Model Output Discussion

[ChartViewer]

Interesting GEFS ensembles for 06z around the 17th-19th period. Really looks a tough one to call for that period with the PV splitting.............High pressure ends up everywhere on the Panel Maps.

Me I like Panel Map 10 for that Period

Edited December 3, 2009 by ChartViewer

[Methuselah]

Has there ever been a proper cold spell that hasn't been preceeded by a splitting of the PV?

[Shunter]

well the MJO doesn't appear to be listening to NOAA's forecast, its heading through phase 7.

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

[Cheshire Gap]

Sorry to sound ignorant, could somebody please briefly explain the MJO for me? I under stand the charts, PV etc, but these phases etc are giving me abit of a head scrather.

Help would be greatly appreciated

Thank you

C.G

[Fozfoster]

Sorry to sound ignorant, could somebody please briefly explain the MJO for me? I under stand the charts, PV etc, but these phases etc are giving me abit of a head scrather.

Help would be greatly appreciated

Thank you

C.G

MJO-Madden-julien Oscillation, not totality sure what that means! Acronyms and abbreviations are in the learner area

Edited December 3, 2009 by fozfoster

[Shunter]

Sorry to sound ignorant, could somebody please briefly explain the MJO for me? I under stand the charts, PV etc, but these phases etc are giving me abit of a head scrather.

Help would be greatly appreciated

Thank you

C.G

http://en.wikipedia.org/wiki/Madden%E2%80%93Julian_oscillation

Brief explanation...

[Methuselah]

http://en.wikipedia.org/wiki/Madden%E2%80%93Julian_oscillation

Brief explanation...

Thanks for the info, Shunter...

[Thundery wintry showers]

Has there ever been a proper cold spell that hasn't been preceeded by a splitting of the PV?

I think it can happen, but I'm yet to come across any notable "easterly" episodes that weren't preceded by the above. It tends mainly to be cold spells that are set up by northerly outbreaks.

December 1981- PV displaced over to Scandinavia:

http://www.wetterzentrale.de/archive/ra/1981/Rrea00119811206.gif

January 1959- PV set up in the usual place on the 1st, then 3 weeks of northerly winds:

http://www.wetterzentrale.de/archive/ra/1959/Rrea00119590101.gif

17 January 1958- PV displaced over to Scandinavia:

http://www.wetterzentrale.de/archive/ra/1958/Rrea00119580117.gif

[snowmadchrisuk]

well the MJO doesn't appear to be listening to NOAA's forecast, its heading through phase 7.

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/phase.Last40days.gif

Should make for some good interesting Evening runs , Although weather it stays in Phase 7 is well open to question at the moment.

[KTtom]

Should make for some good interesting Evening runs , Although weather it stays in Phase 7 is well open to question at the moment.

OK, now we all know what it is, can anyone actually explain what it has to do with our prospects, and which phase is best?

[Cheshire Gap]

Thank you Fozfoster and shunter!

C.G

[Glacier Point]

Should make for some good interesting Evening runs , Although weather it stays in Phase 7 is well open to question at the moment.

You can see the MJO wave in the Pacific around 170W:

http://cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/OLR/m.3d.html

http://cimss.ssec.wisc.edu/tropic/real-time/wavetrak/winds/wavetrkP.html

Watching this over the last day or so possibly some hint of this activty intensifying and therefore greater amplitude to the MJO.

With the Global Wind Oscillation stuck between phase 0 and 4 (4 more likely in the next day or so once updated date gets fed in), I would avoid MJO composites for phase 7 as the GWO will be the more important influence.

http://www.esrl.noaa.gov/psd/map/images/gcm/gwo_40d.gif

The MJO will be of significance though in helping to contribute further westerly wind additions to angular momentum - which has greater significance in terms of late December and January's pattern.

So for me, remaining unsettled with the longwave trough still stuck close to the UK feeding in rain, wind and average or slightly above conditions.

With the MJO edging slightly east towards and past the Dateline, expect the GFS to continue to show easterlies in the extended output though. Model candy which IMO only becomes of relevance when the GWO orbits into phase 5.

[snowmadchrisuk]

OK, now we all know what it is, can anyone actually explain what it has to do with our prospects, and which phase is best?

You will need to follow GP's posts for more explanation , but from my limited understanding phase 7 and 8 are best for Northern Blocking .

[Weather-history]

Manchester pressure and temperature ensembles.

Seems to be pressure rise trend and also a cooling trend after two milder humps.

http://91.121.93.17/pics/MT2_Manchester_ens.png

[mountain shadow]

Having been away from the models for a bit it is very encouraging at the moment, if not for the consistency of the models runs, but more with how things are panning out in terms of many winter forecasts, namely mild and wet to start, turning colder mid month.

The models have actually been performing well in the reliable IMO with a continuance of the current set up of atlantic driven troughs which fail to get passed the meridian. In the medium term turning more seasonal with perhaps still a shot at a very cold spell.

As many have said, patience is required whilst the building blocks fall into place. If a cold spell has not started or is within T+144 by the 16th of this month, then I will start to worry.

[cooling climate]

Here's to a good afternoon of model watching...hopefully.

[Eugene]

I'm much more encouraged today over mid to late decembers prospects than yesterday, we look to be in for a colder and more settled mid to late december, not much snow but after all the active weather lately i just want some prolonged nice calm cold weather.

I feel HP blocking to our east will keep us cold with a southeasterly flow but no really cold snowy weather that so many want until later in december into January as we get a battle between a lively atlantic and strong blocking to our east.

[karyo]

After reading GPs earlier post I feel that model watching for the next few days is less important than before! This is because as he explained, the models are likely to react to the MJO moving into Phase 7 (i.e northern blocking) but as the GWO is not co-operating any cold spell is looking unlikely for the time being.

Late December or early January is where the hope is currently but that may or may not materialise.

Karyo

[snowmadchrisuk]

After reading GPs earlier post I feel that model watching for the next few days is less important than before! This is because as he explained, the models are likely to react to the MJO moving into Phase 7 (i.e northern blocking) but as the GWO is not co-operating any cold spell is looking unlikely for the time being.

Late December or early January is where the hope is currently but that may or may not materialise.

Karyo

I Think if we get some decent blocking going then it will be only a matter of time. Nearly all the Winter Forecasts go for a cold spell mid December . As long as we don't get stuck with southerly's I'll be happy .

[mountain shadow]

Deep Vortex over Baffin, i thought this supported Greenland height rises?

http://209.197.11.166/c9s4a5k3/cds/gfsimages/gfs.20091203/12/144/npsh500.png?dopvhost=charts.netweather.tv&doppl=841a626ccf0d848ecf5d84de1e988f95cf5d84ff&dopsig=48d3660b87434e3e8dcba98f4672467c

[mountain shadow]

The 12z pushes a trough into Scandi with moderate height rises over Greenland. I wonder if we should be looking to Greenland for our first winter shot rather than to the North East. The ECM 0z I think was similar to this run and could evolve a mid month northerly.

http://209.197.11.95/c9s4a5k3/cds/gfsimages/gfs.20091203/12/240/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf0d886d&dopsig=34b344b16f776aed9f24cc43c352f876

[snowmadchrisuk]

The 12z pushes a trough into Scandi with moderate height rises over Greenland. I wonder if we should be looking to Greenland for our first winter shot rather than to the North East. The ECM 0z I think was similar to this run and could evolve a mid month northerly.

http://209.197.11.95/c9s4a5k3/cds/gfsimages/gfs.20091203/12/240/h500slp.png?dopvhost=charts.netweather.tv&doppl=841a626ccf0d886d&dopsig=34b344b16f776aed9f24cc43c352f876

Well the 12z is totally different to the 6z , nothing really reaching the uk , but the amount of blocking starting to appear to our north is impressive and is a very good sign IMO

[nick sussex]

I'm quite pleased with this gfs run and here we see the euro high helping to change the pattern, many times we see the euro high with low heights to the north meaning it can't develop a colder pattern , the difference this time is we have building pressure to the north and ne. As i said in an earlier post IMO this is a plausible way forward because the trough to the west will eventually force a pressure rise over southern europe, its not far fetched and doesn't rely on too many factors, we need to see the other models go for this, so a glimmer of hope this evening so far, lets hope it lasts.

[mountain shadow]

Well the 12z is totally different to the 6z , nothing really reaching the uk , but the amount of blocking starting to appear to our north is impressive and is a very good sign IMO

Yup, flood gates would open from the west after this and would be sustained as well, not a toppler.

http://209.197.11.167/c9s4a5k3/cds/gfsimages/gfs.20091203/12/384/h850t850eu.png?dopvhost=charts.netweather.tv&doppl=841a626ccf0d8983cf5d89d31e988298cf5d89f3&dopsig=b7d5c0573cb8bc5786dca3e2c64451fb

Netweather Winter forecast went for a mid December northerly I think, and would be more likely than an easterly. Need to wait for the ensembles of course, but i think the chance of an easterly in December is getting more unlikely. Look north I say.

[Cecil Hogmanay Melchett]

Awful gfs.

Wet,windy and mostly above average.No sign of a let up in the Atlantic.

Im really not expecting anything approaching cold for 2 weeks at least,and even thats based on desperation!

ukmo might bring some cheer but im not counting my chickens.

Edited December 3, 2009 by happy days