Model Output Discussion 18th Nov.2013-12z onwards.

[bluearmy]

 

BA is implying that the ECM ENS have a higher vertical resolution than the operational- 50KM V 16km- I doubt that. Im sure the ECM op has been upgraded to 90KM Vertical- but I may be wrong.- whatever though it should be more than than the ENS nice spot for this weekends northerly- V the MEAN also highlights there poor resolution on the shortwave pattern.

 nope steve - the ens have 91 and the op 137. the ens are at 50km and the op 16km. no arguement that the op doesnt whoop the ens on resolution. my point was that the ens at 50km and 91 layers should do a pretty good job of resolving complex scenarios in general. maybe this one will be the one where the op excels ?

[Frosty.]

Not a bad start to the winter then

[Mr_Pessimistic]

come on guys, does no one ever learn??  we are talking about charts waaaay out in fi!  come the day, it will be a slack northerly with less cold uppers bringing snow to maybee scotland,, nothing unusual, thats IF we even get a northerly..

[nick sussex]

The upstream pattern looks good as long as the shortwave clears east and doesn't drag along its partner in crime.

These are the highlights from the NOAA morning update which effect us in Europe.

UPPER PATTERN IS FORECAST TO AMPLIFY IN THE NORTHEAST PACIFIC NEXT

WEEK... WITH A STRONG RIDGE CENTERED OVER THE ALASKA MAINLAND.

THIS SHOULD DRIVE A STRONG UPPER LOW SOUTH-SOUTHEASTWARD OUT OF NW

CANADA INTO WA/OR/ID BY MID-WEEK NEXT WEEK. DOWNSTREAM RESPONSE

OVER THE EASTERN CONUS WILL BE TO RAISE HEIGHTS BY WED-THU/D6-7.

LASTLY... ALSO

PREFER TO LIMIT THE EJECTION OF ENERGY EASTWARD THROUGH THE

DAKOTAS AND MAINTAIN THE SOUTHWARD PUSH THROUGH THE INTERIOR WEST

THOUGH AS THE MOST RECENT 00Z GFS SUGGESTS. IN THE EAST... SFC LOW

IS STILL EXPECTED TO FORM OFFSHORE BUT ITS TRACK/INTENSITY HAS

VARIED OVER THE PAST SEVERAL MODEL CYCLES... TRENDING SLOWLY MORE

OFFSHORE BUT WOULD STILL BRUSH NEW ENGLAND AND THE MID-ATLANTIC

COAST WITH SOME PRECIP.

I'm actually a bit more interested in what could come after any possible northerly as this could determine whether its a snap or spell of colder weather. Theres enough in both the ECM and GFS at 240hrs to suggest we could get an east/ne flow but need the initial amplification upstream to build the high further north.

The ensembles so far are reluctant to get on board with this northerly, but this could be more down to the complexity of the evolution, generally alot of northerly topplers we see start with a simple retrogression of high pressure as the pattern in the eastern USA amplifies, here the evolution isn't this straightforward, the shortwave being ejected east into the Atlantic cuts through the high clears east and then the high edges nw as the partner in crime shortwave phases with another moving through the USA.

Overall I'd have higher confidence in the normal northerly toppler evolution than this one and we should bear in mind that because its a bit more complex then it's easier to derail.

Because of the complexities of this pattern and because we need a shortwave trigger I think it's best to view this from a more easterly stand point, in that scenario the ensembles are very slow to come on board and its the operationals that generally lead the way, also the ensemble means of both the ECM and GFS aren't really very illuminating as they wash out and dilute the picture.

Edited November 28, 2013 by nick sussex

[lamppost watcher]

come on guys, does no one ever learn??  we are talking about charts waaaay out in fi!  come the day, it will be a slack northerly with less cold uppers bringing snow to maybee scotland,, nothing unusual, thats IF we even get a northerly..

I don't think anyone is saying the northerly is nailed on, people are suggesting possibilities and using charts to back up their forecasts....better than just writing it off with no evidence just pessimism.

[Summer Sun]

The met office are also going for milder westerly winds to break through after the cold spell, backs up Ian's tweets earlier on

 

This is from the 3rd to 12th of December

 

Temperatures initially around normal for the time of year in the south, but it is set to turn colder from the north. Later in this period, the cold weather will gradually give way, first in the north, but finally in the south with milder westerly winds and unsettled weather reaching the north later. The south will probably remain more settled.

Edited November 28, 2013 by Summer Sun

[terrier]

Reading the met office update I think here in the model output we need to be realistic apart from a northerly toppler that looks like bringing snow to Scotland this once again looks like a bit of a non starter before the westerly pattern becomes established once again

[Cheshire Freeze]

Reading the met office update I think here in the model output we need to be realistic apart from a northerly toppler that looks like bringing snow to Scotland this once again looks like a bit of a non starter before the westerly pattern becomes established once again

 

 

Until he pops up on twitter and states it could last longer than expected...as what happened yesterday? I think the change in emphasis (several times) highlights the uncertainty going forward. It's quite possible the S remains under a continental influence post northerly.

 

 

As Nick S has been trying to say, it's possible we could head straight into an easterly after the potential northerly shot......something which almost certainly wouldn't be picked up by the modelling at this range.

 

I find it rather sad that some people have potential cold and snow put under their noses then transfix their attentions on mild weather that may not even happen (as it's beyond the timeframe of the cold).

Edited November 28, 2013 by CreweCold

[Mair Snaw]

The met office are also going for milder westerly winds to break through after the cold spell, backs up Ian's tweets earlier on

 

This is from the 3rd to 12th of December

 

Temperatures initially around normal for the time of year in the south, but it is set to turn colder from the north. Later in this period, the cold weather will gradually give way, first in the north, but finally in the south with milder westerly winds and unsettled weather reaching the north later. The south will probably remain more settled.

 

The thing with these updates is they are always being changed and very rare are they correct at anytime..be it winter spring summer or autumn...how often in the past have they said cold and snow and we end up with mild rain and even sometimes the other way around...the truth is and always will be that the weather will do what the weather will do...not what a computer says it will/should do...yes it is fun to watch the models predict what may/maynot happen and i for one love this thread the way it is toys prams etc along with great posts from some...it makes for a really interesting few months every year and yes it is exciting and sometimes painful...

[Frosty.]

 

  It's logical that it would turn milder after a cold spell..that's what happens 99.99% of the time on our little island in the nw corner of europe, exposed to the atlantic.

[karlos1983]

Reading the met office update I think here in the model output we need to be realistic apart from a northerly toppler that looks like bringing snow to Scotland this once again looks like a bit of a non starter before the westerly pattern becomes established once again

 

The Met office updates change quite often. Just because they change there outlook, it doesn't change what the models are showing right now for that time frame, consistently over recent runs.

 

After all that is why we are all here,to review the current output.

 

 

Currently both GFS and ECM going for cold. Longevity is in question for sure, but more runs will give us a better idea of that.

 

Cheers

 

Karl

[Jason M]

Steve said 'Its highly unlikely the resolution of the ensembles is better than the operational- you may want to check that.'

I'm sure I've seen somewhere that the GFS ensembles run at a lower resolution to the opp but the resolution does not drop after 192 hours like the opp run. If true this means that you give added weight to the opp until 192 then go with the ensemble 'trends'. This makes sense from a logic viewpoint.

The opp is often the mildest run which assuming the above is correct makes sense as it tends to default quickly back to zonality once low res kicks in.

Jason

Edited November 28, 2013 by Jason M

[Frosty.]

The Met office updates change quite often. Just because they change there outlook, it doesn't change what the models are showing right now for that time frame, consistently over recent runs.

 

After all that is why we are all here,to review the current output.

 

 

Currently both GFS and ECM going for cold. Longevity is in question for sure, but more runs will give us a better idea of that.

 

Cheers

 

Karl

I agree karl, at this stage I would go for a 3 day cold spell with a risk of snow and for widespread sharp frosts followed by a frosty high with bitterly cold nights across the snow fields, then a snowy atlantic breakdown followed by another wintry reload.

Edited November 28, 2013 by Frosty.

[Ian Brown]

Until he pops up on twitter and states it could last longer than expected...as what happened yesterday? I think the change in emphasis (several times) highlights the uncertainty going forward. It's quite possible the S remains under a continental influence post northerly.

 

 

As Nick S has been trying to say, it's possible we could head straight into an easterly after the potential northerly shot......something which almost certainly wouldn't be picked up by the modelling at this range.

 

I find it rather sad that some people have potential cold and snow put under their noses then transfix their attentions on mild weather that may not even happen (as it's beyond the timeframe of the cold).

 

CC, whether there is a northerly or not the METO are detailing the likely evolution thereafter; a toppling with the Atlantic rolling in over the top. Depending on how far the High sinks, then as we know we can see very mild SWerlies from this set-up.

[Man With Beard]

Reading the met office update I think here in the model output we need to be realistic apart from a northerly toppler that looks like bringing snow to Scotland this once again looks like a bit of a non starter before the westerly pattern becomes established once again

Regarding an extended cold spell, of course what you say is an option, but regarding the potency of the northerly, I wouldn't be discounting snow chances further south just yet. If the coldest runs verify, it will be pot luck - it could be dry, but equally a disturbance may develop running through the country north to south, which, given the 850 profiles, would be all snow. Given the tightness of the isobars and the origin of the air, I'd actually back the latter scenario. IF the coldest scenarios verify!But it will all be speculation till t96/t120

[Cecil Hogmanay Melchett]

Until he pops up on twitter and states it could last longer than expected...as what happened yesterday? I think the change in emphasis (several times) highlights the uncertainty going forward. It's quite possible the S remains under a continental influence post northerly.

 

 

As Nick S has been trying to say, it's possible we could head straight into an easterly after the potential northerly shot......something which almost certainly wouldn't be picked up by the modelling at this range.

 

I find it rather sad that some people have potential cold and snow put under their noses then transfix their attentions on mild weather that may not even happen (as it's beyond the timeframe of the cold).

Obviously it could all change BUT without sustained heights to the NW any northerly will be a toppler.METO going for what will be a mid Atlantic high toppling into the UK with milder Atlantic air going over the top.

Seems a pretty good bet to me.

[The Post-modern Winter]

Reading the met office update I think here in the model output we need to be realistic apart from a northerly toppler that looks like bringing snow to Scotland this once again looks like a bit of a non starter before the westerly pattern becomes established once again

 You're either attempting to annoy people with your constant pessimism or you love cold but have a severe case of negativity bias. Either way I'm sure many people would appreciate you backing up your thoughts with charts or at least presenting a more realistic and balanced (not pessimistic - many people on here seem to confuse the two) view of what is actually being shown. Today you are taking the Met's word as gospel yet yesterday you were inclined towards Gibby's assessment and ignored Ian F saying the 'cold snap' may develop into something more sustained. At least many of the coldies on here, even the hopelessly optimistic, do acknowledge when mild is the most likely option or at least on the table. 

Edited November 28, 2013 by The Post-modern Winter

[Cheshire Freeze]

 

 

Obviously it could all change BUT without sustained heights to the NW any northerly will be a toppler.METO going for what will be a mid Atlantic high toppling into the UK with milder Atlantic air going over the top.

Seems a pretty good bet to me.

 

 

Yet just 4 days ago, according to some people, there wasn't even a sign of anything other than a westerly pattern. My point is the situation is dynamic.

[WhiteFox]

Steve said 'Its highly unlikely the resolution of the ensembles is better than the operational- you may want to check that.'I'm sure I've seen somewhere that the GFS ensembles run at a lower resolution to the opp but the resolution does not drop after 192 hours like the opp run. If true this means that you give added weight to the opp until 192 then go with the ensemble 'trends'. This makes sense from a logic viewpoint.The opp is often the mildest run which assuming the above is correct makes sense as it tends to default quickly back to zonality once low res kicks in.Jason

 

I'm never sure quite where I stand on this question. What you say makes some sense; however, I always feel that if the ensembles run at a lower resolution from the start then they are more likely to be in the wrong place by the time the operational moves into low resolution. So, even though the ensembles may run at the same resolution as the operational after 192 hours (although I don't know if that is the case - conjecture on my part), they are starting from a point which is based on a forecast using a lower resolution than the Operational. Does that make sense?

If that is the case, then my feeling would be that more weight could be applied to the operational run at the further reaches than the ensemble runs, but that in order for any confidence to exist in a foreacast there needs to be some agreement from some of the ensemble members. So, the Operational from the 0z GFS run is clearly a proper outlier as it has no support from any ensemble runs. Having said that, if there is significant scatter in the ensemble runs (usually the case - can't view the 0z any more as it has been superseded by the 6z) then the operational run is just as valid as the ensemble mean. All IMHO of course.

[Cecil Hogmanay Melchett]

Yet just 4 days ago, according to some people, there wasn't even a sign of anything other than a westerly pattern. My point is the situation is dynamic.

Yep, i posted something along those lines earlier.

At this juncture a Northerly type toppler looks a good bet to me.The depth and nature of the Northerly is subject to change but the profile to the NWest continues to look poor and i include a very cold strat osphere in that desciption.

[Gibby]

Having read some comments in posts mentioning my name this morning and in recent days it still seems a little unclear what my reports are all about. For most people on here and certainly those that read them via my website are only interested in whether it's going to rain or snow or not and it's these folks that my reports are directed towards. The sciences are drawn by many knowledgeable posters much more educated and qualified people than me and illustrated on this and other forums well. Remember my reports are posted across from my website and are compiled with my websites readers in mind and not any forum. If people on here think that I just use to blanket an approach perhaps it might be better just for me to provide a link to my website for the report each day and to not clutter up forum space. What do you think?

[Jason M]

I'm never sure quite where I stand on this question. What you say makes some sense; however, I always feel that if the ensembles run at a lower resolution from the start then they are more likely to be in the wrong place by the time the operational moves into low resolution. So, even though the ensembles may run at the same resolution as the operational after 192 hours (although I don't know if that is the case - conjecture on my part), they are starting from a point which is based on a forecast using a lower resolution than the Operational. Does that make sense?If that is the case, then my feeling would be that more weight could be applied to the operational run at the further reaches than the ensemble runs, but that in order for any confidence to exist in a foreacast there needs to be some agreement from some of the ensemble members. So, the Operational from the 0z GFS run is clearly a proper outlier as it has no support from any ensemble runs. Having said that, if there is significant scatter in the ensemble runs (usually the case - can't view the 0z any more as it has been superseded by the 6z) then the operational run is just as valid as the ensemble mean. All IMHO of course.

Yes, agree with this. I tend to only use the ensembles to any great degree if they have some similarity overall to the opp at 192 hours. For instance the 06Z suite I've just reviewed is there or thereabouts at 192 so i'll discard the opp solution thereafter and go with the trends shown in the ensembles. Looking through the latest batch I fee a 50 / 50 split between northerly followed by zonal or Northerly followed by easterly with poorly aligned Scandi Heights (ie a mildish easterly at 850 level with no deep cold).Jason

[MPG]

Having read some comments in posts mentioning my name this morning and in recent days it still seems a little unclear what my reports are all about. For most people on here and certainly those that read them via my website are only interested in whether it's going to rain or snow or not and it's these folks that my reports are directed towards. The sciences are drawn by many knowledgeable posters much more educated and qualified people than me and illustrated on this and other forums well. Remember my reports are posted across from my website and are compiled with my websites readers in mind and not any forum. If people on here think that I just use to blanket an approach perhaps it might be better just for me to provide a link to my website for the report each day and to not clutter up forum space. What do you think?

Your model round ups are great Gibby. As you say they are not aimed for forum readers, so maybe stop SS from posting them. You did link your winter forecast on a few pages of this forum though mate....so expect some questions etc related to your short and long term thoughts.

Edited November 28, 2013 by MPG

[gottolovethisweather]

Having read some comments in posts mentioning my name this morning and in recent days it still seems a little unclear what my reports are all about. For most people on here and certainly those that read them via my website are only interested in whether it's going to rain or snow or not and it's these folks that my reports are directed towards. The sciences are drawn by many knowledgeable posters much more educated and qualified people than me and illustrated on this and other forums well. Remember my reports are posted across from my website and are compiled with my websites readers in mind and not any forum. If people on here think that I just use to blanket an approach perhaps it might be better just for me to provide a link to my website for the report each day and to not clutter up forum space. What do you think?

 

Your views are respected by myself and many others, so I would choose to do what you feel best Gibby.

 

Whilst this is certainly not aimed at yourself Gibby, my post from earlier seems to fallen on deaf eyes.

 

http://forum.netweather.tv/topic/78508-model-output-discussion-18th-nov2013-12z-onwards/?p=2847469

 

Perhaps, we should all pause before posting and check whether the post abides by forum rules and brings anything additional to the MODEL OUTPUT DISCUSSION. Alternatively, maybe we can simply shut up shop in between model runs.

Edited November 28, 2013 by gottolovethisweather

[SMU]

To say that we should not be worrying about the GIN (corridor of death) area is unbelievable Steve, pre-2009 or not, cyclogenesis in this area is the well established quick fire route to end a Northerly. The most important thing to remember here is that shortwaves developing at the Eastern end of the jet streak will not be picked up until this is around T120 on the NWP.

The GFS has a better formation of pressure rise in the first place than the ECM, and there will be changes to come from both models as this comes into the higher resolution but remember when LP has broken the link between HP in the Atlantic and Greenland OR when lower heights have crossed the Greenland plateau, it’s game over for our Northerlies.

 

Did neither of you read point 2?

 

High ridging NE to the west from the central states & a high ridging North to the south in the atlantic- wheres your divergence going to come from?

 

S

Edited November 28, 2013 by Steve Murr