18z model discussion - models pah, just use the 5 min radar!

[mackerel sky]

I summary, the 00z upto about +66 hours is falling better into line with the UKMO.

No doubt that will upset some people and delight others in the short term. If you look at another way, there is lots of scope in the UKMO output to give a large part of the country snow beyond this time frame as its much less progressive.

And again, no doubt there will be the fickleness. Yes it is a model discussion thread and we should be discussing and scrutinising every each GFS run, but I'd had enough on Saturday and its still the same. Its easy to work out though, if someone says this is "an awful run", and adds nothing else - all you need to do is look at their location. If its a good run and its hardly F.I., then a minority of members go out of there way to counter it, even in the face of mounting evidence. Fair enough, if its to provoke reasoning and prevent ramping, thats a good thing.

But it has become all a bit too predictable. You have the far left and the far right, but they chop and change. And a minority of the centre parties.

The predictable response to that will be, "you don't have to post on here if you don't like it". I like it, but it can get tedious sometimes.

With any luck the next few days will settle a few people down if a decent snow dump occurs, and we can bring back some of the mutural respect and love for model watching (and each other), plus the weather in general which I hope brings us here.

Goodnight all.

Edited February 6, 2007 by mackerel sky

[wellington boot]

Yep low further South again on this run.

Better height rises to the North East compared with the 18z.

Its looking as good as it can really for me here in oxford. Im literally along the line of highest risk/highest gain. It looks on all the ppn charts as if surface temps at least are never above 1 or 2 during all the spells of ppn, sometimes zero minus 1, while were also south enough to get the heaviest ppn falling. could be a complete damp squib, or a major snow dumping, or somewhere in between.

Most interesting chart at 102, with this for ppn:

http://www.wetterzentrale.de/pics/Rtavn1024.png

some really heavy stuff there, but with 2m temps of 2-3 degrees, its a bit dodgy:

http://www.wetterzentrale.de/pics/Rtavn10217.png

though evaporational cooling with that kind of heavy ppn could easily lower the temp enough for snow.

anyway, specifics that far out are pointless i know. But fun to look at.

More likely for snow is the 48-60 window in which temps certainly look low enough down here, but ppn stalls a bit this run so comes in later and weaker, rather than heavier and in the night. well see though.

From your point of view pp, and others up north/north east, youll surely get some snow showers off the north sea over the next few days, and as the easterly draw bites. Witha bit of luck you could see some decent snow.

out at 180, the whole setup is very different. heights look much more positive generally, with potential, if the high to the north could dig in a vbit more, for some easterly winds and a succession of cold lows. Looking a bit far ahead me thinks though...

[fender]

I will take it as it stands, although it would be even better if the mild air could hold off a bit longer.

But pretty good for this area even so.

[grab my graupel]

Its looking as good as it can really for me here in oxford. Im literally along the line of highest risk/highest gain. It looks on all the ppn charts as if surface temps at least are never above 1 or 2 during all the spells of ppn, sometimes zero minus 1, while were also south enough to get the heaviest ppn falling. could be a complete damp squib, or a major snow dumping, or somewhere in between.

Most interesting chart at 102, with this for ppn:

http://www.wetterzentrale.de/pics/Rtavn1024.png

some really heavy stuff there, but with 2m temps of 2-3 degrees, its a bit dodgy:

http://www.wetterzentrale.de/pics/Rtavn10217.png

though evaporational cooling with that kind of heavy ppn could easily lower the temp enough for snow.

anyway, specifics that far out are pointless i know. But fun to look at.

More likely for snow is the 48-60 window in which temps certainly look low enough down here, but ppn stalls a bit this run so comes in later and weaker, rather than heavier and in the night. well see though.

From your point of view pp, and others up north/north east, youll surely get some snow showers off the north sea over the next few days, and as the easterly draw bites. Witha bit of luck you could see some decent snow.

out at 180, the whole setup is very different. heights look much more positive generally, with potential, if the high to the north could dig in a vbit more, for some easterly winds and a succession of cold lows. Looking a bit far ahead me thinks though...

Yep agree with that W.B.

Does look more likely now that the heaviest precipitation is more Southerley.

Whether this will fall as snow or not in the South is still to be answered, still

very marginal IMO.

I think my chances are diminishing with every run, and am only expecting maybe a bit of

light stuff now.

Still time for more changes and will be interesting to see what the Meto shows.

Height rises still looking stronger to the North East, which pleases me as this

Improves the prospects of something better later into February.

Many Questions still left unanswered though.

Night all.

Brian.

Edited February 6, 2007 by grab my graupels

[SMU]

Morning Folks- Back on UK Terra Firma!!!

The 00z GFS Continues to move back to the Location of the UKMO/FAX solution- & The precipitation risk for snow has moved South with it-

After the 06Z yesterday that was probably the low point of the forums postings yesterday there has been 3 consecutive runs of SW Correction & I think there is still time for a couple more 'jogs' SW- This turnaround from the GFS is being by driven the fact that the Polar vortex & associated trough extension do not hold onto the shortwave running into the English Channel-

The key chart of the day ( & FOR CRUCIAL FURTHER IMPORTANCE is this one)

http://www.wetterzentrale.de/pics/Rtavn481.png

http://www.wetterzentrale.de/pics/Rmgfs541.gif

The high Res GFS shows that the Small shortwave does NOT phase & interact with the depression in the atlantic-

As a result INSTEAD of rotating North/ North East like yesterdays model indicated, it is ejected further Eact & will struggle to make ANY in roads North- Here again you can see it at 66-

http://www.wetterzentrale.de/pics/Rmgfs601.gif

This is Excellent news for 2 reasons-

A) because its now a relative 'Shallow' feature compared with the main depression the abililty to Mix in the warmer air to the SW is increasingly difficult & regions across its Centre & to the north continue to be shrouded in the Cold air-

http://www.wetterzentrale.de/pics/Rmgfs572.gif

Notice the zone is Further South Combined with the PPN-

http://www.wetterzentrale.de/pics/Rmgfs573.gif

http://www2.wetter3.de/Animation_00_UTC/54_30.gif

Whilst we certainly cant pin down an Un-conventional band of PPN 2 days away I would at this stage be starting to formulate a 'Zone' of risk that lends itself to the combined track of the GFS & METO Model-

http://www.wetterzentrale.de/pics/Rmgfs541.gif

http://moe.met.fsu.edu/tcgengifs//ukm/2007020600//slp8.png UKMO 00z

The zone I think at MOST risk from this initial band ( pointed out yesterday) is in a line ( Northern limit) from say Chester South East across to Leicester & Out to roughly Peterborough- This would be the Periphery with the most intense PPN ( SNOW) across the Shires, & parts of the West-

The Rain to Snow line looks like to be located 'Somewhere close to the M4 corridoor'- Southside-

I think this gives people the general gist of where we go for Thursday Am- remember we CAN & will see adjustments in that 'zone' & if pushed I still say further South is probable-...........

THE UKMO HAS THIS ZONE ANOTHER 100 Miles NORTH at the same timeframe-

People in Counties like LInc will prey for this one to varify-

http://moe.met.fsu.edu/tcgengifs//ukm/2007020600//slp12.png

B ) We have seen a shortwave spin off & Under the main depression once & so the possibility of it happening again could be quite real-

http://www.wetterzentrale.de/pics/Rtavn721.png

This chart is quite unexpected from where we were yesterday at 06z- but a real 'twist' that could develop in the scenario-

Notice another peice of the polar vortex in tht atlantic has started to come under to the SW of the weakening depression to the West of Ireland-

The significance of this- Combined with the 'robust' heights towards Iceland will act as sufficient force to at the very least 'Hold' that depression 'in situ' or better still pull it SW again-

This then MAY throw another more potent Lp up into the Channel & potentially North into the Colder air again-

Remember the same rules apply as before & the milder air from its Southern quarters MAY struggle to get advected Northwards-

Here it is pushing in at 84-

http://www.wetterzentrale.de/pics/Rmgfs841.gif

the key to the Snow line on this one comes from how much COLD air is forced back ahead of the front from the advancing High Over the North sea to Norway-

This feature has steadily grown over the last few days & was 'Intense' to say the least on the UKMO 12z yesterday-

http://moe.met.fsu.edu/tcgengifs//ukm/2007020600//slp14.png UKMO 00z-

The UKMO 00z keeps BOTH systems on a Strong Southerly track & expect the Fax charts to demonstrate this as well-

although the final outcome in the 00z Meto still wants to push EVERYTHING NW eventually ( Dont bet on that one..)

In summary then - the first band comes in -into the Zone that I highlighted above, expect Another heavy band to come after which may well spread further North- but DONT hold your breath-

For regions sandwiched North of the Action, the predominent windflow that develops especially in the latter stages of the week becomes E N E & in such an unstable enviroment with heights LOWER than 528 DAM at 500 MB & thicknesses good-

http://www.wetterzentrale.de/pics/Rtavn663.png

Then you can expect Showery PPN of probably in the form of snow as well..........

ANY CHART POST say T78 isnt worthy of belief at the moment- whether that shows more snow or rain approaching, such is the complexity of this situation lets take it one step at a time for now......

regards

S

Edited February 6, 2007 by Steve Murr

[nick sussex]

Hi Steve hope you had a good time up there in Iceland, its nice to see you back seeing as theres loads to talk about at the moment. Going back to what you said in your post the latest radio 5 live weather with everton fox certainly was ramping up a possible signiificant snow event on thursday but I missed the areas mentioned as the bloody dog barked at that moment! talk about bad timing! anyway I agree with you things have been pulled a little further south. I dont think I'm that favoured here but north of the M4 looks like a good marker.

Edited February 6, 2007 by nick sussex

[wellington boot]

Hi steve good to have you back on board the netweather ship! Very interesting post - most illuminating, and for me, encouraging. Here in Oxford, Im pretty much bang in the middle of your danger zone, or perhaps the southern half of it. At a good 20-30 miles north of the M4, im hoping that ppn will hit us hard and will be snow.

Post thursday, things are looking good too, so plenty of potential for all in this setup.

[nick sussex]

If you're still around Steve what are your thoughts on the slating that some of the models got yesterday in discussions over at NOAA, the most slated was the gfs 12hrs operational run.

http://www.hpc.ncep.noaa.gov/discussions/pmdepd.html

The funniest thing is mention of the polar front at the bottom of the page sitting near florida and cuba! I think the expectation over in the usa is that the ridge over the east pacific will hold but drift north with a strong subtropical jet forming rattling lows east aross the southern usa into the atlantic, if we get blocking to the north this could get interesting but we really need the ecm to stick to yesterday evenings solution.

Edited February 6, 2007 by nick sussex

[Roger J Smith]

The GEM which always gets the knock as being too progressive is (LOL) less progressive on the 00z run than the GFS, and that is also backtracking from earlier runs.

I've applied the in-house research model to this admittedly difficult forecast scenario, and what it shows is quite encouraging for snowfall.

It may take most of the next 24 hours to set up, but an arctic frontal boundary should develop tonight across the southern Irish coast through Cornwall into northern France. Fairly energetic low pressure should develop west of Ireland and move east to ESE along this boundary and bring a period of moderate to heavy snow across large sections of southern and central England as well as much of Wales. This will of course be sleety nearest to onshore coastal areas but it does seem that the cold air gets well entrenched and this should lead to most places having all snow from this event, which should last 24-36 hours from late Wednesday to early Friday. Then there is likely to be a sort of cease-fire without any real movement of fronts, so a little more light snow or freezing drizzle Friday, followed by a similar event on Saturday but this time with some northward movement of fronts, so eventually southern counties get back into milder air and rain. This will send the heavier snow gradually north through northern England into Scotland, as well as Northern Ireland.

I will stick my neck out and say there is potential in all of this for 10-20 cms of snow in a fairly large portion of the U.K. and also 5-10 cms in parts of Ireland. Hope it works out that way. There's a bit of a vacuum over Scandinavia as this all comes together, space that the GEM fills with a rapidly swelling 1035 mb high. That feature is much weaker on the GFS but still the gradient is what counts, and it seems to be increasing steadily after tonight.

[Matty M]

Well well well the UKM has triumphitanlly stuck to its guns..

Heavy snow for much of Ireland and England

[MAF]

......

I will stick my neck out and say there is potential in all of this for 10-20 cms of snow in a fairly large portion of the U.K. and also 5-10 cms in parts of Ireland. Hope it works out that way. There's a bit of a vacuum over Scandinavia as this all comes together, space that the GEM fills with a rapidly swelling 1035 mb high. That feature is much weaker on the GFS but still the gradient is what counts, and it seems to be increasing steadily after tonight.

thanks Roger. another good precise and lets hope your neck is stuck out far enough

[disco-barry]

I don't understand i can 'basically' understand the models and i see no easterly which is being forecast day in day out by paul hudson on the bbc look north, they forecast thursday as overcast but i really see this snow as pushing north and saturday they forecast heavy snow which i do see.

Ta, DB.

[Iceberg]

I was going to post up some precip charts from the raw Meto output, but these represent it perfectly.

Sorry about the SW one, but it's very rare to get that many snow symbols down here !.

The small feature on Wed is still progged to give a bit of snow to the south cost, i.e Devon, Cornwall, south Dorset and south Hampshire.

Meto keeps the precip on wed further south than before from the wash to chester downwards. but keeps most of it as snow.

[nick sussex]

The GEM which always gets the knock as being too progressive is (LOL) less progressive on the 00z run than the GFS, and that is also backtracking from earlier runs.

I've applied the in-house research model to this admittedly difficult forecast scenario, and what it shows is quite encouraging for snowfall.

It may take most of the next 24 hours to set up, but an arctic frontal boundary should develop tonight across the southern Irish coast through Cornwall into northern France. Fairly energetic low pressure should develop west of Ireland and move east to ESE along this boundary and bring a period of moderate to heavy snow across large sections of southern and central England as well as much of Wales. This will of course be sleety nearest to onshore coastal areas but it does seem that the cold air gets well entrenched and this should lead to most places having all snow from this event, which should last 24-36 hours from late Wednesday to early Friday. Then there is likely to be a sort of cease-fire without any real movement of fronts, so a little more light snow or freezing drizzle Friday, followed by a similar event on Saturday but this time with some northward movement of fronts, so eventually southern counties get back into milder air and rain. This will send the heavier snow gradually north through northern England into Scotland, as well as Northern Ireland.

I will stick my neck out and say there is potential in all of this for 10-20 cms of snow in a fairly large portion of the U.K. and also 5-10 cms in parts of Ireland. Hope it works out that way. There's a bit of a vacuum over Scandinavia as this all comes together, space that the GEM fills with a rapidly swelling 1035 mb high. That feature is much weaker on the GFS but still the gradient is what counts, and it seems to be increasing steadily after tonight.

Morning Roger as much as I would love to believe the gem this morning its not really backed by the ukmo or gfs, although having said that its view of taking the jet further south is picked up by the ecm in the later timeframe as this builds a decent scandi high later on. I still think we havent seen the last of the changes and as long as the PV sticks to canada and doesnt head out into the atlantic then I think we've got a chance at seeing further cold weather next week. The models have been desperate to break down the east pacific ridge but have failed on numerous occasions, if that holds and the PNA doesnt go negative then this would certainly help matters downstream for us.

[robert]

Nice to see how good the charts are this morning.

I look forward to more upgraded charts today

I hope all you snow lovers get something out this.

Keep safe out there and have a good day ahead. Maybe a bit early for cookies but *passes around cookies and hot chocolate*

Robert

[MAF]

Nice to see how good the charts are this morning.

I look forward to more upgraded charts today ..........

Robert

so the 10th is still looking good then Robert???

[Yeti]

I have to complain. The 00z shows the front moving NE but fizzling out - the Southerners are stealing my snow again

Edited February 6, 2007 by Yeti

[yido]

Hi Steve

Good to have you back. Perhaps a few people could do with reading SM's post today and hold off posting the same things over and over again.

[Yeti]

However, Saturday looks very good, if marginal... although we're driving to Hull to catch a ferry that day!

[nick sussex]

Overall this morning those looking for cold to hang on have something to cheer about and those looking for milder weather also have something that pleases in the models.

So heres the list.

UKMO cold and wintry till 120hrs then milder

GFS cold and wintry till 120hrs then milder

ECM cold and wintry a slight lull then colder again

GEM sensational

GME excellent

NO GAPS cold and wintry till 120hrs then milder

So something for everyone but seeing as most of the people on here like cold weather lets hope the trend picked up by the ecm yesterday and continued today by the ecm, gem and gme is the correct call.

Edited February 6, 2007 by nick sussex

[robert]

so the 10th is still looking good then Robert???

Yes Mick I am sticking to my 10th February prediction

Have a great day

Robert

[Osbourne One-Nil]

This is a discussion about the models. Please find another thread for anything not model related. We don't say this to be fussy, but simply to be fair to everyone so they know where to find the information they're looking for without having to trawl through lots of off-topic posting.

[frozencanals]

Hi All

Not strictly on topic, but Everton Fox was, for the second day running, ramping a snow event for Thursday across Southern England, although today he dropped the 'even the London area' part of the ramp. I still think this is going to be marginal regarding snow in the south, having said that for the first time this winter driving from Southend to London the external temp gauge in the car finally registered a minus figure for about 8 miles before going positive again.

My guess, with my un-trained eye, from the current charts is sleety rain south of the Thames unless the colder air can push further south, still time for a few more changes though

Cheers all

FC

[The PIT]

GFS back tracks again to earlier runs prior to yesterdays 06oz 00oz although perhaps the lows stay a little to far south. UKmo 00z just sneaking out so can't really comment. Although I'm not supposed to say this this mornings breakfast forecast only mentioned a slight chance of Snow down in southern areas. So still looking marginal. After all the teasing it could be a cold snap that fizzles away to nothing just giving us a few frosts in the meantime.

[kold weather]

Hi Yeti, I did suspect that the models would shift the front a little southwards, though in this set-up it wouldn't matter to much hopefully because it'll take several systems it appears to shift this cold air.

I myself coulsn't be more happy with todays runs as the shift southwards means I'm right where the heaviest snowfall would be possible and in the borderline of the mild air where the front should be the strongest, hopefully!

As for the GEM, its quite different from the other models but we shouldn't rule it out, esp given the 0z GFS isn't that far off what it actually suggests, just not as strong in terms of high pressure:

http://www.wetterzentrale.de/pics/Rtavn1201.png

GEM is stunning though, coldest month since 91 if that were to occur I dare say.

finally in the longer term be very careful, I think the models are over-doing that jet quite a bit by 240hrs and is going to be quite a lot more amplified then that...nearly every ensemble member has a decent HP to our east by 264hrs, while the 0z op doesn't at all so be careful wit hthe op runs, don't think they are picking out that high very well myself.

Unlike the ECM which appears to show it quite nicely. not only that but note that large LP complex is slowly decaying southwards and yes there is another deep depression in its wake but the movementr of LP's SE is a bvery good thing n the long term.