Model Output Discussion 30/06/2012

[Uncle_Barty]

We've seen these tentative signs of falling Greenland heights a number of times before recently only for later model output to extinguish that flicker of hope.

I need to see inter-model agreement and it to become consistent and within the reliable timeframe before believing it has a chance of happening before the end of the summer.

Greenland blocking will be gone in Sept anyway, for its seven month holiday before it inevitably returns next April or May.

Edited July 5, 2012 by Jim_AFCB

[Methuselah]

We've seen these tentative signs of falling Greenland heights a number of times before recently only for later model output to extinguish that flicker of hope.

Aye we have. Almost weekly, since the start of April...

[bluearmy]

hmmm ........ shoots of promise from various output today. certainly the further south you find yourself. nothing conclusive by any means but it seems that its stopped getting worse and maybe is turning for the better. those naefs blue anomolys are weaker than they've been for a while in 2 weeks time. maybe, just maybe ............

[Cheshire Freeze]

Will ask permission before posting.

Tried looking at that site for weather warnings but to no avail...all I get is a blank screen where the warnings should be. Tried on various browsers. It's a shame because the warning format used to be very well presented and informative. Don't know whether you have to be signed up to the site now to access the information?

[P-M]

From KJ over on null an update as of 18.39:

null ADVERSE WEATHER ADVISORY issued:

!! SERIOUS FLOOD THREAT - HEAVY SHOWERS & THUNDERY RAIN - Fri 6th July 2012 !! - North West England 60%, Northern England 80%, North East England 80%, Yorkshire 90%, Northumberland 80%, Cumbria 60%, Midlands 60%, North East Anglia 50%, South West 70%, S Wales 50% Elsewhere 40%

Thunderstorms have developed today across the expected areas of Northern England, and they will continue for a while this evening. A highly complex cut-off low circulation that has undergone weakening in the past 24 hours will spin back into East Anglia and much of Northern England in the next 24 hours as we approach Friday. Their is an increasing probability that the highest rainfall totals will be along the high theta-ew plume across Northern England, Yorkshire and the North East - however some high totals will also be possible across the North Midlands.

The next concern turns to the South West as model guidance continues to suggest cyclogenisis (strengthening) of the cut off low as the curculation crosses Central England and becomes stalled across the South West. This strengthening of the low and the stalling does mean that Devon and Cornwall need to be on an early alert for the potential of some high rainfall totals and resulting floods. As the low looks to intensify, their is also the additional threat of strong winds, perhaps gales with uprooting of trees a possibility. The rate of intensification and trajectory of the system is highly unpredictable and thus our confidence for South West England remains quite low. Their is certainly potential for some very severe weather though, locally extreme.

This severe weather could extend into Friday Night and Saturday Morning across the South West.

Some of the rain will be locally thundery with hail and torrential downpours across parts of South Wales, South West England and perhaps Central Southern England.

null Director/Forecaster AKA Thermohaline Conveyor

Homepage: http://www.null.co.uk

MM GFS: http://www.null.co.uk/GFS_viewer.html

GFS Ensembles: http://www.meteociel.fr/modeles/ensembles.php

*** Into The Light & Out Of Sight ***

Tried looking at that site for weather warnings but to no avail...all I get is a blank screen where the warnings should be. Tried on various browsers. It's a shame because the warning format used to be very well presented and informative. Don't know whether you have to be signed up to the site now to access the information?

Just pasted it now have a look

[Cheshire Freeze]

cheers

[P-M]

cheers

No worries mate, whatever happens happens! lol

It's going very misty here from the North Sea now, not sure what to expect tomorrow!

[ICETAB]

I'm going to st ives in cornwall next week. Am a right in saying that there is a glimmer of hope showing for this area between monday afternoon and friday. GFS looks the best bet, which is odd seens int was the ECM showing that ridge of high pressure a couple of days ago.

Not far to winter now... Lets hope its a cold one.

[Paul33]

I'm going to st ives in cornwall next week. Am a right in saying that there is a glimmer of hope showing for this area between monday afternoon and friday. GFS looks the best bet, which is odd seens int was the ECM showing that ridge of high pressure a couple of days ago.

Not far to winter now... Lets hope its a cold one.

Certainly hope so as I'll be just round the corner in Portreath next week !!!

[damianslaw]

Lots of weather to talk about in the days ahead - in these situations it is very much a case of nowcasting, you can't bank on what the models are suggesting will actually verify, the position of frontal features and the track of the low pressure system remain very uncertain. So expect sudden developments in the next 72 hours, some places could see some very nasty conditions indeed, its a very similiar worrying set up to last Thursday - perhaps not as extreme in terms of sudden flash flooding thanks to lower temps, but more troublesome in that the unsettled conditions will persist for much much longer in some places.

Further ahead - models seem keen to weaken the strength of heights to our NW somewhat which will allow a more traditional westerly atlantic assault, consequently it looks like northern and western parts will suffer the most in terms of rainfall and suppressed temps with the south and east perhaps seeing something a but drier and warmer as we head towards the middle of the month - but the overall synoptic pattern remains a very unsettled one with the atlantic trough continuing to rule the roost with a jetstream south of its normal summer position.

[Summer Sun]

Not a bad end to FI from GFS tonight but we've been here before

http://www.netweather.tv/index.cgi?action=nwdc;sess=

ECM is unsettled through-out

http://www.netweather.tv/index.cgi?action=ecm;sess=

As is UKMO

http://www.netweather.tv/index.cgi?action=meto;sess=

[Backtrack]

I'm going to st ives in cornwall next week. Am a right in saying that there is a glimmer of hope showing for this area between monday afternoon and friday. GFS looks the best bet, which is odd seens int was the ECM showing that ridge of high pressure a couple of days ago.

Not far to winter now... Lets hope its a cold one.

Seriously? I'm going next week too, Monday 9th till Friday 14th, madness!

Models looks quite good last time I checked, warm, sunny spells with the Azores high in charge for the week! No severe weather in sight for the week we go.

[shedhead]

More tumbleweeds blowing through the MDT this morning and to be fair that's hardly surprising given the latest outputs. Some broad disagreement between the big two at T+240hrs, ECM having significantly higher pressure centered over Brittany while GFS goes with yet another depression in the N Sea, but the latter looks far more likely to verify considering the background signals. Into FI any hope of ridging from the Azores has been well and truely crushed on the 00 run, with the Jet taking aim right at us and firing in system after system towards the 4th week of the month. IF this verifies, July is as dead as a Dodo regarding dry, warm and sunny weather.

ECM 240hrs

GFS 240hrs

GFS 384hrs

Edited July 6, 2012 by shedhead

[phil nw.]

Yes it`s difficult to be upbeat with such outputs Shed.

I had a look at the NAEF`s pressure Ens.and they show a persistent Upper trough across NW Europe for the next 2 weeks with the Azores High displaced further West much of the time.

http://176.31.229.228/modeles/gens/naefs/run/naefs-0-0-144.png?12

http://176.31.229.228/modeles/gens/naefs/run/naefs-0-0-240.png?12

The best we can hope for at the moment is some short drier interludes between the rain bands from brief ridges.

[shedhead]

Yes it`s difficult to be upbeat with such outputs Shed.

I had a look at the NAEF`s pressure Ens.and they show a persistent Upper trough across NW Europe for the next 2 weeks with the Azores High displaced further West much of the time.

http://176.31.229.22...-0-0-144.png?12

http://176.31.229.22...-0-0-240.png?12

The best we can hope for at the moment is some short drier interludes between the rain bands from brief ridges.

Reluctantly have to agree 100% Phil, with the $64,000 question for me now being can/will we break this pattern come August? If not then surely we will be staring down the barrel of a truely remarkable Summer, admittedly for all the wrong reasons in most peoples eyes (me included), but still truely remarkable nonetheless.

Edited July 6, 2012 by shedhead

[Thundery wintry showers]

After a dull wet day for most today, the fronts will retreat into Scotland tomorrow allowing England and Wales to brighten up with some slow moving thundery showers, and the north of England may climb to 21-23C again inland, and it's a similar story from the Midlands southwards on Sunday but with persistent rain spreading through Scotland and into the north of England.

I'm tempted to say that the GFS outputs for next week suggest a bright, showery outlook (albeit persistently cool with the north to north-westerly flow) rather than a cloudy wet one, but of course we've been there before with fronts turning up at short notice and turning two or three of the days into overcast ones. In this setup any import of relatively stable air from Scandinavia also tends to switch a bright showery outlook into a grey drizzly one for eastern areas in particular. This morning's UKMO run perhaps hints at troughs giving some rather more persistent rain around midweek.

What has certainly changed in general, though, is the delay in the arrival of the southerly tracking depressions- next week looks set to be dominated instead by a slow moving trough over Scandinavia. This does suggest that it won't quite be a washout on the scale of many recent weeks. For the convection/storm fans out there, probably not as interesting a week from that perspective with an emphasis on cooler and generally less unstable airmasses despite the possibility of some sunshine-and-showers type days.

[shedhead]

After a dull wet day for most today, the fronts will retreat into Scotland tomorrow allowing England and Wales to brighten up with some slow moving thundery showers, and the north of England may climb to 21-23C again inland, and it's a similar story from the Midlands southwards on Sunday but with persistent rain spreading through Scotland and into the north of England.

I'm tempted to say that the GFS outputs for next week suggest a bright, showery outlook (albeit persistently cool with the north to north-westerly flow) rather than a cloudy wet one, but of course we've been there before with fronts turning up at short notice and turning two or three of the days into overcast ones. In this setup any import of relatively stable air from Scandinavia also tends to switch a bright showery outlook into a grey drizzly one for eastern areas in particular. This morning's UKMO run perhaps hints at troughs giving some rather more persistent rain around midweek.

What has certainly changed in general, though, is the delay in the arrival of the southerly tracking depressions- next week looks set to be dominated instead by a slow moving trough over Scandinavia. This does suggest that it won't quite be a washout on the scale of many recent weeks. For the convection/storm fans out there, probably not as interesting a week from that perspective with an emphasis on cooler and generally less unstable airmasses despite the possibility of some sunshine-and-showers type days.

Agreed, next week does look better as far as heavy, persistent rain is concerned, indeed some parts of S Wales and SW England may not see much rain at all as winds swing into a northerly quarter. Once agan tho we are kinda trying to make a silk purse out of a sow's ear, the setup for next week is still a poor one in the overall scheme of things and if GFS is to be believed, it will be all downhill again from next weekend as the Atlantic fires up.

Edited July 6, 2012 by shedhead

[Weather Boy]

After a dull wet day for most today, the fronts will retreat into Scotland tomorrow allowing England and Wales to brighten up with some slow moving thundery showers, and the north of England may climb to 21-23C again inland, and it's a similar story from the Midlands southwards on Sunday but with persistent rain spreading through Scotland and into the north of England.

I'm tempted to say that the GFS outputs for next week suggest a bright, showery outlook (albeit persistently cool with the north to north-westerly flow) rather than a cloudy wet one, but of course we've been there before with fronts turning up at short notice and turning two or three of the days into overcast ones. In this setup any import of relatively stable air from Scandinavia also tends to switch a bright showery outlook into a grey drizzly one for eastern areas in particular. This morning's UKMO run perhaps hints at troughs giving some rather more persistent rain around midweek.

What has certainly changed in general, though, is the delay in the arrival of the southerly tracking depressions- next week looks set to be dominated instead by a slow moving trough over Scandinavia. This does suggest that it won't quite be a washout on the scale of many recent weeks. For the convection/storm fans out there, probably not as interesting a week from that perspective with an emphasis on cooler and generally less unstable airmasses despite the possibility of some sunshine-and-showers type days.

Hats off to you, in the end you were right about it being bright rather than grey and wet this week (at least in my part of the world).

My interpretation of the ECM (whilst the GFS updates) is that next week will be cooler but a gradually improving picture with fewer showers after about Monday, especially in the south, and I would expect it to be bright. The ensembles seem united in a modest pressure rise around 10-14 July which may be sufficient to kill off many showers in the south at least. Few ensembles going for a very dry picture though and it looks to be transitory affair, with a more westerly regime hereafter. ECM going for a pressure build end of FI, but we've seen that before (but not in real life, yet). A possible scenario is that that will happen, but only for a very short period.

I would expect the imposition of normal summer weather after Monday, which may be a relief for many!

[johnholmes]

I will, issue my latest 500mb check later today or tomorrow but the first signs seem to be showing of something of a possible change to the longer wave upper air pattern. Its highly tentative at the moment but IF the trend is maintained then a more westerly flow COULD develop.

The change in all 3 is quite unusual for it to happen so quickly. More in my 500mb update this evening or tomorrow.

[PubliusEnigma]

We've seen these tentative signs of falling Greenland heights a number of times before recently only for later model output to extinguish that flicker of hope.

I need to see inter-model agreement and it to become consistent and within the reliable timeframe before believing it has a chance of happening before the end of the summer.

Greenland blocking will be gone in Sept anyway, for its seven month holiday before it inevitably returns next April or May.

The greenland High and mid atlantic ridge is certainly becoming something of a semi permanent weather feature. Whereas in the past the Azores High ridging over the British Isles was more

of a summer feature, I certainly feel the summer Greenland High and a southerly tracking jet is something we will have to contend with in years to come. It does however coincide with notable

warm spring spells and late autumn spells, with a long rainy season in between.

Back on to the models and something of a minor pattern change establishing next week as we finally get rid of these wet east and south easterly winds from the continent, and a much

fresher cooler northerly wind sets in..

There will still be occasional outbreaks of rain however there will be more of emphasis on cloudier weather as opposed to wet weather. Thundery weather should die riht

down too, so that rainfall amounts should be a lot nearer to the norm for July, with the south east and south seeing much lower totals. There will be dry cool nights too

and brighter mornings before any stratocumulus develops mid morning. So whist remaining changeable, there should not be any repeats of this weekends deluge.

[bluearmy]

I will, issue my latest 500mb check later today or tomorrow but the first signs seem to be showing of something of a possible change to the longer wave upper air pattern. Its highly tentative at the moment but IF the trend is maintained then a more westerly flow COULD develop.

The change in all 3 is quite unusual for it to happen so quickly. More in my 500mb update this evening or tomorrow.

The greeny anomolys certainly seem to be pulling back a bit nw on the ens charts. nothing dramatic but then it may not take too much of a movement to allow a change. noaa cpc were discussing the possible shift east of the mean usa ridge in week two. i suspect that could be the trigger for a change in the lw trough/ridge pattern and it is certainly quite evident from the recent fi output from gfs/gefs/naefs that a more mobile west to east flow is on the cards

[johnholmes]

The greeny anomolys certainly seem to be pulling back a bit nw on the ens charts. nothing dramatic but then it may not take too much of a movement to allow a change. noaa cpc were discussing the possible shift east of the mean usa ridge in week two. i suspect that could be the trigger for a change in the lw trough/ridge pattern and it is certainly quite evident from the recent fi output from gfs/gefs/naefs that a more mobile west to east flow is on the cards

tend to agree with those comments ba-I'll be watching the anomaly charts(pc allowing) over the next 2-3 days.

[Thundery wintry showers]

I agree with the general observations and it may be a precursor to a more "traditional" type of unsettled pattern arising during mid to late July with pressure falling a touch to the north (though still only tentative signs of erosion of the northern blocking) and highest pressure transferring towards the Azores.

Whether this will result in any pronounced pattern change is open to question though- the UK as a whole could still end up similarly cool, cloudy and wet under a westerly type if the jet is strong with frequent depressions moving over, but southern and eastern areas would be near-certain to end up comparitively warmer, drier and sunnier than was the case during June. For many western areas, conversely, there is a possibility that next week may prove to be both sunnier and drier than what follows, as northerly types such as the one progged for Monday-Thursday tend not to bring as much cloud and rain in off the Atlantic.

[Frosty.]

The Ecm 00z shows a possible end to this desperately poor summer with a chance of high pressure pushing up from the south but the Gfs 06z in the same timeframe just shows a flat ridge pushing east with yet more low pressure soon following, the gfs 06z in particular has some truly miserable charts well into next week with a cool N'ly flow and showers but then we could see the jet buckle as pressure rises from spain/france extend north but the gfs continues with the miserable wet and breezy unsettled or at least changeable weather for the next 2 weeks +.

[johnholmes]

IF the 500mb charts are on to something-its too early to tell, then the unsettled westerly with low contour heights north and north west of the Uk MIGHT just allow, from time to time, the oft mentioned Azores high to extend its influence into the UK from 'time to time'. Note the phrase NOT all the time!

It really is too early to tell if this type of weather pattern in the upper air is going to develop, give it 2 or 3 days, and IF all 3 models show a similar view by then it would be a fairly solid foundation to start to build that weather pattern into.