Model Output Discussion 18z 28/07/13

[Man With Beard]

The moment you wake up to find the fine weekend has been cancelled...

 

[BLAST FROM THE PAST]

 

That small LP that sits over Southern UK has moved NW from Germany.  Seems a bit odd that one.  There is a chance of pretty unsetled weather to come this weekend but it seems the models don't know how it will come yet.  It could be interesting especially with the bit of heat building as the week goes on, could be some localised torrential downpours.  ECM moveS the HP further to our north than yesterday and it settles to our NE bringing more pronounced easterly flow .

 

 

 

 

28c to be reached this week?  I think so

 

BFTP

Edited September 2, 2013 by BLAST FROM THE PAST

[Captain Shortwave]

Well that 36 hour period of model consistency is well and truly down the toilet, like the bank holiday, FI is well and truly when the energy starts to split so I think everything up to Thursday is still pretty safe, after that who knows but all the models have corrected the low about 500 miles further north in pretty much one run.

On the up side we have 4 very decent days coming up, despite whatever awfulness that gets thrown by the long rangers for this month, September always seems to deliver a decent spell of weather. I can't remember a September which was poor, let alone awful.

Edited September 2, 2013 by Captain shortwave

[ANYWEATHER]

Well that 36 hour period of model consistency is well and truly down the toilet, like the bank holiday, FI is well and truly when the energy starts to split so I think everything up to Thursday is still pretty safe, after that who knows but all the models have corrected the low about 500 miles further north in pretty much one run.

On the up side we have 4 very decent days coming up, despite whatever awfulness that gets thrown by the long rangers for this month, September always seems to deliver a decent spell of weather. I can't remember a September which was poor, let alone awful.

Obviously, youre young and of course there has been many Septembers over the years which have not been good weatherwise Anyway, models are showing more consistency that a breakdown in the fine conditions from Thursday onwards look likely. As to any detail at the moment, its a case of waiting to we get nearer mid-week!

[johnholmes]

There seems enough concensus with the anomaly charts over the last 3 days, not total but enough. to suggest that the upper air pattern will involve some kind of trough in the UK vicinity. Whether it will be a full blown cut off as shown below on the latest ECMWF-GFS output or the lesser issue shown below that on the 6-10 NOAA from last evening is still not clear.

http://www.meteo.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

 

http://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

 

The 8-14 shows a less marked trough but along similar lines.

[Summer Sun]

So this morning all the models are agreeing on an unsettled weekend again with lower temperatures than shown over the past few days

 

 

Longer term the far north may hang on to the drier weather with pressure highest here for the south unsettled looks favored

 

[No Balls Like Snow Balls]

A very unsettled Saturday being progged by the ECM 00Z for Southern and Central UK. Yesterdays ECM 12Z showed the majority of the rain coming on Friday, obviously at this range timing of any rain is still gonna not be nailed down.

 

 

 

 

 

Some very cool daytime temps also being forecast by ECM 00Z.

 

London Fri 16c, Sat 13c

Manchester Fri 14c, Sat 15c

Glasgow Fri 13c, Sat 14c

 

The ECM has being showing a cool down from Friday for a fair few runs now.

 

GFS 00Z also showing some very cool days at the end of this week.

 

 

 

The heavIest of the rain seems to miss most of us in the South though

Edited September 2, 2013 by No balls like Snow Balls

[Summer Sun]

Here is the latest from Gibby on the models

 

Good morning folks. Here is the report on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Monday September 2nd 2013.

 

All models support High pressure close to the South for the next 48-72 hrs as it transfers slowly East along the English Channel towards Europe. The North lies covered in a slack Westerly flow with cloud, rain and drizzle at times principally in the NW. By Thursday and more notably on Friday a trough of low pressure moves in and across the UK from the West with a Low centre forming close to SE England likely by the weekend while once the trough is passed a High pressure ridge will move in close to the North. In weather terms after several days of fine and very warm weather across the South and cloudier conditions further North the weather turns more showery for all areas for a time later in the week. Over next weekend the North would be likely to become drier again while the South maintains showery weather with limited brightness.

 

The Fax Charts show the above trend well but as the front clears SE on Friday it shows only the SE half of England left with rain at times with Low pressure developing near SE England.

 

GFS then shows slack Low pressure close to Eastern England for several days before relaxing it away to the South of the UK in 10 days time or so with rain or showers continuing off and on, especially in the South. Late in the run a new Low from the Atlantic keeps the unsettled and changeable theme going with rain at times extending to all areas in average September temperatures.

 

The GFS Ensembles are a little cooler in the South than those shown last night with a notable cool and wet slot this coming weekend for the South. Thereafter changeable conditions look like remaining with some drier interludes indicated by many members but with some rain too almost anywhere at times in temperatures relatively close to average.

 

The Jet Stream currently flowing East to the North of Britain develops an arm which pushes South over the UK and around the developing depression close to SE Britain at the weekend. This cut off low then keeps this weak Jet Stream arm in situ for several days while a new surge of energy within the main core of the flow pushes East close to Northern Britain late in the run.

 

UKMO today shows Low pressure having formed close to or over the South late in the weekend. As a result some rain and showers will affect many areas but Scotland could escape the worst spare a cool East breeze off the North sea for the East coast.

 

GEM also highlights the Low at the weekend over the South trapped in situ for several days before easing it away slowly South at the end of the run. There will be several days of rain and showers over chiefly but not exclusively over Southern Britain with the risk declining towards the far South by the end of the run.

 

NAVGEM too shows a cool pool trough over the UK at the weekend and start of next week with an upper shallow Low maintaining the risk of heavy showers or outbreaks of rain going across England and Wales especially.

 

ECM shows Low pressure over the South at the weekend gradually pulling further towards the SW with High pressure over Scandinavia bringing dry and bright weather to the North and East while the South and West remain at risk of rain at times throughout the final half of the run.

 

In Summary today we are back to where we were yesterday morning as this morning's output has reverted to maintaining some sort of low pressure area over or close to Southern England next weekend and the start of the following week. This would mean showers and outbreaks of rain in rather humid conditions for many while the north sees High pressure close by either directly to the North or NE over Scandinavia maintain the chance of some fine and dry periods here. After the dizzy heights of temperatures expected in the South and East through this week it looks like temperatures will fall off somewhat to more like the seasonal average given the large amounts of cloud expected over the UK as a whole.

 

http://www.norton-radstockweather.co.uk/Model-Analysis%282859336%29.htm

 

[No Balls Like Snow Balls]

Another cooler, wet run from the GFS 06Z for the end of the week and weekend.

not as cool as the ECM 00Z or the GFS 00Z with some warmth managing to hang on in the SE. With the heavy rain though i doubt very much it would feel 21c / 22c. Rain on Fri some heavy, with more rain to come on Sat.

 

 

 

 

 

More rain to come on Sunday

 

 

Could be looking at a pretty unsettled spell of weather coming up at the end of this week?

 

 

 

 

 

 

 

 

Edited September 2, 2013 by No balls like Snow Balls

[Captain Shortwave]

Another cooler, wet run from the GFS 06Z for the end of the week and weekend.

not as cool as the ECM 00Z or the GFS 00Z with some warmth managing to hang on in the SE. With the heavy rain though i doubt very much it would feel 21c / 22c. Rain on Fri some heavy, with more rain to come on Sat.

 

Rtavn10817.png

 

Rtavn1024.png

 

Rtavn1264.png

 

Rtavn13217.png

Yeah I have no faith in the output beyond thursday, the temperatures are a full 12C warmer in places on this GFS run compared to the 00z

00z

06z

Take a look at places like Calais in France, a 16C swing in one run!!! 14C to 30C. 

Brilliant work GFS by the way, drop the consistent output over 24 hours for 2 runs, other models back it and then

 

Move back to something similar to the output of yesterday 

Just to note this is more in line with both the GFS and ECM ens which had the low further south west than the operational outputs.

 

Edited September 2, 2013 by Captain shortwave

[Yarmy]

Did a model comparison for Saturday afternoon (Bewilderwood with the kids!), but it's a waste of time really because small adjustments can make such a big difference. 

 

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=0&ech=120&size=2

 

Genuine lol at the CMA although to be fair it seems to be showing the run from 31 Aug instead of the most recent run. Nevertheless, if people are posting CMA charts in January you'll know we are in trouble.

[pandit-scholar]

You may find the thread one poster by the name of chio runs from the end of September a help. He will give lots of links for reading and also explanations of what he is talking about. The 2012-13 link is somewhere on the site if you would like to start by reading his first post from last September-well worth reading.

Thanks very much for informing me. I have read Chio's first post, which was very interesting! Will be looking at it closely from the end of this month.

[mushymanrob]

not sure why theres so much signs if disappointment this morning, we are going to get a warm/very warm few days, before a cooler spell later this week. this was always expected. meanwhile its still possible at some point that this chart or something similar might evolve, theres good support for it, so its not written off just yet!

 

 

IF this chart (or something like it) varifies then we could well be in for some bonus heat. but this is still in fi, so no matter how many runs show it, it isnt certain just yet.

 

 

[Weather Boy]

Did a model comparison for Saturday afternoon (Bewilderwood with the kids!), but it's a waste of time really because small adjustments can make such a big difference. 

 

http://www.meteociel.fr/cartes_obs/comp_panel.php?mode=0&ech=120&size=2

 

Genuine lol at the CMA although to be fair it seems to be showing the run from 31 Aug instead of the most recent run. Nevertheless, if people are posting CMA charts in January you'll know we are in trouble.

 

I think I've highlighted some important wording of yours here.

 

Very difficult call after Thursday in the southern half of the UK as small shifts in the low's position can have a huge impact on surface weather.  We could be looking at a day like Saturday into early Sunday of the BH weekend again, on the worst case scenario.  Alternatively, if it's shifted south or south-westward it may only affect a small part of the country, or it could miss us altogether and we'll be suprised at dry weather.

 

Scotland looking much more secure with a benign outlook for the weekend (with possibly northern England joining it) on more or less any scenario.

[No Balls Like Snow Balls]

not sure why theres so much signs if disappointment this morning, we are going to get a warm/very warm few days, before a cooler spell later this week. this was always expected. meanwhile its still possible at some point that this chart or something similar might evolve, theres good support for it, so its not written off just yet!

 

Rtavn1742.png

 

IF this chart (or something like it) varifies then we could well be in for some bonus heat. but this is still in fi, so no matter how many runs show it, it isnt certain just yet.

 

 

Uh oh first sign of the heat lovers straw clutching. Must mean only one thing that winter is coming lol. Just having some friendly banter. 

Edited September 2, 2013 by No balls like Snow Balls

[William of Walworth]

Uh oh first sign of the heat lovers straw clutching. Must mean only one thing that winter is coming lol. Just having some friendly banter. 

 

 

I know you say you're joking, but you and at least one other regular contributor on this thread look like you're unsettledness-ramping

 

Not saying a spell of some unsettled weather at the weekend and perhaps after (for some areas) isn't a likely scenario, it currently looks like it from most recent output.  But nothing's nailed on yet, especially not in the detail.

[No Balls Like Snow Balls]

I know you say you're joking, but you and at least one other regular contributor on this thread look like you're unsettledness-ramping

 

Not saying a spell of some unsettled weather at the weekend and perhaps after (for some areas) isn't a likely scenario, it currently looks like it from most recent output.  But nothing's nailed on yet, especially not in the detail.

If you call saying what the models show as ramping, then guilty as charged your honour

 

Yes i like unsettled and cool weather but so what

 

Don't see why it matters what someone's preference is aslong as that person speaks truthfully about the model output.

Edited September 2, 2013 by No balls like Snow Balls

[Captain Shortwave]

GFS has now backtracked to the solution shown on yesterdays 12Z, the low parked over the Bay of Biscay

 

 

Rain still on Friday pushing north, but mainly dry on Saturday apart from a couple of showers

 

Temperature distribution is also different now, 

 

Still warm in the south east, 3 layer weather for northern england 

Saturday

Steep thermal gradient will mean the potential for a lot of rain.

 

UKMO is horrid, or awesome to those who like rain by the keg-load

 

Charts like these would produce temperatures in the mid-teens at best whilst the GFS solution

 

Yeah getting close to 30C

Going to be an interesting couple of days model watching. Toys primed 

Edited September 2, 2013 by Captain shortwave

[Captain Shortwave]

Aside from this I've noticed something interesting on the recent GEM outputs

 

 

 

 

GEM has consistently wanted to develop a strong tropical depression and move it up the western Atlantic, none of the other models are picking this up, something to watch as this could affect our weather in over a weeks time if the GEM is onto something.

[tinybill]

If you call saying what the models show as ramping, then guilty as charged your honour

 

Yes i like unsettled and cool weather but so what

 

Don't see why it matters what someone's preference is aslong as that person speaks truthfully about the model output.

i a  agree  just looking  at  the  models  after  the weekend its  looking  a  bit wet  and looking into fantasy world  its looking  like summer  over!!

Edited September 2, 2013 by tinybill

[ANYWEATHER]

i a  agree  just looking  at  the  models  after  the weekend its  looking  a  bit wet  and looking into fantasy world  its looking  like summer  over!!

The north will do best from the weekends onwards, the south ,unsettled, with some heavy rain in places , thundery downpours, but as ever this far out .caution is needed!  

[No Balls Like Snow Balls]

ECM 12Z still showing a pretty wet Saturday for many.

 

 

 

 

 

Deep FI looks particularly unsettled with plenty of troughs over or near the UK.

 

 

Feeling cool in the rain with temps of 18c in London on Sat, 12c in Manchester and 14c in Glasgow.

 

I think if the same scenario is still shown on the ECM come Weds then i think it is game on for a unsettled weekend.

Edited September 2, 2013 by No balls like Snow Balls

[Captain Shortwave]

The GFS ensembles back the op pretty well to be honest, but with every op showing a different solution at T120, confidence in any output is pretty low.

 

 

[tyson99]

Hi all

 

just wondering if any of you clever folk on here have any predictions for the weather in south west ( cornwall ) for period Friday 13th sept till Saturday 21st sept

[Man With Beard]

ECM T240 - very weak Atlantic not really getting anywhere, Azores High back in position and could push in yet again. No sign of autumnal Atlantic activity just yet. Interestingly the appearance of northern blocking "a la" winter 2012/13 but way too early to be setting a trend for the winter.

 

 

BTW - I'm seeing a lot of ECM predicted temperatures on this thread - I guess they come from the Norwegian site - I followed these temperatures earlier this year, in the winter they didn't do too badly but this summer I have found them very unreliable - for example, during the July heatwave they were often 5C or more out from the actual values at T24-T48. I'd be very suspicious of what they're saying for this weekend.