Spring Model Discussion 18Z 6/3/13 onwards....

[peterf]

last time i saw anything like that i was 7 year old and looking through my kaleidoscope lol

it actually made more sense than what you posted Ian.

[DEYS(Kent)]

No: holding fire on totals until all data assessed tonight. But check out these two profiles from GM: tell the story far better than any raw PPN charts. White: classic dynamic snow profile, 12z Mon, Lyme Bay area.... the yellow, by contrast, for Norfolk coast, midnight Mon into Tues.

ECM PPN takes the risk to Kent towards the end of the day Monday. Does the UK4 model think different then? Or are you only talking about dynamic snow?

Edited March 8, 2013 by DEYS(Kent)

[nick sussex]

Its amazing we've been following these synoptics for days,were only 48/60 hours from T Zero and we still have to be wary....Surely no last minute change now..Bye the way i always rate your assumptions and views nick..

Thanks, well this aspect of the set up really wasn't originally likely as the models wanted a more clean clearance of the cold front.

It's really what the nw Biscay Low does that will determine how far north the precip gets. And that's why the UKMO can't be more sure of things.

In terms of amounts of snow that could vary so widely that any firm forecast now could be wide of the mark by tomorrow. I know its frustrating to still not know whats going to happen but the set up is one of those that often goes down to the wire.

[winterof79]

last time i saw anything like that i was 7 year old and looking through my kaleidoscope lol

it actually made more sense than what you posted Ian.

Quite,more for the technical thread than for us norberts. Perhaps a little explanation.

[Captain Shortwave]

Quite,more for the technical thread than for us norberts. Perhaps a little explanation.

Agreed here haha. I will make the assumption it's not good for me (norfolk coast).

If anyone is questioning amounts of snow at the moment bear this in mind.

Yesterday morning the total rainfall prediction for where I live was around 10-15mm for the coming 7 days according to the gfs. The regional forecast for where I live is predicting 50-60mm from this afternoon until tomorrow evening. Disturbances can turn up and enhance precipitation at quite short notice. Just hope if it happens to you lot it isn't just bringing joy to the ducks

Edited March 8, 2013 by Captain shortwave

[Dave Kightley]

ECM mean at 72h.. Around the same as the Op.. Maybe slightly further south but not by much at all. I lie maybe slightly better.. M4/Bristol would be a good shout on how North it gets.

Edited March 8, 2013 by Dave Kightley

[Summer Sun]

ECM full ensemble once again trends milder after from around half way

Edited March 8, 2013 by Gavin.

[LomondSnowstorm]

ECM PPN takes the risk to Kent towards the end of the day Monday. Does the UK4 model think different then? Or are you only talking about dynamic snow?

As opposed to the static kind?

I think he meant the skew-t profiles for the south coast looked very conducive, while those on the Norfolk coast (perhaps in the so called convection shield)had a cap which would limit convection there.

[nick sussex]

As opposed to the static kind?

I think he meant the skew-t profiles for the south coast looked very conducive, while those on the Norfolk coast (perhaps in the so called convection shield)had a cap which would limit convection there.

Is it a tephigram or skew t-log, can't decide which one, the wind directions by height maybe the former. If not I'm stumped!

If its a tephigram then this gives a short but decent description:

http://en.wikipedia.org/wiki/Tephigram

Edited March 8, 2013 by nick sussex

[chionomaniac]

Low to SW is 5mb stronger at T+42 on GFS 18Z - that will lead to a slightly further north track and the precip further north - but so will the colder 850 temps be further north!

Edited March 8, 2013 by chionomaniac

[SMU]

Low to SW is 5mb stronger at T+42 on GFS 18Z - that will lead to a slightly further north track and the precip further north - but so will the colder 850 temps!

yes agree- I have the 48 PPN & its almost close to North wales- all ready to slide East-

The Tephigrams presenting dynamic snow is a long way better than the last poor capped easterly.-

S

[manutdmatt1986]

Low to SW is 5mb stronger at T+42 on GFS 18Z - that will lead to a slightly further north track and the precip further north - but so will the colder 850 temps!

Yep. I was just about to say the low looks slightly further North. 18 z - http://images.meteociel.fr/im/2533/gfs-0-60_khu5.png 12z - http://images.meteociel.fr/im/649/gfs-0-66_ngl5.png

[SMU]

http://www.wetterzentrale.de/pics/Rmgfs722.gif

Look at the very fine margins that the UK operate under with a channel low-

I dont think the low will move anything 'milder' in from the south- but such a thin margin where the gradient is 11/12 degrees!

PPN is further North this run with extensive snow for the 'sussex', kent London, surrey, berkshire & hampshire etc-

Looking good - places on the south downs if these 'type' of PPN rates varify are upwards of 10/15cm

S

[chionomaniac]

yes agree- I have the 48 PPN & its almost close to North wales- all ready to slide East-

The Tephigrams presenting dynamic snow is a long way better than the last poor capped easterly.-

S

So far this winter we have seen these systems get modeled further north between days 5 to 2 but at that point stabilise. The majority of times we have seen that lead to a squeeze on the 850's lead to temps to the wrong side of marginal and sleety rain events. Now it is March though but if this trend continues we will see this work to our favour ( to those south of the M4!). And for those further north a stronger easterly flow could bringer better showers due to increased instabilty from the more northerly positioned trough.

Edited March 8, 2013 by chionomaniac

[-uksnow-]

So far this winter we have seen these systems get modeled further north between days 5 to 2 but at that point stabilise. The majority of times we have seen that lead to a squeeze on the 850's lead to temps to the wrong side of marginal and sleety rain events. Now it is March though but if this trend continues we will see this work to our favour ( to those south of the M4!). And for those further north a stronger easterly flow could bringer better showers due to increased instabilty from the more northerly positioned trough.

Chio, to those of us south of the M4 - surely we do not want this system moving a whole lot further north than its currently projected? Or will that only intensify our snow..

[chionomaniac]

Chio, to those of us south of the M4 - surely we do not want this system moving a whole lot further north than its currently projected? Or will that only intensify our snow..

There is a perfect line for you, me and everyone else- for maximum snowfall whilst keeping the lowest temps - but that line is different for us all. And there lies the difficulty - we all want that perfect line falling over our own heads! I think that currently the GFS is great for those on the south coast, but the ECM and UKMO (and GFS) could all do with a northwards shift for all wanting a dynamic snowfall. ( Not that the models control the weather of course!)

[Nick F]

Still another day or two of fine tuning over the extent north of precip from the low moving through northern France, this far there's still a largish margin of error for the models ... 50 miles north or south will make a big difference to whether southern counties of England see lots of snow or nothing ... doesn't sound too much but over our small island it's alot.

Before the threat from this low, GFS seems alot more bullish with rain to snow amounts coming south on Sunday than UKMO GM and ECM, so not sure there will be too much of a threat from snowfall on Sunday away form northern hilly areas, but one of those dynamic situations which needs watching too.

[Freezing-Point]

http://www.wetterzen...cs/Rmgfs722.gif

Look at the very fine margins that the UK operate under with a channel low-

I dont think the low will move anything 'milder' in from the south- but such a thin margin where the gradient is 11/12 degrees!

PPN is further North this run with extensive snow for the 'sussex', kent London, surrey, berkshire & hampshire etc-

Looking good - places on the south downs if these 'type' of PPN rates varify are upwards of 10/15cm

S

Steve, I am going for another north east streamer as a trough intensifies showers on Sunday night. What do you think?

[SMU]

Yes mate- NE looks very good in the flow- streams of showers- all the fuss in the south & the NE could get some +20/30 totals-

S

[Mucka]

NAVGEM has the low a little further North again than last run.

[Cloud 10]

The pub run looks to be heading for a proper Greenland high.

[Snowman.]

We looked for a GH all winter then it comes to march and its a very strong one. Which has no real cold effect.

Edited March 8, 2013 by SN0WM4N

[Cheshire Freeze]

We looked for a GH all winter then it comes to march and its a very strong one. Which has no real cold effect.

The bad thing is it's very slightly too far west....

[Mair Snaw]

The pub run looks to be heading for a proper Greenland high.

Now if that could just stay where it is until november/december then we could be well in....

[Cloud 10]

The bad thing is it's very slightly too far west....

....at the moment...