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Model output discussion 25th Jan - The final third of winter beckons..


Paul

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Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    The GFS 06hrs run has a semi-tease with that high pressure over Scandi but with the PV lobe located over east Canada will have no chance.

    The lack of amplitude upstream just puts too much pressure on that high with the energy piling mostly ne. The ECM does have some shortwaves running east along the base of the trough which might give something wintry on the northern flank but too far out to put too much faith in.

    Any interest doesn't really arrive till after day 7 and its marginal, any shortwaves that do form you'd want to be weak and not deepen, that would increase any wintry potential.

    It's really  at the moment trying to scrape some interest until we see a change upstream, all our eggs are really in the strat warming weakening the PV and the MJO together working to bring about a change to the NH pattern to help deliver a better chance of some snow and deeper cold.

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    Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
    2 minutes ago, nick sussex said:

    The GFS 06hrs run has a semi-tease with that high pressure over Scandi but with the PV lobe located over east Canada will have no chance.

    The lack of amplitude upstream just puts too much pressure on that high with the energy piling mostly ne. The ECM does have some shortwaves running east along the base of the trough which might give something wintry on the northern flank but too far out to put too much faith in.

    Any interest doesn't really arrive till after day 7 and its marginal, any shortwaves that do form you'd want to be weak and not deepen, that would increase any wintry potential.

    It's really  at the moment trying to scrape some interest until we see a change upstream, all our eggs are really in the strat warming weakening the PV and the MJO together working to bring about a change to the NH pattern to help deliver a better chance of some snow and deeper cold.

    The ensembles are excellent wrt long term though, the blocks are being built. Regarding the shortwaves - yes you want them to be shallowish at surface level but you still want low heights so thicknesses are low, I always look to the area in between the main troughing and the shortwave in those setups where the calmer conditions might give evaporative cooling a chance.

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    Posted
  • Location: Pembrokeshire
  • Weather Preferences: Snow
  • Location: Pembrokeshire

    06z GFS continues with the concept of loco-zonal with troughing unable to make inroads into europe. We are thus left in a quasi atlantic airmass. We need troughing to dive into west/west central europe and then we are very much game on. With loco-zonal please expect short term suprises. No double digits today - delays inevitable. Enjoy !

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    Posted
  • Location: Linslade, Beds
  • Weather Preferences: Deep cold
  • Location: Linslade, Beds
    8 minutes ago, Jonathan Evans said:

    06z GFS continues with the concept of loco-zonal with troughing unable to make inroads into europe. We are thus left in a quasi atlantic airmass. We need troughing to dive into west/west central europe and then we are very much game on. With loco-zonal please expect short term suprises. No double digits today - delays inevitable. Enjoy !

    What's Loco-zonal mean ?

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    Posted
  • Location: Pembrokeshire
  • Weather Preferences: Snow
  • Location: Pembrokeshire

    It's a phrase to describe a more localised spell of zonality - with full zonal conditions never quite developing - pressure is strong over europe - maybe stronger than models can determine - we need this pattern to break and for lows to dive into europe - increasing the chances of pressure rises following on behind.

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    Posted
  • Location: st albans
  • Location: st albans
    42 minutes ago, fromey said:

    morning all.

    just read in the strat thread theres been a large spike in the 10hpa temps and the 30hpa temps.

    surley this is going to begin to throw the models out, im expecting a lot of chopping and changing/flipping and flopping.

    fromey 

     

     

    no

    bored with explaining it 

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    Posted
  • Location: Surrey and SW France.
  • Location: Surrey and SW France.
    28 minutes ago, nick sussex said:

    It's really  at the moment trying to scrape some interest until we see a change upstream, all our eggs are really in the strat warming weakening the PV and the MJO together working to bring about a change to the NH pattern to help deliver a better chance of some snow and deeper cold.

    There are more promising signs of a wave2 development on the 06Z GFS - that would be the first step to get a better pattern above and then rely on this being reflected further down.

    from this f65886d8ee938597f9496202c1206d69.gifto this d2a507aa8ad96437a707ec9033001b41.gif

    At first glance, it may seem as if the core vortex is setting up in the worst possible location but there are plenty of historical situations where this has worked out well if a proper split occurs - simply because of the suggestion from Ed (I think) that the jet does not cross the split.

     

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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    The best way of looking at the prospects for roughly the next 10 to 14 days is anything wintry is a bonus. The better chance of seeing anything develop is after that point.

    The NH pattern currently isn't condusive to any prolonged cold or snow. The UK's prospects of salvaging a decent spell are likely to be more towards the second half of February.

    I'm still optimistic that we'll see some changes and theres a better chance that the MJO could have a greater impact on the NH pattern at that point if it can get into phase 7 and 8. Much of the winter its impact has been muted by continual interference, NCEP expect this interference to lessen, allied with the PV likely to be in a weaker state later into February the odds are more in favour of cold and snow.

     

     

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    Posted
  • Location: frome somerset 105m ABSL,
  • Weather Preferences: cold snow, thunderstorms
  • Location: frome somerset 105m ABSL,
    37 minutes ago, bluearmy said:

    no

    bored with explaining it 

    wasnt really asking, more of a statement 

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    Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
    40 minutes ago, Jonathan Evans said:

    It's a phrase to describe a more localised spell of zonality - with full zonal conditions never quite developing - pressure is strong over europe - maybe stronger than models can determine - we need this pattern to break and for lows to dive into europe - increasing the chances of pressure rises following on behind.

    And there i was thinking it meant crazy zonal. 

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
    1 hour ago, Jonathan Evans said:

    It's a phrase to describe a more localised spell of zonality - with full zonal conditions never quite developing - pressure is strong over europe - maybe stronger than models can determine - we need this pattern to break and for lows to dive into europe - increasing the chances of pressure rises following on behind.

    Is this a phrase that has any official meaning or just another one from the web?

    Never heard of it myself so just wondering where it originated.

    thanks for any reply

     

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    Posted
  • Location: Broxbourne, Herts
  • Weather Preferences: Snow snow and snow
  • Location: Broxbourne, Herts
    5 minutes ago, johnholmes said:

    Is this a phrase that has any official meaning or just another one from the web?

    Never heard of it myself so just wondering where it originated.

    thanks for any reply

     

    No. I believe it to be  user-defined terminology that is little more than gibberish

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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    Theres no law in this thread saying we have to use only standard terms. We've had lots of new terms pop up including Sceuro high etc, loco zonal sounds perfectly fine to me. I think its pretty evident, zonality for the UK but not blasting well into Europe.

     

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Well  the chase for cold and snow continues, a bit less frantic than before I had my holiday. In truth perhaps rather more chance of passing deepish cold than then!

    Why?

    Well with a reasonably mobile Atlantic, some quite deep surface lows, passing not too far from our northern shores thus giving some cold outbreaks on their western side.  Of course the NW'ern areas will fare most from this, and at long last the Scottish ski areas might get some trade. It must have been one of the worst seasons, so far, in a long long time for them. As each low passes then the deepish cold I mentioned may well penetrate well south. So the higher ground from N Wales and the Peak District could see temporary coverings of 24 hours or so from this pattern. Maybe a few flakes on low ground further south. more interet for weather fans than the past few weeks. I managed a mean of just 2.0 C over the 8 days I was away. The coldest spell for a couple of winters I think.

    Looking at the inevitable anomaly charts below and the 500mb flow shows what I mentioned above on all 3.

    http://www.cpc.noaa.gov/products/predictions/610day/500mb.php and the 8-14 shows a similar pattern

    http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

    Beyond two weeks, not my area of experise so I will leave that for others.

     

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    Posted
  • Location: Shaw… lancs
  • Weather Preferences: SNOW… XTREME SNOW n COLD
  • Location: Shaw… lancs
    6 hours ago, Weather-history said:

    I point out that it wasn't really a UK cold spell, you even hint at this  yourself, they were odd days but frosts were limited by cloud cover that's why the CET isn't that low because the largest -ve anomalies are to the SE of the CET area. The further north you go the milder it was.

     

     

     

    Irlam...isn't to far from Oldham and to be honest it's been cold/very cold for sometime here, I work outside half of the working day and get called summat rotten for only wearing a t-shirt at work :)...while my work mates are wrapped up like polar bears :D...so I'd say no to mild, it's been cold, it's been more like a 70's-ish style winter...than we've had for some time...as in cold n dry!!

    Just needed to point this out!!

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    Posted
  • Location: Pembrokeshire
  • Weather Preferences: Snow
  • Location: Pembrokeshire
    2 hours ago, johnholmes said:

    Is this a phrase that has any official meaning or just another one from the web?

    Never heard of it myself so just wondering where it originated.

    thanks for any reply

     

    It's a web phrase i'm afraid - that said all phrases have to begin life somewhere ! (a la - murr sausage)

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    Posted
  • Location: NR LOURDES SW FRANCE
  • Location: NR LOURDES SW FRANCE

    A very unsettled GFS 12hrs run upto T240hrs with the trough parked over the UK. A succession of shortwaves at the base of the troughing run east into the UK, at this range the 850's and chances for anything wintry on the northern flank still uncertain, could be some surprise snowfall but very marginal.

    The main PV does look to edge further to the nw and its certainly better looking in terms of overall NH pattern than the 06hrs run at that stage.

     

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    h850t850eu.png ukmaxtemp.png

    So that sneaky little low is back but about half a day later than once shown, crossing E&W on Sunday afternoon and into the overnight period. This leaves the northern half of E&W under relatively cool air for Monday, compared to the balmy double-digits that was being shown before the small low was reintroduced to affairs.

    The super-mild air for Tuesday faces more opposition than before, which has a dramatic impact on the max temps for eastern parts;

    From ukmaxtemp.png  to ukmaxtemp.png

     

    This could easily adjust back though, as the small low is shallower on the 12z UKMO, GEM and ARPEGE runs. Still - it goes to show how sometimes it can take almost as little to suspend mild air as it all too often does to do so with cold air :)

     

    12z GFS goes on to produce too much cyclogenesis in the western N. Atlantic for enough Arctic or polar maritime air to get into the circulation to make things more interesting.

    ALL_emean_phase_full.gif

    Meanwhile the MJO is finally getting a move on, but  JMA has lost interest and GEFS is not as keen as it was yesterday. ECMF and UKME remain steadfast and it can only be hoped that they are seeing the true path with less interference from other equatorial phenomena. The ECMF mean is now sufficiently amplified in phases 5-6-7 that some significant and favourable adjustments to the longwave pattern may occur in response, both for getting a colder flow to the UK and assaulting the polar vortex. It's pretty much our last clear hope for the season, but it's shining as brightly as any I've seen these past two months. Or maybe that's just the fact that the line is yellow :laugh:  

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    06z: npsh500.png 12z:  npsh500.png

     

    Terrible consistency here but this is the first GFS operational run in quite some time to show the tropospheric vortex in tatters just outside of the 10-day range. Given the GEFS predictions for the MJO, which the op appears to have followed based on data on the NOAA site, and that the model continues to make relatively little of the second bout of stratospheric warming at 30 hPa this is surprising... maybe there's something going on in the lower levels of the strat.

    npst30.png

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    Posted
  • Location: Erith. SE London/kent 40m asl
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Erith. SE London/kent 40m asl

    Certainly an improvement there out in FI.

    graphe_ens3-1.gif

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    Posted
  • Location: st albans
  • Location: st albans

    Clearly the GEFS are making a better first of interpreting some downwelling from the strat  as we head through week 2 

    slowly becoming more of a theme, run by run.

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
    2 hours ago, Jonathan Evans said:

    It's a web phrase i'm afraid - that said all phrases have to begin life somewhere ! (a la - murr sausage)

    Why not simply say what it is?

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    Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

    17021100_2812_02.gif 17021100_2812_04.gif

    Signs of trough disruption from two minority clusters at 20% and 10% and way out at 14 days range, but hey, we have to start somewhere :drunk-emoji:

    Generally today has brought with it a sense that Feb might not be 'written off' for quite as long as some sources might have had you  believe. Interesting to see more of a positive stratospheric influence from GEFS this evening - it'd be nice not to be placing all our eggs in the MJO basket for wintry chances this side of mid-month - by which I mean sustainably so; not transitory sleet/snow on shortwave lows running into the base of a broad trough, as fun as that might be for some on high ground at least.

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