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Model Discussion Thread - January 13th


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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Both the GFS and ECM haven't escaped criticism over the last few days by NOAA in terms of continuity, today its the GFS which gets the flak:

RECENT RUN TO RUN ISSUES

OF THE ECMWF SEEM TO HAVE SETTLED DOWN WITH THE LAST 2 RUNS AND

ITS NOW THE GFS WITH BIGGER RUN TO RUN CONTINUITY ISSUES.

Full discussions here:

http://www.hpc.ncep.noaa.gov/preepd/preepd.html

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Posted
  • Location: Eastbourne and Larnaca,Cyprus .
  • Location: Eastbourne and Larnaca,Cyprus .

Nick, I always find your NOAA extracts interesting viewing; what is their view today, do you know?

I know they were largely dismissive of the GFS Op's modelling of the energy exiting, favouring the ECMWF's interpretation. I wonder if this has changed at all, mindful of ECMWF's slight tempering of its own output?

You must be psychic I was just posting that! I think we're seeing a problem regarding low pressure development in terms of amplification and depth and until this is settled we won't know what the impact will be on the PV, the ECM runs that had that high cell to the north developed low pressure more vigorously upstream which impacted on that PV as it headed east by helping to pull this further to the nw.

It's no surprise therefore that as the ECM's settled into less low pressure we see that high gone and troughing instead, this is why the Newfoundland area is key in terms of PV and low interaction.

We really need to see deeper low pressure to develop in the eastern USA, an amplified trough there will phase with the PV as it heads east and give it a jolt westwards,as this pulls the PV nw high pressure will have to form to the north of troughing, if you just get the PV pushed eastwards we'll then have to hope the block to the east forces that energy to dive se wards.

The domino effect is then as that amplified troughing pulls the PV west, the high builds in around Iceland some of the energy from that trough then heads se and not ne.

The ECM for the timebeing has dropped this idea, plan B is that the block to the east holds troughing near the UK and energy from the PV is forced se into the troughing this is the more likely option at present.

Edited by nick sussex
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Posted
  • Location: st albans
  • Location: st albans

looking at the 06z parallel ens and they give a 25 to 30% chance of snow in london next weekend. of course thats only indicative that between 5 and 7 members show snowfall on those dates. 'surely shum mishtake' i hear you say. the ncep suite is steadfast behind the gfs op. yea, course it is - the op being only 5c warmer than the mean next sunday.

time for a walk methinks before the ecm op trends a bit east and the gfs even further west.

Edited by chionomaniac
Yes I agree but he likes the reaction
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Posted
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

Some of us feel that the UKMO is becoming more like the ECM, later in the week (it only goes up to 144), however to me it looks much more like GFS, albeit with differing timing, so that the UKMO for Friday is very similar to the GFS on Sunday:

post-2595-0-98359900-1326551584_thumb.gi post-2595-0-76311200-1326551657_thumb.pn

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

You are

perfectly correct Frosty there is nothing to my eyes which suggests the posibilty of snow across the south for the next 10 days minimum.

In a PM NW airflow the west of Scotland NI and NW England maybe parts of the midlands are the best locations.

The GFS and its ensembles do offer some short sharp PM incursions as per METO outlook.Im quite interested in late next week here and expect some snowfall here in the NW of England.Now that the chances of yesterdays ecm ops have all but evaporated the main interest is getting enough amplification to allow some decent pm shots although they will be transient in nature id be happy to see falling snow its mid Dec since we had snow here.The meto long ranger does not scream anything in the way of HLB so it might well be that PM shots are the best thing on offer for a good while.

Hi hd,

I am not ruling out a change in the outcome, I will just go with the flow of whatever the models are showing but the ecm has downgraded from a pattern changing situation to a cold snap and the gfs 6z is currently the best option going forward, quite a change since yesterday! I'm looking forward to the 12z as we are now seeing some real interest as we enter the second half of the winter. I think a colder spell with some snow potential is now highly likely with the north of the uk most affected although the 6z does delay the change a little longer than the ecm 00z.

Edited by Frosty039
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Afternoon All-

I think this will be the afternoon where it all starts coming together in the models- the divergence cannot continue for much longer-

we are reaching the 100 timeframe where broadly speaking the Longwave 500MB pattern is usally well & truely resolved- so the GFS should start to wake up-

Remember the 12z & 00Z are statistically the best GFS outputs, although the 12z does always seem to be a little progressive in the region- so we shall see-

Lets keep the commentary realistic & close to what the actual model is displaying remember

GFS FAST with the eastern shortwave & 100 & no amplification

ECM SLOW with the eastern shortwave & +VE amplifaction-

the slower the better to get as much jet amplification as possible!

S

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Just one last thing - other background signals to note are the GFS & ECm showing an acceleration of the jet at a very sharp SSE angle - down from Eastern canada- that needs watching & its so accute will promote some kind of high pressure to the NE....

this is around the 180-192 mark

S

Edited by Steve Murr
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Posted
  • Location: Cork City(Southern Ireland)
  • Location: Cork City(Southern Ireland)

Just one quick question Steve, are you surprised at how mild and benign the uppers have been directly to our North and particularly our Northeast ?

The Siberia region, to me looks more akin to early November rather than mid Winter

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Posted
  • Location: South Essex
  • Location: South Essex

I suspect ECM is close to where we will end up. Its important that people (more aimed at any newbies reading this!), are not expecting snowmaggedon next weekend, because I simply cant see it happening.

ECM is showing a standard winter cold spell / snap and if it verifies I suspect many places will see some snow, I just can't see most places getting big snow. In the longer term there is (IMO) little support for anything more severe and based on current output the Azures high could easily boss the weather well into Feb.

Lots of time for something better to show up in the charts but there is no point in pretending that a big freeze is due when its just not supported in the output.

Jason

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

I suspect ECM is close to where we will end up.

That would suit the southeast as the gfs is not really that promising for the south, good luck!

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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

Both the GFS and ECM haven't escaped criticism over the last few days by NOAA in terms of continuity, today its the GFS which gets the flak:

RECENT RUN TO RUN ISSUES

OF THE ECMWF SEEM TO HAVE SETTLED DOWN WITH THE LAST 2 RUNS AND

ITS NOW THE GFS WITH BIGGER RUN TO RUN CONTINUITY ISSUES.

Full discussions here:

http://www.hpc.ncep....epd/preepd.html

So what they are saying is that now ECM have backtracked on their mega cold spell and has published two sensible runs they are now somehow better than GFS? No, I must be missing something here. They cannot be saying that after a U-Turn and two runs that have aligned, ECM is somehow showing greater continuity than GFS! Wow, who are these guys at NOAA? Surely with such small changes having significant impact downstream runs that flip are not a prerequisite for a bad model? To me it is what we would expect from such a tenuous situation. Neither should be lambasted for that, although for me it is harder to forgive ECM's climbdown.

Apart from the PM shot next week modeled by ECM, it probably has the poorest outlook into FI. The so called flip today by GFS has improved it's outlook for cold for some lucky Northerners as well as a better background for cold, as we enter late January; though none of the synoptics are anywhere near giving us prolonged cold or anything to write home about. Its a case of jam today or jam tomorrow but with only very small portions.

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Just one quick question Steve, are you surprised at how mild and benign the uppers have been directly to our North and particularly our Northeast ?

The Siberia region, to me looks more akin to early November rather than mid Winter

Not really surprised- they have had a persistent southerly flow for a long time with only transient cold shots-

Hopefully now with the polar heights on the increase this winter will be a game of 2 halves...

S

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PS looking at the ECM the way the heights are sitting you have a primed jet for another Scandi high-

The ECm in the 168 timeframe hasnt changed- past that the modelling of the polar heights & the rate of change of modality is key to success ( teh change influenced by the strat changing)

lets see where the 12's go

S

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Posted
  • Location: G.Manchester
  • Location: G.Manchester

Not really surprised- they have had a persistent southerly flow for a long time with only transient cold shots-

So you don't feel the this will become problematic if we do manage to pull in colder shots from that region? We have differing opnions on this issue (which wasn't really a problem in the winters between 2008 - 2010 due to a great increase in those regions to become colder earlier on in the season)

The ECM 00Z from 144 hours + would only be interesting for me if there was a great deal of cold to be dragged across. It's certainly lacking. The distribution of very cold air this year (and last) has been on the other side of the atlantic.

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Posted
  • Location: Aviemore
  • Location: Aviemore

Going to lock this one in now ready for a new thread as the 12z starts to roll.

Will leave it 15 minutes though to maybe give everyone an opportunity to reset and relax..

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