Model Output Discussions 12z 01/06/2017

[Frosty.]

Looking at the Gfs 6z operational, another warm fine day tomorrow with plenty of sunshine further s / se where it will be very warm / hot with temps of 27-28c across the southeast and widely into the low to mid 20's c across the rest of england and wales but with more cloud further n / w and some rain then showers for n.ireland and scotland where it will be cooler and fresher. Tuesday still looks very warm across the SE corner with sunny spells but turning cooler and fresher further n / w with a weakening band of rain sliding down across southern uk followed by brighter skies with a few showers.

The mid week period looks changeable with temps closer to average before pressure rises towards next weekend with more in the way of fine weather and temperatures recovering back to the warm low 20's celsius across southern uk.

The rest of high res looks very respectable further south with ridging, warm temperatures and a lot of fine weather but continuing changeable and cooler across northwest uk and then during low res we all see a gradual descent into more unsettled, cooler autumnal conditions from the w / nw with a very windy unsettled and cool end to the run.

Edited August 27, 2017 by Frosty.

[Frosty.]

Nobody else posting?.ok

The Gfs 12z shows another nice warm spell developing later in the week ahead which continues throughout next weekend into the first half of week 2 thanks to high pressure, the best weather across england and wales. As with the 6z op, low res gradually becomes more changeable / unsettled from the w / nw but that's well into the future...Bank Holiday Monday looks a cracker across southern uk, especially further s / se with temps into the low 80's F and plenty of strong late August sunshine. Tuesday again looks very warm across the SE corner but generally tues / wed / thurs look cooler, fresher and more changeable before that big improvement I mentioned above..enjoy the summery weather tomorrow if you're off work.

Edited August 27, 2017 by Frosty.

[Man With Beard]

Hi Frosty

Well a wonderful end to August here in the south, not bad up north so far this weekend i believe though the warmest weather likely to be restricted to the south east corner after tomorrow.

Lots of complications showing for the second half of the week and into next week too, so likely that this spell will be the last chance of the year to record a 30C somewhere. Tomorrow probably the best chance, though some serious heat is tantalising close to the SE corner by even up to Wednesday lunchtime, so Gravesend might get some surprising high figures up until then if the incoming front is held up just slightly more.

[Frosty.]

20 minutes ago, Man With Beard said:

Hi Frosty

Well a wonderful end to August here in the south, not bad up north so far this weekend i believe though the warmest weather likely to be restricted to the south east corner after tomorrow.

Lots of complications showing for the second half of the week and into next week too, so likely that this spell will be the last chance of the year to record a 30C somewhere. Tomorrow probably the best chance, though some serious heat is tantalising close to the SE corner by even up to Wednesday lunchtime, so Gravesend might get some surprising high figures up until then if the incoming front is held up just slightly more.

Hi MWB you summed things up very well, lots of complications, especially from the Ecm 12z, I much prefer the Gfs 12z solution as I described above. All we know for sure is that high pressure will be ridging in again from the southwest from thurs / fri and hopefully means another fine warm weekend to come.

Something to potentially celebrate tomorrow with the warmest late August bank holiday Monday if the temperature goes above 28.4 c and I think I've heard 29 c 84 f is achievable across parts of the SE tomorrow.

Edited August 27, 2017 by Frosty.

[Kentspur]

3 hours ago, Man With Beard said:

Hi Frosty

Well a wonderful end to August here in the south, not bad up north so far this weekend i believe though the warmest weather likely to be restricted to the south east corner after tomorrow.

Lots of complications showing for the second half of the week and into next week too, so likely that this spell will be the last chance of the year to record a 30C somewhere. Tomorrow probably the best chance, though some serious heat is tantalising close to the SE corner by even up to Wednesday lunchtime, so Gravesend might get some surprising high figures up until then if the incoming front is held up just slightly more.

Oh  good as I am indeed an adopted Gravesendian. It's been a long time since our last 30c day! Early July I think was the last of the heat here though two days of 26c and blue skies have been perfect especially falling on the bank holiday weekend

[Summer Sun]

Big changes ahead for the south especially close to 30c for some today

Struggling to reach the mid teens on Wednesday

[Frost HoIIow]

Notable how the 20C 850's are beginning to retreat further south as we go into September after being an almost permanent feature over Spain & Portugal over the last couple of months. The Northern hemisphere is beginning to go into Autumn mode.

[damianslaw]

Yes noteworthy how those cold uppers are set to descend across Greenland in the days ahead, with sub-freezing temps.. not sure whether this is quite normal for this stage in the year, but in recent years, the arctic has remained exceptionally mild well into September.

Back to the models,a very topsy turvy changeable outlook, with cool uppers moving through the UK over the next 36 hours, the SE will hold onto some summer warmth tomorrow, but will also be in the cool air by Wednesday. Nothing overly wet on the way, with fairly weak atlantic fronts, before we see a strong build of heights from the SW ridging through the country in time for the weekend bringing hopefully some dry sunny pleasantly warm conditions, but some cool nights as well possibly. Longer term, signs the atlantic will fire up, and fronts will eventually move through with a potent low pressure system possibly anchoring down, bringing with it some gusty winds and a very autumnal feel. Very much a bit of everything to start the new season.

Edited August 28, 2017 by damianslaw

[ANYWEATHER]

Evening All , hope you have had a great bank holiday ,well those England and Wales .....Sorry Scotland Anyway back to the weather, once that cold front clears southeast England on Wednesday which will prove to be a troublesome feature , we are left in some very chilly air and as the dark is growing longer than the light  there could well be some frosts up and down the uk given clear skies in the more frost prone places.  A stark contrast to the last few days of warmth.....

[ANYWEATHER]

The ten day period offers from ecm and gfs a lot of Stir crazy weather

Edited August 28, 2017 by ANYWEATHER

[blizzard81]

1 hour ago, damianslaw said:

Yes noteworthy how those cold uppers are set to descend across Greenland in the days ahead, with sub-freezing temps.. not sure whether this is quite normal for this stage in the year, but in recent years, the arctic has remained exceptionally mild well into September.

Back to the models,a very topsy turvy changeable outlook, with cool uppers moving through the UK over the next 36 hours, the SE will hold onto some summer warmth tomorrow, but will also be in the cool air by Wednesday. Nothing overly wet on the way, with fairly weak atlantic fronts, before we see a strong build of heights from the SW ridging through the country in time for the weekend bringing hopefully some dry sunny pleasantly warm conditions, but some cool nights as well possibly. Longer term, signs the atlantic will fire up, and fronts will eventually move through with a potent low pressure system possibly anchoring down, bringing with it some gusty winds and a very autumnal feel. Very much a bit of everything to start the new season.

Good point with regards to your first paragraph. No science to back my thoughts but can't help feeling that it can't be a bad thing  to have those cold uppers over our side of the northern hemisphere this early in the season.  

Edited August 28, 2017 by blizzard81

[stodge]

Morning all

No comment from the usual suspects so I thought I'd have a go.

It's once again a mixed bag from the morning output. After what may be summer's last real hurrah today with temperatures in the SE likely to peak in the high 20s, a complete reverse for these parts tomorrow with a lot of rain and temperatures may be in the mid teens at best.

The weekend looks reasonable as a long ridge of the Azores HP is encouraged NE by LP coming off the eastern seaboard of the US. That should mean dry, pleasant conditions for most with perhaps chilly mornings and fog patches inland but fine days and temperatures close to or slightly above the late Aug - early Sep values.

Into next week and things get more "interesting" as more unsettled conditions look to spread in.

The GFS 00Z OP at T+240 as follows:

With the Azores HP held out west and pushed north  by a small LP now over the islands, it's a NW'ly flow for the British Isles which won't be that warm and the likelihood of showers to northern and eastern parts.

ECM 00Z plays with an option we often see which drops the trough between a suppressed Azores HP to the SW and heights over NE Europe:

Probably fairly unsettled with rain or slow-moving showers.

GEM 00Z OP isn't too far removed from this:

While the GFS 06Z OP also seems to be exploring the idea of dropping an LP close to the British Isles in the middle of next week though perhaps further to the SW than ECM which might allow warm SE'ly winds to affect the south and east:

[Man With Beard]

Thanks Stodge

The struggle for continuity in the mid-range is also evident on the ECM ensembles today (and yesterday too):

I think most of the ideas represented by the ops are on there somewhere. 

Maybe a slight bias to ridging to our west - so maybe NW winds favoured and always the better chance of being dry the further south one is.

Beyond this into the D10-D15 period, even less certainty. Deep troughs, strong ridges, all coming up with no really sense of which one is in the supremacy. The mean chart, consequently, not of much use this morning.

[mb018538]

I think the total lack of posts tells you all you need to know at the moment. Following one of the coolest summer holiday periods of recent times, nothing of note to get excited about as we head into September. Things look decidedly average and just mundane really. No big heat, no storms, nothing cold....just average.

[ANYWEATHER]

Hello Folks! As we close summer and enter Autumn a gentle slip into the season of Autumn mists and fruitfulness  Models show this in the short term , Gfs shows changeable conditions by day ten ecm shows unsettled conditions  Either way this September is looking extremely different to the normal September , given many factors.......But any forecast given the " Disorganized Ripple Effect"   the other side of the pond ,in the ten days ahead may well be regarded as a Chocolate Teapot

[stodge]

Afternoon all

For the second day, 06Z OP has picked up this idea of a cut-off LP developing in Biscay and sending a warm SE'ly flow across for the end of next week.

To be fair, as others have said, it's a difficult time with plenty of tropical activity to confuse/bemuse/befuddle (delete as appropriate).

[Frosty.]

Dare I say the Ecm 12z ends autumnal?..seeing as the meteorological autumn starts on Friday..I dare!..roll on winter, the fun season / best season on netweather!!..dead as a dodo in here..that will change soon.

Edited August 30, 2017 by Frosty.

[stodge]

46 minutes ago, Frosty. said:

Dare I say the Ecm 12z ends autumnal?..seeing as the meteorological autumn starts on Friday..I dare!..roll on winter, the fun season / best season on netweather!!..dead as a dodo in here..that will change soon.

 

It's not dead, I'm here

The key to tonight's 12Z output is how the models handle TS IRMA which looks set to become a significant hurricane. GFS keeps it away from land and sends it recurving back north east into the Atlantic as a significant LP which sends HP over the British Isles.

ECM is very different sending IRMA into the Caribbean and then north to Florida by T+240. That means no push of HP into the British isles and LP around Iceland can be influential.

GEM is probably nearer GFS but slows IRMA considerbaly leaving it still just east of the Windward Isles by T+240.

The current track for IRMA as shown by the NOAA has it heading toward Martinique on a WSW'ly course which would take her more into the southern Caribbean.

So, plenty of confusion and contradiction and guidance in short supply but IRMA is the key.

[Sky Full]

12 hours ago, Frosty. said:

Dare I say the Ecm 12z ends autumnal?..seeing as the meteorological autumn starts on Friday..I dare!..

 

Hi Frosty - keep the place warm for a few more days because things could change very suddenly at this time of year.  These images from the GFS are 12 days away, admittedly, but go to show what could be in store before we even get to Winter.....

   

Things may not turn out like this, of course...  it could be better - or worse!  Who knows with the British weather!   Not too long to wait before things get more interesting again.....

 

Edited August 31, 2017 by Sky Full
Edit

[mb018538]

I think average just about sums it up - no heatwave, no washout, just a bit of everything.



The main arm of the jet is to the north for the moment though, with not much oomph in our vicinity. Net result is slower moving weather pattern.

[stodge]

Morning all

Changes in low-res this morning dependent on how the models treat IRMA in the medium term.

GFS 00Z OP at T+252:

This is the critical point. The GFS 12Z OP yesterday had Irma re-curving cleanly into the Atlantic as a vigorous extra-tropical feature and that had the effect of pushing HP up from the Azores over the British Isles and western Europe,.

This morning, IRMA is held by a northward ridge from the HP and instead shifts north to make landfall around Maine and passes north to the west of Newfoundland before being absorbed into the LP to the SW of Greenland. The Azores HP doesn't ridge and our weather becomes dominated by LP from the north west.

ECM 00Z is very different - here's T+240:

 

IRMA is right on the very left heading into the Gulf of Mexico as a potentially dangerous hurricane. It's prevented from shifting north by the strong HP over the eastern seaboard which steers the storm into the Caribbean and the Gulf of Mexico. A long ridge of HP is over the south of the British Isles but the Iceland/Greenland trough is gathering to push towards us.

GEM 00Z OP is different again:

As we saw with the 12Z yesterday, GEM is the "slowest" of the three models in bringing IRMA along. Indeed, the three models have stuck to their guns from yesterday in terms of track of this storm. IRMA is well to the east of the Caribbean but the HP over the Atlantic with a weak ridge to another HP over the Upper Midwest "could" mean a westerly turn for IRMA and a strike along the Carolina coast or the storm could break through the ridge.

The NHC forecast is for IRMA to turn more WSW as the Atlantic ridge strengthens putting Martinique right in the firing line

 

[karyo]

Indeed stodge, all the interest (and uncertainty) for the coming days is on Irma and the direction she will take. Obviously at this range there is quite a difference in the models. What looked like a fish a few days ago now looks increasingly likely to make landfall somewhere from the Caribbean to northeastern states.

To be honest, I can't even be bothered to look at what the pressure pattern will be in the UK next week. My eyes are on Irma!

[Frosty.]

A summery end to the Ecm 00z this morning in complete contrast to last evening's 12z which became autumnal.

Edited August 31, 2017 by Frosty.

[stodge]

1 minute ago, karyo said:

Indeed stodge, all the interest (and uncertainty) for the coming days is on Irma and the direction she will take. Obviously at this range there is quite a difference in the models. What looked like a fish a few days ago now looks increasingly likely to make landfall somewhere from the Caribbean to northeastern states.

To be honest, I can't even be bothered to look at what the pressure pattern will be in the UK next week. My eyes are on Irma!

Indeed, for Irma to be a Tropical Storm already with the very warm waters of the mid-Atlantic still to cross makes me think she/it will be a very dangerous storm in a week's time. As you say, predictions on track are varied but GFS, ECM and GEM have all maintained their 12Z projections through to this morning for the most part.

ECM is far and away the most worrying as that model takes IRMA through the Caribbean and into the Gulf of Mexico and while it's hard to be sure it looked as though New Orleans might be right in her path but that's still 10-12 days away and could very easily be wrong. Neither GFS or GEM offer much of an immediate threat to land though GFS 00Z would mean a landfall in the far NE of the US or the SE of Canada between Newfoundland and Nova Scotia and that wouldn't be pleasant.

So much also depends on shear and how the storm evolves in terms of eyewall development which will no doubt be observed by the recon planes which undertake these missions but I would already be worried if I was on Martinique for example and given how close these islands are both St Lucia and Dominica may be under threat with only a very slight shift in track.

For us, IF Irma misses land and re-curves into the Atlantic as a vigorous extra-tropical LP the path would likely pull up a lot of warm air over the British Isles and western Europe and shift the jet firmly north giving us a prolonged benign spell but if she remains a western hemisphere feature, the signs for a descent to cooler and more unsettled conditions approaching mid month are there.

[karyo]

4 minutes ago, stodge said:

Indeed, for Irma to be a Tropical Storm already with the very warm waters of the mid-Atlantic still to cross makes me think she/it will be a very dangerous storm in a week's time. As you say, predictions on track are varied but GFS, ECM and GEM have all maintained their 12Z projections through to this morning for the most part.

ECM is far and away the most worrying as that model takes IRMA through the Caribbean and into the Gulf of Mexico and while it's hard to be sure it looked as though New Orleans might be right in her path but that's still 10-12 days away and could very easily be wrong. Neither GFS or GEM offer much of an immediate threat to land though GFS 00Z would mean a landfall in the far NE of the US or the SE of Canada between Newfoundland and Nova Scotia and that wouldn't be pleasant.

So much also depends on shear and how the storm evolves in terms of eyewall development which will no doubt be observed by the recon planes which undertake these missions but I would already be worried if I was on Martinique for example and given how close these islands are both St Lucia and Dominica may be under threat with only a very slight shift in track.

For us, IF Irma misses land and re-curves into the Atlantic as a vigorous extra-tropical LP the path would likely pull up a lot of warm air over the British Isles and western Europe and shift the jet firmly north giving us a prolonged benign spell but if she remains a western hemisphere feature, the signs for a descent to cooler and more unsettled conditions approaching mid month are there.

Yes, imagine if she makes it to the gulf of Mexico where the waters are even warmer than the Atlantic! I agree in general that the main models have kept the path from yesterday's 12z but looking back the gfs has shifted a bit west hence it puts the northeast states under threat.