrated role in preconditioning/charging the Warm Pool over the West Pac The build-up of the West Pac Warm Pool provides the “fuel” for El Niño to grow later in the yr This yr is a classic example👇

How do our low-level zonal wind anomalies over the Indo-Pacific the past few months compare to the onset years of every El Niño since 1950? Almost a perfect match overall. The westerly low-level wind anomalies deep in the Warm Pool are doing a lot of damage already to our current La Nina state

The mean Indo-Pacific Warm Pool last month looks similar to what preceded the 1982, 1997, 2006, 2014, & 2018 El Ninos The Warm Pool is plenty strong enough for El Niño later this year Note that 30C SSTs are centered ~160E & extend to nearly the dateline below the equator

Euro weekly 7-day avg precip anomaly fcst for mid Jan (left) vs correlation b/t the CPC’s EP/NH index & OLRa (right) Note the Eq. Rossby Wave ~150-160E in the Eq. Pacific in both images, where 2 anomalous centers of convective heating straddle the equator. That’s usually how you get -EPO in winter

Rather unsurprisingly, the easterly trade winds are MIA relatively speaking as this -NPO pattern strengthens its grip on the North Pacific

NDJF N Pacific SLPa 1 year before El Nino (left) vs the Euro weekly forecast thru early Jan (right) This year has a classic negative N Pacific Oscillation (-NPO) pattern that often precedes El Nino events in the following calendar year See Vimont et al (2003): journals.ametsoc.org/view/journal...

The ongoing MJO event in the West Pacific has led to a *gigantic* build-up of westerly momentum in the tropical troposphere, w/ GLAAM anomalies approaching 3 sigma! Very El Nino-like

TAO buoy subsurface animation for this past month Notice the thermocline is quickly deepening and the subsurface anomalies are beginning to advance eastward over the West-Central Equatorial Pacific.

The thermocline in the West-Central Eq. Pacific is already responding to the Westerly Wind Burst event & -IOD collapse that occurred earlier this month in association w/ the MJO. A downwelling Kelvin Wave is forming over the West Pacific & will help eventually destroy La Nina in a few months or so.

The GEFS and Euro AIFS ensembles trying to give me some hope for snow in early December. Surely, this must be a trap.

The low-level westerly wind burst in the pacific is what’s really driving the MJO into the Western Hemisphere (phase 8) in Dec (left) That to me is a very telling of how hard the atmosphere is pushing the ocean away from La Niña & possibly towards an El Niño state this coming spring or summer

The warmest water on the entire planet is sitting ~160E in the Equatorial Pacific & a prolonged Westerly Wind Burst event is about to occur here This will trigger a downwelling oceanic kelvin wave that should destroy La Niña ~3 months from now & begin moving the ocean towards El Niño conditions

We might be in a La Niña at the moment, but the tropical troposphere already looks very El Niño-like with a huge build-up of deep-layer westerly wind anomalies In the grand scheme of things, El Nino is likely knocking on the door 🚪

For all my S2S junkies out there, here’s another invaluable tool to add to your arsenal: An annual archive of polar cap geopotential height anomalies going back to 1940 using ERA-5 & a 30-year sliding climatology 👀 hebweather.net/prod/gph_arc...

Cool study came out earlier this yr looking at the dynamical origins of the extreme 2023 Heatwave in the Desert SW They concluded that the warm Tropical Atlantic was the primary culprit The partial regression analysis (left) & AGCM forcing (right) are pretty telling www.nature.com/articles/s41...

I still can’t get over how similar this year’s zonal wind anomalies in the tropics are to 1981

This increase in tropical westerly momentum favors an equatorward shift in the Pacific Jet Stream, which leads to an increase chance of high-latitude North Pacific blocking (-EPO), consistent with current model forecasts & Winters et al (2019) journals.ametsoc.org/view/journal...

Quietly while La Niña persists, the tropical upper troposphere is becoming very El Niño-like A large build-up of westerly momentum (+U) in the tropics is being supplanted by a West Pac MJO orbit & repeated bouts of positive E Asia Mtn Torque (+EAMT) fluxing/squeezing +U equatorward

The global tropics zonal wind anomalies this year are evolving very similarly to late 1981, which of course preceded a “Super” El Niño event in 1982 Note how this yr & 1981 have a big & slow westerly wind burst over the Indian Ocean & Maritime Continent in Oct-Nov that moved into the Pacific in Dec

As you might expect from the very strong -IOD event strengthening La Nina’s footprint globally, this October’s observed pattern has deviated very little from the last 30 years worth of La Ninas over N America

Even when you look at November, this year really isn’t doing anything out of the ordinary for a La Niña

The latest Euro weekly forecast thru mid-December is almost exactly what you’d expect for typical a La Niña December over the last 30 years: A faster-than-usual start to winter over the East-Central US with plenty of high-latitude blocking

thanks ant 😃! I found the east qbo/solar max tendency for strong late winter/early spring +NAM to be weird at first, but It‘s indeed very real. agupubs.onlinelibrary.wiley.com/doi/full/10....

La Niña is living on borrowed time. The extreme -IOD we're currently seeing (right) is about to collapse because the warm water in the Equatorial Indian Ocean will get flushed into the tropical West Pac at depth over the next month in this MJO event's westerly wind burst (left)

Also, the current global tropics SSTa are also almost the exact opposite of the MJO phase speed & SST correlation pattern derived from Suematsu & Miura (2021): journals.ametsoc.org/view/journal...

Many things are lining up for a fast start to winter this year in the East-Central US For ex: being in a La Niña w/ a slower-moving and more amplified MJO (due in part to easterly QBO) makes a subsequent -NAO/AO more likely Fig from Lee et al (2019): agupubs.onlinelibrary.wiley.com/doi/full/10....