Temps into low mid 20's early next week before a return to mid teens

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Hi everyone. A little late today but here is the report from the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday September 17th 2013.

All models show a cool and unstable airflow over the UK with a wave depression running SE then East across Southern and SW areas of the UK through the day with a period of rain, sometimes heavy here. The North and East will continue bright and showery and all areas away from the far SW will be cool. Tonight sees changes as the rain steadily clears East out of the South tomorrow with rising pressure over the UK to give a dry and bright day tomorrow with just isolated showers here and there in the North. Through Thursday a new depression will be crossing East to the North of Scotland with it's fronts crossing the UK with rain followed by clearer weather again with a few showers in the NW. It will become somewhat less cool. Friday should be a dry and bright day for most with just isolated showers possible in the North. Then on Saturday winds back SW and warm and moist air is filtered NE on a warm front bringing low cloud and drizzle for a time to many parts to start the weekend, especially in the North and West. By Sunday this is shown to be pulled away North with skies breaking over the UK with some warm or very warm sunny spells developing on Sunday as High pressure centres close to the SE.

GFS then shows a sustained fine spell for quite a while in the second half of it's run with dry, bright days with misty and sometimes foggy nights. Late in the output Low pressure from the Atlantic does gradually exert it's influence towards Northern and Western Britain and the strongest warmth late in the weekend and start of next week does ease away but all in all not a bad GFS operational run today.

UKMO shows warm SE winds wafting NW over the UK from Europe with High pressure close to the SE. Most if not all areas would be fine and warm by day with sunny spells and patchy mist and fog problems overnight.

GEM is very anticyclonic today with High pressure having arrived at the weekend sustained for the rest of it's run close to or over the UK with fine and quite warm conditions but again with fog problems quite hazardous overnight, slow to clear in the morning's locally.

NAVGEM paints the same picture with High pressure dominant over the UK at the start of next week.

ECM also shows High pressure over the UK dominant next week before it shows signs of slipping further North later next week with fronts queuing up to the SW with rain knocking on the door of the far West late next week. As with the other output fairly warm conditions by day would be balanced by cool and misty nights and mornings.

The GFS Ensembles show a distinct and sustained period of above average uppers from the weekend and through next week only easing off to more average levels at the end of the run. Rainfall is very limited for all areas as the High pressure becomes influential picking up a bit in quantity at the end of the run as low pressure battles the high for supremacy. With such mild uppers above and radiation loss under clear skies at night mist and fog near the surface could become quite a hazard night and morning.

The Jet Stream Ensemble show the current NW to SE flow over the UK backing over the next few days SW to NE as well as being pumped north clear of the UK at the weekend and through much if not all of next week.

In Summary a settled spell is on the way. We have more or less universal support now for a spell of fine and potentially warm early Autumn weather next week though we will be reminded that we are now into Autumn by the chance of extensive mist and fog problems night and morning almost anywhere. High pressure is shown by all models to settle over or near the UK for quite some time this morning with the longer range models only showing incremental evidence of a potential breakdown from the West later in their outputs. So when compared to the early Autumn type weather at the other end of the spectrum that we will all experience through the remainder of this week it is a good example how September in the UK can offer some diverse and wide ranging of weather types. 

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Thank you Martin.

Unsettled it remains...Not too warm after I hope..Do not need cold catching weather...

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That's how I see it as well if the way the models show the HP moving position pans out in the way shown.

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Phew that's nice.

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Well the GFS 00z would keep many of us in the high teens to low 20's right out to the end of the month

ECM is even warmer out to day 10 - a real stunner of a run.

If only it didn't all hang on not only a tropical system but also that system dropping some energy to our SW - that's two things that the models tend to struggle with, combined into one short period.

The good thing is, any corrections so far have been in the direction of a stronger ridge being generated and a bit more residual energy to the NW to slow down or prevent any retrogression towards Greenland, which I'm totally fine with until later next month

Here's hoping a very fine Indian Summer is upon us from the weekend, even if we do end up contending with some morning fog (which it has to be said could be dense and widespread for a time if the HP sits right over us to give very slack winds).

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Stunning output! 🤤 fingers crossed.

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ECM ensembles:

http://www.weathercast.co.uk/services/ensemble-forecast.html 

Warmish but probably not exceptionally so.

Note how the mean maximum for London is hovering in the high teens, take away the cold outliers and you'd get a mean around 20.

At least this time of year we won't get searing sun and it becomes much harder to maintain really high dewpoints.

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Those graphs are consistantly 3-5c below what actually happens for some reason. They were that wrong all the way through summer.

 

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Yes, it is quite possible to get temperatures into the mid or even high 20s in late September. Remember two years ago when we were the smallest whisker away from getting 30C in October!

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Yep I remember it well It's not over till October is out

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Speak for yourself Rob its never reached 30c here in late September or early October though it has reached 27c here but thats pushing it.

The sun has last its punch and will continue to only weaken from here on in as we move though the autumn equinox 20/21st September.

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I don't think Rob was referring specifically to your back garden

But 2 years ago it reached 29.2c at Sutton Bonnington on 30th Sept 2011, 29.9c at Gravesend on the 1st Oct and 29.3c at Santon Downham on the 2nd Oct.

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And 29.4C on the 2nd IMBY

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Good evening. Here is tonight's look at the 12 noon output from GFS, UKMO, GEM, NAVGEM and ECM for today Tuesday September 17th 2013.

All models show rain clearing the SE this evening as a wave depression clears away SE drawing back down the rather cool air over the North over the rest of the UK overnight. tomorrow shows a NW flow but rather lighter than of late with some good spells of dry and bright weather and just well scattered showers chiefly in the North. Tomorrow night looks like being chilly as a ridge crosses East over the UK ahead of a Low pressure centre crossing o the North of Scotland carrying troughs East across the UK delivering wind and rain followed by showers in the NW where gales are possible again. On Friday brighter skies will extend to all areas as winds decrease and back towards the SW later. On Saturday High pressure ridges strongly towards Southern Britain with a warm front moving NE over the UK with rain and drizzle in the west and north but little if any rain but cloudy weather in the South. It is shown to become warmer and more humid through the day. High pressure continues to build across more of the UK over Sunday with drier air imported from Europe allowing some warm daytime sunshine but with clear overnight skies the risk of fog increases. The far NW could stay cloudier with a little rain.

GFS then shows an Atlantic High pressure arch over the North over the UK and absorbing the High to the SE to lead to a belt of High pressure stretching across the UK for much of the next working week. By the following weekend cloud will increase from the West as Low pressure moves in over a weakening High pressure area with some outbreaks of rain with increasingly cooler and more unsettled weather for all shown to end the run.

UKMO tonight shows High pressure over the North Sea at the start of next week with a warm and dry spell continuing for many with sunny spells by day and the risk of mist and fog patches in rather chilly nights.

GEM shows High pressure well established over the UK next week with fine weather with light winds and sunny spells by day when it will feel quite warm and nights which could be quite chilly and misty with fog patches at times. By the end of the run the pressure is on the High pressure from both the East and West as Low pressure just about holds off over the period.

NAVGEM shows High pressure early in the week slowly declining away SE as a SW flow develops over the UK but only a little rain looking likely towards the NW with temperatures staying well up to average or a little above.

ECM shows a High pressure ridge extending across Britain from High pressure over Scandinavia with fine and warm days with sunny spells and chilly and misty nights with very light winds at the start of next week and that's pretty much how it stays with High pressure locked in over Britain with all rain bearing fronts and Lows hundreds of miles away from the UK. The weather felt at the surface will be warm and dry days with sunny spells but with an ever present risk of dense fog formation night and morning slow to clear in places. 

The GFS Ensembles show above average uppers and dry weather over the South from the end of the week for a week or so before a slow decline in conditions to more changeable weather with rain at times appears in the South by the end of the run and before in the North where the ensembles show much spread from the mid point of the run.

The Jet Stream shows the flow blowing down over the UK later this week before lifting further North in response to rising pressure from the South. It then blows on a West to East track well North of the UK next week.

In Summary a fine spell looks like affecting most of the UK from later in the weekend. As always there are differences in the position of the High centre but most output looks favourable in allowing some warm and sunny conditions for many Southern areas at least next week. Later in the output it looks like a slow decline in temperatures are likely as the erosion of the High pressure begins to take place in one form or another.

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Some amazing charts here.

http://www.jp2webdesign.co.uk/ds/gfs.htm

I can see some very nice autumn weather here. At the same time I can see the potential much later on in the autumn for a severe cold spell.

And no - I am not deliberately cold ramping.

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Of course it does require exceptional synoptics and I am not suggesting we will see anything like that. All I said was it is quite possible to get temps into the mid-high 20s at this time of year. After all 90F (32C) was recorded on September 19 back in 1926! In the upcoming spell I think 25C is not out of the question.

 

http://www.torro.org.uk/site/hightempsyear.php  <--- this list is out of date as the 2011 heatwave isn't included.

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Sensational Arctic blocking in GFS FI Far too early for that!

GFS is more progressive with the Atlantic days 5-7 than ECM, UKMO and GEM. This has singificant impacts down the line in terms of where the Arctic High goes; GFS has a big trough preventing it from heading to our NE, so it goes to our NW. Meanwhile ECM doesn't have that trough anywhere near as far east, meaning that the blocking heads to our NE and the HP cell over the UK is able to relax and have a good time rather than being attacked by a blast of Arctic air from the north.

If we do then see the large trough complex to our W/SW day 10+ as per both GFS and ECM, then we could see a very warm start to October (relative to averages). On the other hand, warm air advection could trigger a build of heights to our N or NW, leading to a very chilly start such as we see on the GFS 12z op run.

Fascinating times ahead, especially in terms of the N. Hemisphere pattern as a whole

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http://www.wetterzentrale.de/pics/Rtavn3241.png

unlike the last couple of runs GFS has a HP over us at the start of October

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Good morning folks. Here is today's look through the midnight outputs of GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday September 18th 2013.

All models continue to reflect the pattern as the past few outputs of changeable conditions with further Atlantic fronts bringing a further spell of wind and rain East across the UK tomorrow after a brief ridge brings a drier and brighter interlude today. It will be somewhat less cool. Through Friday and the weekend High pressure builds from the South with dry and increasingly bright and warm conditions affecting the South and East. After a bright day on Friday the North and West will be cloudier with some rain and drizzle as a warm front spreads warm and moist air across the upslopes of Northern and Western Britain.

GFS then shows a new High build in over the top of developing Low pressure well to the SW of Britain, extending across the UK and maintaining fine and relatively warm conditions across the UK with some cool and misty nights. By the second weekend things will slowly become more unsettled from the West as troughs associated with Atlantic Low pressure turns the Southerly drift into a stronger SW then West flow with rain at times for all for a time before fine and dry conditions return right at the end of the run as High pressure builds back once more from the South.

UKMO today closes its run with a High pressure belt across the UK with only the far SW seeing any sort of breeze from the SE. Fine and pleasant days would ensue with mist and fog problems night and morning.

GEM is probably the most interesting run this morning in that it shows High pressure over the UK with its parentage in the form of an intense High over Greenland. In addition a very deep Eastern European Low feeds a lot of very cold air over Russia and the North of Europe while in the Atlantic another deep deression has a lot of warm and moist air in it's circulation. If these ingredients came together they could make for a pretty potent and stormy spell of weather but as it is the UK lies in the void between the systems with quiet and benign conditions with mist and fog at times before some cloud and rain finally reaches the SW late in the run.

NAVGEM shows a large bubble of High pressure across the UK and Western Europe in the middle of next week with pleasantly warm and sedate conditions with sunshine by day and mist and fog at night. The far NW could be a little cloudier at times in something of an Atlantic drift.

ECM shows High pressure to the East next week with a warm Southerly drift across the UK with fine and warm conditions very likely with some sunshine especially across the South. The far west and NW may see cloudier skies later as a weak front brushes by to the West.

The GFS Ensembles today point to a warm and settled period to come before things slowly turn somewhat cooler and more chageable towards the end of the output.

The Jet Stream continues to be programmed to become pushed further North from the weekend where it remains for much of next week before indecision in output makes it's course difficult to call at this range this morning.

In Summary a fine and settled spell is still the most likely probability next week with some warm sunshine by day but with the chance of mist and fog problems night and morning. As always in the extended outlook period changes in the position of our High pressure are shown which could have fundamental effects on conditions in any one place but overall rainfall amounts will be small with only the far North and perhaps SW at risk later on. GEM throws up an interesting setup at the end of it's run which would deliver an early taste of Winter to parts of Russia and Northern Scandinavia with the UK ridge separating this from warm moist and rain laden air in the Atlantic which does make some inroads into the SW late. This is probably an outlier in isolation as it is not well supported from any other output I have seen so far this morning or at least not as extreme.

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Thanks Martin.

If GEM pans out then it would be quite a shock to the folks of Northern Scandinavia where they have been enjoying an extension of summer well into September. Hammerfest in the far north of Norway has seen temperatures reaching 15C or more on a regular basis recently.

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ECM FI brings cold air down into parts of eastern Europe and western Russia.

http://www.wetterzentrale.de/pics/Recm2162.gif

http://www.wetterzentrale.de/pics/Recm2402.gif

 

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I don't think Duane bothers to actually reads posts

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I reckon that needs an eye keeping on - Could lead to some interesting weather in October.

 

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Good evening. here is tonight's look at the 12 noon outputs issued by GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday September 18th 2013.

All models show another depression steaming over the Atlantic to the North of Scotland carrying a system of troughs over the UK tomorrow with a spell of cloud, wind and rain for all before brighter skies return later in the day in milder air than of late. Through Friday, the weekend and the start of next week High pressure will build across the UK from the South, taking its time to reach the North with a few more days of cloud and drizzle here before fine and dry weather extends up here as well early next week. With warm air over the UK the temperatures should comfortably reach the low 20's in the afternoons in the South but nights will be cool with mid single digit minima and an increasing risk of fog as winds stay light, slow to clear in the morning.

GFS then shows several more days of fine and settled weather as High pressure just slowly ambles East of the UK with a Southerly flow developing in the West. However, any rain from this is very limited in its spread Eastwards with te High to the East holding ground and warding off any major attacks from the West of any wind and rain and maintaining a lot of dry and benign conditions especially in the south and East.

UKMO shows High pressure close to the SE on Monday with fine and warm conditions away from the far NW. by Tuesday a new High builds in from the Atlantic lowering the temperatures somewhat as fresher air moves in with fine and bright days continuing but with mist and fog by night in rather chilly conditions.

GEM tonight maintains High pressure over the UK only slowly slipping SE later in the week maintaining a ridge back up over the UK from the SE. Though temperatures may fall a little later in the week as the warmest of the air leaks away the weather will stay generally pleasant and benign with bright and dry days with some sunshine and cool and misty nights with some fog patches.

NAVGEM too looks very similar as High pressure is shown to lie across the British Isles for much of next week with fine and bright days and the aforementioned mist and fog at night.

ECM shows a temporary blip through the middle of next week as a Low crosses by to the North and sends a rain bearing trough across the UK before the return of high pressure builds up from the SW again late in the week.

The GFS Ensembles show good support for a fine and warm period through next week with a slow decline in temperatures as the week ages with more changeable and cooler conditions arriving for most by the end of the run.

The Jet Stream is scheduled to move North through the rest of the week to the North of the UK where it remains for some considerable time. The pattern in the longer term is far less clear tonight and not worth commenting on.

In Summary the weather is set to become anticyclonic over the weekend and for much of next week. There is a blip shown by ECM through the middle of next week as an Atlantic Low and fronts brush by but this seems the exception to the general rule of fine weather continuing for the reliable timeframe albeit the warmest conditions by day will be early in the week as there is some support for temperatures declining somewhat later in the week with cool and potentially locally foggy nights throughout.

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