Model Output Discussion 12z 03/04/13

[johnholmes]

thanks GF I'll save that and have a look to see just what it is showing in terms of a check-thanks

again no idea why anyone cannot pm me, have asked Paul and he can see nothing, WIB has found he can pm me!

Of course we can all disagree with one another and also what UK Met push out but not sure what you mean you are disappointed Frosty? Surely they have a better handle on things than we can hope to get. Why not e mail them with your comment and ask why they have not gone the way you suggest. Not a daft question but it may help explain things to us all?

[Frosty.]

Of course we can all disagree with one another and also what UK Met push out but not sure what you mean you are disappointed Frosty? Surely they have a better handle on things than we can hope to get. Why not e mail them with your comment and ask why they have not gone the way you suggest. Not a daft question but it may help explain things to us all?

I was just a bit surprised John after looking through the gefs and ecm mean charts this morning, it suggests a nationwide anticyclonic spell eventually (beyond T+168) whereas the met office reserve the fine and warm weather for the south and east, not saying they are wrong, it's just disappointing.

Edited April 12, 2013 by Frosty039

[phil nw.]

Of course we can all disagree with one another and also what UK Met push out but not sure what you mean you are disappointed Frosty? Surely they have a better handle on things than we can hope to get. Why not e mail them with your comment and ask why they have not gone the way you suggest. Not a daft question but it may help explain things to us all?

I was just a bit surprised John after looking through the gefs and ecm mean charts this morning, it suggests a nationwide anticyclonic spell eventually (beyond T+168) whereas the met office reserve the fine and warm weather for the south and east, not saying they are wrong, it's just disappointing.

Re-reading that Frosty and reading between the lines so to speak it does suggest the rain and strong winds dying down just beyond the start of that forecast period which is 17th.

This coincides nicely with our views of a better next weekend.

As we thought it still looks like that the NW of the UK remains at risk for more changeable interludes.

Looking at the ECM mean again for next weekend at the moment confirms the high further north which suggests a window of good weather pretty widely.

However signs after into week 2 that it sinks SE somewhat allowing those NW districts in particular to come under the attack from Atlantic frontal systems again.

http://www.meteociel.fr/modeles/ecmwf/runs/2013041200/EDM1-240.GIF?12-12

http://modeles.meteociel.fr/modeles/gens/run/gens-21-1-240.png?6

I don`t think the Met outlook has changed anything really indeed very much a NW/SE split for much of the next 2 weeks as we have been saying.

[Summer Sun]

Looking at GFS this morning and the lowest temperatures become confined to Scotland later next week especially on Friday 19th 21c in the south east and just 5c to 8c at best for northern Scotland

 

 

Lots of heat building in France later next week as well

Edited April 12, 2013 by Gavin.

[Frosty.]

You summed it up perfectly phil, I jumped the gun a bit because there is mention of ground frosts returning to northern and central areas by the end of next week which suggests at least a temporary strong rise in pressure for the north but then for the anticyclone to continue to drift east which would eventually expose nw britain to more low pressure but for most of the uk it's an improving story with southern and central britain likely to become warm and settled during the last 2 weeks of april. 

[Milhouse]

Looking at GFS this morning and the lowest temperatures become confined to Scotland later next week especially on Friday 19th 21c in the south east and just 5c to 8c at best for northern Scotland

 

 

Lots of heat building in France later next week as well.

 

Thats some notable warmth for this early in the season. Hopefully the trend will continue to send some if it our way.

[Methuselah]

I'm not too concerned by the prospect of a westerly or south-westerly wind-regime...Surely, with the North Sea being so anomalously cold just now, predominantly off-shore breezes would help (in some small way) to improve prospects, later on?

[Frosty.]

The GEFS 06Z mean looks rather more like the latest met office update describes with another trough moving towards northwest britain and with high pressure holding to the southeast, so very much a northwest-southeast split on the 6z mean, the trough then makes further progress east  to bring at least a brief unsettled spell to all areas before the trough fills and pressure slowly rises but it leaves the uk and a much wider area within a slack pressure field and probably a perfect breeding ground for heavy thundery afternoon showers.

[Summer Sun]

GFS is going a different way tonight with the high building to the east setting up the potential for some warm uppers next weekend

 

 

There is plenty of heat to tap into over France as well

 

 

Another easterly to end the month?

 

 

 

 

Edited April 12, 2013 by Gavin.

[Frosty.]

A spell of very pleasant spring weather on the gfs 12z with persistent high pressure throughout FI, the main high drifting slowly to the east with a SEly flow as low pressure becomes anchored to the west and especially the southwest, no way for the low to make progress towards the uk but the result would be a strengthening but warm SEly airflow sourced from southern europe, beyond that we get colder air from northeast europe but that's deep FI. It looks like we are heading towards above average sunshine totals but a brief return of slight overnight frosts for northern and central areas by the end of next week but night time minima then trending milder once the high is to the east and winds become Sly to SEly with max temps comfortably into the 60's F.

Edited April 12, 2013 by Frosty039

[Summer Sun]

A spell of very pleasant spring weather on the gfs 12z with persistent high pressure throughout FI, the main high drifting slowly to the east with a SEly flow as low pressure becomes anchored to the west and especially the southwest, no way for the low to make progress towards the uk but the result would be a strengthening but warm SEly airflow sourced from southern europe, beyond that we get colder air from northeast europe but that's deep FI. It looks like we are heading towards above average sunshine totals but a brief return of slight overnight frosts for northern and central areas by the end of next week but night time minima then trending milder once the high is to the east and winds become Sly to SEly with max temps comfortably into the 60's F.

 

 

Sorry for the OT post but how did you get your images side by side? I haven't managed to do it since the update

[Panayiotis]

Sorry for the OT post but how did you get your images side by side? I haven't managed to do it since the update

Instead of copying and pasting the images (I think thats what you have been doing) you go on the full options and upload the images from your computer. That puts the images next to each other however they are placed to the bottom of your post therefore you can really explain what each one is representing.

 

Ignore the above, I just tried copying and pasting and it worked, so like Frosty said beneath my post, clear your history and change the BBCode. (light switch in the top left corner when you post a comment).

Edited April 12, 2013 by Panayiotis

[Frosty.]

hi gavin, did you clear your cache? and press the BBCode mode in top left of screen next to font, otherwise i'm just doing the same thing as always with the images, hope the mods are ok with this OT Post.

[J10]

http://forum.netweat...log-12th-april/

 

Latest Ski Blog now out, turning much milder this week, with a Spanish plume pushing up over the Alps.

 

So even the Alps getting in on the warming up conditions.

Edited April 12, 2013 by Jackone

[Summer Sun]

hi gavin, did you clear your cache? and press the BBCode mode in top left of screen next to font, otherwise i'm just doing the same thing as always with the images, hope the mods are ok with this OT Post.

 

Yeah done all that done a Ctrl refresh ect but no different

[Mapantz]

Yeah done all that done a Ctrl refresh ect but no different

 

You may have to do it through the web browser rather than using shortcuts.

CTRL  + F5 doesn't always work, all it does is bypass the cache in the hope it gets new information from the server, it can actually bring back the older information if the server takes no notice of no-cache headers. I suggest going to your browser options, clearing the data there and restart the browser.

 

[Summer Sun]

ECM once again builds pressure later next week

 

 

Then into the following week we get what looks to be a short lived cooler snap from the NW

 

 

By Monday pressure is starting to build from the south west once again which starts to push away the cooler winds

 

 

RE to my picture sizing problems its fine in IE 9 but its FF where the issue appears to be

[Panayiotis]

After some warm temps and high pressure on the ECM we go back to a relatively cold end, something which I feared when looking at the consistent CFS last night.

An advection of warm uppers towards the pole at 192hrs forced by high pressure in Europe and low pressure to the west:

 

This injection of warmer uppers north allows a wedge of heights to build which forces the low to the NW of the UK to move SE into Europe:

 

 

That low will continue to move SE into mainland Europe with the Azores ridging towards Greenland giving us a northerly. I wouldnt mind if this verified in January but for April, cold from the north will only result in snow showers for the North and rain showers for everywhere else.

Edited April 12, 2013 by Panayiotis

[Milhouse]

Maybe the chances of 20c on Sunday are not gone afterall.

 

[Tim Bland]

ECM FI goes with EC 32 dayer, a cool end to April looks likely IMO

[Gibby]

Sorry for the intermittent reports at the moment guys. Time is a precious commodity in my life at the moment but should be back to normal soon. No report here tomorrow morning though.

 

Good evening. Here is the report of the 12z output from GFS, UKMO, GEM, NAVGEM and ECM for tonight Friday April 13th 2013.

 

All models continue to show the process of the change to milder and unsettled weather across the UK now complete. Over the coming days the UK will be under the influence of a deep low pressure moving steadily NE to the NW of the UK. A warm front will sweep NE over the UK tomorrow bringing a spell of rain to all parts before a cold front weakens as it moves slowly East over the UK on Sunday bringing a spell of showery rain as it goes. As winds lighten on Monday a bright day with scattered showers occurs in a WSW flow before a new depressions swings past NW Scotland on Tuesday with another spell of wind and rain for all.

 

GFS then shows the midweek period with High pressure transferring slowly East across the South with troughs of low pressure moving gently East before the weekend with some showery rain for all. Then as High pressure ridges North behind the troughs towards Scandinavia a SE flow develops with reasonably warm if breezy conditions likely away from chilly and foggy Eastern coasts.Things then slowly turn more unsettled as low pressure to the South takes hold, lowering temperatures and bringing the threat of rain, especially in the South with an accompanying chilly east and later NE wind. high pressure does regain control towards the end of the run though it would still be a little on the cold side, especially at night.

 

The GFS Ensembles tonight show the operational once more well above average for the last half of the run, cooling off quickly towards the end especially in the north. Rainfall amounts are generally suppressed once we move into next week and again more especially in the South.

 

The Jet Stream shows that the UK is home to the Jet stream for the reliable timeframe as it moves NE across us over the next week or so.

 

UKMO for next Thursday has High pressure to the SE and a slack SW flow over the UK with rain bearing troughs affecting parts of north and west Britain while the South sees drier, brighter and warmer conditions overall.

 

GEM tonight also has High pressure building slowly north across the UK later next week with the wetter conditions giving way to more settled, brighter and warmer conditions later. Winds will fall light too.

 

NAVGEM follows a similar course with the NW maintaining the most unsettled conditions through the midweek period and the South and East becoming dry and warmer, extending to all areas by the weekend as high pressure sits close to eastern Scotland by then.

 

ECM tonight shows a weakening Westerly flow midweek with scattered showers largely dying out by Thursday as pressure builds from the South with warm sunshine developing for many by Friday. Over the weekend things stay set fair briefly but a invigorating trough moves across from the West over saturday night with much cooler and windier weather with showers crossing all areas by Sunday and continuing into Monday.

 

In Summary the weather has all but turned milder for all now and will continue that way for the next week or so. The models diverge in how things move on after midweek with some rather good looking charts around with some pleasantly mild conditions to be enjoyed. There are some caveats though from all models and ECM dishes up another cool end to its run with winds from a chillier NW point. So all in all although we have seen the last of the cold and unseasonal conditions recently endured we may not be stepping into summer quite yet with more typical Spring contrasts likely.

 

 

[Frosty.]

The best thing about the Ecm 12z is the brief respite it brings from all the wind, rain and cool temps across nw britain later next week, high pressure ridging in from the west and the high drifting across the north but the air would be cool and there would be a brief return of frosts but with a few sunny and pleasant days before low pressure again attacks the nw of scotland. The south and east of the BI looks like having the best of the weather from sunday with above average temps and a lot of fine and dry weather but with occasional rain as fronts push through but pressure will be higher so the fronts will weaken as a result, then we get that big pressure rise and warmer air encroaches into the far south but beyond that looks more unsettled and becoming cooler with winds veering north of west with polar maritime air with a sunshine and showers mix, it's a similar sort of run to the 00z earlier and nowhere near as settled as the 00z ens mean.

Edited April 12, 2013 by Frosty039

[lorenzo]

Interesting month ahead to see how far the extent of ridging impacts the UK, the 6-10 day mean from ECM Ensemble paints the picture quite well on the proposed warmer interlude. Out of the analog years featuring a strongly negative March AO the  second half of April 1970 the best match in terms of the build up of warmth from the south.

 

 

This temp profile is supported by the GEFS reforecast, these for 6-10 days.

 

 then 8-14 days.

 

At 144 you can see the troughing into the US is limited in depth, this was more bullish on previous runs, previously the extent of cold into CONUS drained out that pool over Greenland with a sharper drop of cold into the continent.

 

ECM 216 hrs on the 12z probably sums up what is fast becoming Aprils theme on the NW / SE split as cold spills in from the NW, less initial dilution leading to a procession of NWrly incursions.

 

In relation to the MJO the latest update clarifying that the MJO activity proceeds to the Maritimes before fading and therefore other modes of forcing take precedence, with the oscillation within the origin zone, one can project little from the base analogs for this teleconnection. 

 

GWO really is the one we need some insight on for April > May, miss having GP around for this. Anyhow had an attempt at reading the charts available and happy to be educated here, doodles corrected etc. If following the adage that the atmosphere balances itself out and what goes up must come down again perhaps some additional westerly momentum in the atmosphere over the next 14- 21 days. Have highlighted the mean flow on one chart here and also the significant torque event.

 

Wondering just how much of a Spring this is going to turn out to be if a resurgent jet is determined to fire that remnant cold at us..

 

 

Edited April 12, 2013 by lorenzo

[weather_it_will]

ECM 12z ends with cooler weather which is not what most people hoping for.

A NW wind with top temps of 4-8°C is not what most were hoping for near the end of April.

(forum bug means can't post charts)

Edited April 12, 2013 by Deep Freeze

[Milhouse]

ECM 12z ends with cooler weather which is not what most people hoping for.

A NW wind with top temps of 4-8°C is not what most were hoping for near the end of April.

(forum bug means can't post charts)

Didnt know the ECM did temperature charts. I can say for certain that most places would see double figures from that.