Stratosphere temperature watch - 2016/17

[Snowman.]

That's SSW territory if I have seen it. 

Edited January 13, 2017 by SN0WM4N

[KyleHenry]

4 hours ago, iapennell said:

@KyleHenry; Certainly, if these Stratospheric developments come off as-per the predictions above there is certainly potential for some very cold Maritime Arctic outbreaks over the UK going into February. If a big blocking-high results over Greenland that is certainly possible (maybe even something like what happened in February 1955), but if it positions further south and west (i.e over Canada) its more likely that deep depressions will pass to the NW of Britain instead in which case it will be milder with just short north-westerly snaps (as during the second half of this week).

I bow down to Glacial Point's expertise in these matters.

This winter the EPO has dictated the pattern with the Trop and Strat decoupling. 

This SSW forecasted could sync them was again. 

If we go back to 2013 

We had a sustained event occurring 14 days+ prior to 2017. 

WQBO 2013/17 have near equal indexes https://www.esrl.noaa.gov/psd/data/correlation/qbo.data

PV reformed and NAO remained positive for approx 40 days then came a sustained period of -NAO.

ftp://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.nao.index.b500101.current.ascii

Different factors this year could lead to extensive cold spell from mid Feb. Or an extremely cold Spring aka 2013. 

That change resulted from SSW and only when HP returned to North Pacific.

I need to see what way SSW effects PV  and if more attacks continue after this event to access if 3 weeks or 6 week response.

[stodge]

Evening all

ftp://ftp.cdc.noaa.gov/Public/gbates/reforecast2/teleconn/4indices.png

The current state of some of the teleconnections with NAO set to go negative and the WPO going positive along with the EPO.

I understand the role of the NAO and the AO for us but less certain about the role of the EPO and how it might affect European winters. 

I note southern California has had a lot of rain recently from the so-called "Pineapple Express" and it's my assumption the EPO plays a role in the weather in that part of the world and that has downstream implications for the Atlantic and Europe but the inter-relationship isn't something I'd considered until Kyle's comments above.  

 

 

 

[knocker]

 

[stodge]

Isn't the NAM just another term for the AO ?

Current forecast:

Further into the month, negative NAO and AO are forecast but that's only half the story.

[KyleHenry]

59 minutes ago, stodge said:

Evening all

ftp://ftp.cdc.noaa.gov/Public/gbates/reforecast2/teleconn/4indices.png

The current state of some of the teleconnections with NAO set to go negative and the WPO going positive along with the EPO.

I understand the role of the NAO and the AO for us but less certain about the role of the EPO and how it might affect European winters. 

I note southern California has had a lot of rain recently from the so-called "Pineapple Express" and it's my assumption the EPO plays a role in the weather in that part of the world and that has downstream implications for the Atlantic and Europe but the inter-relationship isn't something I'd considered until Kyle's comments above.  

 

 

 

Where do I start, in its simplest form "The Pacific is king". 

I'm UK centric in all my thoughts. So I trace upstream patterns following each meterlogical/climate process along the way at each relay point to locate the source of UK weather pattern/influences.

Note EPO-HP North Pacific classic La Niña pattern. Create warm Eastern US with amplification which leads to MLB for UK hence the pleasant calm overall winter. 

So in many ways the Pacific is earth's thermostat. Absorbs solar radiation over hundreds of years during active phases. Thermodynamic processes occur between ocean and atmosphere in the form of ENSO phases.Look at PDO reaction during solar hibernation periods.

Edited January 13, 2017 by KyleHenry

[stodge]

2 minutes ago, KyleHenry said:

Where do I start, in its simplest form "The Pacific is king". 

I'm UK centric in all my thoughts. So I trace upstream patterns following each meterlogical/climate process along the way at each relay point to locate the source of UK weather pattern/influences.

Note EPO-HP North Pacific classic La Niña pattern. Create warm Eastern US with amplification which leads to MLB for UK hence the pleasant calm overall winter. 

So in many ways the Pacific is earth's thermostat. 

Thank you, Kyle. Yes, no one can and must underestimate the importance of such a huge area of water on the world's weather. 

I recognise the long draw S or SW'ly across the CONUS which keeps the west coast wet and the east coast mild and dry. The cold air which usually flows south out of Canada into the Great Plains and the east coast is held back but I struggle with the correlation between the pressure systems from the eastern Pacific across to western Europe.

Trying to think it through, low heights over Greenland usually mean HP over Hudson Bay and the LP systems slip below it dragging cold air south into North America. What we see with a west-based negative NAO is strong HP development linking eastern Canada oriented toward Greenland under which LP systems can move and head toward western Europe.

An east-based negative NAO sends the Greenland ridge either south into mid-Atlantic or SE toward Iceland and the British Isles. Either way we are on the cold side of the jet.

We talk a lot in the MOD about the Aleutian HP or LP - is that measured by the EPO and does a very positive suggest a particular synoptic development - our holy grail would be cross-polar ridging as an example.

[damianslaw]

4 minutes ago, stodge said:

Thank you, Kyle. Yes, no one can and must underestimate the importance of such a huge area of water on the world's weather. 

I recognise the long draw S or SW'ly across the CONUS which keeps the west coast wet and the east coast mild and dry. The cold air which usually flows south out of Canada into the Great Plains and the east coast is held back but I struggle with the correlation between the pressure systems from the eastern Pacific across to western Europe.

Trying to think it through, low heights over Greenland usually mean HP over Hudson Bay and the LP systems slip below it dragging cold air south into North America. What we see with a west-based negative NAO is strong HP development linking eastern Canada oriented toward Greenland under which LP systems can move and head toward western Europe.

An east-based negative NAO sends the Greenland ridge either south into mid-Atlantic or SE toward Iceland and the British Isles. Either way we are on the cold side of the jet.

We talk a lot in the MOD about the Aleutian HP or LP - is that measured by the EPO and does a very positive suggest a particular synoptic development - our holy grail would be cross-polar ridging as an example.

Off topic - Somebody posted a synoptic from 17 Jan 1940, a perfect example of a cross polar ridge, slap bang over the Pole, with what looks like a smashed PV, with one lobe dropping through scandi and our way, what a wonderful chart. I think it delivered the heaviest single snowfall of the last century here, and the coldest min temp of the last century, dropped down to -21 degrees around here night of 20/21 Jan. The infamous ice storm occured a few days later. Ooh to have experienced Jan 1940, often not discussed.

Anyway back to the strat watch, interesting developments, potential for major warming event at least which if verified could have significant implications for increasing chance of pronounced cold later in the winter with some high lattitude blocking.

[bluearmy]

33 minutes ago, stodge said:

Isn't the NAM just another term for the AO ?

Current forecast:

Further into the month, negative NAO and AO are forecast but that's only half the story.

Little sign on the extended ens (cross model) of neg AO and the NAO becoming closer to neutral trending slightly positive through week 2

[stodge]

13 minutes ago, bluearmy said:

Little sign on the extended ens (cross model) of neg AO and the NAO becoming closer to neutral trending slightly positive through week 2

If I read this chart correctly, the AO is basically neutral, oscillating between slightly negative and positive values in the next 14 days.

NAO also close to neutral over the 14 day period with a similar oscillation to the AO slightly positive and slightly negative.

 

Edited January 13, 2017 by stodge

[bluearmy]

27 minutes ago, stodge said:

If I read this chart correctly, the AO is basically neutral, oscillating between slightly negative and positive values in the next 14 days.

NAO also close to neutral over the 14 day period with a similar oscillation to the AO slightly positive and slightly negative.

 

The AO chart you showed looks odd compared to the GEFS (too many low returns after the initial positive phase)

i woukd expect these NOAA issued charts to be fairly reflective of the GEFS 

 

[Interitus]

6 hours ago, knocker said:

 

This is a bit unsatisfactory and highlights again the arbitrary nature of SSW definition, about which Dr Butler is a published author of course.

Technically March 2016 counts as a final warming which are often not used in SSW research, but it was a strong SSW with the second greatest 10mb wind reversal just behind Jan 2009, which may well have helped prevent the vortex reforming and westerly wind returning. As a result the reversal on around 5/6th March is by far the earliest final warming in the MERRA data, with 175 days the longest period of summer easterlies ahead of 160 days in 1986 and 151 days in 1985

[Interitus]

Interesting that the CFS runs are now in fairly close agreement regarding timing of a possible SSW (the control goes for a record breaker) -

The early reversal or record-breaker looks unlikely, and from the GFS forecasts (and MERRA data) it is not certain to happen at all yet though should be close. The wave activity chart looks just like waning at the end of the runs, an extensive wave break in the upper levels gives a brief reversal but the vortex looks like reforming, and temperatures in the middle vortex eg 30-50mb are not really warming much to give a reversed poleward temperature gradient.

[stodge]

Thank you for this, Inheritus. 

As you say, a significant event but too early to shatter the vortex though the reviving vortex would be much weaker which might have some impact down the line.

MY concern at present is Steve Murr's comment the warming will be from the Eurasian side - that tends to send the PV back over to Greenland - so we may not benefit in terms of cold conditions.

Mid February is a long way off and as you say, it's a prediction not a certainty.

[Weather-history]

 

[Interitus]

Following on from a previous post examining individual Rossby waves, this excellent site looks at wave packets or wave trains, including GFS forecasts and archives -

http://atmos.msrc.sunysb.edu/research/climate-dynamics-and-variability/wave-packets/

The site should contain more than enough information, and most people should be familiar with the concepts, but a forecast upcoming wave train amplification from today's 00z GFS is a good opportunity for a quick review.

The typical diagnostic is use of meridional (v) wind anomalies at 300mb, i.e. anomalous north/south wind - the signal in zonal wind tends to be swamped by other factors. Here is the latest  northern hemisphere 30-60°N v-wind anomaly forecast in the form of a Hovmoller plot on the left hand side, with calculated wave packets on the right -

A close-up shows the structure in this data with approximate troughs and ridges highlighted by the blue and red lines, and the wave packet propagation by the black line. As is normal, motion is from west to east, but the individual waves travel much more slowly by the phase velocity, seen in the slope of the red/blue lines, compared to the anomalies i.e. the amplification, which travels by the group velocity shown by the slope of the black line -

From 20/01 to 27/01 an amplified wave packet can be seen travelling from around 150°E over the Pacific to reach the eastern Atlantic region 0°W. The start of this is amplification is highlighted by the black box in the zoomed image above which corresponds to area highlighted in this map and is probably caused by baroclinity of cold Siberian air meeting warm Pacific, with possibly some Earth torque -

and two days later the amplification travelling at group velocity can be seen to be advancing ahead of the original wave to enhance anomalies downstream (green box) -

Unfortunately these particular charts stop at 192hr but the suggested onwards wave propagation to the Atlantic in the Hovmoller diagram can be inferred by the amplified jet pattern such as seen here -

Interestingly, working backwards shows an initial disturbance which is present in a couple of days around 90°E over Siberia, preceded by southerly jet to the east of the current Euro trough. So this can be seen to travel round the northern hemisphere inside 2 weeks. Much of this can be deduced from commonly used charts, but this site makes it easier and clearer and can be thoroughly recommended.

 

 

Edited January 15, 2017 by Interitus

[Iceberg]

Pls delete 

Edited January 15, 2017 by Iceberg

[Weather-history]

 

[summer blizzard]

Which other winters saw the double weakening?

[sea swim]

great question! what other years indeed?

[Gray-Wolf]

With such a messy start to the polar winter in the strat I'm not really sure what the current disruption really is? Will it turn into a simple warming event or will it turn into a bigger disruption to the PV?

Should we see another early final warming then we haven't got long for the strat to sort itself into some kind of 'normal' operation before its time to say tarra! for the summer!

[Gael_Force]

1 minute ago, Gray-Wolf said:

With such a messy start to the polar winter in the strat I'm not really sure what the current disruption really is? Will it turn into a simple warming event or will it turn into a bigger disruption to the PV?

Should we see another early final warming then we haven't got long for the strat to sort itself into some kind of 'normal' operation before its time to say tarra! for the summer!

Fergie's tweet posted in MO mentions the Met office doing a blog if they see positive signs of a SSW/final warming. I wonder if there are indications of a repeat of last year: waves of warmth followed by an early FW. The warming signal is waxing and waning a bit too much on the GFS for confidence.

[knocker]

 

[Summer Sun]

 

[bluearmy]

3 minutes ago, Summer Sun said:

 

well done matt - back end gfs charts are beginning feb !