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This is the focused model discussion - please only post about the model output. 

For a more laid back, bantery model discussion please use the Cold hunt - models and banter thread.

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The warmer air creeping east today with the font And to digress for a moment. I was in a taxi just now and the driver started wittering on about how he loved cold weather. I thought, '

Interesting morning and really encouraging IMO in terms of the set of model suites we were looking at on Thursday and Friday being chipped away at then collapsing into something else late Friday into

What we need to see is exactly what you are seeing here, though by pacific trough I'll translate that as Aleutian low. We need the pattern to retrogress to pull the power out of the Canadian lobe, and

Posted Images

Notable model trends from the 12z runs:

  • Slightly increased support for the Tue-Wed LP to affect S England to a significant extent snow-wise; at least 50-50 on this now.
  • Increased proportion of deterministic runs predicting a track of the Thu-Fri LP down across the Channel by Fri afternoon, increasing S UK snow potential, but with this dependent on the low remaining sufficiently weak and elongated west-east, which doesn't yet have much support (UKMO very notable though - a similar ECM 12z would raise eyebrows even for the far-south).
  • Signs of sudden widespread Arctic height rises from UKMO and ICON; resembles the negative zonal wind anomalies finally managing to punch through into the troposphere on a more than localised basis. At just 6 day's range this needs keeping a close eye on.
  • Hints that even without those Arctic height rises, further disrupting & sliding LP events may occur by next Sunday.
  • Pattern responses to the MJO propagating east across the Pacific at moderate amplitude remain only loosely represented in the modelling (lows sliding right down across Europe resemble MJO P6 response but models struggling to do this Thu onward), despite the latest obs showing this to already be underway and at a good clip too. 


The MJO factor does lead me to consider a more southward track for the Thu-Fri system than the latest det. runs have explored - one more like the GFS 18z of yesterday. It's tricky, though, to determine whether we have a case of the models underestimating the signal propagation, or a conflicting forcing limiting the ability of the MJO to drive the N. Atlantic - European pattern.

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3 hours ago, in the vale said:

I know it's the CFS, but this is a strong -NAO / Greenland blocking signal for week 3. 

wk3.wk4_20190125.z500.gif

Indeed. UKMO run this afternoon opens up a path towards that solution. Many a path has been a dead end so far this season....can it click this time? Time for the downwell. MJO progression and concurrent phase of torque cycles to produce th goods.

UKMO 144 image gives me hope. And lurking in the wings a huge Atlantic bomb off eastern US that could create all kinds of mischief if we can at least get the alignment and strength of block to split the flow. 

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30 minutes ago, Catacol said:

 Time for the downwell. 

I'm glad it's just not me thinking this. Many folk have concluded that the surface effect of the December SSW event is behind us or that the cards fell wrong this time. I do not believe it has really started. The type and length of the event have few analogues so most models have really struggled with the 'work in progress' state of the atmosphere. Signs seem to be emerging that the cold EC46 view a couple of weeks ago may have been correct, albeit delayed like all other models. There'll be valuable learning available from this. Genuinely fascinating times, unique in my utterly unreliable recollection of weather stuff.  

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A quick look at the ecm this evening

It runs the deepening wave into norther France on Tuesday so some wet weather in the south for a time but with dew points a tad above freezing mainly rain on low ground apart maybe the back edge in the south east, Then a transient ridge before the intense upper trough that exited NE America midnight Tuesday arrives west of  Ireland on Thursday  This could bring a belt of rain, sleet and snow as the associated front tracks north east across the country through the second half of Thursday. The main trough moves slowly east as the subtropical high ridges sharply in the west so un unsettled and cold couple of days to follow, The ridge is then pushed east over the UK by further pressure from the west and by the end is looking not unlike the EPS anomaly

t126.thumb.png.b7c13e543581d9757a4d3e7f49fe88af.pngt168.thumb.png.280289fede84a87a478e396d37391573.png

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This is known as an emphatic statement

index.thumb.png.a9c79f00e4aea585227af98c6c9f6f36.png

And changes are afoot as the esx EPS loses the European trough as it builds high pressure over Scandinavia and the UK

 

 

Edited by knocker
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1 hour ago, in the vale said:

I'm glad it's just not me thinking this. Many folk have concluded that the surface effect of the December SSW event is behind us or that the cards fell wrong this time. I do not believe it has really started. The type and length of the event have few analogues so most models have really struggled with the 'work in progress' state of the atmosphere. Signs seem to be emerging that the cold EC46 view a couple of weeks ago may have been correct, albeit delayed like all other models. There'll be valuable learning available from this. Genuinely fascinating times, unique in my utterly unreliable recollection of weather stuff.  

I don’t believe the actual first reversal wave is expected into the trop at 500 hpa until after around 7 feb... ....should be coming into range of the fi modelling now 

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5 minutes ago, knocker said:

I rather exaggerated my earlier comment but the change in the ext mean EPS is quite obvious

index.thumb.png.286f104b8ab71b6a2b17dbf5c50e034a.png

And NOAA perhaps picking this up as well

814day_03.thumb.gif.9786ad724cda994463c564b2230096fa.gif

 

Northern blocking growing slowly but surely ....presumably we will get a feel for where it will concentrate over the next few days and the reds will get stronger in a more specific area ...I note the lower anoms growing in the Azores area over the back end of the last few runs too. Of course that noaa chart is naefs at the weekend so no eps in there 

Edited by bluearmy
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5 minutes ago, bluearmy said:

Northern blocking growing slowly but surely ....presumably we will get a feel for where it will concentrate over the next few days and the reds will get stronger in a more specific area ...I note the lower anoms growing in the Azores area over the back end of the last few runs too 

Yes it will be interesting to see how this does pan out. Currently the cold air is forecast over western Russia so presumably the orientation of any  high cell will have to encourage a east > west cold feed

Edited by knocker
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To me it actually looks like support is growing for a block to establish at some point during the 10-20 day period with the Western most extent between Greenland and Iceland and the Eastern most extent somewhere over Scandinavia, but without a very strong signal for severely cold 850mb temps affecting the UK weather, of course surface temps close to freezing.

Edited by feb1991blizzard
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2 minutes ago, knocker said:

Yes it will be interesting to see how this does pan out. Currently the cold air is forecast over western Russia so presumably the orientation of any  high cell will have to encourage a east > west cold feed

The back end  of the eps grows markedly that cold pool probability over e Europe 

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3 minutes ago, feb1991blizzard said:

To me it actually looks like support is growing for a block to establish at some point during the 10-20 day period with the Western most extent between Greenland and Iceland and the Eastern most extent somewhere over Scandinavia, but without a very strong signal for severely cold 850mb temps affecting the UK weather, of course surface temps close to freezing.

I think 15/25th feb will turn out to be the coldest period of the winter 

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1 minute ago, bluearmy said:

I think 15/25th feb will turn out to be the coldest period of the winter 

Yes, starting to come around to that way of thinking after my lunchtime post (albeit slowly), but just wonder whether it might be severely cold but actually significantly drier than average.

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4 minutes ago, knocker said:

That would make yesterdays EC46 wrong

with 51 members, it won’t get that kind of info right at 3/4 weeks!   I’m basing this opinion on the glosea reversals and the clear confidence of the 30 dayer, added to the trends on the extended ens output 

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