Model Output Discussions 18z 31/01/2016

[johnholmes]

1 hour ago, snowangel32 said:

I would be very sceptical of any snow charts the gfs shows. Today is a perfect example even high ground not seeing much snow. Just an absolute rainfest

certainly nothing showing on the Peak District web cams, two at over 1500ft

 

[karyo]

7 minutes ago, feb1991blizzard said:

The GFS 12z is going to show something quite spectacular by 384!!!

Stratospherically, it is very spectacular!

[feb1991blizzard]

Over to Recretos or someone on the strat thread to tell us if its actually a technical SSW or not (I don't think it is) - I thought it would easily be with about 70 hours of the run left, either way, given how far its propagated down the atmosphere at 384 and the complete destruction at the top, I cant help feeling it would be the beginning of the end of the strat vortex and signal an extended period of trop blocking starting over Greenland.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2016021712&var=HGT&lev=10mb&hour=384

 

 

Edited February 17, 2016 by feb1991blizzard

[bryan629]

1 minute ago, feb1991blizzard said:

Over to Recretos or someone on the strat thread to tell us if its actually a technical SSW or not - I thought it would easily be with about 70 hours of the run left, either way, given how far its propagated down the atmosphere at 384 and the complete destruction at the top, I cant help feeling it would be the beginning of the end of the strat vortex and signal an extended period of trop blocking starting over Greenland.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2016021712&var=HGT&lev=10mb&hour=384

 

 

Brilliant annihalation of the strat vortex at 300 

Then by 384.. its a case of `` see ya next november`` 

 

[chris55]

Will the winter tease ever actually deliver lol!

As Nick said above, big differences in the way UKMO and GFS deal with the Low to the West into Monday next week.

UKMO more likely to continue with a much colder outlook.

[feb1991blizzard]

5 minutes ago, bryan629 said:

Brilliant annihalation of the strat vortex at 300 

Then by 384.. its a case of `` see ya next november`` 

 

Yes, although it still left the lobe nearest us (thus stopping a technical SSW), its so weak and in a favourable position, the strong bigger lobe is way way out of harms way and the whole vortex displaced and elongated right down to 70mb.

[phil nw.]

An interesting contrast over the weekend between the north and south of the UK

Wintry conditions and lower temperatures never really leave the far north as a brief milder spell pushes up from the south.

The GFS run generally continues to show a below normal temperature regime of a west/north westerly pattern.Some quite cold polar maritime air getting south at times.

 

[nick sussex]

We have a good test for one of the higher resolution models. The AROME Hi Res now has snow developing ahead of the front over East Anglia. Looking at the dew points the far se and parts of EA currently have negative dew points.

 

 

[Eskimo]

6 minutes ago, nick sussex said:

We have a good test for one of the higher resolution models. The AROME Hi Res now has snow developing ahead of the front over East Anglia. Looking at the dew points the far se and parts of EA currently have negative dew points.

 

 

And also across much of the Humber area, which is quite surprising. Possibly stalling a lot earlier now? 
 

[nick sussex]

17 minutes ago, PerfectStorm said:

And also across much of the Humber area, which is quite surprising. Possibly stalling a lot earlier now? 
 

I'd be interested to see if the AROME is any good here because its the first model that I've seen develop anything wintry ahead of the front. The slower the front moves through the better for locations currently behind the front as that would give more time for the undercut. At the moment any zero dew points still seem to be over Ireland or the far east/se.

Its a shame the surface flow ahead isn't from the se because dew points in ne France are generally between -2 and -4c.

On a separate note I can't find any proper support for the UKMO T144hrs solution in the GEFS. If the ECM was to back that solution then it would really lower confidence in what the GEFS is showing in terms of evolution going forward. The end point might still be similar in terms of low pressure diving se but the middle part might look different.

Edited February 17, 2016 by nick sussex

[TheBigFreeze]

17 minutes ago, nick sussex said:

I'd be interested to see if the AROME is any good here because its the first model that I've seen develop anything wintry ahead of the front. The slower the front moves through the better for locations currently behind the front as that would give more time for the undercut. At the moment any zero dew points still seem to be over Ireland or the far east/se.

Its a shame the surface flow ahead isn't from the se because dew points in ne France are generally between -2 and -4c.

On a separate note I can't find any proper support for the UKMO T144hrs solution in the GEFS. If the ECM was to back that solution then it would really lower confidence in what the GEFS is showing in terms of evolution going forward. The end point might still be similar in terms of low pressure diving se but the middle part might look different.

Nick, I am bang in the middle of East Anglia, I shall now be radar watching and curtain twitching, and will post as it happens lol. Looking at the models the most I  was hoping to wake up to was some slush on the windscreen. I still think we will have a back loaded winter of the likes of 2013.

[nick sussex]

6 minutes ago, TheBigFreeze said:

Nick, I am bang in the middle of East Anglia, I shall now be radar watching and curtain twitching, and will post as it happens lol. Looking at the models the most I  was hoping to wake up to was some slush on the windscreen. I still think we will have a back loaded winter of the likes of 2013.

Lol! Oh no don't stay up to the early hours on account of the AROME!

[phil nw.]

The gefs ens mean ht.anomalies show the gradual weakening of the polar vortex.

A look at the days 5.10 and 15 

 

we can see the gradual build of cross polar height rises and the tendency of pressure falling across nw Europe.

A pattern change for early March looking more possible and viewing the latest MJO forecasts show most of the forecasting models heading nicely into Phase 8

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

at quite a decent amplitude for which we have a composite something along the lines of the gefs hts above

so if these forecasts hold we would continue to see our cold westerly/north westerly pattern possibly evolve into some heights further north.

ECM has a similar MJO forecast and although it only goes out to 10 days for us on here you would expect to see some signs of these +ve ht anomalies further north start to show soon.

 

[Nouska]

53 minutes ago, nick sussex said:

We have a good test for one of the higher resolution models. The AROME Hi Res now has snow developing ahead of the front over East Anglia. Looking at the dew points the far se and parts of EA currently have negative dew points.

 

Looks to have captured current situation in as far as it picked up wintry precipitation rather than pure snow.

  

[Swave Snow]

1 hour ago, nick sussex said:

We have a good test for one of the higher resolution models. The AROME Hi Res now has snow developing ahead of the front over East Anglia. Looking at the dew points the far se and parts of EA currently have negative dew points.

 

 

Looks like its just starting to do so on the Netweather Radar i've circled it in red

[nick sussex]

The ECM is a combination of the GFS/UKMO at T120hrs.

The UKMO has a separate lobe of high pressure to the northwest and this really is the key difference going forward.

The ECM and UKMO agree on the troughing to the ne and the location of the PV lobe in ne Canada but the Atlantic is the area they are diverging.

The evolution on the UKMO would be different past T144hrs because the troughing upstream is more amplified.

 

Edited February 17, 2016 by nick sussex

[The Enforcer]

5 hours ago, Nouska said:

The AROME higher-res version of that.

Are you able to provide a link to the AROME please?

[sawan]

6 hours ago, bobbydog said:

currently a strong signal for snow virtually everywhere on sunday. (much stronger than todays feeble effort anyway) just 4 days away-

and what are the caveats please???? I think we shouldn't be biased around what we desire. These charts are bound to change significantly by the time we reach t48.

[nick sussex]

2 minutes ago, The Enforcer said:

Are you able to provide a link to the AROME please?

Here you go:

http://www.meteociel.fr/modeles/arome.php?ech=3&mode=142&map=0

[nick sussex]

Oh dear brace yourselves! Even with that dodgy middle part the ECM is set to deliver another of its T240hr specials.

[feb1991blizzard]

Just now, nick sussex said:

Oh dear brace yourselves! Even with that dodgy middle part the ECM is set to deliver another of its T240hr specials.

Yes, snow down the western flank of the low possible at 216 which is not the usual spot you would look at with the slider, decent cold pool building to the NE is the most important thing though.

[nick sussex]

Frustratingly the ECM whilst good synoptically doesn't have enough cold air to the east. We really need to see some sub -10 850s that can be advected west. Theres still time for changes because that set up with sufficient cold is a convective snow machine.

[phil nw.]

Just looking at the NH overall pattern we can see all 3 models have the same theme with Atlantic ridging and trough extensions se towards Europe,especially further on.Probably helped by the ongoing Russian ridging forcing the jet se as it reaches the E.Atlantic.

This would maintain the colder west/north westerly flow as the Azores high is prevented from heading east and instead is sometimes forced further out into the Atlantic.

 The effect of the height anomalies developing over the pole also helping to push the polar air further south. Jet stream heading towards the Med.at the end of the ECM. 

Details of course will change but we can see the possibilities of a further pattern change towards month end.

Edited February 17, 2016 by phil nw.

[feb1991blizzard]

5 minutes ago, nick sussex said:

Frustratingly the ECM whilst good synoptically doesn't have enough cold air to the east. We really need to see some sub -10 850s that can be advected west. Theres still time for changes because that set up with sufficient cold is a convective snow machine.

Yes although the cold pool has improved, not so long ago we were progged to have +ve uppers to the East, you really need to see the -15c isotherm to the East maximum because allowing for modification over the North sea then that would mean just under -10 for us, as we saw with feb and March 2013, at this time of year even that isn't a guarantee of a widespread dumping.

Edited February 17, 2016 by feb1991blizzard

[mcweather]

3 minutes ago, nick sussex said:

Frustratingly the ECM whilst good synoptically doesn't have enough cold air to the east. We really need to see some sub -10 850s that can be advected west. Theres still time for changes because that set up with sufficient cold is a convective snow machine.

Yes Nick I would be calling this another ECM240 up the garden path job were it not for the fact that it is almost identical to the latest GFS 12Z AT 252.