Some interesting trends developing with regards to the stratosphere....
The vortex has began to quickly strengthen after a strong wave 1 warming and EAMT surge last week. Upper stratospheric temps are now returning to below normal levels as solar activity ramps up. Been looking more into stratospheric analogs for the upcoming winter, based on a -PDO, neutral ONI and +QBO state. Best years include 78-79, 01-02, 90-91, 61-62 and 66-67. With these analogs we saw a tendency to see early winter Canadian warming's with December 78 and 66 showing this response.
Dec 1978 warming at 10hpa:
Reduced: 90% of original size [ 565 x 437 ] - Click to view full image
Tropospheric response shows a very anomalous alaskan block with CPF evident from siberia to NA. There was also a very strong -VE anomaly across western europe/ east asia with a gradient pattern look for the UK.
Reduced: 90% of original size [ 565 x 437 ] - Click to view full image
In Dec 1966 the CW response was greater across the mid and lower levels of the stratosphere with a similar 500mb setup afterwords. Notice how the western siberian block becomes dominant with mean troughiness across the mid latitudes.
Reduced: 90% of original size [ 565 x 437 ] - Click to view full image
Reduced: 90% of original size [ 565 x 437 ] - Click to view full image
In terms of other years in the dataset, 61-62 had no Major SSW events and 90-91 had a Major late winter warming with a classic wave 1 response. In the 01-02 season, despite several significant disruptions to the upper vortex, it was tough for these warm anoms to down well, which made minimal impact on the surface pattern until spring.
What may end up occurring this year is we either see a significant warming early on in the winter or no major warming's at all until Late feb into April. The stratosphere looks increasingly vulnerable to some sort of early winter response, especially if we see the MJO moving into phases 4-7 by DEC. This would help force an EAMT surge with bering sea troughiness and possibly a wave 1 response.
If their is no DEC warming, a Final warming event would be favoured with a heightened HT effect coming into play this year. This would become most likely if the monthly SSN drops off and we can get help from tropical forcing as KW's upwell warmth over the western Tropical PAC. The ENSO modelling is honing in on this type of situation, although the -PDO forcing will try to resist any FW attempt's. Many factors are coming into play here but the two period's to watch closest this winter look to be Dec and late winter in the SSW department.
The vortex has began to quickly strengthen after a strong wave 1 warming and EAMT surge last week. Upper stratospheric temps are now returning to below normal levels as solar activity ramps up. Been looking more into stratospheric analogs for the upcoming winter, based on a -PDO, neutral ONI and +QBO state. Best years include 78-79, 01-02, 90-91, 61-62 and 66-67. With these analogs we saw a tendency to see early winter Canadian warming's with December 78 and 66 showing this response.
Dec 1978 warming at 10hpa:
Reduced: 90% of original size [ 565 x 437 ] - Click to view full imageTropospheric response shows a very anomalous alaskan block with CPF evident from siberia to NA. There was also a very strong -VE anomaly across western europe/ east asia with a gradient pattern look for the UK.
Reduced: 90% of original size [ 565 x 437 ] - Click to view full imageIn Dec 1966 the CW response was greater across the mid and lower levels of the stratosphere with a similar 500mb setup afterwords. Notice how the western siberian block becomes dominant with mean troughiness across the mid latitudes.
Reduced: 90% of original size [ 565 x 437 ] - Click to view full image Reduced: 90% of original size [ 565 x 437 ] - Click to view full imageIn terms of other years in the dataset, 61-62 had no Major SSW events and 90-91 had a Major late winter warming with a classic wave 1 response. In the 01-02 season, despite several significant disruptions to the upper vortex, it was tough for these warm anoms to down well, which made minimal impact on the surface pattern until spring.
Reduced 36%
991 x 496 (39.59K)
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What may end up occurring this year is we either see a significant warming early on in the winter or no major warming's at all until Late feb into April. The stratosphere looks increasingly vulnerable to some sort of early winter response, especially if we see the MJO moving into phases 4-7 by DEC. This would help force an EAMT surge with bering sea troughiness and possibly a wave 1 response.
If their is no DEC warming, a Final warming event would be favoured with a heightened HT effect coming into play this year. This would become most likely if the monthly SSN drops off and we can get help from tropical forcing as KW's upwell warmth over the western Tropical PAC. The ENSO modelling is honing in on this type of situation, although the -PDO forcing will try to resist any FW attempt's. Many factors are coming into play here but the two period's to watch closest this winter look to be Dec and late winter in the SSW department.
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