Model Discussion - January 17th

[sn0wman]

The result is that the jet stream is less strong and more amplified.

This measns that the the LP is more likley to go

SE and the Azores high dissappear off as seen in the later frames.

Sorry for my ignorance, but could you tell me where the PV is on this chart and also, how do

you tell it apart from other low pressure systems? Thanks.

Edited January 17, 2012 by sn0wman

[Grimsby Snow Lover]

Sorry for my ignorance, but could you tell me where the PV is on this chart and also, how do

you tell it apart from other low pressure systems? Thanks.

I personally look for those very dark blues and purples over the Pole. As far as I can tell that is the Polar vortex

[Tim Bland]

Low pressure next week further south on GFS 12Z. Looking at the PV it is weakening and as that lobe from Greenland ejects SE there is scope for higer pressure over Greenland. In the short term this means cool zonal with snow for higher areas in the north. Longer term it increases our chances of a Northerly outbreak IMO. Jetstream is also pushed well South of the UK.

Edited January 17, 2012 by Tim Bland

[danm]

Chalk and cheese comparing the GFS 12z with the 6z at t174.

12z:

6z:

Azores high backing west, ridging slowly towards Greeny, Russian high ridging westwards towards the Arctic/Svalbard, PV further west, trough digging SE through the UK. If the trough continues to dig SE'wards, and the Azores high continues to back west and north, then it could show an interesting solution in the medium term with many more options for cold and snowy weather.

Edited January 17, 2012 by danm

[Radiating Dendrite]

Sorry for my ignorance, but could you tell me where the PV is on this chart and also, how do

you tell it apart from other low pressure systems? Thanks.

The PV is the area with low damn values.

Basically the Purple areas.

Edited January 17, 2012 by Radiating Dendrite

[danm]

The only problem at t186 is that pesky low exiting Newfoundland. It prevents the Azores high from properly ridging up towards Greeny and as a result the Azores high starts to get pushed south and flatten out slightly. But a better run so far.

GFS @ t186:

[mulzy]

UKMO pretty zonal - no significant height rises around Greenland.

http://www.meteociel.fr/modeles/ukmo2.php?nh=1&ech=120&carte=1021

http://www.meteociel.fr/modeles/ukmo2.php?nh=1&ech=144&carte=1021

[Grimsby Snow Lover]

Sorry for my ignorance, but could you tell me where the PV is on this chart and also, how do

you tell it apart from other low pressure systems? Thanks.

Just to add to my previous reply these two charts from last December show how the PV can get dislodged from Greenland and affect areas much further south, including us. Note the dark blue/purple colours.

http://www.wetterzen...00120101216.gif December 16th 2010

http://www.wetterzen...00120101217.gif December 17th 2010

Edited January 17, 2012 by Grimsby Snow Lover

[swilliam]

The low res part has blown up that low to the West of us so probably best to ignore the rest of this run.

Edited January 17, 2012 by swilliam

[danm]

Post t192 it goes tits up as the low exiting newfoundland blows up, flattens the pattern and resets into a more zonal flow. The signs up till then were encouraging for medium term prospects and the evolution of the GFS run all depends on the track of that low leaving Newfoundland at t168.

[Tim Bland]

High over Russia is at 1056MB and spreading further west. Unfortunately the lows to our NW and PV is still raging so we are stuck in the middle.

[Cecil Hogmanay Melchett]

Not much to like in the 12z runs is there.

Little amplification,strong jet.

Back to square 1,i rather think so.

[Radiating Dendrite]

As has been said many times before, anything in the low-res is best ignored.

Up until that point the signs were encouraging.

As is always the case, the GFS blows up lows in the low-res part and flattens the pattern.

[Radiating Dendrite]

Not much to like in the 12z runs is there.

Little amplification,strong jet.

Back to square 1,i rather think so.

Not sure where you are getting that from.

The jet was much better positioned in the hi-res run compared to the 6z with better amplification.

The canadian high is also seen to be continuing its development which is a good sign and the PV was shifted further west yet again.

It went wrong in FI, but the GFS always flattens the pattern in FI.

[ukpaul]

GFS very disappointing, building blocks are being put in place but only leading to relentless zonality (and not even of the cold sort). If it is getting the signals then either the competing ones are much stronger or we are in the wrong place pretty much every time to benefit, we should be seeing a change now in output according to changes in NAO, PV etc. but none of this seems to cut any ice (literally!)

[Cecil Hogmanay Melchett]

Not sure where you are getting that from.

The jet was much better positioned in the hi-res run compared to the 6z with better amplification.

The canadian high is also seen to be continuing its development which is a good sign and the PV was shifted further west yet again.

It went wrong in FI, but the GFS always flattens the pattern in FI.

Well looking at the jet stream charts was enough for me just a contiunation of what we have seen all winter is what im seeing on the 12zgfs.

Not sure ukmo looks all that mind blowing either.

[Buzzit]

As has been said many times before, anything in the low-res is best ignored.

Up until that point the signs were encouraging.

As is always the case, the GFS blows up lows in the low-res part and flattens the pattern.

Agreed. i was encouraged that up to +96 there was very little difference between 6z and 12z if not slightly better in the 12z. Quite a variation in FI at times when looking at the jetstream which I find interesting, I see further hints of a NW, SE tilt when excluding the FI mega lows.

[Radiating Dendrite]

GFS very disappointing, building blocks are being put in place but only leading to relentless zonality (and not even of the cold sort). If it is getting the signals then either the competing ones are much stronger or we are in the wrong place pretty much every time to benefit, we should be seeing a change now in output according to changes in NAO, PV etc. but none of this seems to cut any ice (literally!)

BUT IT WENT WRONG IN THE LOW-RES PART OF THE RUN.

I am sorry, but people are still treating the post 180 period as gospel.

What does the GFS nearly always do to lows in the low-res part of the run..............answers on a postcard!

One clue.....bomb.

[The Northern Ramper]

I found the trends of the vortex and Russian high further west, heights over greenland and the vortex displacing quite promising.

[The PIT]

GFS heading back to average to slightly above average with each run. Need to keep an eye on the feature at T111 in case it winds up more. Otherwise any cold air spends too much time over the Atlantic to bring anything of note.

Yet another reality check for ice age hunters.

[The Northern Ramper]

Not sure where you are getting that from.

The jet was much better positioned in the hi-res run compared to the 6z with better amplification.

The canadian high is also seen to be continuing its development which is a good sign and the PV was shifted further west yet again.

It went wrong in FI, but the GFS always flattens the pattern in FI.

If people cannot see that the gfs low res is a joke then i give up, every run it just goes against the set up pre 192.

[ANYWEATHER]

GFS very disappointing, building blocks are being put in place but only leading to relentless zonality (and not even of the cold sort). If it is getting the signals then either the competing ones are much stronger or we are in the wrong place pretty much every time to benefit, we should be seeing a change now in output according to changes in NAO, PV etc. but none of this seems to cut any ice (literally!)

Yes a powerful Jetstream looks like resetting itself across the Uk as in previous weeks, apart from this brief and welcome respite of the last 5 or 6 days. Little sign of anything substantially Wintry in the forseeable future, but as I mentioned yesterday the Scottish Mountains picticularly look like getting Plastered with some substantial snow as frequent Polar Maritime air picticularly for Scotland looks pretty much the case in the Near future, based on the recent output.

[Harsh Climate]

If people cannot see that the gfs low res is a joke then i give up, every run it just goes against the set up pre 192.

How do you know it's a joke?? It could be right for all we know

[nick sussex]

There is a question mark regarding how long that flattish zonal flow will last for in the USA, this from their morning update:

LARGE SCALE UPPER PATTERN OVER NORTH AMERICA INTO NEXT WEEK SHOULD

FEATURE THE LARGE POLAR VORTEX CURRENTLY LOCATED NORTH OF HUDSON

BAY TO SPLIT IN TWO. ONE PIECE WILL RELOCATED WESTWARD OVER ALASKA

WHILE THE OTHER WOBBLES EASTWARD TOWARD BAFFIN ISLAND. THIS WILL

KEEP A RATHER ZONAL FLOW THROUGH THE CONUS WITH POSSIBLE BUCKLING

OF THE PATTERN BY EARLY NEXT WEEK.

This will have an effect on the pattern in the Atlantic re the Azores high and Greenland in terms of whether we see a more amplified trough developing in the ne USA.

[No Balls Like Snow Balls]

Could be pretty stormy down Eastern side of UK on Sunday according to 12z GFS at T120.

or could be Stormy on Monday Further North according to UKMO, take your pick, disagreement at T120 between UKMO and GFS.

Good heights still over Greenland in high res part of run on GFS. Did not bother looking into FI.

Edited January 17, 2012 by No balls like Snow Balls