Winter Model Discussion 18Z 5/2/13 onwards.

[Timmytour]

A sign of the times

Last Nights FAX for 12z Friday:

And todays:

That occlusion shifted a fair way west, reflecting the overall trend of the day

SK

From page two of this thread. An example of the shifts that can take place in the very short-term!

i think it's right that folks discuss what the models are showing. I think what is a bit ridiculous is to get downhearted on the basis of what they show a few days in advance, as if it must be nailed on.

[Ryan Dutch Weatherman]

Incidentally, the GFS operational remains far out of touch with its ensemble suite (along with that of the GEM) in terms of its NAO/AO outlook:

Extended ensemble outputs continue to favour any stronger heights to be focused around the Greenland locale:

Medium range outlooks remains uncertain, and I suspect we may end up just on the wrong side of the Atlantic vs Eastern block, but as GP as alluded to over the past few days, the 11-15 day signal seems even stronger at present

SK

Thank you sir for your excellent postings.

That i like .

[Tim Bland]

Loving Ryans input on here, laughing out loud in the office Keep up the good work Ryan! It may be that Ryans perceptions of temps needed for snow come from his location? Holland sees less modification due to its proximity to the atlantic.

I dont understand why people in the Se are getting worried. Local BBC SE forecaster saying on twitter that rain will turn to snow on sunday night and persist most of Monday with disruption possible. Lots o fpeople are focusing on Sunday and not the bigger picture into next week. It could rain all day in the SE on Sunday and snow in the North, through Sunday night the low is projected to slip south and east. IF this stalls in the channel it could collect extra energy and keep dumping on the South / South East through Monday and into Tuesday meaning these parts Could have the deepest snow by midweek.

All conjecture of course and open to change but models in agreement of the low slipping SE and so all areas bar the Far SW and perhaps coatal southern areas will see at least some snow. I would hazzard a guess that IF it stalls in the south / Channel, then somwhere like the Chilterns / Cotsworlds could have very deep snow (circa 25cm) by Tuesday.

[Coast]

OK, getting back to the content and analysis of the models here for the UK....

[snowking]

Yes yes , but i said also it will turn over snow .\.

End look your wind direction .

Look the douwpunt.

Look the tickniss of the cold dam.

End its also cold at low level.

Why are you stribbeling.

Even the highest resolution model WRF 10 km.

Is saying possible 20 cm snow or more , WRF say that ,. If you angry for the HIGHEST short term resolution model the most accuraat for this range , than go fight with them.

Well it would be very interesting for you to point me in the direction of an NMM output that current stretches as far as Sunday at the moment, as I have been unable to locate such an output?

For now, we are stuck with the lower resolution outputs, which for now suggest Sunday to be rather the wrong side of Marginal for much of England/Wales (the locations under the precipitation) away from higher ground (where I would agree 20cms is possible - but thats not much use when most of the population live between 0-70m):

With dew points largely between 1-3c (higher than that in some areas) for the majority, without some major evaporative cooling (which neither you nor I could call at this stage), that is not conducive of snowfall to lower levels during Sunday. The precipitation then largely clears according to this output further south, whilst further north we have the lower dew points, this amount of precipitation is hardly going to lead to 20cms:

As I wrote earlier, we await the higher resolution modelling to come into range. In the meantime, if you are able to post some charts to back up your point of view, I would be more than happy to continue this debate, particularly if you are able to point us in the direction of WRF NMM output that currently shows us the situation for Sunday.

Kind Regards

SK

[Ryan Dutch Weatherman]

Ok , I only want to support some people here.

I have my self weather forum , i am the admin from holland.

But i have contacted also 5 britisch wetterman , end they agree with me , .

You know them , but the agree with me in private.

But yes i be aware that UK is UK en not Holland.

Dont worry , .

[MR EXTREMES]

can anyone tell me is the pv on the move ?

because i was wondering is the pv moving towards greenland because it seems strange that the heights to our north east seem to be shunted away so very easy.

now if the pv was push west or northwest could this be why the heights around out northeast is being pushed aside i think the lower and deeper the pressure to our southeast could aid in developing the northeast block it could be that we need to wait until the weekends event has moved in to see how stubbon low heights to our south or southeast aid northeastern blocking.

its also know that the vortex is gaining strength as the ssw event wares of is this the downfall throwing energy one after another into the north alantic although the nao by some and ao look like deepening which would suggest renewed blocking in the alantic hopefully getting as far north as possible blocking of the alantic allowing futher blocking to our north or northeast.

[Summer Sun]

Details are likely to change slightly but some one some where could see a lot of snow by Tuesday morning The Midlands, Northern England and southern & eastern Scotland looks the best bet at the moment with maybe parts of wales

Some places could see rain and others could see rain turning to snow

Snow totals by 06:00 Tuesday

[Barking_Mad]

Matthew Hugo â€@MattHugo81

10KM WRF-ECMWF model highlights 6mm to 12mm of 'precip' for N Eng down into the Midlands later Sunday, most of that is snow (>10cm poss)

[R.P. McMurphy]

No i stop the discussion here. I will post lot of things in coming hours from my self

You dont have to ask me , you will see.

I dont like to be get hunted.

Becouse i think i kwow you , wen i post that you will find a way to switch en ask more n more.

Sit down relax , fasten your seatbell my boy.

Watch en see.Dont hunt. Than you will learn from me.

Keep posting as much as you can. We all enjoy it! I think your spot on with Sunday / Monday & Into Tuesday. It does not look very good for the South East, but things can change. At the moment the NW, N Eng, NE, Scotland, Midlands and North Wales is looking quite special in some areas.

Edited February 7, 2013 by Glenn W

[Glacier Point]

Incidentally, the GFS operational remains far out of touch with its ensemble suite (along with that of the GEM) in terms of its NAO/AO outlook:

Extended ensemble outputs continue to favour any stronger heights to be focused around the Greenland locale:

Medium range outlooks remains uncertain, and I suspect we may end up just on the wrong side of the Atlantic vs Eastern block, but as GP as alluded to over the past few days, the 11-15 day signal seems even stronger at present

SK

Today's 00z GEFS has toned that mid Atlantic ridge anomaly down (still very evident), which maybe reflects the divergence in modelling (of the longwave pattern) at the moment.

Interesting that yesterday GEFS was alone with its AO forecast. Could be significant that GGEM has joined the party so to speak,

Edited February 7, 2013 by Glacier Point

[Captain Shortwave]

Modesty is not your strong point, is it?

I think he's Steve Murr's long lost Dutch Cousin

I think there will be plenty of snow potential from late Sunday until Wednesday for quite a few areas, devil in the detail though.

After that the ops are in agreement of the decline of the Scandi high, though I remain to be convinced personally that it would be that easy.

[Tim Bland]

=Another adjustment from the 06z (Gavins above is from 00z) It actualy has the sweet spot around East sussex in the SE as the precip is heavy and focused on a small area not moving for circa 24hrs

Sorry all the links just go to Netweather Datacentre, but you can see for yourselves. It is marginal for the SE and still great for the North but just illistrating how its not all doom and gloom for the backbone of the economy in the SE

http://www.netweathe...ction=nwdc;sess=

http://www.netweathe...ction=nwdc;sess=

http://www.netweathe...ction=nwdc;sess=

http://www.netweathe...ction=nwdc;sess=

http://www.netweathe...ction=nwdc;sess=

Edited February 7, 2013 by Tim Bland

[Cecil Hogmanay Melchett]

Today's 00z GEFS has toned that mid Atlantic ridge anomaly down (still very evident), which maybe reflects the divergence in modelling (of the longwave pattern) at the moment.

Interesting that yesterday GEFS was alone with its AO forecast. Could be significant that GGEM has joined the party so to speak,

But again,those anomoly charts will count for absolutely nothing come the end of next week IMO as the shortwaves can and invariabley will change the bigger picture dramtically!

[Mark Neal.]

Quick Question considering all models are agreeing at moment for a rain to snow event, considering the ground will be wet, is there any chance it is likely to settle or will the temperature have to be below 0c? Heavier precipitation could settle i guess if falls as snow?

[johnholmes]

I don't know how many times this has to be said, yes the anomaly charts cannot give detail but it is the upper air NOT the surface that decides what will happen. The end of next week is 7/8 days=192 hours away.

If you expect that kind of detail that far ahead you will be constantly disappointed.

I no longer keep daily copies of every anomaly chart like I did over the previous 12 months. However, I will have a look and see if I have anything relevant for next Friday to see IF we can deduce anything in the upper air to suggest a small disturbance (I hate the term short wave).

[johnholmes]

To try and illustrtae what my post above shows I am doing a quick pdf-hope it helps

[latitude]

But again,those anomoly charts will count for absolutely nothing come the end of next week IMO as the shortwaves can and invariabley will change the bigger picture dramtically!

Very true. Those anomloy charts have been showing hight pressure over or towards Greenland all winter. They are not worth the paper they are written on until it starts showing in the models (which it never has all winter).

[TEITS]

Very good NOGAPS at +144 which like the 06Z GFS is a vast improvement compared to the 0Z.

One more thing I will add about this weekends LP is you have to take into account that once inside +48 the models have a tendancy of moving the LP further S than progged. So if you live in N England/Scotland you must take this into consideration.

[Ryan Dutch Weatherman]

[Cecil Hogmanay Melchett]

Very good NOGAPS at +144 which like the 06Z GFS is a vast improvement compared to the 0Z.

http://modeles.meteo...0-144.png?07-11

One more thing I will add about this weekends LP is you have to take into account that once inside +48 the models have a tendancy of moving the LP further S than progged. So if you live in N England/Scotland you must take this into consideration.

? 06zgfs has the atlantic moving in on wed night with rain for many!!

[Severe Siberian icy blast]

In the mean time the gfs at t150 looks good , with the Azores high separate to the Russian high and very close to a long fetched easterly with another big slider looking probable to slip in-between the high pressures and dive southeast . Very good looking set up there compared to the 0z

[Cecil Hogmanay Melchett]

In the mean time the gfs at t150 looks good , with the Azores high separate to the Russian high and very close to a long fetched easterly with another big slider looking probable to slip in-between the high pressures and dive southeast . Very good looking set up there compared to the 0z

not sure i agree gfs06z has temps above freezing by wed night as tm air moves in.

[TEITS]

? 06zgfs has the atlantic moving in on wed night with rain for many!!

Sorry HD but that just illustrates your poor interpretation.

The Atlantic isn't moving in on the charts I posted in the sense that you mean it. If you look beyond +144 you will see we see more undercutting.

[Cecil Hogmanay Melchett]

Sorry HD but that just illustrates your poor interpretation.

The Atlantic isn't moving in on the charts I posted in the sense that you mean it. If you look beyond +144 you will see we see more undercutting.

http://modeles.meteo...gfs-0-174.png?6

well for pretty much all bar nengland and scotland any snow will have been washed away wed night so for my money thats a very short cold snap teits.