Model Output Discussion 12z 20/04/13

[Frosty.]

Much of the Gfs 06z op run is dominated by anticyclonic weather but just occasionally it becomes more unsettled, especially across the north of the uk. The 6z is showing some pretty warm and rather humid weather next week with temps approaching the mid 70's F at times and generally the temps remain above the seasonal average although it looks cooler at times across the north of the uk. Around the middle of next week looks briefly unsettled with outbreaks of heavy rain and showers with probable thunder, the southeast corner of england may escape the rain and remain warm and dry but then pressure rises across the uk. Further into FI shows a few unsettled blips but generally warm and settled, occasionally more humid with isolated heavy showers.

[snowmadchrisuk]

Really lovely looking 6z GFS 5 full days next week of 20 deg plus temps .... 25 in Kent will be reached easy on them charts ... 

[Alex]

I haven't posted here for a while however anyone writing off a decent May this early is likely to be going against the signals.

MJO is heading through phases 1-2-3 - the composites for May suggest a ridge near to the UK with the exception of phase 3 which is more unsettled further north.

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

Angular momentum is relatively neutral (neutral/negative in May tends to promote ridging for mid latitudes)

http://www.esrl.noaa.gov/psd/map/images/reanalysis/aam_total/gltotaam.sig.90day.gif

Moving forward towards the middle of May I believe that a more unsettled blip is likely (perhaps with some very warm air for a time too), however perhaps the GFS 06z is too early in that blip and I would think that this blip is more likely next weekend or even beyond in line with a eastward movement of the MJO towards phase 3.

The MJO is then likely to head into Phases 4/5 towards the 2nd half of May and a steady AM is likely to promote another bout of settled weather.

The majority of the GFS ensembles (00z) also don't buy the early breakdown as progged in some recent runs.

http://www.wetterzentrale.de/pics/MT8_London_ens.png

My May forecast on my twitter account @alexbweather is a good read for less technical details.

Enjoy the sunshine!

Edited May 2, 2013 by Alex

[Frosty.]

The latest GEFS 00z mean is now looking a lot warmer compared to yesterday, especially the earlier runs which trended much cooler towards the end, the 850's now look mild or warm throughout with the warmest uppers across the south. Pressure also looks rather high for much of the time with just the occasional trough interrupting the generally warm and settled pattern. So, both the ecm and gefs mean are looking good so far today, the gefs has been playing catch up again.

[mushymanrob]

well, re the mushy post-hardly!

Further to my first post this morning and the differences in NOAA at 6-10 and 8-14, see below for the output this morning from ECMWF-GFS

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

Those that read my 500mb anomaly comments will know that continuity between the 3 I use and with themselves is needed. The above shows a totally different pattern to what they showed yesterday, gone is the upper ridge over the UK area and +ve area. Now either the ECMWF flat trough type w'ly or the n of west trough type shown by GFS. Couple this with the 8-14 pattern on NOAA last evening and we either have a couple of out of kilter outputs or the start of the end if you like of the upper ridge over the UK?

Perhaps those lucky to have it over the weekend and start of next week had better enjoy it while it lasts!

 

see below Carirg, hope that answers your question, if not ask again please and I'll try to explain

John

 

sorry john, i was being flippant i know theres nothing showing that would indicate another washout summer.... but tbh imexpecting it, and the synoptic charts along with the teleconnections might soon be showing this as a possibility. after all, here we are in another dry may, with little scope for much precipitation for the southeastern half of the country...

[Milhouse]

6z GEFS mean once again very high pressure dominated. Just as it seems high pressure is losing its grip towards the end of the run it comes back over the UK.

[Frosty.]

6z GEFS mean once again very high pressure dominated. Just as it seems high pressure is losing its grip towards the end of the run it comes back over the UK.

The latest met office update cannot be described as high pressure dominated, low pressure dominating at least for the northwestern side of the uk throughout, will spring ever spring in nw britain I wonder, n.ireland and scotland indicate no settled weather worth mentioning, just rain and windy at times and cool to average temps. The warmest, driest, sunniest weather across southeastern britain, so a northwest-southeast split seems appropriate for the next few weeks, occasionally unsettled even for the drier and warmer areas. I'm surprised at how poor the met office update sounds compared to the rather more encouraging gefs and ecm mean today, they are mostly dominated by high pressure.

Edited May 2, 2013 by Frosty039

[summer blizzard]

All ensemble means seem to strongly suggest high pressure will influence the UK, perhaps further west over time.

 

Certainly nothing supporting the random low.

[Frosty.]

All ensemble means seem to strongly suggest high pressure will influence the UK, perhaps further west over time.

 

Certainly nothing supporting the random low.

mogreps must be showing something different to the largely settled gefs/ecm mean then, the mo update is poor unless you live in the southeast quarter of the uk.

[Summer Sun]

UKMO is looking quite settled now away from Scotland at first and last

 

 

Edited May 2, 2013 by Gavin.

[Milhouse]

UKMO is looking quite settled now away from Scotland at first

 

Not bad at all. The dry spell is going strong out as far as Wednesday of next week and the warmth is building all the while. The way that low pressure is going the settled weather would last another day at least.

[Frosty.]

Well the Gfs 12z operational shows a lot of Anticyclonic weather throughout the run, much drier than the 6z and some very warm days next week from monday onwards but especially tuesday and wednesday when 24-25c is possible with a general 22-23c for central and eastern england, This is a much better run for the north with scotland getting some fine and fairly warm weather compared to the wet & windy 6z.

 

The Ukmo 12z shows an increasingly warm and sunny outlook but then turning unsettled in the northwest but the southeast becoming very warm with high pressure in control the further south and east you are.

[johnholmes]

mogreps must be showing something different to the largely settled gefs/ecm mean then, the mo update is poor unless you live in the southeast quarter of the uk.

If it is the 6-15 day outlook being referred to then this is what they actualy printed

UK Outlook for Tuesday 7 May 2013 to Thursday 16 May 2013:

A lot of dry weather is expected across the south and east of the UK at first, with northern and western areas most likely to see thicker cloud with some rain and strong winds at times. Cloud and rain is then likely to edge further eastwards on Wednesday. Temperatures near average in the west, but rather warm elsewhere. Towards the end of next week there could be some rain at times in the south, but generally a good deal of fine and dry weather for England and Wales, but more unsettled towards the north of the UK. Cooler than earlier in the week, though still rather warm at times in the southeast. Thereafter, a lot of uncertainty, but indications that conditions may turn a little cooler and more generally unsettled.

Updated: 1230 on Thu 2 May 2013

[Frosty.]

If it is the 6-15 day outlook being referred to then this is what they actualy printed

UK Outlook for Tuesday 7 May 2013 to Thursday 16 May 2013:

A lot of dry weather is expected across the south and east of the UK at first, with northern and western areas most likely to see thicker cloud with some rain and strong winds at times. Cloud and rain is then likely to edge further eastwards on Wednesday. Temperatures near average in the west, but rather warm elsewhere. Towards the end of next week there could be some rain at times in the south, but generally a good deal of fine and dry weather for England and Wales, but more unsettled towards the north of the UK. Cooler than earlier in the week, though still rather warm at times in the southeast. Thereafter, a lot of uncertainty, but indications that conditions may turn a little cooler and more generally unsettled.

Updated: 1230 on Thu 2 May 2013

Yes it's a poor MO outlook for the north/nw but happily the gfs 12z looks a lot better for all with nationwide anticyclonic weather for much of the run.

Edited May 2, 2013 by Frosty039

[Frosty.]

Another nice and warm GEFS 12z mean, things have changed significantly with the gefs mean in the last few days, it was recently showing a much cooler northerly towards mid may but now has the uk in relatively warm upper air and occasionally very warm (T850 hPA) in the south, it's also a generally Anticyclonic run, much more settled than today's met office update indicates with even the north and west under high pressure for some of the time.

[Summer Sun]

Well what can we say about ECM at t120 completely on its own is a good place to start when compared to UKMO

 

 

Compared to UKMO

 

 

Shorter term and the bulk of the UK is in for a decent BH weekend though Scotland is the place most prone to any rain

 

 

EDIT t144 is completely against UKMO (right) as well

 

 

T168 it finally gets there with the high building

 

Edited May 2, 2013 by Gavin.

[shaky]

Well what can we say about ECM at t120 completely on its own is a good place to start when compared to UKMO

Compared to UKMO

Shorter term and the bulk of the UK is in for a decent BH weekend though Scotland is the place most prone to any rain

EDIT t144 is completely against UKMO (right) as well

And knowing our luck ecm is probably right!!this happens everytime its so frustrating!!gfs amd ukmo agree then the ecm has to be a party pooper after a good 0z run!!

[Frosty.]

Phew..this looks much better, actually it's almost a repeat of the ecm 00z so far.

[shaky]

Phew..this looks much better, actually it's almost a repeat of the ecm 00z so far.

Yup that 168 hour chart is something refreshing!!thank god it came up with something like that after 144 hours otherwise i would have been pulling my hairout!!i long for a nice hot spell!!

[IDO]

GFS 12z has a different solution to the trough at T144. The high ridges over the trough and the UK remains under higher pressure:

GFS: UKMO: GEM:

GEM and UKMO push the trough east, with only timing at odds. ECMW is the most progressive of them all: . With a trough hitting the UK by next Tuesday.

Some support to maintain HP at that time on the GEFS: ...but the range is circa 20 hPa, and with its deviation from the mean, low confidence on that solution at the moment.

The Dublin pressure chart highlights the split at D7 (NCEP 0z): As many go with the pressure falling as go with HP in situ. Nothing conclusive from the Ens members stamps at T168, an event split between HP or a UK trough: http://www.meteociel.fr/cartes_obs/gens_panel.php?modele=0&mode=1&ech=168.

From then, GEM remains unsettled, T240::

Whilst GFS tries another trough at T240: for 2-3 days, before HP returns (T300).

So still no nearer the models pinning down next week. Though the general trend is for any troughing to be a passing affair, with HP soon pushing back in.

Enjoying this mild spell and it looks like getting warmer for early next week, especially the SE:

[snowmadchrisuk]

Monday Tuesday looking great , It does look if the ECM is correct then High pressure will move back in , Just hope it doesn't leave to much left over cloud , as it seems except for a blip , Most of next week could remain mainly settled in the South . 

[Frosty.]

It trends unsettled and showery, just like the Ecm 00z, synoptically it's very similar to the 00z but a touch cooler at the end. 

[Frosty.]

The Ecm 12z run really goes downhill at the end, similar to the Gfs 00z but even worse with the jet tilting nw/se, hopefully the ensembles will paint a better picture shortly.

[Summer Sun]

The ECM ensemble keeps the high further west on Tuesday which would give those in the east and SE another decent day

 

Op left ensemble right

 

 

Further through and we have support for a pressure rise

 

 

Right at the end we have low pressure over Iceland and high pressure out in the Atlantic

 

Edited May 2, 2013 by Gavin.

[ribster]

sorry john, i was being flippant i know theres nothing showing that would indicate another washout summer.... but tbh imexpecting it, and the synoptic charts along with the teleconnections might soon be showing this as a possibility. after all, here we are in another dry may, with little scope for much precipitation for the southeastern half of the country...

Couldn't agree more mushy, I was thinking this afternoon, this has a very strong sense of deja vu about it. A quick scan of the output as you say, shows little precip down this way, and there hasn't been a lot for quite a while. I know where I'd be putting my money...