12z Model discussion - rain, sleet or snow?

[SMU]

couldnt agree more. as i said in a post a few minutes ago this is stuff of the good old days!

yes I agree & I like the word Nowcast.......

The final say in PPN location may well run down to just t6...........

S

[PersianPaladin]

Loving the progression of these charts, some of the younger members, this was what the good old eighties was like, but usually started at the end of december, Steve M now this could be like the days of old

Paul Sherman

Please elaborate on this hideously over-inflated ramp......

Edited February 6, 2007 by PersianPaladin

[VillagePlank]

they look like classics partic at the weekend! cold everywhere and snow potential everywhere!

Not sure: 850hPa's not great with a line London to Holyhead and SW-ward, indeed consider that more further N and E! Almost certainly rain in that area on Saturday, from this run.

[Optimus Prime]

It certainly looks nostalgic, the synoptics but the conditions are far more modern day.

The SE winds are blowing from a mild and green continent. If this was the old days it would be blowing of a frozen white continent.

No sub zero max on a countrywide scale that was achieved in February 1994 in a similar situation.

Marginal these days seems to be the word mentioned everytime snow is in the same sentence.

[VillagePlank]

The final say in PPN location may well run down to just t6...........

S

Almost certainly. I'm thinking of it as a band of organised showers (which is what it is really, anyway) with all of the unpredicatability that goes with it.

[michesnowsbest]

yes I agree & I like the word Nowcast.......

The final say in PPN location may well run down to just t6...........

S

Hi Steve is the anyway that you could do a quick run down of a forcast for the next few days for us on the forum it would be greatly appreciated

Regards

Michesnowsbest

[Yeti]

Please elaborate on this hideously over-inflated ramp......

LOL you haven't seen this one:

it looks like 1683 all over again!

Tbh the whole thing looks like fizzling out a bit later on in the day, although the precip does make it up here. I've had my eye on Saturday for a while now, though whether the 12z is correct remains to be seen.

PLEASE say there is some hope that the low will not go too far S so that we see nothing. How awful it would be to miss out on heavy 100 miles to the S!

[Paul Sherman]

Please elaborate on this hideously over-inflated ramp......

PP

The synoptics over the last few years whilst on Net-Weather have shown piddly showers from the North East without the correct Block, or pattern from the charts, this ramp is fully justified in some places are going to reap the benfits from the "Battle Royale" from the next few days and if the pattern persists then the good old eighties style snowstorms will ensue, My location could not get anything and I know that but some places will get it hard and then could keep getting it for a part of February.

Ramp Over

Paul S

[yamkin]

Looking at the snow forecast charts it seems to still be rain for the south

Looking at the snow forecast is one thing, but I can tell you that there will be snow South of the M4 too for a time.

[wellington boot]

well ive been marking my location on subsequent runs of the gfs to see where exactly i fall on the temp and ppn charts. This latest one, its still all coming in fractionally too slowly for my liking. I wish it would arrive just a bit earlier in the night.

Though having said that the gorund temps up to midday at least look better again, and probably enough for snow, as far south as the M4 pretty much. Further north, the temps look favourable enough for the midlands if the ppn can actually push that far;

Also, just to point out, the 850s show some nice reintroduction of -5s after that low passes through. If they could travke a bit further, then a later event would start to look better and better.

850s

Edited February 6, 2007 by wellington boot

[Steady Easterly]

PP

The synoptics over the last few years whilst on Net-Weather have shown piddly showers from the North East without the correct Block, or pattern from the charts, this ramp is fully justified in some places are going to reap the benfits from the "Battle Royale" from the next few days and if the pattern persists then the good old eighties style snowstorms will ensue, My location could not get anything and I know that but some places will get it hard and then could keep getting it for a part of February.

Ramp Over

Paul S

I agree, these synoptics are as rare as hens teeth! reminds me very much of the late seventies/early eighties.

[VillagePlank]

. . . and some consider the 12z to be a rather warm run

(I'll just run and hide, now)

[Snowyowl9]

It certainly looks nostalgic, the synoptics but the conditions are far more modern day.

The SE winds are blowing from a mild and green continent. If this was the old days it would be blowing of a frozen white continent.

No sub zero max on a countrywide scale that was achieved in February 1994 in a similar situation.

Marginal these days seems to be the word mentioned everytime snow is in the same sentence.

Never underestimate the east or SE winds to me it has much more of a bite to it than a NE.

If this came off there could be some fun and games surface winds would be east/SE.

http://85.214.49.20/wz/pics/Rtavn901.png

[Snow storm]

Heres a chart I made.

[PersianPaladin]

I agree, these synoptics are as rare as hens teeth! reminds me very much of the late seventies/early eighties.

Sadly...the jet is stronger to the south than in the past; SST's are warmer, the continent is considerably less cold, less cold-air advection at mid-levels, weaker and more flimsy height rises to the north, etc. It's just marginal, marginal, marginal.

1982, the year of my birth, was very cold and very snowy in North Yorkshire and the North-East. Younger members here would be shocked to witness the amount of snow and intensity\length of cold back then.

[SMU]

Micheal-

With refernce to the Shortwaves tracking in on Weds eve/Thursday Night-

These shortwaves & their interaction with the main depression off to the West of ireland is almost impossible to button down-

Simply put, the Max Northerly extent of the Snow will be realised if the Shortwave fully phases with that atlantic depression & is pulled rapidly North with little easterly jog-

The max Southerly extent is obviously where the shortwave totally missed a phasing event & just carries sailing on by-

This will then see the best scenario develop for the Southern areas-

These 2 developments are highlighted perfectly for me within the METO 00z & 06Z run- ( look at the 'tilt' of the lows here-

firstly look at the 00z-

http://moe.met.fsu.edu/tcgengifs//ukm/2007020600//slp10.png

One System that has formed will push northwards- Notice how the tilt of the low has that NE orientation- looking at it you expect the natural progression to be slightly more NE-

More importantly though is the fact that one stronger circulation can advect more warmer air into the block ahead of the frontal band-

Now look at the 06z-

http://moe.met.fsu.edu/tcgengifs//ukm/2007020606//slp8.png

The tilt look more SE not NE & we have a smaller shortwave developing which will have less ability to advect warmer air into the Front-

In essence the 06z IMHO wold be a slight upgrade for snow potential WRT temperatures along the frontal Boundry-

Its a pity the 06z doesnt go out past 60 because the next chart would have been key-

Also again worthy of note if it was missed from this morning is the Second bout of PPN coming through -

I highlighted the fact that rather than the WHOLE system moving North it could stall out to the west of ireland & send anotyher shortwave around the base into the Colder air-

The 06z Does develop this feature- As for snow out of this it would be down to the flow returning from the NE at the time & highlights perhaps a region in a similar sort of area to the first band-

here it is- although this again COULD slide EAST-

http://www.wetterzentrale.de/pics/Rmgfs781.gif

In terms of the longer range output- I think 99% of people believed the synoptic pattern wouldnt develop to such an extent where by at t 48 we are discussing a posible large scale snow event-

Its very understandable this- many many let downs in the past, Last minute model changes never delivering cold, features not occuring at the right time, rain instead of snow-

we have ALL been there - However we must realise now that in part we are over that 'major' error in terms of any cold/snow being missed & we are into the 'finer' tuning stages of the run in-

The evoltion though POST thurs & friday is far from set in stone- Taking this at face value we are in a rather unique situation & to my mind have only been here a handful of times in the last 20 years - What we should have learned is that the model bias & lack of raw data from regions that have the greatest impact on this evolution gives enough weakness & margin of error to still expect the models to back track away from the 'progressive' type scenario current displayed to one of continued southerly tracking Shortwaves & blocked conditions-

I draw you to this mornings GEM - Usual disclaimers apply here because its NOT one of the big models however I 'think' in the mid term its feel for the flow perhaps is better than the ECM & GFS-

I know thats a big statement - however in this heightened period of model error- historic examples ( Although few & far between) lead me to believe the Cold - deeply manifested to the NE wont be a pushover & may well over come the drive from the atlantic escpecially given that the PV is WAY AWAY to the west...

http://www.wetterzentrale.de/pics/Rgem1081.gif

The 108 Chart shows how the atlantic hasnt driven East & the small shortwave energy is sliding SE away from the main vortex- Ring any bells-??

All the GEM is doing is continually splitting the Vortex - where as the main models keep bringing it together & surging it east-

If you believe the PV can be split once-

http://moe.met.fsu.edu/tcgengifs//ukm/2007020606//slp8.png 06Z

There is no reason why it wont continue that way - that would be my take on the evolution past 96-

If this to occur what you will see is both the GFS & UKMO etc limiting the extent of the northern energy & starting to pull it South again- This would occur in the 96-120 range-

If it does this archive chart here:

http://www.wetterzentrale.de/archive/ra/19...00119790207.gif looks very similar to the current prognosis- which went to here-

http://www.wetterzentrale.de/archive/ra/19...00119790211.gif

& finally here-

http://www.wetterzentrale.de/archive/ra/19...00119790214.gif

http://www.wetterzentrale.de/archive/ra/19...00119790215.gif

I dont think this milder weather is all said & done- I would say & hope that the amalgamation of the atlantic into one single vortex again is model bias rather than model integrity-

Lets hope so eh.....

S

So in summary for you - very cold overnight- i would go for you -4C, tomorrow dry & sunny +2 or 3C then tomorrow evening its radar watch from 11 onwards-

Your temp will drop rapidly below freezing, perhaps again as low as -4c but recover ahead of the frontal band-

You are expected to see leading egde snow- however from yours & mines perspective its how far the band progresses North-

The further it goes the warmer the air starts to become along the back edge & certainly you then run the risk of snow>> rain...

Anyway- my advice would be continue to watch the next 18/24 hour model runs- hope for a slight southerly jog from the GFS then you could be in the sweet spot-

Also save the images from the GEM run for 108 & 120 - thats what THIS region wants for NIMBY at the end of the week..........

S

[grab my graupel]

LOL you haven't seen this one:

Tbh the whole thing looks like fizzling out a bit later on in the day, although the precip does make it up here. I've had my eye on Saturday for a while now, though whether the 12z is correct remains to be seen.

PLEASE say there is some hope that the low will not go too far S so that we see nothing. How awful it would be to miss out on heavy 100 miles to the S!

Yes I agree, I detect quite a bit of ramping on here today.

Although, the prospects do look good for Saturday, and indeed for something

more prolonged down the line.

Regards this week, I think for us, snow will be miminal.

[wellington boot]

Never underestimate the east or SE winds to me it has much more of a bite to it than a NE.

If this came off there could be some fun and games surface winds would be east/SE.

http://85.214.49.20/wz/pics/Rtavn901.png

Yes you're right, that chart has huge potential. As you say, with surface winds close to east south east, and pressure sub 1000 mb for many, we could see plenty of hefty of showers all over the place, not to mention the possible frontal event.

On a different note, the bbc has finally decided to give me heavy snow for thursday, Hooray!, though only light rain and sleet for friday and sat. But you know, its the worst forecast we have, so itll prob be wrong about friday and saturday....

[Anti-Mild]

Where's The Enforcer? I reckon even Abingdon may get some snow from this event!

[Joneseye]

I agree, these synoptics are as rare as hens teeth! reminds me very much of the late seventies/early eighties.

Too true!

I agree with Paul when he says "My location could not get anything and I know that but some places will get it hard and then could keep getting it for a part of February."

The models are showing the potential for a decent snow event for some of the less favoured locations in recent years. I will be happy to hear that people have got a decent dumping out of this.

Still worth remaining cautious for Saturday in light of the fact that there have been inconsistencies in the models within a very short timeframe. FI for me is still within 48 hours after the Thursday event. I am looking forward to the Ensembles with great interest!

IJ

Edited February 6, 2007 by Joneseye

[joespontiac]

well ive been marking my location on subsequent runs of the gfs to see where exactly i fall on the temp and ppn charts. This latest one, its still all coming in fractionally too slowly for my liking. I wish it would arrive just a bit earlier in the night.

Though having said that the gorund temps up to midday at least look better again, and probably enough for snow, as far south as the M4 pretty much. Further north, the temps look favourable enough for the midlands if the ppn can actually push that far;

and if you put me on that chart you can see we are quite close

[Steady Easterly]

Sadly...the jet is stronger to the south than in the past; SST's are warmer, the continent is considerably less cold, less cold-air advection at mid-levels, weaker and more flimsy height rises to the north, etc. It's just marginal, marginal, marginal.

1982, the year of my birth, was very cold and very snowy in North Yorkshire and the North-East. Younger members here would be shocked to witness the amount of snow and intensity\length of cold back then.

You should of seen 79!! anyway, im starting to think we may do ok from this, if only from snow showers, the goalposts have been moved since those days i agree.

[nick sussex]

I'm not sure whether the gfs has got the early stages correct here but the overall trend continues that of this morning and backs the ecm and a few of the cannon fodder models. For those that love the atlantic its heartbreak this evening as its decided to go and bother someone else. The PV looks to remain over canada and the ridge from the east is likely to back westwards, all those weak lows in the atlantic is just a sign the gfs loses its way but the fact remains that the trend shouts extended cold spell after a brief lull.

Good riddance to the atlantic and its pesky mild mush, see you at some point in the future but not anytime soon!

[wellington boot]

and if you put me on that chart you can see we are quite close

Wont you look at that. Either side of the 0 degrees!!

and other interesting bbc forecasts, for those who enjoy looking at the bbc ramping snow for once, even if their little five day forecasts are useless, nottingham has two days of heavy snow forecast, while bristol even gets heavy sbnow on thursday, despite having temps no lower than 4 degrees...

Just to acknowledge the uselessness of the bbc though, dublin has no ppn til saturday, amazing given that a huge swathe of ppn, be it rain or snow, passes directly over them thursday.

[kold weather]

WB, that set-up on Saturday is the best set-up I've ever seen at such close range on the GFS, its the type of set-up you usually only see at 300hrs!

Very intresting little period of weather coming up.

By the way Steve, nearly 50% of the esnemble runs have the frontal boundary further south, with a couple having the northern extent only being the far S.Midlands with us in the sweet spot so to speak.

Also control run also brings in the same mas sof precip as the 12z opdoes on Saturday with heavy snow for all north of the M4.

Edited February 6, 2007 by kold weather