phil nw.
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Posts posted by phil nw.
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The time lag of the downwelling of the Strat.warmings will try our patience in the coming days.
Latest ecm strat. forecast shows zonal winds going into. reverse around months end,day 8,only at 30hPa,which is mid level .
Lower down zw slowing to low single figures so we can see that it seems like forever as the weakening filters down.
The full effects on the 500 pattern, probably as long range ens guidance suggest, likely to imprint towards mid March .
There is another warming imminent which will continue to undermine any vortex recovery.
We could do with the whole process being quicker because of the lateness of the season but details of how cold we could get is obviously too soon to tell.
The shape of the trop.pattern that looks likely,based on the longer ens.,looks a cold one and because of the ongoing pv weakness looks likely to hold for a decent period.
Whether it will deliver a white outcome remains to be seen.
Interesting to follow though whatever the actual weather on the ground is next month.
Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4808690-
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The time lag of the downwelling of the Strat.warmings will try our patience in the coming days.
Latest ecm strat. forecast shows zonal winds going into. reverse around months end,day 8,only at 30hPa,which is mid level .
Lower down zw slowing to low single figures so we can see that it seems like forever as the weakening filters down.
The full effects on the 500 pattern, probably as long range ens guidance suggest, likely to imprint towards mid March .
There is another warming imminent which will continue to undermine any vortex recovery.
We could do with the whole process being quicker because of the lateness of the season but details of how cold we could get is obviously too soon to tell.
The shape of the trop.pattern that looks likely,based on the longer ens.,looks a cold one and because of the ongoing pv weakness looks likely to hold for a decent period.
Whether it will deliver a white outcome remains to be seen.
Interesting to follow though whatever the actual weather on the ground is next month.
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I have been quietly monitoring things from the sidelines the last few days waiting for signs of the warming effects.
I think it's reasonable to say that there are now clear signs in week 2 of a response to the filtering down of the Strat.reversal.now at 10hPa.
A look at yesterday's ecm strat zw forecasts show zonal winds are forecasted to get close to zero at 30hPa by day 10 and down to 3/4 m/s lower down.
The strat pattern looks to be imprinting on the 500 pattern with the vortex draining towards Scandinavia/Russia and clear support on Atlantic ridging.
This trend along with increasing momentum from the MJO phase 7 should see a continuing build of heights into the Arctic and a trough to our east.
For once notice can be taken of the week 2 charts I reckon.
Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4807656 -
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I have been quietly monitoring things from the sidelines the last few days waiting for signs of the warming effects.
I think it's reasonable to say that there are now clear signs in week 2 of a response to the filtering down of the Strat.reversal.now at 10hPa.
A look at yesterday's ecm strat zw forecasts show zonal winds are forecasted to get close to zero at 30hPa by day 10 and down to 3/4 m/s lower down.
The strat pattern looks to be imprinting on the 500 pattern with the vortex draining towards Scandinavia/Russia and clear support on Atlantic ridging.
This trend along with increasing momentum from the MJO phase 7 should see a continuing build of heights into the Arctic and a trough to our east.
For once notice can be taken of the week 2 charts I reckon.
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A way to monitor the downwelling of the warmings is to follow the ecm srat. forecasts.
Reversal is underway at the very top and will show at 10hPa in the next day or so.
Lower down at 30hPa the reversal doesn't quite show within the next 10 days,based on the chart from yesterday.
On the plus side zonal winds even at this mid level are forecasted to slow right down,3 to 4 m/s. and this reduction extends right down to the lowest level with forecasts zonal wind speeds down to 7 m/s.
The troposphere pattern should start to reflect this in the later outputs from now with a more ridgy and slowing jet.
Probably why we are just starting to see some interesting charts in the later frames.
Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4805729 -
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A way to monitor the downwelling of the warmings is to follow the ecm srat. forecasts.
Reversal is underway at the very top and will show at 10hPa in the next day or so.
Lower down at 30hPa the reversal doesn't quite show within the next 10 days,based on the chart from yesterday.
On the plus side zonal winds even at this mid level are forecasted to slow right down,3 to 4 m/s. and this reduction extends right down to the lowest level with forecasts zonal wind speeds down to 7 m/s.
The troposphere pattern should start to reflect this in the later outputs from now with a more ridgy and slowing jet.
Probably why we are just starting to see some interesting charts in the later frames.
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We are forecasted successive warmings which will prevent the spv relocating to the pole.
At least this will extend reversal of the zonal winds higher up and continue to weaken them down to mid level.
I am thinking the eastward moving MJO lag effects could be the final blow to a vortex already weakened and displaced.
Probably still outside nwp range yet if we expect a dramatic turn around to a negative nao/ao.come early March.
Of course we still need the good fortune to end up on a cold side of any blocking.
It's an interesting watch for now though not knowing how this will pan out.
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Good luck to you and yours Matt always enjoy your posts.I hope you can come back on here in time if you can.
Meanwhile looking at day 7 higher up at 10hPa in the stratosphere we can see 06z gfs and the last ecm chart from Berlin University pretty much agreeing on the current warming being across the pole by day 5 and the displacement of the spv.
We can see the reversal(easterly winds)across the pole as the core of the spv is pushed south.Now it's a case of waiting and watching to see if this reversal filters down and how it may affect the 500 pattern,which is the great unknown.
Only limited data available from Berlin but as Mike shows above signs that downwelling of the negative zonal winds are showing towards month end from the GFS suite.These from stratobserve.
These are forecasts at 100hPa the lowest Strat.level at day 10 and day 15
Indications of the pv heading towards Siberia and Atlantic ridging.It would be naughty of me to speculate that we could see an early March northerly....
Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4804718 -
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Good luck to you and yours Matt always enjoy your posts.I hope you can come back on here in time if you can.
Meanwhile looking at day 7 higher up at 10hPa in the stratosphere we can see 06z gfs and the last ecm chart from Berlin University pretty much agreeing on the current warming being across the pole by day 5 and the displacement of the spv.
We can see the reversal(easterly winds)across the pole as the core of the spv is pushed south.Now it's a case of waiting and watching to see if this reversal filters down and how it may affect the 500 pattern,which is the great unknown.
Only limited data available from Berlin but as Mike shows above signs that downwelling of the negative zonal winds are showing towards month end from the GFS suite.These from stratobserve.
These are forecasts at 100hPa the lowest Strat.level at day 10 and day 15
Indications of the pv heading towards Siberia and Atlantic ridging.It would be naughty of me to speculate that we could see an early March northerly....
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50 minutes ago, Neil Harris said:
Still treads like there's frost in my lawn.
I'm not a gardener, however I had new turf laid last Spring, should I be cutting it in February?
If it looks long enough.
No hard and fast rule really .I raised the cut height on my mower and waited until the afternoon when the frost and dew had lifted.
It did need a light trim as I had left it longer this Winter as this helps to keep the moss down.
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The overnight ecm clusters show an interesting trend as we go from day 10 to day 15
Day10 Day15
Going from the current +ve NAO pattern we currently have with the high nearby to the south towards a change to heights ridging north and troughing appearing to our east/northeast.
Some differences within the later clusterings but we can imagine a trend towards something more of a -ve NAO pattern evolving in the following days.
With the warmings above and the movement eastwards of the MJO the timing of this pattern change towards month end is looking more feasible.
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So far this month has seen a glorious spell of weather around here.
Sunny days and frosty nights with almost calm conditions.
Great for walks and it has enabled me to give the lawn it's first light cut.
Got a feeling we may see more cloud towards the weekend but it's been great so far.
If we can't get snow then this is a decent second prize.
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1 hour ago, mushymanrob said:
ay up .... whats happening here?
Interesting mushy.Models just starting to factor in the ssw and MJO effects,as we thought towards month end.
The Tropospheric pv over Scandinavia is a good trend.
A way to go wrt to surface detail but promising signs if looking for a late cold spell.
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Just now, alexisj9 said:
On a promise for what, yes it looks like a SSW will happen, but what it will do down here weather wise is not set in stone. We'll see once it's happened whether it works for us or not this time.
Indeed.What a strong ssw will do though is weaken the polar jet and make it more undulating.
High pressure getting into Arctic latitudes forcing deeper troughing sending cold air south.
We just need the good fortune to be on the cold side of the trough.
The quicker the troposphere response the better now as we head towards Spring.
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59 minutes ago, Vikos said:
What if gfs sniffed something like a true (but tiny little) SSW-mw the days before and had it as a starting parameter leading to scandi-blocking? Now, after the first peak it disappeared from the starting parameters and this leads us to no scandi high?
I honestly can't say Vikos.If some starting data imputed was different to other models that may explain the colder outputs.
The modeling of the jet digging further south as the Canadian trough heads into the Atlantic causing a more downstream ridging over Europe perhaps.
Certainly it's not unusual for cold outlier operational runs to appear in week 2 but those GFS runs were notable for showing at much earlier time frames.
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Will we ever know where the recent cold GFS runs came from ?
Yes there are signs of a weakening spv along with it's displacement now underway but the trop.vortex to our north remains stubbornly positioned.With the MJO showing in the warmer phases over the Pacific area an easterly was against the background signals really as well as most other model suites so those GFS runs came out of left field.
We now seem to have normal service with pretty reasonable agreement with a uk high which may well give frosty nights but compared to what GFS offered recently it is a bump back down to earth for cold and snow fans.
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1 minute ago, nick sussex said:
No ridge will survive that rounded PV blob .
The ECM is better than this morning and does at least try and take the jet more se by day ten but we need to see this better outputs at that point count down .
Yes that's one hell of blob Nick.
Frustrating to see the ridging attempts being continually thwarted.
I hope that the displacement higher up will maybe drag that pv away eventually as the spv gets pushed around and zonal winds decrease.
It's always difficult to work out the effects of a displaced strat.vortex on the 500hPa pattern so it's a straw to clutch rather than expectation.
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Yes the only positive from the gfs/ukmo 12z runs is the predominantly dry outlook with the high staying around.
It 's remains just too far south to give any chance of some cold off the continent.If anything the trend to move it's centre east towards France means the jet backs more south westerly thus reducing the chances of even the brief colder shots from pm air that will give us a glancing visit early next week.
Our Balkan friends look to do well out of this pattern though if cold is their thing.
I wish i could find something to cheer us coldies up but with this pattern there is very little to shout about- very average temps maybe even milder at times and with the cloud mixing in from the Atlantic even frosts will be very patchy.
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Later in week 2 on GFS 06z shows the displaced spv away from the pole hence the forecasted rise in the 10hPa temperatures then.
The spv still shows it's intact over the Atlantic side but somewhat weaker.
Modeling at 500hPa won't really show any effects yet as it is only now showing this polar displacement at the extended range.
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My thinking is that the displaced spv heading towards Canada in the modeling was mirrored in the troposphere pretty closely over last weekend.
No surprise to see this 500hPa pattern going into next month.
I was hoping for some amplification in the Atlantic jet but I think for now that it is too strong.
Beyond the next 2 weeks would I hope see better ridging as mean zonal winds continue to decline.We would then see more chances of some colder shots from the north or maybe east if ridging takes off towards Scandinavia.
The later in February the better chance of a late cold spell when the jet weakens and the MJO may assist in entering a more favourable phase.
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7 minutes ago, on the coast said:
Look at the brutal cold going into America. Very severe stuff again for them.
Yes the Canadian pv is quite a deep feature showing severe cold and as it rotates around.As you say the main thrust is into NA but some of that spins off towards us but we get the scraps in the UK
The coldest flow is just a little too far east with the high too close by in the Atlantic.Frustrating really as we are not a million miles away from returning to more cold- instead just temporary glancing blows for us.
At least the prospect of an immediate switch to a broad and mild south westerly prospect is delayed for now.This coming week it looks like more north westerly at times.Week 2 though,less said at the moment the better i think mmm.
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25 minutes ago, Don said:
Much inline with the Met Office extended forecast then?
I haven't looked tbh Don,just my own thoughts.No surprise though given the trend over the last few days with this high sticking around for a while.
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Looking through the layers from the latest gfs run the warming is well underway and by day 5 we can see the displacement starting to show.
Looking at the 500 pattern for the same time
It can be deduced that this looks like a good connection to whats playing out higher up with the main spv/tpv favouring our side of the Arctic.This doesn't bode well for higher latitude blocking if the displacement plays out like this.
Later frames show this trend continuing with the spv being squeezed but not fractured on our side of the pole.
Day 10 below
We know the zonal winds are forecasted to slow but a chunk of vortex left to our north west is a hurdle unless we find a spell of tropical forcing to amplify the pattern later on.The mjo is not currently in a favourable phase but may well get there later in February.
Given the time lag this is making any change to a cold pattern very late in the day but for now that seems the only straw to clutch given the way this displacement is forecasted to go.
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The high pressure looks like it's not going far and if we can rely on current extended ensembles it will be around into week 2.
Just some variation in exact positioning which will see slightly colder air brushing around the top and down to the east when it locates further west at times.
Around here in the midlands it's been a decent frosty few days/nights with some sparkling Winter sunshine but already high cloud has moved in today. I fear this will become the trend across most areas as the week goes on as more of the Atlantic air gets into the high.Likely a couple of frosty nights to come in some southern locations before the faux cold gets mixed out.
Not a lot of excitement it must be said in this slow moving pattern with any real weather across the north from time to time and then heading south east into parts of Europe.
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Model Output Discussion - Into February
in Forecast Model Discussion
Posted · Edited by phil nw.
Yes following the trend on those is as good as any other tool at the moment.We are seeing some cold gfs operationals at times but i think until the second ssw has filtered down there remains this uncertainty on whether those narnia charts will be close to the outcome.
It looks pretty certain now that we will see that initial Greenland ridging and a Scandi.trough as the vortex does it's clockwise trip towards the Siberian side of the Arctic.The differences then show up amongst week 2 differing operational runs as to how far south west towards the UK that cold trough gets.
I tend to believe the current outputs are more influenced by the MJO in phase 7/8 with the lag effects built into those later charts.I must admit i am not too impressed with the latest eps/gefs ens means out at the end of week 2 where there are signs that we will only get the edge of the cold pattern before the mjo loses it's influence and we lose the cold.
It looks to get colder for a while but given the time of year we really need a direct hit from the ne where we can draw on the coldest air.I am concerned that at least for a while the expected cold pattern will not last or be strong enough to deliver what us coldies want and so then we look for one last chance from the upcoming ssw warming.
Looking at the Strat again and up to day 10 zonal winds do not reverse below mid-Stratosphere although dropping off to low single figures lower down.If we are to see any real effects from the next warming then we are looking to mid-March and beyond and that's if it filters down to the surface.
Of course we are still learning the effects of these ssws and things may work out for one last shot of cold but that imo is another wait beyond current ens guidance.