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La Niña and the latest indicators from the stratospheric polar circle, developments «3B Meteo

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Stratospheric polar vortex
Stratospheric polar vortex

The stratosphere, in these opening bars, is characterized by some warming. One during October brought the area’s average winds down to 10 hPa after previously severe. The transfer of energy towards the stratosphere has weakened the polar vortex, which is becoming decentralized towards western Siberia. After the last pulse of these days IEcmwf model shows rapid increase in area velocities During November, consistent with the deepening of the stratospheric polar vortex. Despite the enhancement, the stratosphere appears to be completely unrelated to the troposphere. It is reasonable to expect that the downward spread of the stratospheric signal may have modest effects on the region’s circulation in the coming weeks. In practice, after this dynamic stage with saccades and clear vertical lands It is possible to establish a more reasonable period in the middle latitudes, although not very long. But this will depend on the degree of contact between the stratosphere and the troposphere.

Speed ​​at 10 hPa according to Ecmwf
Speed ​​at 10 hPa according to Ecmwf

The MJO, which does not have much influence at the moment, could modify the Atlantic jet later. s.In fact, it looks like a lower-capacity Phase 5 is possible over the next few weeks. Under La Nina conditions, the pattern in this case would be characterized by the development of an anti-vortex outcrop in the Atlantic. It remains to be seen how this will affect even if the Ecmwf model suggests a scenario compatible with the MJO phase by the end of November.

The scenario expected by the ecmwf model at 500 hPa
The expected scenario from the ecmwf model at 500 hPa

Let’s go back to the velocity graph at 10 hPa; We see that at the end of the group there is a slight downward trend for the average. Some projections also show values ​​at 10 hPa which correspond to an intense stratospheric warming event in early December with a region inversion. Although in the context of a high degree of dispersion These signs should be followed in the coming weeks where It appears that the stratosphere tends to be warmer than past seasons, and therefore weaker-

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Meanwhile, the intensity of the La Niña phenomenon is intensifying With cold waters swelling in the equatorial Pacific, in both the central and eastern regions. In contrast to last year, the North Pacific also has a negative PDO designation. This pattern would also be consistent with the anti-whirl ridge on the Aleutians rather than bending against the West Coast as we have observed in recent winter years.

The source of the surface water anomaly is somewhat
The source of the surface water anomaly is somewhat

in a Years with La Nina or El Nino increase the greenhouse potential for plants with Enso neutral, Especially when the stratospheric winds are easterly like this year.

QBO . direction
QBO . direction

It is therefore unlikely to have a cold and highly compressed stratospheric polar vortex in the long term.


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