General Model Output Discussion

[full_frontal_occlusion]

Snow in N Africa?

Lol.

Perfectly normal. That is after all, the location of the Atlas mountains rising to 4150m (14,000').

Winter sports are common and snow lasts until late spring.

ffO

Edited December 31, 2009 by full_frontal_occlusion

[Lewis]

I must be missing something here.

All the model runs I have seen suggest possible snow showers into NE England/E Scotland/E England. Now the GFS 0Z indicated snow showers moving into the wash and then moving SW tonight. However the UKMO doesn't sugggest much snow for E Anglia tonight but they do suggest snow showers moving S tomorrow.

SO I have to ask where in the model runs was heavy snow suggested for W Midlands/Wales?

How inaccurate the GFS is with plotting precipitation,

I don't see that near the wash/ea do you?

[Kiwi]

The low coming in from the SW is further north (again)on this run giving a potential for some snow in the far SW of England.

Edited December 31, 2009 by Kiwi

[Totoro]

Bloody hell, how did my post become so mangled? Oh well, here's the short version:

I remember that 1978 blizzard VERY well as I lived near Bristol at the time. There's certainly the 'potential' for that to happen again given the current setup, I live in hope.

BTW, can you (or someone) remind me of the link to that site with those old synoptics please? I had it book-marked but can't find it any longer. Thanks.

Edited December 31, 2009 by Totoro

[Glacier Point]

Given this mornings model output I'm happy to stick to my thoughts of yesterday evening shown below:

An interesting trend developing in the ensembles which i've been keeping an eye on, a few days back many more southern european locations had a switch to milder conditions as the models were keeping the southerly tracking lows further north with of course these areas more often on the warmer side of these. For a few runs now more colder options appearing, for London some colder members down to around -12, now interestingly for Paris some down to -15 aswell as Toulouse. Now looking at Iceland a warm up going on up there later next week this seems now to suggest that possible high pressure closer to the north and possibly ne.

Just one thing to add here from yesterday evening are this mornings NOAA discussions:

A CLOSED HIGH /POSITIVE ANOMALY/ OVER GREENLAND IS EXPECTED TO

PROGRESS THIS PERIOD AS AN INCREASINGLY AMPLIFIED WESTERN RIDGE

DEVELOPS WHICH FORCES TROUGHING DOWNSTREAM IN CENTRAL NORTH

AMERICA WHICH KICKS THE VORTEX NEAR THE NORTHEAST/ATLANTIC CANADA

NORTH AND NORTHEASTWARD.

If the high can stay far enough north as it moves eastwards then a chance of a Scandi high or high pressure centred to the north around the Iceland area with some reinforcing colder upper air backing westwards especially for more se areas.

Ties in nicely with my thoughts Nick [see other thread].

It does look like some flow will increase on the northern arm of the jet. The eddy-formation is likely to result in some form of blocking setting up towards our north or north-east. I would go for the north as the more likely here given the state of the polar vortex and also upwelling wave to our north.

[johnholmes]

I must be missing something here.

All the model runs I have seen suggest possible snow showers into NE England/E Scotland/E England. Now the GFS 0Z indicated snow showers moving into the wash and then moving SW tonight. However the UKMO doesn't sugggest much snow for E Anglia tonight but they do suggest snow showers moving S tomorrow.

SO I have to ask where in the model runs was heavy snow suggested for W Midlands/Wales?

quite right TEITS-quite what some see on model runs escapes me at times.

[Neilsouth]

Yay for vanishing posts!

Anyway just checking the thickness's too see where exactly the much colder air is due to sweep the south and at the moment it's still way up north but by tomorrow...

http://expert.weatheronline.co.uk/daten/proficharts/en/2009/12/31/basis06/ukuk/tpps/10010103_3106.gif

As for snow , Gfs push's it in with the cold air early friday so don't expect any snow tonight in ea or south east.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=gfs&MODELLTYP=1&BASE=-&VAR=prty&HH=24&ZOOM=0&ARCHIV=0&WMO=

[mezzacyclone]

Brief but solid ens. agreement (3rd Jan) for rises in aforementioned areas Oslo and but fax charts showing none of it???

any more ideas/thoughts chaps & chapesses?

(silent respect as always for the "tech depth" post gp ;])

[Paul]

How inaccurate the GFS is with plotting precipitation,

I don't see that near the wash/ea do you?

That chart is for the period 6am to 9am, and in that time there has been up to (approx) 1mm in some of those areas, that chart shows up to 1.5mm, so it's a little overdone but nothing that bad. You have to remember the GFS is a 0.5 degree model (ie approx 50km), so it's not going to paint details on when it comes to showers etc, it's going to slap precipitation on with a fairly broad brush.

[Weather-history]

Here is the 0z NAE preciptation for New Year's Day

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2009/12/31/basis00/ukuk/prty/10010118_2_3100.gif

[johnholmes]

Just one thing to add here from yesterday evening are this mornings NOAA discussions:

A CLOSED HIGH /POSITIVE ANOMALY/ OVER GREENLAND IS EXPECTED TO

PROGRESS THIS PERIOD AS AN INCREASINGLY AMPLIFIED WESTERN RIDGE

DEVELOPS WHICH FORCES TROUGHING DOWNSTREAM IN CENTRAL NORTH

AMERICA WHICH KICKS THE VORTEX NEAR THE NORTHEAST/ATLANTIC CANADA

NORTH AND NORTHEASTWARD.

If the high can stay far enough north as it moves eastwards then a chance of a Scandi high or high pressure centred to the north around the Iceland area with some reinforcing colder upper air backing westwards especially for more se areas.

the quote from NOAA is, as I'm sure you know Nick, one they have posted in one part or other of their short and longer term comments regarding the +ve anomaly over southern Greenland for much of the past week. Their 500mb anomaly charts and also those of GFS and ECMWF are all pretty similar.

The risk of any major LONG TERM breakdwon in the cold spell, note the capitals, as opposed to short term encroaches being possible into parts of southern UK from lows yet to form in the Atlantic, is, in my view, and also noting what GP has just posted, fairly slight for 10-14 days and probably out to 21 days. Sorry its a long sentence. beyond that then as I suggested last evening best to go for a reading from, is it, Mystic Meg, for the rest of the winter!

As to where the major blocking in our area of the northern hemisphere is more likely then I suspect there is no favoured zone. IF and its still relatively early days, this does develop into a winter of some standing, maybe the most notable from a 'cold' viewpoint for over 20 years, then all the classic winters showed blocks varying from the NW (Greenland/Iceland)-north and north east into Scandinavia with occasionally extensions of the climatic Siberian/Asian winter high into this area.

Like I said its very early days yet but there is so much cold pooling going on over much of the northern half of the northern hemisphere that its difficult to see how a major change can take place much before the end of January IF then.

No doubt I'll be asked to eat humble pie in a week or so as the Tropical Maritime air rushes in!

[BLAST FROM THE PAST]

Probably-

in the meantime we have 9-10 days of potential snow, ice, blizzards, frost & windchill to talk of- not to mention the possibility of record cold minima -

S

Yes, at least. The severe warning I issued which RRR initially had on his sig was for real. This is a humdinger of a cold spell coming AND WILL STAND UP TO ANY OF THE GREATS IN 70s and 80s......wtach this space and watch for snowfall upgrades. Not everywhere will get it at the same time but each fall 3-5, 7-10, 15-20 will be very notable for those that have it.

Just got to love the post from JH above, that one is what NW community need to take note of.

BFTP

Edited December 31, 2009 by BLAST FROM THE PAST

[Lewis]

That chart is for the period 6am to 9am, and in that time there has been up to (approx) 1mm in some of those areas, that chart shows up to 1.5mm, so it's a little overdone but nothing that bad. You have to remember the GFS is a 0.5 degree model (ie approx 50km), so it's not going to paint details on when it comes to showers etc, it's going to slap precipitation on with a fairly broad brush.

Exactly, valid point there Paul.

Which shows that given the resolution, the GFS should not be taken as Gospel. So if people want to be 100% sure or near enough, get Netweather Extra, the NMM model is fantastic.

Lewis

Edited December 31, 2009 by Storm Force Lewis

[TEITS]

get Netweather Extra, the NMM model is fantastic.

Lewis

That was the first model I looked at today and I agree with your comments like I said earlier.

Back to the 06Z and looking at +144 and comparing to the other models and I can't much agreement with this run. Far too progressive and I believe the PV will be further E than the 06Z suggests.

[karyo]

Here is the 0z NAE preciptation for New Year's Day

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2009/12/31/basis00/ukuk/prty/10010118_2_3100.gif

Plenty of precipitation for Northwest England and Wales! Ties well with the latest bbc24 forecast saying snow showers moving from Scotland into northern parts of England and then further south.

Karyo

[Lewis]

I did not state it's a let down, i just said how inaccurate the GFS is with precipitation on that chart. It got the NE Scotland, SW England precipitation correct, but way off closer to the East Coast.

Given the resolution just like Paul explained on his above post, it's fairly accurate, but even that small difference at the given resolution, can be far out locally. So that's why i tend to dismiss the GFS precipitation charts 9 times out of 10, only time i trust it is when it's a low pressure.

I always wait for the NMM to update to the latest run, as i find the NMM models especially during this last cold spell, spot on the money.

Lewis

[andy_leics22]

What??????

That area of precipitation lies DIRECTLY over the Wash, just as TEITS says.

As for snow in the West Midlands tonight - it was never forecast at any point to my knowledge. Either people have problems remembering the charts, or their knowledge of British geography is disappointing!

There was PPN slap bang on the center of the Midlands on all yesterdays GFS runs for Friday. It would have been snow but now this morning the GFS has backtracked and shows nothing of the sort.

I don't even know why people talk about T144, even T72 isn't nailed on in this kind of set ups.

[East Herts Snow]

Hope TEITS is looking at the 6z run....

GFS developes a bitterly cold Easterly by +216, straight from the Urals!

Okay I know this is not strictly true, but it originates from near The Urals vicinity.

Edited December 31, 2009 by North Londoner

[Geordiesnow]

GFS once again toying with the idea of the PV setting up shop in Greenland with the high sinking towards us, although with low heights over the med, it would take a while before it fully sinks and the atlantic coming into play.

Must be noted, GFS has been toying with this idea for a while albeit, yesterday's output did not really show this but previous outputs did. Hence why i can remember Kold Weather's comments saying the GFS is being WAY over progressive sinking the high.

At this stage, i don't think this cold spell will be a classic in snow amounts but in terms of the length in the cold department, pretty good and better than what we been used 2. Shame when we do get height rises in Greenland, the lows don't act as we like them 2, all is looking a bit too slack at this moment in time.

[snowmadchrisuk]

Here is the 0z NAE preciptation for New Year's Day

http://expert.weatheronline.co.uk/daten/proficharts/en/nae/2009/12/31/basis00/ukuk/prty/10010118_2_3100.gif

Yes and here is the 6z NAE prediction . The flow now looks to be much more of a slack Northerly .

[andy_leics22]

Yes and here is the 6z NAE prediction . The flow now looks to be much more of a slack Northerly .

Your link is NAE working my friend.

[nick sussex]

Ties in nicely with my thoughts Nick [see other thread].

It does look like some flow will increase on the northern arm of the jet. The eddy-formation is likely to result in some form of blocking setting up towards our north or north-east. I would go for the north as the more likely here given the state of the polar vortex and also upwelling wave to our north.

Hi GP

Yes i think the really good thing is how the PV just wants to keep meandering about, personally i think the gfs 06hrs run has the pattern quite similar to the ecm just a little too far south, as you said high pressure centred near Iceland or a little further ne but overall i'm happy to go with this pattern, the gfs 00hrs might be good eye candy right into FI but i don't buy it, i think this trend will continue and with alot of cold pooling to the east then of course Steve M in particular will be liking this!

I think whats most interesting is how this pattern has unfolded, an interesting journey with the final stop still not known, however given the output so far today I expect the coldest upper air to be advected westwards towards southern and se areas with the snow risk highest for these regions in the later output.

Overall though just some wonderful synoptics, really perhaps something many people thought not possible again. And even i might see a few snowflakes down here but just relieved to see the back of this current low which caused a big foehn effect here earlier in the week. Thankfully snow forecast for later today and a big relief to the ski resorts.

Edited December 31, 2009 by nick sussex

[Geordiesnow]

Indeed just like this severe cold Jan spell coming

Looked at the 06z...and as usual I have binned it.

BFTP

Why may i ask? Seems plausible to me if the PV does start coming back into Greenland and what was a solid block now becomes more feeble and slowly heads south and east towards us however with low heights in the med, it stops the high from sinking.

A severe cold spell i would describe as very cold upper air with strong northerly/easterly winds, we don't seem to have neither at the moment. An fairly slack easterly with showers peppering the coast is what we do have, as we know though, things can change for the better(or worse).

[Solar Cycles]

Plenty of precipitation for Northwest England and Wales! Ties well with the latest bbc24 forecast saying snow showers moving from Scotland into northern parts of England and then further south.

Karyo

Is it me, or does there appear to be a mild sector entrenched within that.

[snowmadchrisuk]

Your link is NAE working my friend.

Hi Andy , it is an image insert and is coming up fine on my screen . but you can check the latest NAE here :

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=ukuk&MODELL=nae&MODELLTYP=1&BASE=-&VAR=prty&HH=0&ARCHIV=0&ZOOM=0&PANEL=0&WMO=

I think it is just a matter of time now before things start to look better to be honest. If nothing else with all the rain we have just had I Expect the severe Frost to come back and the pavements to turn white again from tonight onwards. Some Low mins starting tobe predicted on all the Models.