In Depth Model Discussion and Summaries

[johnholmes]

the operative word being IF

Nor am I sure of what time scale any MJO forecast is valid for-will have a look to see if there are dates given=

 

yes there is above the MJO forecast chart, it seems to be for 14 days so in the case quoted it is for 5-19 September NOT October

Edited September 6, 2013 by johnholmes

[johnholmes]

from the model thread and also re post 2344 page 118

Noaa

6-10 and 8-14 pretty similar to last issue

 

Along with ec-gfs outputs to me this suggests surface pressure rising off w/sw eire to settle wx down over much of uk but trough is close enough out to day 14 to e’ernmost areas on ec(6-10) and noaa(6-10 and 8-14) to ‘perhaps’ keep far e parts of uk less so. Met do not suggest this so they must have some further data, ec 32 perhaps more like their own long range mogreps suggests the trough far enough away not to have any effect in range beyond 6-8 days?? Or maybe I’m mis reading the anomaly charts

Have a look at naefs 500mb?

7 days time=T+168, see below;

http://www.meteociel.fr/modeles/naefs_cartes.php?mode=0&code=0&ech=6&map=&runpara=

 

Further out and there is really no anomaly showing on it around the uk area e/w/n/s

So maybe there will be no residual e’ern troughing effect and the main feature day 6-15 will be ridging at 500mb with a surface high close by/over w’ern areas of the uk?

[Isolated Frost]

Oh no! I'll save the composites next time, I'll have another go.

Current Arctic Oscillation values (forecasting/modelling to 20 Sep) seems to be suggesting a near neutral September after a +ve AO start. A lot will depend on the last 10 days.

 

Anyway, these are September neutral (-0.5 to 0.5 value) AO composites for the last 30 years (for November-January)

-ve anomaly across the UK and to the W/NW, large +ve anomaly to the N/NE. Suggesting a pretty cold outlook for the UK, with the atlantic battling a strong northern/continental block.

The GPH values however indicate the lack of blocking o/ Greenland, and a strong atlantic. So, that seems to be the 'benchmark' of neutral September AO values.

 

But remember, that is November-January. Roll that forward to December-February (the signal will weaken as it is more long-term)...

Let's retrogress... the signal for +ve heights shifts west towards Greenland, and -ve anomalies towards Nova Scotia. No full on Greenland block, but more positive signs for cold weather into January and February you would imagine.

 

The AO is by no means a guaranteed forecast projector, far from it, with the use of ENSO/QBO/Stratosphere (increasingly popular I see) and shortwaves (!), but I believe the Arctic is a major driver in our weather, and think this summer has shown that reasonably well. I will go further on this in a bit, as Sep may not end neutral- and I will try some more Sep-Oct-Nov pairings to gain reliability. I would love anyone to give any feedback on this post!

 

So, in essence, a neutral September AO is likely to provide wetter weather in the early part of the season, with a strong block to the NE and the chance of colder Easterly incursions, before the block triumphs later on in the season, and gives drier and cooler weather by February.

[Isolated Frost]

Right then, now here's one for you. Some of you will LOVE this I'm sure.

Say, September ends neutral (likely), and October ends up positive (we don't know yet). 4 years have done that, 1985, 1986, 1990 and 2008.

 

Anything?

4 years in the last 30 have had a neutral September AO and a +ve October AO, 85, 86, 90 and 08.

February 86, January 87, February 91 and February 09. Probably some of the most extreme snow/cold events of the last 30 years have all occurred during this scenario, which is a really weird turnout!

It appears as though if September stays on course and the Arctic has +ve AO during October, we could end up w/ another big event.

 

 

One of the more interesting composites about... maybe a wet and stormy December followed by a continental blast in January or February?

Edited September 9, 2013 by Isolated Frost

[Isolated Frost]

September neutral and October neutral

Alternatively, if September stays on course and October goes neutral as well... have yourself a Euro high and a half. Stream of mild S/SW'lies with big -ve heights o/ Greenland +ve heights o/Europe... coldies look away!

 

September neutral and October negative

...or, October goes negative AO wise, and we see a pretty wet and stormy winter in general; but with northern blocking around, the jet drifts south and we're in for cold.

 

Generally, if September is neutral (which is likely), and October is neutral - expect a wet but mild winter. If September is neutral and October negative - expect a mixed winter, with some wet and mild and some cooler and drier weather. And if September is neutral and October positive - expect a wet and stormy start, and then something potentially special in January or February.

 

Will definitely make a winter forecast once the values for Sept and Oct come out, will be interesting to see whether these composites based on only one value can be so consistent and/or reliable. I'll do the September positive-October... and September negative-October... composites in a bit. And maybe do some monthly ones later on (for Nov, Dec, Jan/Feb).

[Isolated Frost]

Looking at AO modelling; we seem to be spiralling into a potentially neutral-negative September. Accompany that with the August oscillation- and we're looking at an...

 

Aug Neutral-Sep Neutral (1984, 1985, 1990, 1993, 1997, 2000, 2002, 2003, 2007, 2008)

Aug Neutral-Sep Negative (1996)

 

Aug N - Sep N - Oct P (40%) 1985, 1990, 2008

Aug N - Sep N - Oct N (40%) 1984, 2000, 2007

Aug N - Sep N - Oct N-ve (10%) 1993, 1997, 2002, 2003

 

Aug N - Sep N-ve - Oct P (4%)

Aug N - Sep N-ve - Oct N (4%) 1996

Aug N - Sep N-ve - Oct N-ve (2%)

 

Based on current composites, I'd say 85/86, 90/91, 08/09 are the most likely winter composites to come up, and then 84/85, 00/01, 07/08.

[lorenzo]

Awaiting the latest MJO update due to be published this evening, last entry is 09/09, updates every Monday for those who don't look at this one. Still with the move from the origin point of the chart into low amplitude phase 5 and phase 6 analogs.

 

Phase 5 / Phase 6

 

Phase 6 being one of the most bizarre offerings from MJO, led me to wonder about it's composition and thinking through the anomaly chart the components of the strong mid-atlantic ridge are on offer within the output along with the continued attempted Azores ridging, then to counter that the trough element, which is where the bizarre comes in with the pure N-S alignment, could be Phase 6 displays by the end pattern both elements merged out over a period of time.

 

Put simply, I don't think we will see anything in NWP output representative of Phase 6 analog for September, but one can recognise why it is there as both features are heavily prevalent

 

Looking at GWO , this is something I am still patiently waiting for an a+b=c guide on.. even having read Weickmann & Berry paper, I guess you just had to be there !

 

The latest profile is here, the blob of red indicating the jet firing up again in our region a stronger resurgence than the last few months as it awakens from slumber. ( compare with the full on meanderings of the Southern Hemisphere !) In addition, a little pulse of negative anomaly beginning to show at higher latitudes as we progress to Autumn.

 

Jets / Torques

 

 

On Mountain Torques, if anyone wants to decipher the divergence here then please do, trend is reduction in overall, with the weighting of the importance of the Asian Torque in evidence

 

I guess during the Ed Berry era GP studied these as Berry's blog plotted in real time the atmospheric responses in wave pattern, sadly that information and that work in progress that led to the GWO is now fire walled. For now I can only observe the peaks and troughs and phases, not predict with 'thar she goes' clarity. Will hope to devote more time to this in future, but worth keeping active so others can do the same.

 

As an side and looking at our Winter season ahead, I appreciate there is a Winter discussion thread going, however if anyone has thoughts on analog year, when why, this may be a good place to put them to save them getting lost in the rapidly filling threads. I picked 1990 last weak based purely on QBO wind data and the accelerated phase over the last 3 months, with 1990 being the only comparable years on the QBO.dat list. Ed quickly countered this due to the sun phases and rightly so, the solar max and assoc. energy of 1990 a completely different idea. Any thoughts..

Edited September 16, 2013 by lorenzo

[Gael_Force]

My thoughts are that it may be impossible to find meaningful analogues. It is a bit of a cliche to use 'uncharted waters' but that, in effect, is where we are at the moment. Recent papers point to low solar activity and low Arctic ice volume as being major drivers of atmospheric patterns - we've got past solar grand minimums to refer to but no template on the ice.

 

Hathawy's update refers to a solar max as low as in 1906 - we are very close to Dalton levels of 200 years ago, a period known for unpredictability and wild swings in weather type over W Europe - no models, indices etc to refer to make for a challenging time in trying to second guess what a season will bring.

[lorenzo]

Spent yesterday updating an excel sheet for analogs, as useful or useless as some may find them, still an interesting bunch of information and handy referral guide. Years on this are from 1950 til present. 

 

Includes ENSO, Sunspot Counts, NAO, AO, Berlin Strat Data - Major Warmings and Canadian Warmings.

 

The filters are really useful as they let you select for example all Neutral ENSO years, or the Top NAO negative years etc etc. Also you can filter by colour of the cells if you wished to strip out all the Novembers where a Canadian Warming took place.

 

Edit - Updated the settings to allow the filters to work.

https://docs.google.com/spreadsheet/ccc?key=0Ah3v2E9FYXI5dFJiUmJHNWRYMndzZW9iWDlBNjFyS2c&usp=sharing

Edited September 18, 2013 by lorenzo

[MR EXTREMES]

Spent yesterday updating an excel sheet for analogs, as useful or useless as some may find them, still an interesting bunch of information and handy referral guide. Years on this are from 1950 til present. 

 

Includes ENSO, Sunspot Counts, NAO, AO, Berlin Strat Data - Major Warmings and Canadian Warmings.

 

The filters are really useful as they let you select for example all Neutral ENSO years, or the Top NAO negative years etc etc. Also you can filter by colour of the cells if you wished to strip out all the Novembers where a Canadian Warming took place.

 

https://docs.google.com/spreadsheet/ccc?key=0Ah3v2E9FYXI5dDhiSGdQV1FmbXMyclhoTmd1VHlSYXc&usp=sharing

that's incredible stuff it would seem we are due a Canadian warming event although there is certainly is more in this data very intresting excellent stuff.

[lorenzo]

Thanks MR, yes that elusive Canadian Warming, we were all over that in last years strat thread, it would seem it is very overdue.... 2012 November came and went and by that time the excitement was ridiculous about January. Now the fun part, to use the data to make some analogs..

[lorenzo]

As a couple of you know been trying to play around with analogs, and also get them into custom time series.

 

Here are a couple of preliminary composites for October, based on similar positions of the GWO and MJO since 1974, these results are filtered down to lower AAM state, representative of the minimum westerly flow we are experiencing at present and also the MJO cycling in phase 6 for October.

 

All Years since 1974 / Recent 5 years

 

 

 

Bit of an experimental plot, so will see if it proves useful over time..

 

 

 

 

 

[lorenzo]

The fun continues, a little bit of evidence now that a database I have been working on seems to do the trick.

 

Here are the MJO plots for October for Phase 5

 

Current Composite / New Database composite - represents a good match.

 

 

New Composite in 'Map' form vs Polar View

 

Finally with the amplitude filtered for the expected start of October, lesser amplitude in the MJO wave for phase 5 elongating the Arcitc heights and giving a less pronounced trough in our vicinity.

 

So, perhaps what we may see as October begins and the MJO retreats towards it's base state.

Edited September 24, 2013 by lorenzo

[damianslaw]

This thread has been very quiet these last couple of weeks - symptomatic of the current quiet weather I suspect.

 

With the oulook for probably at least the next 10 days more settled high pressure weather, it would be good for more experienced forecasters to post thoughts on more longer term prospects as we move into the middle of the month and whether these may bode a major change to something either much more atlantic dominated or indeed colder from the north.

 

 

[lorenzo]

RE previous post, with the Phase 5 analog. that didn't pan out at all well !! MJO moved on a little, guess if taking anything of note from that were the defined Arctic heights at the time.

 

The plot of phase 7 whilst full of troughing across CONUS does highlight 2 key features cropping up on current output, namely the UK ridging and the location of the Vortex. This is the where the amplitude is below 1. Didn't really expect the ridging anomaly which extends  far North on this plot to appear, interesting to see ECM toy with this in some frames at present.

 

The All amplitude analog and also Alan Huffmans one here for comparison.

 

Looking at MJO forecasts among the models each have very different ideas at present. UKMO fires things up a little.

 

GEFS has a flatter orbit into low amplitude Phase 8, along with the classic MJO plot and the one filtered for again low amplitude. Very different.

 

ECM having none of it and again we are back in the null zone, following the monthly outlook this the version not amended for climatology the EMON, the mid range version alongside.

 

Taking a read on that there is no clear route to prediction with reference to MJO. However some themes there and the High pressure influence is captured well. 

 

GWO main homepage is offline. Nick Schiraldis page is updating and the Start and End forecast remain in the origin zone.

 

Quite an unusual October by all accounts, and the lethargic Hurricane season is my main culprit. Can't help thinking with all that ACE to catch up on in terms of redressing the yearly means then things will spark along sooner or later. Until then I guess the eyes are on the longer term impacts of the SAI for October.

 

Edit just noticed http://www.nhc.noaa.gov/#KAREN The next one's got my name on it, would be ironic if that was the one that unlocked the door to the Atlantic.. hope it's a fish !

Edited October 3, 2013 by lorenzo

[johnholmes]

copied from model thread

 

I know some do not have the same trust in the anomaly charts WHEN they are consistent from day to day and with one another but the 2 below give an indication of what the upper air is most liely to be similar to in the 6-15 day time scale, that is late October. Nothing there in the charts suggests major changes in the pattern or wavelength. They are being consistent over the last 3 days so I would be very surprised if the upper air pattern is markedly different come 19 October or indeed by 5-7 days after that.

http://www.cpc.ncep....10day/500mb.php

 

Does anything further out suggest they may change after this?

The MJO is currently in 6,

http://www.cpc.ncep....O/whindex.shtml

 

the forecast is for this

http://www.cpc.ncep....O/foroper.shtml

 

again a low orbit so its effect is unlikely to have any effect on what we already have.

 

and a fairly low orbit, which suggests 

http://www.americanw...Phase6500mb.gif

 

The AO and NAO (yes i know only a mirror in a way of the synoptic patterns on the models) but neither do they support any marked change from what we have.

 

So I cannot yet see when the current upper pattern is going to change, the major troughs are around the areas west of Alaska and south of Greenland, then way off the northern end of the chart, showing a very large amplitude. Once this type of 3 main trough set up occurs it is quite a long process to change it. I do not have the knowledge to even suggest when or how this might happen. It MIGHT be a tropical storm/Hurricane develops at last. This would certainly have some effect on this long wave pattern. Is there one around?

answer=http://www.nhc.noaa....scus.020.shtml?

 

That seems unlikely, from present data, to be the one but who knows one may develop in the next 2-3 weeks. Their development coming off western Africa is an unknown quantity, only once they have begun to show certain characrteristics do NOAA get a grip on what they may do. Certainly none of the other models do at that stage and the anomaly charts are notorious at showing anything at 500mb until late in the day.

[damianslaw]

Thanks for the posts above - it appears there are no signals at present for any significant change in the longwave pattern as we move into the second half of October. However, at the surface things may be very different, all dependent on where heights and ridging position themselves - if we see a shift NW, then a much cooler pattern would develop with fog and frost very likely whilst staying settled.

[lorenzo]

At first attempt for October using the refined MJO analogs then I am pretty happy with this.

 

 

Everything lined up in our vicinity, the Atlantic troughing, the elongated High Pressure and the core of the vortex, albeit a little farther East than the plot. In addition a couple of the lows on the other side of the hemisphere are also visible within the output.

 

Could be that the new ones with the higher amplitude MJO stripped out give a better outlook. Obviously lots of testing and trialing needed but will keep at it until it works !

 

[phil nw.]

Looking at todays outputs there is everything to suggest we will enter a more typical mid-Autumn Atlantic driven pattern as we go into next week.

The day 10 means from the latest ECM/GFS runs show a westerly setup which combine well with yesterdays MJO forecasts showing enough activity in phase 7to 8 to draw some guidance.

Some variance by the different agencies with the UKMet more bullish on MJO activity.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/UKME_phase_23m_small.gif

 

 

MJO phase 7 and 8 composites for October.

 

 

The main features in the modeled 500hPa pattern are the Atlantic trough near the west of the UK from generally lower heights over the Arctic and Euro.high pressure-a more +ve NAO if you like.

 

The London ens graphs underline the milder and wetter outlook to come as head towards mid-October.

 

 

so the benign and rather dry start to Autumn soon looks like evolving into something more seasonal.

I guess with an ever cooling vortex developing over the Pole it was only a matter of time before this phase of weather would show it's hand as heights started to fall further north.

[summer blizzard]

Looking at AO modelling; we seem to be spiralling into a potentially neutral-negative September. Accompany that with the August oscillation- and we're looking at an...

 

Aug Neutral-Sep Neutral (1984, 1985, 1990, 1993, 1997, 2000, 2002, 2003, 2007, 2008)

Aug Neutral-Sep Negative (1996)

 

Aug N - Sep N - Oct P (40%) 1985, 1990, 2008

Aug N - Sep N - Oct N (40%) 1984, 2000, 2007

Aug N - Sep N - Oct N-ve (10%) 1993, 1997, 2002, 2003

 

Aug N - Sep N-ve - Oct P (4%)

Aug N - Sep N-ve - Oct N (4%) 1996

Aug N - Sep N-ve - Oct N-ve (2%)

 

Based on current composites, I'd say 85/86, 90/91, 08/09 are the most likely winter composites to come up, and then 84/85, 00/01, 07/08.

 

Looks to me like we got neutral all three months giving us 1984, 2000 and 2007 as analogues.

[lorenzo]

Right, will leave this ugly looking analog here, based in particular on the OPI and predicted AO and ENSO neutral range depicted on plot. Here is your DJF analog for all dates. Quite a limited dataset.

 

ENOP.txt

[phil nw.]

Right, will leave this ugly looking analog here, based in particular on the OPI and predicted AO and ENSO neutral range depicted on plot. Here is your DJF analog for all dates. Quite a limited dataset.

 

ENSO Neutral and OPI.gifENOP.txt

That won't go down well with cold lovers L.

Looks like our current outputs!

Can you explain what the OPI is please-is something to do with October snowcover ?

I agree re.ENSO range looks like a neutral range will continue for Winter.

[lorenzo]

OPI is October Pattern Index devised by some Italian Meteorologists, it is an extension of the SAI work by Cohen and claims high correlation with the predicted winter AO.

 

Link is here.

http://www.centrometeotoscana.it/forum/index.php?topic=7473.0

 

Correlation

 

Interesting reading

 

[Cheshire Freeze]

Right, will leave this ugly looking analog here, based in particular on the OPI and predicted AO and ENSO neutral range depicted on plot. Here is your DJF analog for all dates. Quite a limited dataset.

 

ENSO Neutral and OPI.gifENOP.txt

 

Urgh not nice. Icky icky icky.

[phil nw.]

OPI is October Pattern Index devised by some Italian Meteorologists, it is an extension of the SAI work by Cohen and claims high correlation with the predicted winter AO.

 

Link is here.

http://www.centrometeotoscana.it/forum/index.php?topic=7473.0

 

Correlation

OPI 1.65.png

 

Interesting reading

 

Ah i thought it was-i remember  spotting something on that a week or 2 ago but never got around to reading it.

Thanks mate.