Model Output Discussion

[Methuselah]

Here you go, a new one!

[nick sussex]

In answer to snowmad 79's question on the other thread, the models have fresh input every day, the only automated thing that we sometimes discuss in here are the 6-10 and 8-14 day NOAA maps which are done at the weekend, during the week these have input by a forecaster. Regarding the models it probably is better to view the 00Hrs and 12hrs gfs ones when trying to view possibilities as at least we can compare these with the other main global models which run just twice a day at the same time. The gfs 06hrs is okay though in that at least NOAA sometimes weight this into their forecasts, the gfs 18hrs is far too volatile and often is the one run that will go completely AWOL so this is certainly one to always be dubious of. Hope that helps.

[Paul]

Sorry folks, have deleted a couple of posts there as there were a couple of issues with them which made the system go a bit weird for some reason.

[Guest North Sea Snow Convection]

I think around seven to ten days and we will be seeing the first pivotal moment of the winter months, the pattern over the US looks to be setting up for the sort of plunge that leads to a lot of energy coming off the Eastern Seaboard.

How the AO behaves will be important, as this could deflect the jet towards mid-latitude or even further South, but the more likely scenario will be that we will see pressure low to the West and North West with a pressure rise over continental Europe. We know the rest.

What current background factors do you think make this more likely Ian?

Sorry folks, have deleted a couple of posts there as there were a couple of issues with them which made the system go a bit weird for some reason.

It was quite a job trying to keep editing my post into something readable!

Edited November 29, 2009 by North Sea Snow Convection

[Snowmad79]

In answer to snowmad 79's question on the other thread, the models have fresh input every day, the only automated thing that we sometimes discuss in here are the 6-10 and 8-14 day NOAA maps which are done at the weekend, during the week these have input by a forecaster. Regarding the models it probably is better to view the 00Hrs and 12hrs gfs ones when trying to view possibilities as at least we can compare these with the other main global models which run just twice a day at the same time. The gfs 06hrs is okay though in that at least NOAA sometimes weight this into their forecasts, the gfs 18hrs is far too volatile and often is the one run that will go completely AWOL so this is certainly one to always be dubious of. Hope that helps.

Thanks for that Nick, I guess I'll take a more opened view of the weekend model runs from now on. As far as the 18Z is concerned I dont think I've ever bothered to look at that run since I first found my way to netweather and that was a couple of years ago.

cheers again for the info mate

[Eugene]

but the more likely scenario will be that we will see pressure low to the West and North West with a pressure rise over continental Europe. We know the rest.

LOL, Gavin P on TWO thinks your christmas pudding winter LRF is going down the pan already ian, can't say i disagree with him, extremely interesting runs today, mild they ain't

[Guest North Sea Snow Convection]

In terms of the outlook, it is worth looking at a thread on eastern about further warmings quite likely to occur through torque events and impact on the stratosphere with their likely subsequent further effect on the vortex and then how this might impinge on the AO further into December. Two of our resident experts are putting forward very interesting posts to the discussion on there!

The outlook is unclear of course, but chances of a Bartlett and orgainsed Greenland vortex do not appear in tandem with the way developments are likely to go imo

Edited November 29, 2009 by North Sea Snow Convection

[nick sussex]

Regarding Ian B post, agreed that alot more energy will be pumped into the jet once that cold plunge affects the eastern USA but i don't think its a given that this will result in mild weather in western europe, the NH pattern is not typical for this early in the winter and as long as the jet remains far enough south then a good chance it will be a more colder type zonality with heights to the ne deflecting the jet more nw/se.

I don't want to go off topic but banned from TWO! i'm surprised, i don't agree with your christmas pudding view of things but have always had constructive discussions, we often agree to disagree so i'm just shocked at these bans.

[Guest North Sea Snow Convection]

Tamara, I see a positive PNA setting up and with the Atlantic already very disturbed in order to NOT get a mild, progressive pattern we will either need to see the energy held out West by pressure to the East/NE or the energy deflected by blocking to the North. As we know, the latter is particularly difficult to establish in the christmas pudding.

The atlantic is disturbed through a disrupted vortex and the AO going negative in view of the warmer stratosphere than usual - not driven by a strong northern arm, +AO and dominant Azores ridge.. The GWO has locked us into the unsettled phase - but it is not coming courtesy of strength in the northern jet but via troughs disrupting NW-SE across the atlantic into the UK. We might not yet see dominant northern blocking and properly undercut lows, but on the other hand with with the vortex pattern as such not able to organise, and with further warmings quite likely to occur, it is surely going to be quite hard as things stand to get back to the scenario you favour as a blanket response in the UK winter.

Edit - nick,yes, you have basically said the same thing as me

Edited November 29, 2009 by North Sea Snow Convection

[The watcher]

In terms of the outlook, it is worth looking at a thread on eastern about further warmings quite likely to occur through torque events and impact on the stratosphere with their likely subsequent further effect on the vortex and then how this might impinge on the AO further into December. Two of our resident experts are putting forward very interesting posts to the discussion on there!

The outlook is unclear of course, but chances of a Bartlett and orgainsed Greenland vortex do not appear in tandem with the way developments are likely to go imo

Do you have a link to these discussions?

Thanks

Chris

[Cloud 10]

With the AO (arctic oscillation) and the NAO (north atlantic oscillation) both forecast to go negative,any forecast suggesting a mild first half to december must be on shaky ground,especially with (as others have said) the jet taking a more southerly track.

There has been some very interesting model output over the last few days and no doubt more to come as the models try to get to grips with this negative AO/NAO southerly jet combo.

btw,a special link for nick sussex.Merry Forums of My Merry Christmas - Smilies

[Guest North Sea Snow Convection]

Do you have a link to these discussions?

Thanks

Chris

Hi - go to easternwx.com and under the weather forecasting threads you will see one entitled 'the stratosphere vortex is weaker than normal'

Sorry, my own computer will not let me copy direct links on this website. It recovers the webpage after crashing it but loses any links attempted to be copied in the process. Still awaiting repair!

[MR EXTREMES]

Regarding Ian B post, agreed that alot more energy will be pumped into the jet once that cold plunge affects the eastern USA but i don't think its a given that this will result in mild weather in western europe, the NH pattern is not typical for this early in the winter and as long as the jet remains far enough south then a good chance it will be a more colder type zonality with heights to the ne deflecting the jet more nw/se.

I don't want to go off topic but banned from TWO! i'm surprised, i don't agree with your christmas pudding view of things but have always had constructive discussions, we often agree to disagree so i'm just shocked at these bans.

indeed the uk met fax right up until 120hours keeps it cool zonal ofcoarse anything can change by then but always coolest in the north but its a step in the right direction.

even the essembles are average right to the end with colder bit here and there certainly not mild and pressure rise in europe as mr brown suggest is very unlikely.

but nothing so far on northern blocking front but theres plenty of time for that.

this link http://www.easternus...hp?showforum=15

very intresting stuff great stuff from

Glacier Point and chionomaniac :rofl:

Edited November 29, 2009 by badboy657

[The watcher]

Hi - go to easternwx.com and under the weather forecasting threads you will see one entitled 'the stratosphere vortex is weaker than normal'

Sorry, my own computer will not let me copy direct links on this website. It recovers the webpage after crashing it but loses any links attempted to be copied in the process. Still awaiting repair!

Ah, thanks very much, shall grab myself a coffee and have myself an interesting read.

Thanks

[Mark Bayley]

Hi - go to easternwx.com and under the weather forecasting threads you will see one entitled 'the stratosphere vortex is weaker than normal'

Sorry, my own computer will not let me copy direct links on this website. It recovers the webpage after crashing it but loses any links attempted to be copied in the process. Still awaiting repair!

http://www.easternuswx.com/bb/index.php?showtopic=213170

Is this it ?

[MR EXTREMES]

met office outlook looks good not mild average with snow wales north so things are going in the right direction.

:cold:

[Frosty.]

Another FI completely different from the last, it has to be the gfs i'm talking about Actually, some nice charts there with cold zoneality and snow for the north similar to Jan 1984, I like the purples and dark blues, it makes a change from oranges, maybe a new trend

Next week starting on the cold side but less cold with rain midweek, clearing to blustery showers, then drier in the east for a time but generally unsettled from next sunday onwards with gales and rain at times on a s'ly tracking jet with an ongoing chance of snow on northern hills.

[Thundery wintry showers]

I have a feeling that the Atlantic will, indeed, "get its skates on" in about 7-10 days' time. What I'm not so convinced about is the build of pressure over Europe. It looks like the jet is "predisposed" to track further south than I had expected. No widespread snow events for the foreseeable future (the most-likely-localised one tomorrow/Tuesday being the one of largest potential) but nothing exceptionally mild either.

[Iceberg]

Very much agree Ian, average looks likely with, maybe 1C above in the south.

I really can't see any widespread cold this side of the 15th of December. A quick word re the AO predictions, You can see that GFS has persistantly been progging a sharply negative AO, however in reality, it just hasn't been happening. I'd probably go for a neutral +1 to -1 NAO and AO over the next 2 weeks.

[Turnedoutniceagain]

In the very short range, tomorrow's looking rather chilly. I'm struggling to see more than 7-8c daytime max' for the rest of the week also.

Excellent.

[SP1986]

I think the Tuesday frost chance will be confined to the west with the east escaping an air frost. Not sure what the temperature will be here but it will certainly be below 0C

[Backtrack]

I think the Tuesday frost chance will be confined to the west with the east escaping an air frost. Not sure what the temperature will be here but it will certainly be below 0C

You will easily see a minus 2 Stephen, I am expecting a minus 3!

[Stu_London]

another solution to the medium term thrown up by the 12z

A coolish run but not really any potential for any widespread severe winter weather.

Would suggest any newcomers or guests pay attention to the excellent posts by Iceberg, Thundery Wintry Showers, John Holmes, Phil N Warks etc. (sorry if I missed anyone) rather than get carried away with some of the usual model discussion silliness which comes along at this time of the year.

[SP1986]

You will easily see a minus 2 Stephen, I am expecting a minus 3!

I severely doubt it, there's meant to be cloud moving in during the night. I reckon -1C for absolute minimum around here, maybe -2C towards Chester. Could be wrong I reckon -1.3 or -1.4C will be the lowest we'll record.

[The PIT]

Interesting GFS. Country Files lunchtime had the low pressure at the end of the week taking up residence in the North Sea while the 12 oz moves it into the Irish sea. Interesting Jet stream in deep FI as well. So temps near normal for the rest of the week with rain and the far north perhaps snow at times.

UKMO also now has the end of the week low stuck in NW so clearly a change of minds by the models after the country file forecast.

Edited November 29, 2009 by The PIT