Model Output Discussion 12z 20/04/13

[Milhouse]

ECM mean still pointing towards something warmer off the continent in FI.

 

[Milhouse]

Saturday looks poor on the 18z with low pressure very close by bringing showers or longer spells of rain. Thankfully its an improving picture with Sunday and Monday seeing rising temperatures and some increasingly settled conditions the further south you go.

[Guest pjl20101]

Yes I agree, A little unfair to state he cherry picked them, Karl is only one of a few with unbiased veiws regarding the models on this forum.

One of the best posters on here.

I would say Gavin partridge has level headed unbiased views as well my friend, shame he is busy doing other things and on TWO obviously. Really matt Hugo and Ian ferguson are needed on these threads badly as that way we would have consistency and a lot of help basically.

Edit, this is probably the answer to Gael_Force's question:

https://mobile.twitter.com/MattHugo81/status/331650646539390976?p=v

Edited May 7, 2013 by pjl20101

[Polar Maritime]

I would say Gavin partridge has level headed unbiased views as well my friend, shame he is busy doing other things and on TWO obviously. Really matt Hugo and Ian ferguson are needed on these threads badly as that way we would have consistency and a lot of help basically.

Edit, this is probably the answer to Gael_Force's question:

https://mobile.twitter.com/MattHugo81/status/331650646539390976?p=v

 

With all due respect I'm pretty sure NW MOD thread is the best on the net, there is plenty of consistency here with the vast majority of poster's learning from each other, and from a long list of well respected and seasoned posters from all different backgrounds, some even ex METO forcasters. Tweet's show little information as they can only post a certain amount of words and show little information. Yes they can be handy for the ECM 32, but most have little faith in that model alone at that range. 

[Guest pjl20101]

Sorry its late guys but here is the output from CPC NOAA site and the trough is still there. Notice however of a possible retrogression of high pressure from scandanavia too which possibly could head to our shores:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/500mb.php

Something to watch out for.

[summer blizzard]

Low pressure close to the UK looks the order of the day to me, while the anomaly charts do point to an eventual retrogression of the trough (probably to the south west of the UK) there's also in my opinion a chance of pressure building in the Greenland/Scandinavian region.

 

If we want warmth then we need the trough over the UK to sink south east and fade.

[Summer Sun]

The outlook for the next week at least is looking unsettled but slowly turning warmer again into next week from the continent

 

Firstly and unsettled weekend on which UKMO, GFS and ECM agree on with temperatures in the mid to low teens for many

 

 

Now as per yesterday evenings run ECM wants to introduce some warmer humid air from the continent where as GFS is less keen on this

 

Edited May 8, 2013 by Gavin.

[Alex]

Yes definately a chance of retrogression which is more in line of the eastward movement of the MJO towards phase 3, however I do wonder how much retrogression will occur with a fast movement into phases 4/5. Phase 5 within 10-15 days suggests the end of the month may become more settled once again.

Phase 3 for May

http://raleighwx.americanwx.com/MJO/MayPhase3500mb.gif

Phase 5 for May

http://raleighwx.americanwx.com/MJO/MayPhase5500mbAnomalies.gif

In regards to Summer - I am encouraged by positive angular momentum levels and a more active MJO all this bodes well despite a negative PDO.

For more of my weather views - check out my twitter site @alexbweather

Edited May 8, 2013 by Alex

[Frosty.]

The Ecm 00z has continued with the increasingly warm and humid but unsettled outlook which it showed on the 12z last night, it keeps the trough further west and it slides down to the west of the uk well to the southwest and with high pressure to the east, the cooler oceanic airmass changes to a much warmer and more humid continental flow, hopefully this will continue to be the trend. 

 

There is now good agreement that the coming weekend will continue unsettled, cool and breezy with sunshine and showers and also longer spells of rain but a weak ridge is likely to push east across more southern areas on monday and may linger in the far southeast into tuesday with drier, brighter and slightly warmer weather for a time but then becoming cool and unsettled again if the gfs 00z and gefs 00z mean verify, the gefs shows widespread cool uppers on sunday and then again next wednesday before the 850's start to warm up slowly and this trend continues to the end of the run but the trough remains over the uk for a long time, slowly drifting west but taking ages to fill but there is a slow trend to drier and warmer weather from the east towards late may, the ecm 00z would be a fast track to a warm & humid but showery/thundery outlook.

 

Today sees rain spreading north and east across the uk followed by sunshine and showers, some with hail and thunder, tomorrow needs watching closely with very wet and windy weather spreading from the southwest during the day, gales and torrential rain are in the forecast tomorrow, then cooler and more showery for friday & the weekend, the far south and southwest probably less showery with more in the way of dry and bright weather between.

Edited May 8, 2013 by Frosty039

[Gibby]

Hi everyone. Here is the report taken from the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for Wednesday May 8th 2013.

All models have seen the transfer to much cooler and unsettled conditions overnight. The trough bringing the change will move away NE today with the parent depression winding itself up near Ireland with strong to gale SW winds developing over Western and SW areas tonight and tomorrow. There will be some dry and bright conditions following the rain today with a few showers developing more widely after dark and becoming prolonged from the West tomorrow. By Friday the Low will fill slowly and move away to the NE leaving several days of showery West to NW winds with further troughs embedded enhancing the showers at times. A weak ridge over the South on Sunday could dampen the showers down somewhat over the South and SE for a time.

GFS then takes us through next week with further showery and unsettled conditions as Low pressure drifts down over the UK from the NW. It maybe that Southern areas stay largely dry on Monday and Tuesday with more isolated showers. By the end of the week, weekend and through week 2 the pattern is well locked with a Southerly moving Jet over the Atlantic maintaining a deep trough over the UK with showers or longer spells of rain maintained in technically rather cool conditions, though that means in any sunshine it will feel reasonable enough for a time.

The GFS Ensembles has all it's members more or less singing from the same hymn sheet again this morning with a period of sustained normal uppers delivering disappointing and cool conditions at the surface with showers or longer periods of rain at times for all.

The Jet Stream continues to indicate the flow will be taking a Southerly course down over the Atlantic next week with the flow South of the UK around Spain this time next week.

UKMO today shows Low pressure ambling slowly SE down towards the UK early next week maintaining Westerly winds and occasional rain and showers. It maybe with a slightly slacker flow over the South the first few days of next week in the South may not be too bad with just scattered showers and some warm sunny spells.

GEM today shows the theme of the others in bringing Low pressure SE over the UK next week where it becomes complex and slow moving with rain and showers circulating around for all areas.

NAVGEM sets up an Easterly flow by midweek as the Low pressure sinks South over Britain and away to the South leaving the UK in Easterly winds with further outbreaks of rain or showers but these becoming more restricted to the South with time.

ECM today is still adamant in keeping Low pressure over or just off shore of our Kingdom with spells of rain or heavy showers for all. It maybe that as other models show the South may have a window of slightly less showery weather early in the week. Longer term ECM shows an excess of northern blocking with the Jet sent south as a result and the UK locked under cool Low pressure with potentially heavy rain at times.

In Summary today there is little to be added to my previous reports as the synoptics have changed little over the last 24 hours. The only slight window is for the South on Monday and perhaps Tuesday too as the progression of the Low to the NW looks a little slower on some output, especially UKMO but the end result ends the same with a spell of unstable weather with rain at times and mediocre temperatures the most likely outcome from this morning's output. With the GFS Ensembles showing tight agreement on showery conditions through the period of the run this morning and given all the operational's appear fairly in unison it might be some while before we break out of this pattern.

[Frosty.]

ECM today is still adamant in keeping Low pressure over or just off shore of our Kingdom with spells of rain or heavy showers for all. It maybe that as other models show the South may have a window of slightly less showery weather early in the week. Longer term ECM shows an excess of northern blocking with the Jet sent south as a result and the UK locked under cool Low pressure with potentially heavy rain at times.

 

Hi Gibby,

 

Great update as always but the Ecm 00z, just like the 12z last night shows a  warmer and humid outlook rather than cool low pressure, it's the GEFS (GFS) 00z keeping the uk locked under cool low pressure as far as I can see

[SP1986]

In my viewing The ECM at best shows an easterly with dry air intrusion, not humid (except for the far southeast... This may lead to some warmth and humidity for southeast but most other places would find themselves in a dry cool airmass but with rain in central areas. The west would continue cool as the jetstream continued south. The GFS is a none starter, it would be a write off for the next two weeks if that occurred away from the far southeast.

Edited May 8, 2013 by SP1986

[Frosty.]

The Ecm 00z ensemble mean has the trough further east than the operational and the knock on effect means it's a cooler low/trough over the uk although the uppers (T850 hPa) warm up slowly but nothing like to the same extent as the ecm op so apologies to gibby.

[Guest]

The GFS 06z is taking the low pressure much further east before it slips south moves off towards Scandinavia. Not so good.

 

Hopefully it's just off on one, what does everyone think?

Edited May 8, 2013 by Guest

[Frosty.]

The Gfs 06z brings a surprise fine spell next week as our trough quickly migrates northeast during next midweek towards northern scandinavia and an atlantic ridge pushes east into the uk with a window of fine weather bringing sunny spells and average temperatures to the south but rather cold for northern scotland. This doesn't last as another low which develops near iceland begins to slide southeastwards and directly over the uk bringing a very showery cyclonic and rather cool spell although in the sunny spells between the showers, temperatures in the southern half of the uk recover to average but much cooler in the downpours which look widespread, heavy, thundery and slow moving. The trough remains in situ for the rest of the 6z and only very slowly fills and this would keep the sunshine and showers theme intact until the end of the run with a risk of further low pressure then taking it's place.

 

There is also a small window of fine weather for southern britain this sunday and next monday before it turns unsettled for a few days, temps around average for the south during this period but cooler further north and west where it remains unsettled throughout.

 

As i mentioned earlier, tomorrow looks like becoming very wet and windy as an unseasonally vigorous depression spreads heavy rain and gales, possibly severe gale force gusts, north and east across the uk with only the north of scotland escaping and remaining sunny, the heavy rain further south will then be followed by sunny spells and scattered heavy showers with a risk of thunder and temperatures tomorrow look rather cooler at 12-16c from north to south, the southeast today could reach 18-19c this afternoon, there is also a risk of some heavy and thundery showers later today across northern england and lincolnshire after the patchy rain clears northeast, rather heavier rain moving north through southern and central scotland today.

[Summer Sun]

The ECM monthly ensemble for Birmingham is now moving closer to average out to June 5th

 

 

Rainfall looks like going above average with a peak on the 17th before easing back to just above average

 

Edited May 8, 2013 by Gavin.

[bluearmy]

The Ecm 00z ensemble mean has the trough further east than the operational and the knock on effect means it's a cooler low/trough over the uk although the uppers (T850 hPa) warm up slowly but nothing like to the same extent as the ecm op so apologies to gibby.

 

the direction of travel remains the same karl. i wonder if we have reached the farthest point re retrogression of the lw pattern as per the recent ecm op runs? the spreads would show the favoured path for the lowest heights to be running nw/se through ireland. however, with the mean maxes for london ticking up by a few degrees over the past few runs, i'm not convinced we have seen the end of the westward ens mean corrections on the trough. we are now a fair way from the cpc charts from sunday and monday night with the mean trough to the east of the uk.

[Frosty.]

The way I just read the latest met office update sounds like it's going more with the Ecm 00z operational run with winds eventually becoming easterly to southeasterly with higher temperatures and fine weather for at least northern areas but probably remaining showery elsewhere with the prospect of unsettled & cooler than average conditions prevailing thereafter but with significant uncertainty at this stage. This implies that the trough near iceland early next week would slide south to the west of the uk and with high pressure to the east, we would see winds backing to a warmer continental flow rather than atlantic sourced, so that's a good sign.  

 

The extended met office update broadly follows the GEFS 00z mean with a gradual relaxation of the cool trough conditions to somewhat drier and warmer weather as pressure looks like becoming higher to the east and northeast of the uk and our filling trough would then drift west into the atlantic, so we have a blend of the ecm 00z op and gefs 00z mean plus all the extra data (mogreps etc) the MO have at their disposal and expert knowledge.

Edited May 8, 2013 by Frosty039

[Iceni]

I've taken all this talk of humid, or cool but unsettled weather to mean the frost risk is pretty low until the end of May…? I've got courgettes and beans that need to go out of the greenhouse into the veg beds.

 

Mods: delete if off topic, but there are some practicalities to weather forecasting and growing food's one of them.

[Bottesford]

Hi Iceni - head to our very own gardening thread for everything you need to know:

http://forum.netweather.tv/topic/73128-net-weather-gardening-thread/

But yes any kinds of low temperatures are of vital importance at this stage in spring and we should keep a close eye on the forecasts.

[ANYWEATHER]

In my viewing The ECM at best shows an easterly with dry air intrusion, not humid (except for the far southeast... This may lead to some warmth and humidity for southeast but most other places would find themselves in a dry cool airmass but with rain in central areas. The west would continue cool as the jetstream continued south. The GFS is a none starter, it would be a write off for the next two weeks if that occurred away from the far southeast.

Latest Ecm screams thundery downpours for southern Britain, a bit more settled further North. Yes potential for warmth too, but of course likely to be overshadowed by cloud etc. Gfs 06z shows something similar although a cooler run. Whatever way you look at it ,we are now entering a period of  unsettled weather for all with the rainfall potential increasing especially for southern Britain.  

[Thundery wintry showers]

Tomorrow looks like turning wet and unusually windy for May, as a deep depression approaches from the west.

From Friday to Sunday we may end up in a "sunshine and showers" regime but I think sunshine amounts and convective potential are likely to be limited due to a succession of weak fronts circulating around the low pressure:

http://www.wetterzentrale.de/pics/brack2.gif

Those charts suggest to me that for most of us it will be mainly cloudy with showery rain and the odd bright interval. In between the fronts we may get the odd pocket of brighter showery weather with greater chances of thundery activity due to solar heating helping generate enhanced convection, and this is most likely IMHO in southern parts of England, particularly East Anglia and the eastern Home Counties and also perhaps the eastern side of Ireland.

[Frosty.]

I've taken all this talk of humid, or cool but unsettled weather to mean the frost risk is pretty low until the end of May…? I've got courgettes and beans that need to go out of the greenhouse into the veg beds.

 

Mods: delete if off topic, but there are some practicalities to weather forecasting and growing food's one of them.

The new signal for a warmer/humid southeasterly/e'ly flow on the latest met office update would be great news for gardeners and growers alike, let's hope it's a signal that becomes stronger in the coming days, the ecm is hopefully onto something that the other models will soon pick up and run with. We need that trough which will be over iceland early next week to slide south to the west of the BI which will coincide with rising pressure to the east of the uk, we don't want the icelandic low to slide southeast over the top of the uk or it will be cool cyclonic with a risk of grass frost as the pattern becomes locked in with high pressure ridging north in the atlantic and continental high pressure, our trough would have nowhere to go and remain in situ for many days.

Edited May 8, 2013 by Frosty039

[phil nw.]

All the indicators are for a more unsettled period now with more rain or showers about.

The mean NAEF`s and ECM charts at day 10 show the now developing mean trough still situated around the UK area towards next weekend.

 

We have an active MJO now with the main area of tropical convection moving east through phases 3 to 4 during the next couple of weeks with composite patterns for these phases underlining the mean charts.

 

 

 

with jet pushed south it looks like temperatures will be suppressed but between the rain bands or showers the strong sun at this time of year will still make it feel pleasant enough.

[Summer Sun]

A more settled outlook from GFS this afternoon for later next week

 

 

After this it goes unsettled once more