London snow row is 94 on the 06Z, or are you only counting certain days?

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This is the point where I tend to embarrass myself...

The big split on the GEFS begins on the 22nd/23rd. Most Ens members show the low sinking S or SE over the UK, albeit with slight variations on the tracking options. With GFS, it's the next low steaming out of Newfoundland and how that is modelled. Most Ens members force it through over the top of the mid-North Atlantic ridge, which topples the high, initially over the UK.

ECM, on the other hand, also has the low sinking S'wards on the 22nd, but then doesn't develop the Newfoundland low to anything like the same extent. The result is that the mid-North Atlantic ridge develops into a more cut-off high directly north of the UK by 216.

Take the ECM to 240 and there's actually some [what looks like the beginnings of] retrogression, as a low to the UK's ENE builds and extends SW'wards.

 

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London snow row is 94 on the 06Z, or are you only counting certain days?

 

I'm going off the TWO chart:

 

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I'm going off the TWO chart:

 

Hmm, my fingers must have malfunctioned 

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Hmm, my fingers must have malfunctioned 

 

S'ok, I double-checked when I did it, got a different figure from my first, checked again and got another figure entirely. Twas then I cranked up the old abacus.

 

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London snow row is 94 on the 06Z, or are you only counting certain days?

102 the current record Rob, 06z Sunday.

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Snow Rows show less snow forecast in Scotland (more a case of it being drier, rather than too mild), increases in the SE.

 

City	6z 15/01/19	0z 15/01/19	Change
Inverness	274	286	-12
Newcastle	141	176	-35
Edinburgh	136	146	-10
Glasgow	129	142	-13
Aberdeen	127	143	-16
Liverpool	127	134	-7
Belfast	120	129	-9
Sheffield	106	95	+11
Dublin	105	103	+2
Norwich	97	101	-4
Birmingham	92	95	-3
London	86	76	+10
Brighton	78	52	+26
Cardiff	68	63	+5
Plymouth	35	26	+9

 

So indicative of HP to our north and if this is the case then the ECM @ 240 could be the most accurate of all models? I look forward to seeing what the ECM has to say on the 12z run!

How do you gtet the data?

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So indicative of HP to our north and if this is the case then the ECM @ 240 could be the most accurate of all models? I look forward to seeing what the ECM has to say on the 12z run!

How do you gtet the data?

 

From the main TWO site - https://www.theweatheroutlook.com/twodata/datmdlout.aspx

Select the 'GEFS' option, then click on each individual location and count up the snow rows for each. The old fashioned way

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The blocking to north/north east and east increased again in 06z - maybe another growing pattern of a change coming. Positive for cold .
Martin

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Can not fathom discussing model output that is quite likely flawed. Makes no sense surely. It would be like waiting for blood tests to come back knowing samples were contaminated or tampered with in the first place.
Thats my 2 penny worth anyway.

Really measley 850’s all the way when you know what’s really needed for notable cold & snow.
Probably some fun next week up north however... All the signs are pointing to ‘north of the Cheshire gap’ scenarios.

Can not fathom discussing model output that is quite likely flawed. Makes no sense surely. It would be like waiting for blood tests to come back knowing samples were contaminated or tampered with in the first place.
Thats my 2 penny worth anyway.

 

Erm... it's the Model Output Discussion thread.

 

 

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AO looks set for some dramatic changes

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif 

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AO looks set for some dramatic changes

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

Are the forecasts there based on the GFS ensembles? Surprised to see the AO tanking that much based on GFS output.

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AO looks set for some dramatic changes

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

Here is the Caveat - it's the NAO:

Generally Looking to stay positive to me

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Here is the Caveat - it's the NAO:

Generally Looking to stay positive to me

A question. To what extent are the NAO forecasts independent forecasts or are they merely a compilation of whatever the model outputs are showing? If it's the later, then presumably they aren't really any more illuminating in terms of forecasts than simply looking at the ensemble means or whatever. 

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A question. To what extent are the NAO forecasts independent forecasts or are they merely a compilation of whatever the model outputs are showing? If it's the later, then presumably they aren't really any more illuminating in terms of forecasts than simply looking at the ensemble means or whatever. 

Absolutely right. We have the same discussion every winter. The NAO forecasts are just another way of looking at the same data.

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Absolutely right. We have the same discussion every winter. The NAO forecasts are just another way of looking at the same data.

The GFS has often been showing high pressure right over the pole, but with a lobe of the vortex between the pole and the UK, leaving us in westerlies, so it's perfectly possible to have a highly negative AO and still be mild in the UK.

 

According to Wikipedia, the most negative January AO index was in 1977, which coincided with a cold January for the UK but not an exceptionally cold one (CET 2.8C). By contrast it was extremely cold in the eastern USA.

More here:

https://en.wikipedia.org/wiki/Arctic_oscillation

 

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12z ICON at T+168 to kick things off this afternoon:

 

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The link I have posted should explain why I think your reasoning is wrong.

Yes, thank you, I read that. I guess there is something in after all it but I haven't noticed much variability in  the ensembles other than the creeping upwards of the 850 means. Nevertheless there are always some posters saying how bad GFS is when it doesn't show what they want and I think it is often unfairly targeted for the reasons I suggest

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