Model Output Discussion

[Nick F]

Not the first time either with many more times the models forecasting mild to take over only for cool to cold to be as stubborn as a mule and come back very quickly, i see on GFS 12Z its cold until wednesday night now it was mild earlier next week just a few days ago, lots of wintry potential upto early to mid next weke i am astounded at the confidence of mild taking over from some of the posters on here after the way things have gone this winter.

What's to say that SW'erlies may not win out!!? They will do eventually, cold weather doesn't last forever, and the more we head towards spring and the days get longer, the more likely it will get milder. I'm not saying that mild will win out from the SW as shown at face value by GFS and ECM tonight. But it's rather short-sighted to think the models are somehow wrong for showing SW'erlies and it won't come off, even though it's been a cold winter thus far. The cold has to end eventually!

I'd say chances are increasing for less cold from the Atlantic, but still unsettled/cyclonic by the end of next week. But cold hanging on cannot be ruled out, for the north at least.

[snowmadchrisuk]

Just a quick post about tomorrows possible event.

My gut feeling is telling me Leicestershire is in prime position. Some locations like mine will probably see rain intially and then turning to snow.

TEITS Your my new best friend Temps are progged to get a lot lower tonight than they were last night so i'm hoping this will help . Regarding the models well remember all models were showing a North Easterly in FI earlier in the week , well there has been a trend this winter for the models to drop an idea and then come back to it so there is every chance it will do this again . I am not buying A Mild breakdown and a patten reset just yet as the MJO is still hovering around phase 8 and it has been in phase 7/8 for the last 2 weeks this does not usually result in Mild South Westerlys .

[Eugene]

Lots of frosty starry nights likely from tonight especially this weekend into mid next week

I`m surprised nobody has mentioned it when saying how poor the charts are concentrating on charts beyond a reliable timeframe

　

http://www.wetterzentrale.de/pics/Rtavn1817.png

http://www.wetterzentrale.de/pics/Rtavn4217.png

http://www.wetterzentrale.de/pics/Rtavn6617.png

http://www.wetterzentrale.de/pics/Rtavn9017.png

http://www.wetterzentrale.de/pics/Rtavn11417.png

http://www.wetterzentrale.de/pics/Rtavn13817.png

http://www.wetterzentrale.de/pics/Rtavn16217.png

　

TBH who prefers mild wet and windy over that, i see no spring on FI charts just lots of rain as fronts endlessly push up from the southwest with a mud bath in the countryside and lots of cloud cover, puzzles me why some like that.

[chionomaniac]

I am unconvinced by the accuracy of any long term outputs giving the expected outcome of milder SWesterlies for a weeks time. I still believe that the teleconnective signals do not support this. Furthermore there is mishmash of upper and lower hight rises in the polar regions which is inconsistent on a daily basis. The suggestion is that any blocking signal will not be far south enough to prevent a SWesterly incursion. However when looking at the Helsinki ensembles the unreliabilty of events further down the line is emphasized by the extreme variability early on. Yet again we see that stratospheric propagation of easterly winds is poorly modeled in the Arctic. I think it will be worth waiting a couple more days before anticipating a milder SW airstream.

[Tom D]

I am unconvinced by the accuracy of any long term outputs giving the expected outcome of milder SWesterlies for a weeks time. I still believe that the teleconnective signals do not support this. Furthermore there is mishmash of upper and lower hight rises in the polar regions which is inconsistent on a daily basis. The suggestion is that any blocking signal will not be far south enough to prevent a SWesterly incursion. However when looking at the Helsinki ensembles the unreliabilty of events further down the line is emphasized by the extreme variability early on. Yet again we see that stratospheric propagation of easterly winds is poorly modeled in the Arctic. I think it will be worth waiting a couple more days before anticipating a milder SW airstream.

This is an excellent post. That area is very important IMO, some of the ensembles show a much greater block holding when compared to the operational and control, and if a block of some sorts were to establish in that region the low pressure systems which are currently heading north-east would head further south, increasing the longevity of the cold weather.

Most likely, however, the southern half of the UK will likely become milder than present, if only short lived, whilst Scotland in particular could continue to see snow events.

[weather eater]

I think without a doubt that the clear trend is for a gradual warm up as LP systems approach from the SW; this may be the only real way that we will see a reset to much colder spell at month’s end. The alternative it seems to me would be for the LP to stay stalled across the UK, trapped as it were between the a strong southerly tracking jet and high pressure to our North, East and West, this stagnating low would produce a mixed bag, colder in the north and trending milder towards the south and a mix much as we have and will see over the next few days, while I’m sure that would still float many people’s boats, I’m hoping for a bit more than that. It seems to me that the model uncertainty as to what to do with the LP post the weekend is now starting to be resolved. Whether that warm up from the South West is a sign of things to come or a brief blip before a reset to another cold spell we will have to wait and see. I think TEITS has a case when he says that this winter has seen a constant shifting back of milder air, so with that in mind I put it about 70/30 in favour of the present clear trend for a gradual warm up and for it to stay that way out to the first week of March. While we may have some good teleconnection evidence for another possible cold shot, last February was evidence that it’s not always a clear or quick path.

[Cheese Rice]

I can't see mild retuning either, I still think an easterly is likely at the end of Feb/March. Personally I don't really want any warmth in March, it is like wanting snow and cold in October yes it sometimes happens but generally it doesn't.

[492]

ECM shows pressure rising to the east in the latter stages with the atlantic lows skirting the west of the UK. This has been happening repeatedly during the last month giving a week of milder weather until the lows are deflected to the NW. Then a week of cold follows. So the next 6 days look quite chilly and then perhaps a milder interlude until the altantic energy reduces once again and we look to the east or south east for the cold. However actual condition looks unusually blocked in higher latitudes with the polar high engaging the sub -40C air and dragging it westwards albeit a long way north. So although ECM looks plausible I would not be that surprised to see a different outcome along the lines that CC is suggesting.

[bluearmy]

seeing as we're currently sat under the cold trough in a not dissimilar way to december pre xmas, i recall the models then went into sw overdrive for the new year period. the reality was that the sw flow only made it into the south of the uk before the trough sank se and introduced a cold ne flow as heights built to our nw. as TEITS pointed out earlier , the ens didnt get this for several days. the pattern could possily repeat but with longer phases thus the trough hangs around for longer and the sw flow, if it does get into the south of the uk may well persist for a week whilst i believe the north could well stay on the cold side.

[PubliusEnigma]

ECM out to t144 and it looks like its lost the plot again.

Best to stick with the UKMO until the models sort themselves out.

I am quite sure the evolution towards a very cold end of February

and start of March will not be along the lines the ECM is taking.

Just my opinion before all the silly posts come out.

Yep I agree, Im binning all the charts this evening as they all hint

at milder weather returning. GFS shows an easterly at T+360 so the trend

for the cold to remain is still there.

[MR EXTREMES]

lol some great opions coming out tonight ive never seen such a split in the model disscusions.

a fair few now seeming to think the models are broken lol.

its good though because we are in the next few days going to see how reliable they are,

and i can honestly say if yesterday and todays outputs showed anything remotely cold possible,

then id be the first to jump on the coldie wagon.

but in all honesty none, infact even the smaller models all point towards a different setup to what we have been used to,

im also not saying spring either but not as cold as its been all winter,

ofcoarse we still have the current wintry spell to pass,

this looks within the realiable to pass to a more unsettled less cold.

but ofcoarse things can change and i have given my thoughts so lets see what happens:)

[January Snowstorm]

18Z Continues the trend of a snowy and bitterly cold wkd over Ireland

Full of potential with deeply cold uppers nearby and close on record breaking low dew's come Sunday

[damianslaw]

Teleconnections support extensive northern blocking right through to the end of the month at least, whilst the atlantic may try to nudge into the south west, I firmly believe it will not gain any real ground than where it is at present. All signs are for a northerly or north easterly to end the month depending on the tracking of lower heights projected to inch there way from the SW by the start of next week.

It remains a cold outlook, ignore any models snowing the 'default' south westerly pattern, they seem to have been doing this all winter usually a sign that they have very little confidence in how things will pan out.

The reliable timeframe is very short at the moment, the models are struggling with the projection of fronts and troughs within the 24 hour timeframe, nevermind what is likely to happen 5-6 days ahead. This is perhaps the most interesting period of the winter so far for weather forecasting, its all about nowcasting it seems - great unusual synoptics and we have the time of year ahead i.e Spring when we tend to see our most unusual synoptics..

[Eugene]

What an absolutely awesome chart to have at such a short timeframe

http://www.wetterzentrale.de/pics/Rtavn781.png

Heavy snow risk for saturday now as well :o

　

http://www.wetterzentrale.de/pics/Rtavn661.png

　

http://www.wetterzentrale.de/pics/Rtavn664.png

　

http://www.wetterzentrale.de/pics/Rtavn6617.png - Very cold midday temps there :o

[Ben_Cambs]

What an absolutely awesome chart to have at such a short timeframe

http://www.wetterzen...cs/Rtavn781.png

Heavy snow risk for saturday now as well :o

　

http://www.wetterzen...cs/Rtavn661.png

　

http://www.wetterzen...cs/Rtavn664.png

　

http://www.wetterzen...s/Rtavn6617.png - Very cold midday temps there :o

I think this latest GFS run has brought back the snow risk on Saturday night, as was shown in previous runs and the FAX's support this aswell, and on the METO PPN charts you can see the band of PPN on the T+72 about to make landfall

[January Snowstorm]

Do not under-estimate what the charts are showing Fri-Mon

Deep deep cold, polar lows likely to be spawned between Scandi and the UK/Ireland

These are awesome charts!

[Eugene]

As squish says on TWO a stunning GFS 18Z run so far, people moaning about no cold on the models must need their heads read really they do.

http://www.wetterzen.../Rtavn10217.png

Edited February 17, 2010 by Eugene

[Grimsby Snow Lover]

Do not under-estimate what the charts are showing Fri-Mon

Deep deep cold, polar lows likely to be spawned between Scandi and the UK/Ireland

These are awesome charts!

Without wanting to sound too IMBY ish what would the areas (populated) most likely to see any snow over the 4 days you have mentioned? Thanks

[conor123]

Absolute snow fest of a run the 18z which would bring wintry conditions just about everywhere with heavy snow showers across Scotland, Northern Ireland and Northern England with an area of snow tracking across Wales, The Midlands, East Anglia through Saturday and another

snow storm Sunday Night/Monday across the South East followed by a North Westerly dragging heavy snow showers into the Midlands via Chesire Gap.

[mountain shadow]

18Z Continues the trend of a snowy and bitterly cold wkd over Ireland

Full of potential with deeply cold uppers nearby and close on record breaking low dew's come Sunday

Mainly dry though surely? Perhaps a few localised events like this mornings in Fermanagh, but dry mainly.

[492]

18Z GFS upto T+114 shows the cold trough to NE closer to the UK.

[January Snowstorm]

Without wanting to sound too IMBY ish what would the areas (populated) most likely to see any snow over the 4 days you have mentioned? Thanks

Hard to be certain this far out, safe to say almost everywhere would see snow at some point

[Grimsby Snow Lover]

Hard to be certain this far out, safe to say almost everywhere would see snow at some point

Thanks JS. It would be a great way to end winter if everyone saw at least a cm of snow.

Edited February 17, 2010 by Grimsby Snow Lover

[January Snowstorm]

Mainly dry though surely? Perhaps a few localised events like this mornings in Fermanagh, but dry mainly.

These are not dry charts at the wkd, conditions are spot on for polar low development

Polar low is of course technically incorrect, more like disturbances developing caused by deeply cold uppers over the North Sea

[kold weather]

Absolute snow fest of a run the 18z which would bring wintry conditions just about everywhere with heavy snow showers across Scotland, Northern Ireland and Northern England with an area of snow tracking across Wales, The Midlands, East Anglia through Saturday and another

snow storm Sunday Night/Monday across the South East followed by a North Westerly dragging heavy snow showers into the Midlands via Chesire Gap.

Without a doubt its a stunning run, interestingly a few members of the ensembles have been toying with the channel low solution, others bring it further north. We don't want it to head to ofar south though because if the pattern does re-set after it, may as well get a big snow event out of it, go out in style so to speak!

Plenty to watch out for on this run, will be interesting to see how many ensemble members follow the GFS op solution...