Model Output Discussion

[Frosty.]

We won't be seeing anything like that. The GFS is synoptically highly unlikely; Low pressure would develop off S Greenland and topple the High. Many northerlies of this type over the years have seen maximas in the 7 to 9 range for coastal Southern areas particularly. I'm still favouring a quick toppling and a mild early Feb.

This has been a great winter so far, will you be third time lucky with your prediction I wonder, 1 out of 3 if you are right. Super looking models so far today but it could implode by the next run.

Edited January 24, 2010 by Frosty039

[J10]

There do seem to be upgrades on the runs this morning, firstly increasing the potency of the initial northerly, and hopefully also pushing the colder air that much further west to cover the whole of mainland UK. Secondly the initial event seem to be extended in terms of time, with a Polar Maritime source of air following into the Medium Term.

[nick sussex]

I always find it amazing to read often statements such as ' we basically want'. Nothing to do with the charts as are. Basically want depends on which side the fence you are - mild or cold - so does not apply to we want. I would basically want a Bartlett high as that would bring mild into the 50's F temperatures as I like warmth and small heating bills.

However onto the model charts and there is nothing warm about the charts, and nothing has been shown that could be classed as warm. With the cold air so close the the UK a cold outbreak is always going to be likely - and indeed it does look as though we will be getting a cold northerly with snow for many in the near time span. Nothing to indicate a cold spell such as we have had, and I would be surprised to see such a long cold outbreak although we could get a short but more intense cold spell during February - something solar techniques show - but of course nothing to do with the charts at the moment. A lot of talk of February delivering colder and more snow in that month of late? Really - if my memory serves me right February for quite a while has been a warmer month than January - and my weather station records bear that one out. This is not what is termed a 'even larger teapot' - the charts are the kind of charts that were often what we were seeing in the 60's and 70's - but it has to be remembered that even though we suffered severe blizzards and cold spells in them times - apart from 1962/3 there were quite often mild rainly spells mixed in with these..

Since the majority of the people in this thread like cold and snow i'm perfectly within my rights to explain whats better for this to happen! also if you bothered reading my posts you'll find that i always take an objective view of the models highlighting milder outcomes when they're apparent and how cold synoptics could implode.I don't use the word want when the synoptic doesn't have a hope of verifying, its like me saying I want a proper Greenland high when theres zero chance of this happening, an extension of the eastern USA trough is possible for a day or two.

Edited January 24, 2010 by nick sussex

[john mac]

Maybe that explains (the 'face value' bit) why the 06Z GFS has almost as much pink on it - from later today and through Monday - as the old British Empire maps. Yet, bizarrely, BBC radio and TV forecasts this morning don't even HINT at any snow for England! I did hear 'chance of wet snow on the Scottish mountains', but how can the two be so contradictory? Is the current set-up REALLY so hard to work out? Maybe it is...

Im not going to bang in about the BBC on this thread but they will probably wait until later today before the start mentioning even the chance of snow

[Cloud 10]

The gfs 00z ensembles for iceland that TEITS mentioned show that the gfs operational was an outlier with its low pressure in that region, perhaps suggesting a more prolonged northerly outbreak due to the high not being toppled as fast.

Maybe something like the GEM showed this morning.

[Methuselah]

Im not going to bang in about the BBC on this thread but they will probably wait until later today before the start mentioning even the chance of snow

My guess is that they'll wait until the model-runs become more consistent, before issuing any warnings??

[nick sussex]

We won't be seeing anything like that. The GFS is synoptically highly unlikely; Low pressure would develop off S Greenland and topple the High. Many northerlies of this type over the years have seen maximas in the 7 to 9 range for coastal Southern areas particularly. I'm still favouring a quick toppling and a mild early Feb.

Yesterday you liked the GFS and said this was right and the UKMO was wrong! So i see you've ditched the GFS now it shows something you don't want to see! Make your mind up!

[john mac]

I agree with you ther pete, hopefully we can get a nice polar low to form, its been a while since we've had one. Back to the models and some very encouraging output this morning with the GFS 6z showing early signs of an upgrade

[Iceberg]

Well the 06Z GFS matches the UKMET at 144Z. So that's another possible failure for the GFS at that time range.

06Z, generally looks alot better in the none FI range.

[Cloud 10]

GFS 00Z at 150hrs>> GFS 06Z at 144hrs>>

A good example of the difference that higher pressure around iceland makes for the duration of the potential northerly.

[TEITS]

I disagree with Ian B comments about temps.

What Ian is describing is a N,ly via the airmass riding over the top of the Atlantic HP. If this is the case then temps along the S coast can reach 7-9C. However the models are suggesting the airmass comes direct from the N with upper temps ranging from around -8C to -10C. This would result in surface temps being around 0C-3C.

I still think the N,ly will topple after around +72hrs but im not confident of a return to mild afterwards. Infact the forecast beyond the N,ly is very uncertain!

[Glacier Point]

We won't be seeing anything like that. The GFS is synoptically highly unlikely; Low pressure would develop off S Greenland and topple the High. Many northerlies of this type over the years have seen maximas in the 7 to 9 range for coastal Southern areas particularly. I'm still favouring a quick toppling and a mild early Feb.

I wouldn't be so progressive as that Ian with this one. If the ECM modelling of the polar vortex is correct, and there is every chance that it is given cross model (including very solid 00z GFS ensembles), we will have ingredients for a standing wave in the jet. It is a product of the northern arm of the jet, so ultimately a piece of energy spinning off the N.American trough will flatten it out. However, the big question is when ?

With the MJO still yet to hit phase eight, and the polar vortex fully displaced, could well be several days' worth of polar flow. Any high toppling in will also trap surface cold so it will take a little while, possibly end of first week Feb before things get remotely mild.

Edited January 24, 2010 by Glacier Point

[yamkin]

Maybe that explains (the 'face value' bit) why the 06Z GFS has almost as much pink on it - from later today and through Monday - as the old British Empire maps. Yet, bizarrely, BBC radio and TV forecasts this morning don't even HINT at any snow for England! I did hear 'chance of wet snow on the Scottish mountains', but how can the two be so contradictory? Is the current set-up REALLY so hard to work out? Maybe it is...

I am very confused with the latest BBC24 forecast by Peter Gibbs. He shows cold temps then said that next week will be mild while the cold air is never too far away.

After viewing the latest models, I can not see what he is referring to. Does his 'next week' mean Feb 1st? Surely not! He must be referring to this coming week, but the temps are cold not mild with a threat of even colder temps later in the week according to the latest models.

[Cecil Hogmanay Melchett]

06z is nice as it gives us a 4 to 5 day Northerly.With a Atlantic high in play that is not bad going at all.

Only problem is its a very dry northerly with little snow,if 06 gfs is to be believed that is.

The only gripe for me is the lack of heights over greenland,without a solid hp over greeny the high will topple ,as GP says though it might take a wee while longer than a standard 48 hour topppler.

[Snowyowl9]

Well this will be a very good end to a superb January.

I see GFS has even brought the easterly back on the 0z and the 6z but the high slightly further south.

http://91.121.93.17/pics/Rtavn481.png

With the N-ly well and truly upgraded on all models the cold will be staying for the rest of the month in some form now.

http://91.121.93.17/pics/Rtavn6017.png

Snow showers aswell.

Edited January 24, 2010 by Snowyowl9

[john mac]

06z is nice as it gives us a 4 to 5 day Northerly.With a Atlantic high in play that is not bad going at all.

Only problem is its a very dry northerly with little snow,if 06 gfs is to be believed that is.

The only gripe for me is the lack of heights over greenland,without a solid hp over greeny the high will topple ,as GP says though it might take a wee while longer than a standard 48 hour topppler.

I agree with HD, it will obviously depend on how close the HP is to us as to how precipiatation we get, also with posibilities of troughs forming.

[TEITS]

I am very confused with the latest BBC24 forecast by Peter Gibbs. He shows cold temps then said that next week will be mild while the cold air is never too far away.

After viewing the latest models, I can not see what he is referring to. Does his 'next week' mean Feb 1st? Surely not! He must be referring to this coming week, but the temps are cold not mild with a threat of even colder temps later in the week according to the latest models.

I wouldn't worry about the BBC forecasts after the recent farce. If the models continue with the trend then a cold front will be sweeping S during Thurs and by Friday we shall all be under a bitterly cold Arctic airmass.

Back to the models and I can't help but wonder whether a Polar Low may develop in this N,ly. My mother always tells me about the infamous blizzard that hit Peterborough during Feb 7th 1969. This was a Polar Low that hit the E Midlands and remains one of the greatest snowstorms to ever hit Peterborough. Apparently over a foot of snow fell within the space of a few hrs!

[Snowstorm1]

Yesterday you liked the GFS and said this was right and the UKMO was wrong! So i see you've ditched the GFS now it shows something you don't want to see! Make your mind up!

Exactly nick and i got slagged off about arguing with his opinion . Anyways what an upgrade overnight Gfs 06z has upgraded the northerly further and i notice it has grown in length so overall i am happy this morning

[Iceberg]

PL's are not likely in this set up IMO,

With SSTs depressed to our north, I think 500 temps of -39-40C are needed to get the temp differential, likewise pressure of 1010 seem to be best, lower than this and you get too much surface instability.

They are a chance, just not likely IMHO.

Post 180 and the GFS goes into it's post upgrade favour of overly progressive PV movement.

[yamkin]

I wouldn't worry about the BBC forecasts after the recent farce. If the models continue with the trend then a cold front will be sweeping S during Thurs and by Friday we shall all be under a bitterly cold Arctic airmass.

Back to the models and I can't help but wonder whether a Polar Low may develop in this N,ly. My mother always tells me about the infamous blizzard that hit Peterborough during Feb 7th 1969. This was a Polar Low that hit the E Midlands and remains one of the greatest snowstorms to ever hit Peterborough. Apparently over a foot of snow fell within the space of a few hrs!

Not bad 'White Emsemble Line' http://www.wzkarten3.de/pics/MT8_London_ens.png :)

[Methuselah]

I wouldn't worry about the BBC forecasts after the recent farce. If the models continue with the trend then a cold front will be sweeping S during Thurs and by Friday we shall all be under a bitterly cold Arctic airmass.

How can the BBC (Or anyone else?) factor model-runs into their forecasts - before said model-runs appear?? IMO, that would be crazy. It would also leave forecasters open to all sorts of questions and accusations...Maybe expect a change in prediction once the data have all been collated and analyzed?

[john mac]

I wouldn't worry about the BBC forecasts after the recent farce. If the models continue with the trend then a cold front will be sweeping S during Thurs and by Friday we shall all be under a bitterly cold Arctic airmass.

Back to the models and I can't help but wonder whether a Polar Low may develop in this N,ly. My mother always tells me about the infamous blizzard that hit Peterborough during Feb 7th 1969. This was a Polar Low that hit the E Midlands and remains one of the greatest snowstorms to ever hit Peterborough. Apparently over a foot of snow fell within the space of a few hrs!

Yes TEITS i was saying the same thing about a polar low, surely the longer the northerly lasts the better chance we have.

[Guest North Sea Snow Convection]

Good model agreement for an end of Jan/early Feb northerly

The perspective yesterday was simply that we may have seen the peak of the cold this winter, and that is still the case today. However, as stated also might be the case yesterday, it is indeed nice to be wrong about a milder (note not mild) pattern looking less likely today with every chance that the jet patterns will be NW-SE much as we saw last winter in fact. This could well allow fairly cold zonal conditions in between polar northerlies. With the trough over Scandinavia extending right down in central europe and the Alps, then this ensure that we are unlikely to see any milder jet stream pattern - with pressure remaining high over the mid atlantic and unable to ridge eastwards and flatten the pattern out.

The downwelling of the recently warmer stratosphere is a surprise I must say, and really changes the complexion of the outlook as seen yesterday - and does indeed make the possibility of a sustained cold pattern more possible - even if it is 'less severe' than earlier in the winter. That could still mean more snow for many - especially in the north east as well as some western and north western areas I would think too. But the whole of the UK looks to have cold temps with the chance of snow anywhere if there are any features moving south in the northerly

Nice to have been given a valid opportunity to exercise my perogative to change my mind

[cooling climate]

The expected pattern change from mid-week onwards is still evolving as to are the movements

of the polar vortices's. I think some are getting to hung up on this toppler scenario, I would not

be at all surprised to see a potent, very potent north northeasterly last for much longer than some

are thinking.

Great start to the day though.

Cheers Winter79 for your comments in the last model thread.

[Guest North Sea Snow Convection]

I agree with you that a toppler in the true sense of the word is unlikely - and for all the reasons given already by a few this morning