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Stratosphere and Polar Vortex Watch

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Febr hope grows to an SSW -so this must be seen as a start of kicking the PV first

 

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This could have the inpact that we search for to winterweather - weakening of the PV

 image.thumb.png.b28dcc4d4d32b8c2f5cea525f90d3af5.png

 

image.thumb.png.d6e41c70176c024190529f336f55d7c7.png

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are we talking a potnetial  SSW in late Feb that may effect the weather in UK  what 3 weeks later in late March 

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54 minutes ago, Doctor96 said:

are we talking a potnetial  SSW in late Feb that may effect the weather in UK  what 3 weeks later in late March 

I think that’s what happened in 2008, which lead to a white Easter, followed by cold weather into April.

Edited by Don

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2 hours ago, Don said:

I think that’s what happened in 2008, which lead to a white Easter, followed by cold weather into April.

March 2013 was exceptional also. (Though I think the SSW that year was in January)

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3 hours ago, Doctor96 said:

are we talking a potnetial  SSW in late Feb that may effect the weather in UK  what 3 weeks later in late March 

3 weeks later would be mid March. SSW's can have sudden effects as happened in early Feb 09 but also slow long term effects as happened in Feb/March 13. In average I think the effects are about 3 weeks later.

Would not at all be surprised to see much colder synoptics surface in March, with perhaps some cold stirrings by late February.

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45 minutes ago, weatherguy said:

March 2013 was exceptional also. (Though I think the SSW that year was in January)

Yes, the 2013 SSW occurred in early January and did actually have a rapid effect, leading to a fairly prolonged cold spell through mid January.  However, the cold relented by the end of the month and was 'on and off' through February, but come March, strong northern blocking really did set in with a vengeance!  April, May and June were all colder than average but a major flip took place at the beginning of July, which turned out to be a hot month, marking the end of a long run of below average months and the colder 2007-2013 period!  We haven't really had a sustained cold period since.

Edited by Don

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Could we not be seeing the first stirring of the 'final warming' being forecast with this laste Jan event merely the warm up to that Final Warming?

IIRC we have seen late Feb Final Warnings over recent years have we not?

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attention to start Febr : ssw looks coming in

 

image.thumb.png.440d0c161b342870c2c810b3bfb8c7e2.pngimage.thumb.png.61d685c168fd4a1ca2ccb06c07f7b3de.png

 

 

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15 hours ago, Don said:

Yes, the 2013 SSW occurred in early January and did actually have a rapid effect, leading to a fairly prolonged cold spell through mid January.  However, the cold relented by the end of the month and was 'on and off' through February, but come March, strong northern blocking really did set in with a vengeance!  April, May and June were all colder than average but a major flip took place at the beginning of July, which turned out to be a hot month, marking the end of a long run of below average months and the colder 2007-2013 period!  We haven't really had a sustained cold period since.

2015 had 5 in a row, 2019 had 5 but not consecutive.

Only 2008, 2010, 2012 and 2013 saw 6 or more 2008 and 2010 had 9.

2 hours ago, Gray-Wolf said:

Could we not be seeing the first stirring of the 'final warming' being forecast with this laste Jan event merely the warm up to that Final Warming?

IIRC we have seen late Feb Final Warnings over recent years have we not?

Only once in 2016, the result of the strong El Niño.

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2 hours ago, Dennis said:

attention to start Febr : ssw looks coming in

 

image.thumb.png.440d0c161b342870c2c810b3bfb8c7e2.pngimage.thumb.png.61d685c168fd4a1ca2ccb06c07f7b3de.png

 

 

Sorry, i cant read those thumbnails, and magnifying them doesnt change their size either.

 

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The 12z GFS is still going for the Strat warm, and it looks to be staring within what might be considered the reliable. 

 

04B4E99B-09EA-4D5C-A150-A1644A1B14E2.png

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120922CC-D74E-4A28-A5ED-D4AF3D2658DD.png

198A9194-9151-4DEA-B52D-C8E90B4FA189.png

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6 hours ago, bluearmy said:

7321F1B9-9441-4EB4-8011-549E7B06C06F.thumb.jpeg.ccb6ef969d6b0d989291c38f2e2223eb.jpeg

the wider view not without interest either .....

 

T375 on the 12z was the lowest 10mb 60N zonal wind of any GFS op run since before the start of November at 8.3 ms. Gone on the 18z, lowest 23.3 ms.

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10Hpa warming - could be the change end of Febr to winter

 

 

image.thumb.png.23d26f3fde79c94619acfa12777c803f.pngimage.thumb.png.df3da37bf696ac48eae13a91fd4d6577.pngimage.thumb.png.c5afa81c7cbb3bfb0cc4fa043d42f245.png

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On 18/01/2020 at 10:12, bluearmy said:

Definitely reversed at the top

looked like it wasn’t quite below 2hpa 

1D45A1A9-43BE-428A-98B2-3CCBEF021D76.thumb.jpeg.197ee5b3212d59e534341b9df4f18daa.jpeg

To update, this 18/01 00z is a bit of an outlier at the moment, there hasn't been a reversal in the 24 runs since, clustering of the windspeed graph shows that reductions are struggling to get inside the 10-12 day reliable timeframe -

70858536_1mbZMZW.thumb.png.b2c3097d102e22840bbcc15493433d35.png

Edited by Interitus

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3 hours ago, DavidS said:

Yep, GEFS going for a reversal

 

20C83EE2-4D88-4D43-AE2C-3343F648CEDF.png

Only 2 members but its a start, would like to see CFS going for it more as they have in the past usually been aggressive with SSW's

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20 minutes ago, feb1991blizzard said:

Only 2 members but its a start, would like to see CFS going for it more as they have in the past usually been aggressive with SSW's

Yes agreed, the post should have mentioned that it was some gefs members. The mean doesn’t take it to a reversal....yet.

The 6z GFS is still going for the strat warm.

 

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Definite trend downwards starting to show in GEFS in early Feb, some members going negative, but we've been down this garden path before in December at that range, need to get into the reliable to start getting interested

1518644102_u_65N_10hpa_gefs(1).thumb.png.2ab6042eb41771edab05440672f38a82.png

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14 minutes ago, Nick F said:

Definite trend downwards starting to show in GEFS in early Feb, some members going negative, but we've been down this garden path before in December at that range, need to get into the reliable to start getting interested

 

To be honest though i was never quite on board in December, it never looked quite right, added to the fact that we have only just started using the GFS op for this purpose so its inherent biases are not yet fully understood, i am more hopeful with this upcoming event but concerned about the timeframe, also will the displacement SSW be enough to influence the trop favourably? It does displace the SPV into a favourable position but would we require a subsequent split to really have influence and also if we did get a split then where would the daughter vortices go?, the one thing on our side though with it being late in season is it might only need a significantly weakened stratospheric vortex in order for the tropospheric vortex to be able to do more of what it wants with the usual seasonal wavelength pattern changes late Feb.

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2 hours ago, feb1991blizzard said:

To be honest though i was never quite on board in December, it never looked quite right, added to the fact that we have only just started using the GFS op for this purpose so its inherent biases are not yet fully understood, i am more hopeful with this upcoming event but concerned about the timeframe, also will the displacement SSW be enough to influence the trop favourably? It does displace the SPV into a favourable position but would we require a subsequent split to really have influence and also if we did get a split then where would the daughter vortices go?, the one thing on our side though with it being late in season is it might only need a significantly weakened stratospheric vortex in order for the tropospheric vortex to be able to do more of what it wants with the usual seasonal wavelength pattern changes late Feb.

Yes, this slowing of zonal winds certainly seems to have more mileage this time round, plus some of the EPS members in the 10-15 day range have been showing a reversal lately. Seasonal weakening of SPV would be expected as we head through Feb too, which will help. Then if a major SSW occurs we need to hope the response is quick and favours HLB that would position favourably to bring sustained cold to the UK. Lots of hurdles to get over, that’s after we do get a reversal in the bag!

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1 hour ago, Nick F said:

Yes, this slowing of zonal winds certainly seems to have more mileage this time round, plus some of the EPS members in the 10-15 day range have been showing a reversal lately. Seasonal weakening of SPV would be expected as we head through Feb too, which will help. Then if a major SSW occurs we need to hope the response is quick and favours HLB that would position favourably to bring sustained cold to the UK. Lots of hurdles to get over, that’s after we do get a reversal in the bag!

And add to this the QBO now going Easterly 🙏🤞☃️

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On 23/01/2020 at 14:49, summer blizzard said:

2015 had 5 in a row, 2019 had 5 but not consecutive.

 

Good point.  I think 2015 was overshadowed by that horrifying December!

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Split at 10hPa on GFS lala land

anim_zxq4.gif

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