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Despite the positive comments above it would appear to me that GFS aside there has been a considerable downgrade from the Euro and UKMO in terms of support for pressure to build for more than a day or two.

The 21st of August has seen the first dustings of snow in Siberia And we're off......

Today sees the start of the transition to a period of much cooler and unsettled weather, with the upper trough to the NW/N becoming the dominant feature.With this in mind the immediate priority is to firm up the details of the weather over the coming Bank Holiday weekend. The current NH profile As can be seen on the 0300 WV image it is currently pretty cloudy over much of the UK with the cold front and band of rain over southern Scotland. This will track slowly south east during the day leaving cooler and showery conditions in it's wake. But further south of the front which is still in th warm and humid air, where the cloud breaks it will get very warm. All resulting in quite a latitudinal contrast across the regions. Overnight and through Thursday morning the front and rain continue their travels, the latter pepping up for a time, before clearing around lunchtime leaving the whole of the UK in an unstable and cooler north westerly. Thus some heavy squally showers , concentrated more in the west and north where another system involving a wrap around occlusion has arrived on the scene. The occlusion also sinks south east through Thursday evening introducing even cooler air so that Friday becomes quite an unpleasant day with a fresh north westerly and frequent showers, and possibly some light frontal rain effecting the south west during the evening, with temps below average. Lighter winds on saturday as a transient ridge passe through but still some showers around and another cool day. But out to the west the next quite complex system is getting organized and is moving east. And by 1200 Sunday the low is 992mb south of Iceland and the array of fronts has brought cloud and rain to western parts of the UK which will move east, albeit becoming quite patchy. Another quite cool day with temps possibly a little below average. And the NH profile at T120

The Gfs 12z operational shows a north / south split develop next week onwards following the cooler unsettled spell with most of the unsettled weather affecting northern uk whereas the south has higher pressure at times bringing predominantly dry, bright and warm conditions, especially further s / se but even further south is not immune from some occasional rain. For what it's worth I think the extended outlook will become a lot more settled as the 6z mean showed and exeter's latest update which is again excellent longer term for those of us hoping summer is extended to mid september at least!☺

Agree with all this except to add - such a patten is a nailed on heatwave at the end of June, but at the start of September its all about the feed. A little easterly feed can be either warm or cool by then. Settled yes, but temperatures to be confirmed I think.

Here's the forecast based on the 06z GFS Rolling CET... Anomaly to 81-10 rolling avg (Daily Avg: Anomaly to 81-10 daily avg) 18.1C to the 22nd... +1.3 (19.1: +2.6) 18.0C to the 23rd... +1.3 (16.1: +0.0) 17.8C to the 24th... +1.1 (12.8: -3.3) 17.6C to the 25th... +0.9 (12.4: -3.4) 17.4C to the 26th... +0.8 (13.8: -1.9) 17.3C to the 27th... +0.7 (14.0: -1.4) 17.1C to the 28th... +0.6 (13.2: -1.9) 17.0C to the 29th... +0.5 (13.3: -2.0) 16.9C to the 30th... +0.4 (12.5: -3.0) 16.7C to the 31st... +0.3 (12.6: -2.6) A big cool down is now within the reliable time frame. While unlikely to break any records or even get into the 10 coolest days for any individual day, the final 8 days (13.1C) on this mornings 06z could be the coolest since 1986 (12.1C). It could also mark the biggest drop in temperature between the first and last week of August (6.7C), well above the previous record of 5.6C in 1982.

Not sure i necessarily agree. EC clusters all high pressure dominated at day 10, staying that way right out to day 15: Met Office update also reflects this too, so reasonable confidence in some decent weather as we head into september - once we get the chilly and slightly unsettled bank holiday out of the way.

Euro develops a trough near northern Siberia in about a week with -10 air so worth a look then.

And for balance, the min chart for the same time. Also, it’s predicting 30 for London on your chart, hardly widespread.

Tide is always against sustained settled conditions once we hit September - a week or two is feasible, but anything longer is quite difficult to achieve, compared to the March- July period. Factors which make it more difficult include the powering up of the jet, and unknown hurricane activity (which incidentally mind is forecast to be low this year - but one storm can throw things into chaos). In the short term - unsettled and significantly cooler for all, the first northerly I believe since April..As we approach September, yes strong signal high pressure will anchor itself over the UK and most probably ridge NE to scandi. I can see early Sept being a very trying period model watching with not much happening (September is the most uninteresting month for model watching and weather enthusiasts in my opinion - 'wake me up when September ends'..)

What a boring summer for storms this is. Utterly applling

Fair enough Mike . Time will tell mate . Back to this week and the Gem is showing some quite low temps sat night / sun morn . Could be the first ground frost for a while .

I've started this thread a bit earlier than usual, namely due to the forecasted chilly nights expected Friday and Saturday with an outside chance of ground frosts in frost prone spots, who knows Highland location could get down to 0 degrees Sat eve, especially if the ridge builds in sufficiently later on under what will be very cool uppers and light winds. Please use this thread to predict first ground and air frosts of the season - and record your first ground and air frost. Ground frosts before late September are an exception for many away from sheltered northern valleys and glens. Here we tend to record our first ground frost by last week of September, and out first air frost by middle of October. Some years we have had to wait longer, others earlier. In 2012we got down to -3 degrees on the 23 Sept or thereabouts. Some years we have had to wait until November for our first air frost , 2006 springs to mind. I'll keep resurrecting this thread whenever the threat of frost is forecast - it often gets lost as we move further through Autumn, but I will certainly keep it alive..

As we say in winter, get the cold air in place first and then look at snow potential..in the case of the Ecm 12z..get the high in first..worry about the uppers later.

Some odd comments in here today, almost as if some people are subject to cold bias! Even if it isn't winter. Cut right to the chase ECM at T240: On the money as per warm, possibly very warm and settled start to September. Let's go back a bit, T120 bank holiday Monday: Give a more settled bank holiday to the SE, less so further north, and not very warm. Back to the T240 charts, and as well as the ECM we have this from the GFS, GEM and FV3:

Through this evening and overnight the cold front continues to track south east with the rain belt pepping up somewhat in the early hours whilst further north the occlusion will bring further rain to N. Ireland and western Scotland by midnight which will also track south east but fragmenting a little in the morning. Still quite a warm and humid night in the south east but markedly cooler elsewhere. 1500 UTC

The GEFS 6z mean strongly supports a warm anticyclonic extended outlook.☺

Yes, if I'm not mistaken, both the GFS, UKMO, and to a certain extent the ECM, don't show such a clear cut progression to high pressure. The former in particular only show high pressure properly influencing a few days at a time, interrupted by spoiler lows or digs down from the northwest. To me that sounds quite similar to this August.

Another historically great thread. My favourite time of the year is approaching!

The ensemble data is from CFS, downoloaded from here: http://nomads.ncep.noaa.gov I did the chart by myself so at the moment it is only on our server, but hopefully it will soon be possible to interactively add more ensemble data to the chart at http://weatheriscool.com/index.php/stratosfaren-zonalvind-10hpa-60n-gfs-ens/

I'd love to see one in the western dry states (is arizona west?). It's been a long time since I witnessed a rain'less' thunderstorm. It's been a long time since I witnessed a thunderstorm in fact

For ‘more balance’ as temps are normally undercooked by 1-3 degrees that would take many more places above 30*c.

I hope your early suspicion is correct!

I don't agree Ice Cold, they've been showing variably at day 10 yes, but the change happened yesterday, I think. ALL the main models were showing basically the same evolution at day 10, the ensembles and clusters since have followed suit (see earlier posts from others), and of course today the Met Office update is totally behind it too, I'd be amazed if a warm, or very warm settled period didn't happen in early September. And this illustrates something I find interesting re the models, what time is FI? As of now, with the upcoming high pressure slow moving systems, and cross model agreement, it's day 8+. In winter, with possible snow scenarios on the cards it can be less than day 4. What makes the model watching interesting!

These charts have been stuck at Day 10 for the past 5 days mike . They don't seem to be getting closer ? It's suits me fine because I'm ready and waiting for autumn . Quite cool 850s at day 9 especially Scotland

Could do with a month or two of hot days (with storms thrown in of course). Not ready to say goodbye to the summer yet.

Best day since the end of the heatwave. The drier airmass over the continent has drifted far enough north to influence most of the region. A high of 26c with the humidity dropping below 50% for the first time in days.

I tried to add some more members from recent cfs runs (all members from last week) and its quite clear that according to cfs the vortex will get a tough start of the season. Interesting to see such an impressive signal and will be interesting to see how it verifies.

Been a bit quite in here today think summer is dying a slow death !! Time for autumn early autumn heat- this is surely the most agreeable type of heat, warm enough still for the hot brigade - and not too hot for all the oh my god my flat is too hot and never cools down contingent on the other !! ??

You might wish to avoid the GFS maxima forecasts for sunday. Minima are still pretty cool when the high tries to ridge. That keeps the daily mean down.

Yes, agreed, but we're not even into Autumn yet, ECM ensemble means from 12z suite, still looking very promising for a warm up, here T192,T240 Difficult to to tell much from the mean plot, but I can't see any reason the warm up is not the form horse based on today's output.

Agreed.

850s are generally between 4C and 6C though... classic conundrum chart for the time of year, slightly more SE input and its a very warm set up, but if an easterly element gets in, the sun is no longer strong enough to warm us up alone and we stay slightly chilly (as I suspect happens here) . Would not want to call this one yet - settled yes, warm don't know.

Both this evening's fax and the ecm has the UK in a light north westerly at 12 Saturday with some showers around. Twenty four hours later fronts from the system to the west have brought cloud and rain into western areas The front is quite active and develops a couple of little waves as it traverses the UK rather concentrating any rain over N. Ireland, Scotland and the south west of England in the early hours of Monday.

Really unpleasant late August day,very humid,heavy cloud,little breeze...nothing to like at all. So looking forward to those fresher conditions pushing in,a lovely change. Bank holiday weekend looking good as well,bit of rain,no washout but so much fresher,very nice!

Every year, snow-patch enthusiast Iain Cameron conducts a survey of the snow surviving into the summer on the Scottish mountains. This year there’s a bit less than usual. https://www.tgomagazine.co.uk/news/2018-summer-snow-survey-reveals-a-low-snow-year-for-the-scottish-hills/

Gusts up to 196MPH reported. Governor David Ige‏Verified account @GovHawaii #HurricaneLane 11PM update as of August 21 maintains strength of Category 5 with winds 160 mph, Gusts 195 mph, 350 mi SSE of Hawaii island. If you haven’t done so, I urge you to prepare and plan now: http://dod.hawaii.gov/hiema/ #Lane #HiGov #HInews JD Rudd - News5 ☈‏Verified account @jdrudd #HurricaneLane is bigger than the entire state of Ohio. .-.-.-.-.-. Let that sink in for a second. Now imagine that thing swirling around and around with wind speeds over 150mph. Wow.

That's a very good question. I do not have that much experience of the cfs, but it is of course a bit suspicious when more or less all the members behaves like they do in the chart above. I also found this link(http://www.nws.noaa.gov/ost/climate/STIP/FY11CTBSeminars/jperlwitz_092210.htm) where they confirms that there is (or at least used to be) a bias towards weaker polar vortex states in the CFS so the data should be used with great caution. In this case I think it would have been nice to use some kind of model climate (instead of "real" climate) for comparison to get a more realistic signal.

A nice trout in the dour I hope you can see it.

18.0 to the 21st 2.1 above the 61 to 90 average 1.2 above the 81 to 10 average __________________________________ Current high this month 19.9 to the 6th Current low this month 17.7 to the 1st

Indeed it is would expect some elevated storms with good lightning which are very dramatic around the canyon rim

Hoping to rectify my drought with some Arizona action this weekend

Yes it does Karl, this spell looks good to me as practically nailed on now, so it's a case of counting it down on the model runs, as slight changes in the location(s) of the high pressures will undoubtedly change, but the broader scale evolution probably won't. Have to say that T240 chart you quote reminds me of the charts at the outset of the main heatwave starting late June, with the jet north allowing break off high pressures from the Azores. That lasted weeks, I think there's a chance this spell will have some longevity too, although obviously the sun is less strong now. Let's see!

Tonight's Ecm 12z ensemble mean ends on a high note..literally!☺

No change at Kilauea KILAUEA VOLCANO (VNUM #332010) 19°25'16" N 155°17'13" W, Summit Elevation 4091 ft (1247 m) Current Volcano Alert Level: WATCH Current Aviation Color Code: ORANGE Kīlauea summit and lower East Rift Zone The lull in activity at Kīlauea Volcano continues. At the summit, seismicity and deformation are negligible. On the lower East Rift Zone, the only incandescence is at the coast near Ahalanui where a few ocean entries are oozing lava. Sulfur dioxide emission rates at both the summit and LERZ are drastically reduced; the combined rate is lower than at any time since late 2007. Earthquake and deformation data show no net accumulation, withdrawal, or significant movement of subsurface magma or pressurization as would be expected if the system was building toward a resumption of activity. The Hawaiian Volcano Observatory (HVO) will continue to closely monitor Kīlauea’s seismicity, deformation, and gas emissions for any sign of reactivation, and maintain visual surveillance of the summit and LERZ. HVO will continue to issue daily updates and additional messages as needed. The next status report will be issued tomorrow morning unless significant changes occur.

Summer to me is an assault on the senses, its not based on sunshine and heat alone. So whilst we can get late heat, its only part of the banquet that is true summer to me. Seeing the greenery and flora Hearing the screech of the swifts Smelling the scents of the blossoms Feeling the warm air on bare skin.. Sorry guys, im alive ! Lol . So even if we do get more heat, its only half of the meal.

Like a hardened crackhead I'm now browsing buienradar.nl to work out when I might get my next fix of the flakey white stuff!

snow over southend alligned to SE London / SE essex may see a covering out towards surrey when it tracks through my house is by the M20 sign everywhere shut

3 inches & growing fast

Just got ba back from sledding with the kids absolutely brilliant never in my wildest Dreams did i expect this amount of snow this morning it's snowed for three hours now on sheppey am I being greedy if I wish for more later. lol