Model Output Discussion 12z 20/04/13

[mountain shadow]

Yes Gavin, brief interludes of drier conditions is all we can look forward to at the moment based on current output.

[Panayiotis]

For the reliable the latest GFS ensembles keep it unsettled and average for my area: http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=204&ext=1&y=136&run=12&runpara=0

The same can be said further north(Edinburgh):

http://modeles.meteociel.fr/modeles/gens/graphe_ens3.php?x=&ext=1&y=&run=12&lat=55.991902834008094&lon=-3.962264150943394&runpara=0

Edited May 8, 2013 by Panayiotis

[Panayiotis]

NAO not looking good for mid month onwards with it heading in negative territory suggesting that models show HP in the Atlantic which would give us cool, showery weather with some sunshine. I know it is not a driver of the weather but it is worrying that models are driving it negative instead of positive!

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

[weather_it_will]

Low pressure will be dominating our weather for a long time to come.

Can't see any long term warmth or settled weather until at least June.

Certainly nothing as warm as Bank Holiday Monday which could be the highlight of the year.

For all those people moaning about the dry weather, there is plenty of rain on the way!

Edited May 8, 2013 by Hot Wet Windy Cold No Snow

[Iceni]

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.

 

Thank you for all your helpful replies and especially the gardening thread. So not quite out of the woods...  Last year, I had to dash out and try to cover everything with fleece, but even so, the tender vegetables still took quite a few weeks to recover.

[Frosty.]

The Gfs 12z op run is similar to the 6z with an atlantic ridge toppling southeast across the uk later next week after the first trough has cleared to the east/ne but then followed by a prolonged cool cyclonic spell with a slow moving trough settling right over the uk which only slowly fills in situ, the gefs 6z mean is similar to the 00z with a persistent trough over the uk which gradually nudges further west and fills with a slow trend to warmer and drier weather as pressure rises to the east. The ukmo 12z appears to be trending towards the ecm 00z which is to suggest it would eventually slide the trough down to the west of the uk into the southwest as pressure rises to the east and we would then draw warmer SEly/Ely winds up from the near continent, as the met office update is hinting at. The alternative is for a prolonged and cool cyclonic spell with a trough only slowly filling in situ and a mix of sunshine and heavy showers with thunder and cold enough at night for widespread ground frosts from the midlands northwards. The ukmo 12z model is showing a window of relatively fine weather later in the weekend and more especially next monday for the southern half of the uk as a weak ridge pushes east across the south. Tomorrow is looking bad with gales and heavy rain spreading from the southwest to most of the uk during the day, the winds will be gusting to severe gale force in exposed parts of the southwest and the main rain band will be followed by sunshine and scattered heavy and thundery showers, only the far southeast and far north may stay dry for most of tomorrow.

Edited May 8, 2013 by Frosty039

[weather_it_will]

ECM & GFS in agreement out to day 7 on that low sliding south down the western flank of mainland UK.

But GFS has this much earlier.

And the ECM is further west.

[Gibby]

Hi folks. Here is the review of the 12 noon outputs from GFS, UKMO< GEM, NAVGEM and ECM for tonight Wednesday May 8th 2013.

All models show little overall change tonight so I will do a shorter version of the output and just highlight any differences or new trends as we go along. The pattern between now and Sunday sees little change as Low pressure moves NE across the North over the next 24 hours and is followed by a cool and showery WNW flow for all lasting through the weekend.

GFS shows a slightly different evolution tonight as early as later next week as a ridge from a mid atlantic High reduces the shower activity over the UK with some sunny spells if rather chilly conditions. In far FI the model reverts to form with a deep UK trough delivering rain and showers to all again.

The GFS Ensembles show that the operational though well supported for temperature through the mid phase was not with regard to precipitation indicating the ridge from the Atlantic High is unlikely to verify. The operational was a colder outlier in deeper FI.

The Jet Stream shows a UK based trough in the flow later next week with a Southern arm continuing to domiante to the South.

UKMO tonight shows little change from this morning with Low pressure sinking SE towards the UK at the beginning of next week maintaining the basically showery theme.

GEM keeps Low pressure in the vicinity of the British Isles through next week with rain and showers scattered about for all in average at best temperatures.

NAVGEM is depressingly similar with a Low pressure area sinking down over the UK next week with unsettled and sometimes wet weather for all in temperatures on the cool side of average.

ECM tonight is as unsettled as this morning although there is a little more warmth around on the Eastern flank of the Low centred down to the SW later next week. There would be showers or rain at times for all and with the addition of warmth into the mix towards the end of the run the showers could be upgraded to thundery status in places later.

In Summary the weather remains in an unsettled state as Low pressure drifts down from the NW next week. There are differences between the models on positioning of the Low pressure and a few moderations tonight on the effects of this over the UK in the upcoming period but the general message is still the same as much Northern blocking looks like keeping Low pressure close to UK shores for some conssiderable time to come.

[Frosty.]

Well, although less successful on this run compared to the Ecm 12z last night and 00z this morning, the 12z ecm is still trending in a similar direction with the main body of next weeks trough further west in the atlantic and some draw of warmer air coming up the eastern side of the uk and into the north in particular, this run is rather close to how the met office described on today's update with a signal for warmer, drier and brighter weather for the north towards the end of next week with high pressure to the northeast  but probably remaining showery elsewhere with generally lower pressure, so, the trend is still there but the execution on this run is not as good but if the overall trend for the trough to be modelled further west continues, we could see a nice warm up in the near future with high pressure building to the east/ne.

[Purga]

Colossal Northern blocking on offer from ECM 12z

 

 

With cold uppers entering Scandinavia - looks like cool and unsettled for the UK as Low Pressures are pushed right across us.

 

[Purga]

A mean looking mean from GFS & ECM for those seeking warm and dry conditions

 

 

[Summer Sun]

Colossal Northern blocking on offer from ECM 12z

 

 

With cold uppers entering Scandinavia - looks like cool and unsettled for the UK as Low Pressures are pushed right across us.

 

 

Don't see it becoming that cold TBH the ensemble mean suggests milder air will stay over us and most of Southern & eastern Europe

 

Edited May 8, 2013 by Gavin.

[Guest pjl20101]

Apologies for the lateness but it very much looks like a similar scenario to Tuesdays setting except the high atmospheric pressure appears closer and I think its to do with the MJO going into phase 5 and 6. Here is the average chart from the CPC 8-14 day chart:

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

Think we need to keep an eye on this model at all times if we can.

[johnholmes]

pj it is not a chart of 'atmosphereic pressure'

the chart shows the anomalies and heights at 500mb along with the predicted contour lines at that height

[William of Walworth]

Test post -- I've had big issues putting up any posts on here lately.

Just starting to follow the model output thread for this summer. Thanks in particular to Frosty's and Gibby's recent posts which for this amateur offer summaries and interpretation in nice useful measure.

Faint hints on some output of the trough retreating further from us could be something to watch in coming days, to see if those signals disappear or strengthen ....

Edited May 9, 2013 by William of Walworth

[snowmadchrisuk]

Very Unsettled GFS 00z , With Rain or Showers on every single precipitation chart from 0 hours to 384 hours .... Hopefully we can get out of this pattern in time for the next Bank holiday at the end of May  . 

[William of Walworth]

I was hoping in time for the weekend of Saturday 18 May! But that's looking far to much of a wishful think right now, from that GFS model agreed.

Edited May 9, 2013 by William of Walworth

[mushymanrob]

here we go again.... time to write off summer?... :lol:

[Summer Sun]

With the NAO looking like its heading back into negative territory once more with northern blocking becoming re-established (red lines below the black line for those who don't know) we are certainly going into an unsettled period so far the rainfall for many isn't looking as severe as it was last year and hopefully that will remain the case and this blocking won't last too long

 

[Frosty.]

On balance, there is still a window of fine weather for southern britain next monday and possibly tuesday in the far southeast due to weak azores/atlantic ridging but apart from that it looks cool and unsettled, there is good agreement at T+144 hours for a cool cyclonic pattern to be in total control, the gfs has backed off from it's atlantic ridge idea for later next week and keeps cool low pressure over the uk, the ecm 00z also shows a cool cyclonic outlook although the trough is centred rather further west which allows milder/warmer air to push north on the eastern flank of the trough with some warming at T850 hPa but for most of the next few weeks it looks unsettled with sunny periods and widespread showers, some heavy and thundery with hail, and occasional longer spells of rain. Temperatures struggling into the low to mid teens celsius across southern britain but colder in scotland although as the sun is so strong now, in any sunshine it will feel pleasant. The Gfs 00z later in FI shows the trough filling and slowly being shunted northwestwards into the atlantic with a large high pressure block over mainland europe bringing a slow change to warmer, drier and sunnier weather during late may, this also has good support from the Gefs 00z mean.

Edited May 9, 2013 by Frosty039

[Gibby]

Hi everyone. Here is the report on the 12 midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Thursday May 9th 2013.

All models show a familiar and distinctly unseasonal feel about them this morning as we look like we are staring down the barrel of a sustained unsettled spell this morning. The current deep Low pressure over Ireland will sweep Strong to Gale SW winds and heavy rain across the UK today with heavy showers following into the West later. By tomorrow the winds will be less strong and more from the West but still with plenty of showers rattling through on the breeze, especially later as a further showery front blows across the UK from the West. The weekend too looks cool and breezy with some showers for all but probably with a drier interlude in parts of the sheltered South on Sunday.

GFS then takes us into next week with another deep Low pressure sinking South down over the UK from the North with a spell of strong winds and rain gradually being replaced by sunshine and showers again in the rather cool Westerly then cyclonic flow that follows. Then after a few days of less windy though still showery conditions the cycle repeats itself again through FI with yet more Low pressure to the NW spreading further unsettled weather across all areas gradually relaxing SE to a positions near the SE by the end of the run.

The GFS Ensembles show an unsettled and uninspiring set this morning with rain on most days with temperatures little better than normal and often somewhat below.

The Jet Stream shows a NE flow across the South at present which weakens in the coming days as the main arm ridges High in the North Atlantic. Next week it turn sharply South then equally sharply back North to the East of the UK leaving the UK in a deep trough hence the unsettled weather shown by all the outputs.

UKMO today has Low pressure well in control of the weather next week as it sinks South down the western side of the UK. There would be plenty of showers around but some brighter and drier interludes too, especially in the SE. There could well be some longer spells of potentially thundery rain near the Low centre. Winds are shown to be cyclonic light to moderate.

GEM today continues to show it's version of events as very similar to the others dropping deep Low pressure down over the UK next week where it steadily fills in situ before being reinvigorated by reinforcements from the NW. So rain or showers would occur nationwide in this pattern with temperatures no better than normal.

NAVGEM today shows Low pressure slipping South over the UK next week and away to the South later. However, it maintains a slack pressure gradient over the near continent and the UK with a slack Easterly wind with thundery showers or rain at times in temperatures recovering a little later.

ECM finally is probably the worst of the lot if it's dry and fine weather your after as it sinks the Low down over the UK next week as the others show. However, it holds it in quite a deep format near SW England before it moves East and then North towards Eastern England as still a deep and wet feature with copious rainfall and cool conditions dominating in fresh cyclonic winds. With high pressure strong over Scandinavia and further Low pressure off the Southern tip of Greenland the UK looks like remaining the home turf for further Low pressure after day 10.

In Summary today it remains a very unsettled and relatively cool set of outputs. In honesty they are so bad it's difficult to find anything to cling to in hopes of any new emerging trend. The only saving grace is that it is May and in any bright, sunny intervals between the showers and outbreaks of rain (and there will be some) it won't feel to bad but if it's a sustained dry and warm period that your after I would skip this morning's outputs and hope for improvements and a changed trend over the coming days.

[Purga]

here we go again.... time to write off summer?...

Not surprising that METO are going for colder than average conditons for the foreseeable.

 

The GFS ENS show a solid cooler than average picture with little indication of any dry warm weather

[Tamara]

Essentially what we have is a continuation of the semi permanent pattern that has been in place for a few years now that have helped our winters for snow and cold potential (for those of us who have wanted this) but have ruined the late Spring and summers with heavy downpours and cool winds.

 

It is only May and the longwave patterns often evolve differently into summer but one wonders if the traditional summer seasonal development of the jet stream moving north and the Azores High becoming more prominent is being overriden by larger scale and longer term cyclical negative (cooling) feedbacks.

 

That discussion belongs elsewhere, but trough disruption and a southerly tracking jetstream are now as much a feature through most of the seasons it seems, and the models classically display these synoptics once again atm in terms of the upcoming week or two.

 

I would think that once the polar vortex completely breaks up as the stratosphere assumes it summer state, then the energy supply being drained from the Canadian arctic as part of this break up process, will be dissipated. But at present it is invigorating the jet stream due to tightened thermal gradient as our latitudes to the south of us warm seasonally, and sending the current and upcoming low pressure SE'wards across the atlantic towards us as pressure rises once more over the pole. However, whether the jet stream eventually returns further north thereafter on a more sustained basis we will have to see, whatever the t/c's might suggest?

 

Its been a long time since there has been a settled spell of any real duration. Possibly Spring 2012 was the last one, and at present there is certainly no sign of another one for the foresseable future at least.

[Alexis]

I also wonder what the signal was that made the models ditch the strong high pressure we were supposed to under right now. Monday's warmth was supposed to be just the start of a settled spell according to what they were predicting 10 days ago.

[Polar Maritime]

I also wonder what the signal was that made the models ditch the strong high pressure we were supposed to under right now. Monday's warmth was supposed to be just the start of a settled spell according to what they were predicting 10 days ago.

 

The models at 10 days out are always subject to change, I don't recall there being solid agreement anyway for the projected settled few days at the beginning of next week. One thing is for sure, the next 10 day's look very unsettled wet and windy from Atlantic driven weather fronts.

Edited May 9, 2013 by Polar Maritime