iapennell

@Don, Yes it really does not bear thinking about. I remember October 2001 well; warm southerly and south-westerly winds dominated throughout that month and the lowest temperature I recorded at home near Nenthead, over 400 metres above sea-level in the North Pennines was a dismal poor 3C (even this October will better that with 2C). Like this month, October 2001 was not only unseasonably warm but also frequently wet. I lived in Lancaster at the time and frequently recall having to walk home in warm rain late at night after late work shifts, the weather there being even warmer and more muggy than the North Pennines. Suffice to say, I did not enjoy the weather that month! And I don't enjoy the fact that this month is set to be mild and often wet to the bitter end. This will now be the Fifth October In Succession totally devoid of any airstreams coming from polewards of 60N throughout!!!

@weatherguru14, You are correct about recent Octobers, the prevailing wind-patterns in recent autumns hardly allow it. Higher autumnal sea-surface temperatures around Britain's coasts compared to past autumns also helps discourage frost from occurring. However, I have records from my Weather Station going back 35 years and the average extreme minimum for October during the 1980's and 1990's was -3C. Most places in England used to get their first air-frost of the season before the end of October, particularly during the 1970's and 1980's. Why are old gardening books full of warnings about protecting early autumn plants such as dahlias against "September Frosts": Yes! September, Frosts, for the average English County Garden. Frost was viewed as a serious threat to gardens nationwide in September (before October). Indeed, at the colder northern location that is my home, when I very first started doing weather records as a child of 12/13 I have recorded 0C overnight 19/20 August and then -0.5C overnight 27/28 August. That was in 1982. Nowadays, of course, we struggle to get such temperatures before the start of November!!!

I note with typical disgust how the longer term forecast-pattern trends towards warmer wetter regime's as we head through October: Man Alive, this has happened for every one of the last five Octobers (which includes this one)!!!

Second October in five years without a single air-frost beckons for Nenthead, the small village near where I live in the North Pennines. In October 2013 the lowest air-temperature recorded by my AWS was a pathetic 3C, and there was hardly even a ground-frost. Five of the last seven October's have seen us dominated by mild southerlies or south-westerlies almost completely throughout (I include October 2015 for this argument as the south-easterly winds we had were that, from a southerly quarter and they wangled their way 'round to southerlies as the month wore on!) I detest the warm muggy buggy conditions these persistent south and south-west winds bring. Our new neighbours come up to the North Pennines only during holidays, but the man of the house came up on Tuesday complaining that it was "Too Stifling and Oppressive to stay in Manchester!": Manchester! Stifling! Oppressive heat?! On 17th October. This is crackers!! Meanwhile, our home has been infested with rats, our vegetable garden and greenhouse with bugs, pestilence, and blight which has rotted our cabbages, broccoli, tomatoes and cucumbers in the greenhouse. And over the last few days I and my folks have had colds. Cold dry weather helps get rid of pestilence. It also makes for some nice colours on the trees rather than the endless battering of warm winds and- at times- rain that turns leaves brown and has them off the trees before the first frosts get a look in (again, it looks like it'll be November before the first air-frost this autumn). Notice, too how in each of the last four Octobers (and in October 2011) the wind goes 'round to the South (or South-South-South-west) to bring Really Warm Air From A Long Way South during the final ten days of the month, leading to some record warm Halloweens! As if Nature is making This Point Writ Large: YOU ARE NOT GOING TO GET ANY COLD WEATHER UNTIL WELL INTO NOVEMBER!!!! Perhaps this year we will have another first as the mild South-westerlies set to Totally Dominate November - and we have to wait until December for our first air-frost of the season at Nenthead!! What a horrifying thought!!

Interesting too, is the fact that we used to have our first really sharp air frost (with a minimum of -3C or colder) by the end of October in most years during the 1980's and 1990's, yet now we have not recorded an air temperature as low as -3C in October for nine years and (moreover) it's been five years since the air-temperature really got below even 0C in October. These warm south or south-west winds go the whole hog and dominate the autumn months to an extent they never used to. They are ruthless in keeping cold weather well away. Yes, I know that October has traditionally been dominated by cloud wind and rain but there would usually be a few days when Arctic air could break into the North Atlantic pattern and (with the help of a clear night or two) bring the first air-frost of the season, often well before the end of October. There was also an interruption to the normal south-westerly pattern for much of October last year and during 2015: Fat lot of good it did as pressure dropped in the North Atlantic towards the close of both October's 2015 and 2016 and the wind slewed 'Round Towards The South. So we didn't get the Easterlies at the time in October that could have brought the best chance of cold, crisp weather and night frosts! You may also recall that last year, October's Easterlies were often associated with cloud and rain, particularly for the North East and eastern England as North Atlantic depressions rammed into the western approaches off Cornwall: You see, those Wretched Winds That Have To Blow To Stop The Earth Slowing Down can still mess up our weather and bring dank mildness in October even when they stop just short of the UK! Better that these winds (and associated depressions) are EAST of Britain, then we get Cold Northerlies : And that sadly, is all too rare (absent!!) in North British Autumns in These Globally-Warmed Years!

Extreme minimum temperatures in October for each year of the past four decades at my home in the North Pennines at over 400 metres above sea-level (with decadal averages) illustrate how starkly October has changed here since the 1980's and 1990's: OCTOBER (YEAR) EXTREME MIN (C) 1980: Probably below 0C (based on local reports of freezing fog. I was just 11 at the time) 1981: -7C reported by farm helper overnight 14th/15th October 1982: No direct records made. 1983: -8C overnight 28th/29th 1984: -3C 1985: 0C 1986: 0C 1987: -2C 1988: -3C 1989: 2C (no air-frost in October was unprecedented for our location at that time) Mean extreme minima for October in the 1980's (based on actual readings): - 2.6C For October in 1990's: OCTOBER (YEAR) EXT. MIN (C) 1990: -2C 1991: -2C 1992: -6C 1993: -8C (two nights mid-length!) 1994: -3C 1995: 1C (no air-frost in Oct but -3C had been recorded overnight 27th/28th September 1995) 1996: 0C 1997: -5C 1998: -3C 1999: -4C Average Extreme Minimum for Octobers of 1990's: -3.2C And for the Octobers of the 2000's: October (Year) Ext.Min (C) 2000: -1C 2001: +3C (no air-frost until 7th November) 2002: -6C 2003: -5C 2004: 1C (no air-frost until 11th Nov!) 2005: 0C 2006: 0C 2007: -2C 2008: -3C (the temperature has not got this low in October since then) 2009: -1C Average extreme minimum temperature for the Octobers of the 2000's: -1.4C And finally the Octobers since 2010: October (Year) Extreme Min (C) 2010: -2C 2011: 0C 2012: -2C 2013: 3C (no air-frost until 2nd November) 2014: 0C 2015: 0C 2016: 0C 2017: So far this autumn and this month nothing below 2C; judging from the medium-range weather charts nothing below 2C looks likely for the rest of this month! Average extreme minima for October of 2010's to date: -0.1C So quite a climatic shift for North Pennine Octobers!

To add, I so miss the crisp frosty spells of weather that we had in Octobers past. In October 1983, we had a dry cold spell brought by a Greenland High that brought several bright cold days with clear very frosty nights, the minimum temperature falling to -4C or colder on several nights. Ten years later, mid-October 1993 produced ten days with sharp or severe night frosts as low as -8C and fine crisp sunny days following a spell of Arctic winds with a Greenland High moving in. The last time we had anything below -3C in October was in 2003!! There has, I fear, been a sharp climatic transition to our autumns, likely down to Global Warming. The area of Arctic cold is restricted further north and with lower central pressure over Greenland - the frigid air is less capable of interrupting the physical dynamics of the atmosphere on our rotating planet that stipulate persistent Westerlies in higher Western-Margin latitudes even temporarily these autumns. This climatic change away from cold and frosty to mild and wet for our autumns (we regularly used to get air-frost in September as well as October at my home near Alston in the North Pennines) is akin to the big shift from frequently severe winter cold with lots of frost and snow (brought by frequent easterly or northerly winds) to mild wet winter conditions with persistent West or south-west winds that occurred in the late 1980's, as we now know (with a couple of exceptions like 1995-96) this is how winters stayed until the short run of cold winters commencing 2008-09. Since 2013 we have, of course, also reverted back to the mild wet winter pattern! YUCK!!

Dear Friends, October has fallen prey, yet again, to that persistent pattern, with low-pressure stubbornly dominating west and north-west of Scotland whilst high-pressure dominates over central and Eastern Europe and over the Azores: This regime' is occasionally interrupted by the wet, windy blast of some ex-hurricane that skirts the western coasts and brings horribly warm sticky air- totally inappropriate for October - to northern Britain as much as anything else! But it is the relentless prevalence of the High-Pressure over Europe and Low-Pressure South Of Iceland, and the persistent muggy, yucky and damp South or South-westerly Winds this Stubbornly Persistent Weather-Pattern brings that is the greatest cause of concern. These winds bring warm humid air up from the Azores, plenty of dankness and the wind and cloud-cover at night, not to mention the warmth of the airmasses, prevents anything like frost at night. The reasons for this pattern at this time of year are fairly obvious: The North Atlantic is just past it's warmest in October (so strong high-pressure seldom persists over it), whilst seasonal net radiative cooling over Central Europe encourages high-pressure to form there instead. The other main influence on the weather-patterns in mid and higher latitudes in October is the sharp seasonal cooling of the High-Arctic which quickly becomes very cold, though the Arctic cold is seldom extensive enough to help precipitate cold Arctic outbreaks these autumns it is sufficient to cause a big increase in the atmospheric temperature and pressure gradients between the Arctic and still-warm mid-latitude oceans so as to encourage some deep depressions to form. With high-pressure over Europe and the three-wave pattern of the upper Circumpolar Vortex these depressions have a tendency to linger south of Iceland whilst high-pressure dominates Europe. Another elemental reason why we have south-westerlies for much of the year, with the possible exception of late-spring is due to the fact that the Earth rotates. Easterly trade winds in low latitudes constantly impart westerly Atmospheric Angular Momentum to the atmosphere as a result of the winds blowing in a direction opposite to that in which the Earth rotates. This Westerly Atmospheric Angular Momentum does not dissappear as this would transgress the fundamental physical Law of Conservation of Angular Momentum, which stipulates that the total Angular Momentum of a rotating body must remain constant unless acted on by an outside force: Tidal influences from the Moon and Sun are so small as to have no meaningful impact on Westerly Atmospheric Angular Momentum that could really affect our weather. What goes up must, therefore, eventually come down and under current climatic conditions the excess Westerly Atmospheric Angular Momentum in stiff west and south-west winds that dominate in higher latitudes. Problem is, we are getting more of the south-westerly variety rather than north-west or even westerly winds that would be just as (if not more) effective at removing excess Westerly Atmospheric Angular Momentum from the global atmospheric circulation. For us who live in Scotland and the North of England, in particular the causes of the recent autumn weather-patterns are maybe a little academic, but the persistent mildness, damp air and the proliferation of bugs brought by the muggy October weather that results from persistent south-westerlies is starting to grate! It is utterly shocking that we should have to wait until November for the first air-frost! Even at my home in the North Pennines, at over 400 metres above sea-level, these are the extreme minima that I have recorded in October since 2010: 2010:-2C, 2011: 0C, 2012: -2C, 2013: 3C (!!), 2014: 0C, 2015: 0C, 2016: 0C, and the weather -pattern remains most unconducive to frost to the end of October 2017 (extreme low so far just 2C).

Ed Stone, I am definitely round to your way of thinking about the modern 2010's Autumn's: The Wretched Winds That Have To Blow To Stop The Earth Slowing Down bring their Muggy Buggy Warmth from the South South-West, Along with it Runs it's Buddy Wet -Weather! The Greyness, the Dankness and Pestilence and Bugs, And other nasty muck it Brings! And These Yucky Sou'-Westers Keepeth' Away the Crispness and Frosts Til' Well into November! O How I Hate These Wretched Winds That Have To Blow To Stop The Earth Slowing Down!!!

I live just four miles south-east of Alston and at 420 metres above sea-level some 100 metres higher. Another common issue with the weather on clear autumn nights with winds from the west is the tendency of low cloud to form over the North Pennines, caused by up-lift of relatively moist air combined with nocturnal cooling in the lower atmosphere. Winds do tend to be stronger at over 420 metres elevation and this has the effect of stirring up moist air so that the dew-point is reached first well above the surface rather than at the surface. Both the wind and cloud-cover (whether forecast or not) are very effective at arresting any steep fall in temperatures at the surface.

Err, no they don't normally until November (or almost into It). Certainly if the last few autumns are anything to go by! Even where I live in the North Pennines we had to wait until the 2nd November for our first air frost in 2013 and during the last three autumns nothing below 0C occurred until well into November! October this year looks like it may very well be another muggy buggy damp no-air-frost month! Autumn is not a favourite season of mine, if the last few years are anything to go by: Depressions crowd the North Atlantic but don't go eastwards because of high-pressure stuck over central Europe and so we get mild wet south or south-west winds trying to bring summer well after that season is over. The result of those Wretched Winds That Have To Blow To Stop The Earth Slowing Down is muggy grey weather, this encourages rats, slugs, bugs that ruin gardens and get into the house - and bring disease and all manner of pestilence: A good sharp frost in early October would put paid to such problems. The nice crisp mornings with frost-induced golds and crimsons on the trees because such conditions tend to be absent North Cumbrian Octobers and it is wind, rain and greyness rather than night frost that turns the leaves brown and mucky rather than bright oranges, reds and yellows! So no, I do NOT like what autumn has become in These Globally-Warmed 2010s!!

I do believe I included Yorkshire in with Central and Southern England in my seasonal predictions for September-October as I felt it would be on the drier side of the said NW-SE split owing to prevailing south-westerly winds. At Nenthead in the North Pennines (420 metres above sea-level) we had 148 mm (5.8 inches) of rain in September and so far this month (October) I have logged 60 mm (2.4 inches). And we are set to get a lot more rain over the next few days, although being further east and sheltered from south-westerly winds by the Pennines and (further upwind) the Welsh Mountains you will be spared the brunt of it.

I have got WXSIM with WXSIMATE as the file-downloading software up-and-running on my Computer and attached to my Weather Station. However, it looks like I need my Computer attached to the Internet for it to access and download real-time up-wind data and upper-air data on temperature, cloud-cover and wind strengths and directions! For all that, I find WXSIM to be a fascinating little tool to simulate a whole variety of "What If" scenarios- like a week of 10 mph northerly winds from the Arctic in February: It will give a good indication of how cold it is likely to get. The programme has in-built features to suggest when showers or thunderstorms occur (and a guide to likely intensity- though you would have to manually put in rainfall amounts on a second forecast-run based on the descriptions), it predicts conditions such as freezing rain or ice-pellets (this is American software, so it refers to ice-pellets as sleet!). It also predicts when low cloud or fog occurs, something that we get a lot of in the North Pennines (especially over this last week). Certainly, if you have Internet on your Computer and have WXSIM able to get data from your Weather Station (if you have one)- and you have WXSIM Customised for your local area, it will download weather data pertinent to your location and up-wind along with upper-air data (usually GFS data) and WXSIM will produce a forecast for your local area up to ten days ahead. From the feedback I have read about WXSIM the forecasts it produces are often very good. It has to be said though, that even with sophisticated forecasting software, the forecasts can prove wrong- and in the case of WXSIM the forecasts will only be as good as the data you feed into it. In the example I have given of a week of northerlies from the high Arctic in February, the temperature predictions are most realistic if you use the suggested Default data for up-wind temperatures (based on climatological averages for that time of year), although there is a feature that enables you to put in your own up-wind data manually. You could put -80C over the Greenland Icecap with 90 mph winds, for example, but this would be neither realistic or likely; and the forecast that you get will produce temperatures of -30C or colder- very unlikely unless the Norwegian Sea were to freeze over! The programme WXSIM does nevertheless has in-built constraints that do prevent it producing gibberish: If you put rain into the Interrupt Planner (whereby you can stipulate certain meteorological conditions at particular times) it will not predict rain or snow (and the forecast precipitation will be zero) if you also stipulate zero cloud-cover should occur. It will vary diurnal range according to how wet the ground is, whether there is snow-cover and according to cloud-cover and wind-speed and this will be done against the background of day-to-day temperature changes according to wind-directions: this conforms to meteorological physics and it will alter the temperature of overlying air-masses (and at different levels in the atmosphere)- dependent on the directions you stipulate for the upper winds to blow at the start of a Forecast Run. To find out more about WXSIM go to http://www.wxsim.com Ian Pennell

First fortnight of October has been dry and warm in the south-east but a different story for northern England and Scotland where it has been wet (though still milder than normal overall). September has followed a similar pattern though temperatures have been close to the long-term normal in my part of the World (near nenthead in the North Pennines). Hurricane Ophelia looks set to mark the transition to stormier conditions across Britain over the next week, but there is a prospect of drier colder conditions affecting central and southern Britain from the end of next week (according to the BBC long-range forecast). Seem to have got the general prognosis about right, although September in the Midlands and South has proven to be a bit more unsettled than my original assertion of "Plenty of fine sunny conditions".

Interitus, Thanks for the information: Does freely available just mean a month or so trial period? Secondly, it would also be good to know whether you can run this professional weather-modelling software a normal PC with the usual (i.e. Windows) software, or whether it would require the purchase of extra software and a more expensive computer. Anything above £1,000 is out of the question at the moment! However, I will look into what you have just shared with me to investigate whether it's worth proceeding further. Btw I have just purchased the WXSIM Standard Mode with Enhanced Customisation programme. The man who owns the WXSIM enterprise, one Thomas Ehrensperger, is customising the Weather Modelling software for my location at this very moment! It cost £150 altogether. Ian

Just to add Cima-Sim is a related software that Thomas Ehresperger sells that enables one to model how changes in solar radiation, ocean currents and wind speeds (crudely using a mixing factor), carbon dioxide levels change mean monthly and annual temperatures, including average minima and maxima. It is quite crude and does not predict rainfall, snowfall, etc. You would probably have to make an intelligent guess or an estimation for the likelihood of precipitation, although what this Cima-Sim model does do is to allow you to modify surface vegetation types, over which it will assume lower cloud cover and higher diurnal range for desert surfaces but the opposite for forest surfaces. However, the WXSIM programme is the one I am interested in. Do any of you have the software or come across it. I would like to know whether you think it's worth spending £200 to get the full package! Cheers Ian Pennell

Hi all. Have any of you come across this American Company run by one Thomas Ehresperger who sells programmes that enable you to forecast the weather for your own locality? Insofar that one might wish to predict the weather for your area, I wonder whether one can tweak certain variables further afield such as upper-level winds, sea-ice in the Arctic and airmass temperatures- in order to ascertain how it might impact the weather you can predict. I have read some of the reviews on the WXSIM Website, they seem quite positive. I am looking to buy my own weather model (I posted the topic of Buying Your Own Weather Model as a topic earlier this year, as I had in mind to do this. The link to the WXSIM Website is here: http://www.wxsim.com/ If any of you have in mind where one can buy other (better) Weather Models that one can use on an ordinary Computer and without breaking the Bank I would be most grateful. Regards Ian Pennell

Dear Netweather Readers, Apologies for my absence from this site during the last few months, but now I am back! I have had to concentrate on passing my AAT Advanced Diploma in Accounting, there was some quite tough stuff which I needed to learn so I could pass final exams. Thankfully I now have the certificate! I am endeavouring now to make a prediction for the UK Autumn 2017, which is a little belated now it is the 9th September. In the autumn months, the upper Westerlies strengthen and the main baroclinic zones become more defined as the Arctic cools- this makes longer-range forecasting a little easier. Currently, these are the main macro-scale weather-patterns that we are looking at: 1) The eastern (and mid) equatorial Pacific is cooler than usual by up to 2˚C, judging by from the latest UNISYS temperature-anomaly charts. This is indicative of a weak Lá Niná type situation. Cool conditions over such an extensive area of equatorial waters would present as a weakening influence on the Intertropical Convergence Zone (ITCZ), this is likely to present as such when the ITCZ moves over the equator by about November and it is interesting to note the relatively cool waters over the Gulf of Guinea. However, easterly trades blowing from the cool eastern Pacific onto the relatively toasty western Pacific would be expected to be stronger than usual- with extra westerly momentum imparted to the atmospheric circulation leading to a stronger Hadley Circulation and stronger westerlies in higher latitudes. 2) The Atlantic Hurricane season is currently very active, with some powerful storms such as Hurricane Irma that devastated the Caribbean. Very strong easterlies on the northern side of hurricanes (and typhoons in the Pacific- these have also been active) feed westerly AAM into the Northern Hemisphere atmospheric circulation (unless these re-curve well north of the ITCZ so that the very strong westerlies south of the centres of such hurricanes remove westerly AAM from the Northern Hemisphere Circulation). Hurricanes also readily add warm and moisture- and energy- to depressions crossing the North Atlantic where these push north into mid-latitudes. Increased hurricane activity in the North Atlantic therefore tips the balance towards warmer and wetter conditions in Britain (particularly in September/October)- but there might not be much in the way of “wetter” for other macro-scale considerations outlined below. 3) The Quasi Biennial Oscillation (QBO) is back into “easterly phase” after close-on two years of continuous westerlies high over the equator. Average wind-speeds at the 30 mb level in August were 14.4m/s (over 30 mph) from the east; this is likely to impact the Northern Hemisphere in the coming few months- so the impact on our weather will show up in late October-November. An easterly QBO has, in past years, been linked with slightly weaker higher-latitude westerlies overall and an increased likelihood of cold airstreams reaching Britain from the Arctic or northern Russia in the winter half-year. It must be pointed out, however, that air at the 30 mb level is less than one thirtieth of the density it is at sea-level; thus whilst the QBO has a small impact on the atmospheric general circulation via momentum exchanges between it and the surrounding air- the impact will not be great. 4) The Sun is entering a really quiet phase as we draw towards the end of the current Sunspot Cycle. Current Solar Activity forecasts suggest few (if any) sunspots or Solar Flares over the coming month. The Solar Wind has dropped recently from 500 m/s to just above 300 m/s. There is a link between the intensity of upper lows in the sub-arctic and solar activity in the autumn and winter months. When the Sun is quiet this means weaker depressions. The Sun has been quiet for a few months now and all indications are that this will remain the case for the foreseeable future. 5) Sea surface temperatures at the beginning of September have been 1 to 2C above normal in the North Atlantic compared to the long-term norm for this time of year; the North Atlantic “Cold Patch” appears to have warmed out. Meanwhile, Arctic sea-ice extent is close to the long-term normal in the Atlantic/Greenland sector of the Arctic even though it is well polewards of it’s normal extent on the Alaska side of the Arctic. This pattern would dictate for stronger baroclinicity and more intense storms crossing the North Atlantic as we head towards winter. 6) Upper air forecasts for the next three weeks point to the upper-westerlies over the sub-arctic remaining considerably weaker than normal (see weatheriscool website). This strongly suggests a quieter-than-normal pattern with more high-pressure is likely for the remainder of September. In terms of importance to our weather in Britain factors (5) and (2) have several times the impact of factors (3) and (4); the likely impact of the ENSO Phase is more than that of a quiet Sun or the QBO turning easterly. For the next month factor (6) is liable to provide the strongest indication of how the weather is liable to play out, though the impact of more North Atlantic hurricanes is not one that should be dismissed. With all this in mind, the remainder of September is likely to be a little warmer than usual with plenty of fine sunny conditions over central and southern England, Yorkshire and South Wales. Daytime temperatures above 21˚C can be expected from time to time as high-pressure builds north and east over England. However, at this time of year, clear night skies inevitably mean falling temperatures and minima of 5˚C or below can be expected to occur widely across England on at least a few nights during September with early-morning fog and ground-frost likely in valley-bottoms. For Scotland, North Wales and north-west England along with Northumberland and Northern Ireland the baroclinic set-up and Atlantic hurricane activity is likely to result in a more unsettled flavour to the remainder of this month. Depressions passing to the north will bring spells of rain, strong winds from the west will be frequent and daytime temperatures will often remain the cool side of 15˚C, even in the lowlands. However, even in Scotland and the North there will be fine spells with ridges of high-pressure between depressions with maxima edging towards 20˚C but with the clear nights becoming cold enough for ground-frost at times. Frontal influences will also extend further south to central/southern England and South Wales to bring some days of rain, stronger winds and maxima below 18˚C. I do however, expect there to be more sunshine and warmth and less rain than usual for central and southern England on the whole. For Scotland and the north-west of England, along with Northumberland, rainfall temperature and sunshine totals will be remarkably close to the long-term normal overall, but north-west Scotland will be wetter and windier than normal. Gales are likely to occur here two or three times during the second half of the month. During October the cooling Arctic with the North Atlantic liable to remain warmer than usual, combined with continued hurricane activity is likely to mean a stronger atmospheric temperature gradient between the Arctic and the North Atlantic with continued injections of moist tropical warmth from the south: This strongly suggests deeper depressions, particularly later in the month. All things considered, with the rapid cooling of the Greenland Ice-cap and NE Canada whilst the westernmost part of Canada and the North Atlantic remain relatively warm- and with the factors discussed above likely to lead to a Circumpolar Vortex around or slightly stronger than usual for the time of year, I am confident of a so-called “three-wave” pattern with an upper ridge close to the North American Rocky Mountains. This would also place an upper ridge over Western Europe with the result being high-pressure encouraged to occur a little downwind- i.e. over central Europe whilst the upper-air pattern pushes progressively deeper depressions from coastal eastern Canada north-eastwards towards Iceland and then up into the Barents Sea. Thus, during October the prevailing winds over Britain will be south-westerly, and they will increase in strength during the month. During October these winds will often bring wet and windy conditions throughout the country. However, the southern half of the country- all of England except Lancashire, Cumbria and Northumberland along with south and central Wales- will have a good deal of dry fine weather during the first ten days of October (there are indications that the weak upper-air Circumpolar Vortex will remain weaker than normal into October and the absence of a “Cold Patch” in the North Atlantic will encourage the jet-stream to blow further north on coming into NW Europe). The fine conditions will result from extensions of high-pressure from Europe across England and Wales: There will be a run of warm sunny days with maxima near 20˚C with light south or south-west winds; clear nights will again result in temperatures dropping well into single figures and local ground-frost and fog can again be expected. For Scotland, northernmost England and Northern Ireland and North Wales, October 2017 will be unsettled from the outset. Strong winds and rain will be frequent and it will get increasingly stormy. By mid-month the weather will turn unsettled even in the South with some wet and windy spells. Gales and widespread heavy rain will sweep the entire country at least a couple of times during the second half of October and localised flooding is likely to occur in western Scotland, Cumbria and Lancashire. As a couple of the deepest depressions push eastwards late in October colder strong west or north-west winds will sweep the country to bring cold squally showers (with hail locally) and daytime temperatures below 10˚C as far south as Birmingham and the first snow will fall on high ground above 600 metres in Scotland, Cumbria and Northumberland- to provide a real foretaste of winter. There is likely to be at least one night with a ridge of high-pressure following such cold strong north-westerlies when skies clear and winds fall light. Air temperatures will fall close to freezing across the entire country and ground-frost will be widespread. However, except in some rural upland areas of Scotland or sheltered frost-hollows further south, I do not expect the first air frost to occur for most of us until November. The large scale upper-air pattern is likely to bring a return to some fine dry weather lasting just a few days during the second-half of October- again this fine weather- brought about by a westwards extension of the European High will be confined to central and southern England, South Wales and Yorkshire. The fine spell is likely to be associated with cooler European air coming in from the south-east late in October and with weaker late-October sunshine daytime maxima anywhere above 16˚C are unlikely- even in the South. Clear skies at night would encourage temperatures to drop sharply to within a few degrees of freezing point over a wide area and patchy morning fog will be widespread. However, as I have already hinted above, air-frost is unlikely to occur except in some rural low-lying valleys: Most places in England will not be getting their first air-frost of the season until November. Scotland is liable to miss out on any substantial October fine spells altogether. For central and southern England, Yorkshire and South Wales I expect October to be about 1˚C warmer than the long-term normal with mean daily temperatures approaching 14˚C along the South Coast. I expect rainfall totals to be below the long-term October norm in these areas- but not by more than 40%. For Scotland, Cumbria, Lancashire and Northumberland I expect average temperatures to be a little above normal overall (by about 1˚C,- this means mean daily temperatures in lowland Scotland, Cumbria and NE England will be 9 to 10˚C) but for these areas to be significantly wetter than usual (by 30 to 60%): The exception to the wetter-than-normal regimé will be in eastern coastal parts of Aberdeenshire, Tayside and the Northumberland and County Durham Coasts where rainfall totals will be below normal for October on account of the rain-shadow effect to the prevalent south-westerly winds provided by the Pennines, Southern Uplands of Scotland and the Grampians. For November, the influence of Atlantic hurricanes will come to an end and the important factors pertaining to our expected weather will be the steeper-than-normal baroclinic gradient between the Arctic and warmer-than-usual North Atlantic that would tend towards boosting the intensity of depressions. However, the ITCZ will be drifting south over the Equator where (as things stand) sea-surface temperatures are actually cooler than normal and a weak Lá Niná is in operation. This would serve to weaken the Hadley Circulation and (with it) the strength of the upper Westerlies from the subtropics northwards. Then there is the smaller impact of factors like a quiet Sun and the now easterly QBO feeding into the Northern Hemisphere Circulation. This is (therefore) my take on how it is liable to pan out: The Circumpolar Vortex of strong westerlies encircling the Arctic will thus be strong, but not that strong- and it will manifest as the “three-wave” pattern of upper ridges and troughs during November. With an upper “ridge” anchored over the North American Rocky Mountains (through a process called Topographical Locking) this places an upper “ridge” over the UK and north-west Europe (i.e. 120˚ longitude downwind). This would produce the kind of situation where there would be high-pressure over central and eastern Europe (the upper westerlies re-curving clockwise and south-eastwards over this region would bring about high-pressure below); it would also mean deep depressions forming in the Newfoundland area and racing north-eastwards to just south of Iceland. This pattern means mild south-westerly winds over Britain with plenty of rain and gales associated with deep depressions passing further to the north that would affect the northern half of the country. However, that is not to say that rain and wind will not affect the South because the Circumpolar Vortex expands going into winter. That said, bearing in mind influences like the QBO Easterly Phase and a Hadley Circulation weakened by some cooler-than-normal waters around the Equator it is certain that the upper-air Circumpolar Vortex will be weak enough to enable high-pressure over Europe will muscle its way north-westwards to affect England and Wales at some point during November, though it will probably not extend to Scotland. To that end, I am predicting that for about a week during either mid-late November that high-pressure will bring colder drier conditions for England and Wales with the air coming from the south-east off the cooling continent of Europe. The result will be sharp night frosts with patchy freezing-fog as the air cools during the clear long November nights, minimum air-temperatures of -3˚C will occur widely with some frost hollows dipping below -6˚C. There will be sunny but cold days with weak November sunshine with maxima below 6˚C (but below freezing point where any freezing fog fails to clear). For the remainder of November, and throughout the month further north in Scotland, cloud wind and rain is likely to dominate. Heavy rain and gales will batter the west of Scotland and NW England at least a few times during the month bringing localised flooding and storm-damage. Typical daytime temperatures during these wet spells with south-west winds will range from 13˚C in the South of England to 9˚C in the Scottish lowlands; with minima just a few degrees lower at night. Snow will affect the Scottish mountains and the highest Lake District and North Pennines mountains when the wind veers towards north-westerly following some of the deepest depressions: Air-frost will be widespread on the few clear nights that will occur in “ridges” following such colder west/north-west winds. These ridges of high-pressure, occurring between the passages of depressions to the north, will result in a few bright days with weak sunshine across the entire country, though maxima are unlikely to be above 10˚C on such days, even in the South. For the month of November 2017 as a whole the mean daily temperature will be just a little above the long-term November norm across the country, ranging from about 9˚C over southern England and South Wales to 6˚C in the Scottish lowlands. Rainfall totals will be close to the long-term November norm over the Midlands, Yorkshire and the South of England, but up to 50% wetter (and windier) than normal over west and northern Scotland, Northumberland, Cumbria and Lancashire; coastal parts of NE England and eastern Scotland will have November rainfall totals close to the seasonal norm. North Wales and Northern Ireland will also be wetter than normal with upwards of six inches of rain in total falling during the month.

Here in the North Pennines on the Cumbria/Northumberland border at just over 400 metres above sea-level we have yet to record any measurable rainfall this month, that being after scarce over an inch of moisture in all-April! Seathwaite in the middle of the Lake District bone dry with no water in the River Derwent that flows past Keswick.....and I predicted that the second half of April and early May would be wetter than usual across the west and north of Britain! My apologies if folk have relied on this forecast, I got this one a bit wrong, certainly with regards rainfall even though not far out with regional temperatures overall. Although I did explain back in early April that the Circumpolar Vortex weakens in spring/summer and this makes it prone to drastic alteration from quite small-scale underlying influences I should not have got it so wrong only a month in advance: I will certainly need to see where I went wrong with regards to predictions of high and low pressure, affects of sea-surface temperature, ice-cover, etc in order to avoid making such a blunder in future! There is a consensus for rain in the next week or so, but I don't think I can take much comfort from that because April and the first 12 days of May have so far been exceptionally dry. Basically that means my original prediction is already shot to bits- there are already drought measures in parts of the country!

@draztik; As regards temperature I predicted a mean of 9.5C for England and Wales in April 2017, which is not far off the actual CET average of 8.9C which has just been logged: I don't think the actual figures deviate far from what I predicted on that score and there was a cold spell that brought widespread night frosts and some wintry showers, although this occurred later in the month than I predicted it to. For lowland Scotland, I predicted a mean of 7C- and this seems to be close to what the average has actually been. Drier clearer conditions however, seem to have resulted in more frosts at night in some areas although I would not put the overall incidence above average. As regards rainfall, it has however, ended up much drier than my original prediction for 90mm rainfall for England and Wales with total rainfall amounts of just one inch (25mm or less) over a wide area of the South and Midlands. the unsettled wet spell I expected to set in, over northern Britain in particular, did not occur over most of the UK. There was, alas, plenty of cold wet weather but it was rather further north- and east- than I expected it to be: The far north of Scotland- i.e. Wick, Caithness, Tongue and the Shetland Isles did have a wet month in April 2017 with rainfall well above normal (locally over 100% more than usual) and (of course) it was cold with some unusual late snowfalls across parts of mainland northern Europe and over Scandinavia. The upper trough, which I expected to occur near the United Kingdom during the second half of April formed further east and brought the chill wet conditions to Scandinavia, Germany and across the Baltic- indeed they have had some shocking conditions for the time of year. In the North Atlantic, there is a patch of colder-than-usual water and I anticipate that this would cause the upper Westerlies to re-curve south-eastwards and lead to an upper trough downwind- i.e towards the United Kingdom. During April, this unusually cold patch of the North Atlantic has extended further east, and there has been a patch of colder-than-usual water forming in the Norwegian Sea- to the north of Britain. Sea-ice extent around the east Greenland Coast has (if anything) been slightly above normal extent but is well below normal extent for the time of year in the Barents Sea to the north-east: Combined with the Polar Stratospheric Westerlies ending (and being replaced by easterlies) a couple of weeks' earlier than usual and with a Stratospheric High over Greenland this seems to have encouraged higher pressure to the west of Britain as well as over Greenland- leading to the spell of Arctic winds over Britain late in April whilst the passage of sub-arctic depressions was (consequently) well to the north and north-east (over Scandinavia). I also factored into my forecast that there has been a record Westerly QBO (the wind-pattern high above the Equator in the Stratosphere), which has been blowing at record speeds from the West over recent months: I am a little surprised that this has not led to stronger Westerlies coming across the North Atlantic as this excess Westerly momentum is transferred into the general global circulation even though one would expect much less of an influence from the QBO in the Northern Hemisphere late spring/summer. What I will say however, is that (at least where I live in the North Pennines) the weather in April 2017 may have been characterised by low rainfall (32 mm as recorded at my weather-station), but we still had a large number of days with trace or very small rainfall totals (i.e. 0.8mm). The middle and latter parts of April were not characterised by warm sunny conditions overall where we live (though there were some bright fine days) but there was often cloud, cold winds (often from a north or north-west) and light showers- sometimes with hail or snow. On 26th April Cross Fell was white as were mountains in the Lake District. I would suggest that conditions across much of Scotland- along with other parts of northern England have had broadly similar conditions to those that I have recorded, if not as chilly (I live at just over 400 metres above sea-level). Frontal influences did affect the northern half of Britain during mid?late April but they were much-weakened by proximity of high-pressure further south and west.

From the North Pennines just over 400 metres above sea-level: -4C last night with clear starry skies. Just 4C this afternoon, showers of hail and some snow with short sunny periods! Cold northerly winds. Certainly making up for the unusual warmth and sun earlier in April!

18th April: The air temperature fell to -4C overnight at just over 400 metres' elevation in the North Pennines following a chill day with north-east winds yesterday (vicious hail-shower about 7.pm last night). We have the predicted mid-April cold snap! Looking cold and showery for many by Friday (22nd):

At my home in the North Pennines (near Alston, Cumbria) the air temperature dipped to -4C, making this our coldest night since January! Will be interested to see if other inhabited parts of northern Britain got colder last night- and some of the effects on blossoms, flowers and any vegetables folk might have planted out into gardens thinking the danger of significant frost to be over!! Some of the flowers in my mother's garden looking a little sad this morning- particularly the purple denticulata!

@Interitus; You might be interested in this little article about the effects of the Quasi Biennial Oscillation on the Westerlies at higher latitudes: https://books.google.co.uk/books?id=iOfqCAAAQBAJ&pg=PA46&lpg=PA46&dq=QBO+AND+MID-LATITUDE+WESTERLIES,+ANGULAR+MOMENTUM+INFLUENCES&source=bl&ots=T9HNYMMpJv&sig=GBllwYfPTMcpoGoD4lxteqLk6JA&hl=en&sa=X&ved=0ahUKEwi966-p-aPTAhUsLcAKHZnWAyUQ6AEISzAE There is, nonetheless, a link between the QBO phase and the strength of the Circumpolar Vortex. It is, as you rightly point out, rather less in late spring/summer when there are easterlies in the stratosphere in all latitudes and the tropic to polar circulation in the troposphere is weaker. Nevertheless, you have a large area of the tropical stratosphere between about the 20 mb and 80 mb levels where mean winds are from the west at speeds exceeding 10 mph (locally 35 mph where strongest): See here (note of the large blob of blue in the middle of the chart): The Earth-atmosphere system is a closed system as regards angular momentum (save for small impacts from tidal effects of the Sun and Moon and momentum lost through atmospheric out-gassing to space and - periodically- the influence of Solar Flares); such a large area of such Westerly AAM over the tropics is (however it was originally caused) inevitably going to have an impact on the global circulation elsewhere as these unusually strong tropical stratospheric Westerlies work their way down through the stratosphere. Such a large area of strong westerlies will inevitably have an effect through wind-shear and mixing on surrounding parts of the tropical stratosphere and the upper troposphere-some of this westerly momentum will find it's way into the upper part of the tropical Hadley Circulation through which the poleward transport of westerly AAM normally occurs in all seasons. Over the coming months it will carry a bit more of this Westerly momentum than normal despite the seasonal easterlies in the stratosphere above. Now, I would normally agree, that the QBO has little impact on the weather we get in Britain in late spring/summer but the QBO has been breaking records in terms of the strength of the westerly winds and their extent. Westerlies also extend to the Equator at around 100 mb (the top of the troposphere) with just a small scarecely-easterly blip around 70 mb and that is (of course) at the top equatorial end of the Northern Hemisphere Hadley-Circulation. It would be unwise to discount this completely in a monthly-season-based forecast. Here is one of the conclusions in the paper I have referred to above: The main influence on our spring/summer weather will , of course, be the likely positioning of the ridges and troughs in the Circumpolar Vortex in higher latitudes. This will, in turn be influenced by the patterns of anomalous cold and warm water across the North Atlantic and temperature/snow-cover over North America and Eurasia and (of course) the effect of topographical locking due to the Rocky Mountains. You will be aware that there is a region of the North Atlantic that is locally 2C or more colder than normal- to the south of Greenland. This will encourage an upper trough in the upper Westerlies a little way downwind of it (i.e. to the east). The wettest weather associated with depressions tends to be on their south-east quadrant- which would tend to put Britain (certainly the north-west) in the firing line. The extent and strength of the Westerlies high over the Equator would, in that context, underscore and emphasise that the wetter conditions are more likely. Some of the forecast charts for a fortnights' time show signs of bearing this out. Aside from that disappointing picture I do have confidence, however, that during the second half of May that the retreating extent of Arctic pack-ice (which is already at near-record low extent for mid-April) combined with the unusual warmth of sub-arctic waters will result in the Polar Vortex shrinking closer to the Arctic itself. With the northwards extent of the subtropical high-pressure belt that means central and southern England at least can look forward to a good deal of fine and very warm weather by then- of that I am certain.

@Weather-history, You are correct that northerly flows don't (as a rule) result in the highest rainfall because cold airstreams from the Arctic or sub-arctic hold less moisture. However, these airstreams are also convectively unstable in April as the cold air warms over land warmed strongly by a Sun that gets to 50 degrees above the horizon at lunchtime over the Midlands and South and the upper-level temperatures with this type of synopsis will be unusually cold because of an upper trough over and to the east of Britain. You will also notice that, over SE England, surface pressure is around 1010 mb or lower with a depression not much further to the east. This means that the wind circulation at low levels will be in-blowing- with the northerlies picking up moisture over the North Sea before moving over land and with a steep temperature lapse-rate through the atmosphere (a feature of Polar Maritime or Arctic Maritime airstreams in April) strong convection currents over land- as the surface and low atmosphere gets heated by the strong spring sunshine- will result in deep cumulus and even cumulonimbus-type clouds that are certainly capable of bringing sharp showers, including hail and thunder. Regards temperatures, the first eleven days of April have already been much warmer than average (it reached 25C in the SE on Sunday, 9th) and even now- despite cooler conditions from the west temperatures remain a little above the seasonal norm for mid-April in the South. As such, even with a week or more of northerly winds bringing down very cold Arctic air (and I am not predicting more than a week of northerlies) this will not bring mean temperatures to below normal for the month as a whole. Late in April, I am confident that there will be more westerly types that will not bring average temperatures below the long-term seasonal norm. All this considered, I am still confident that I will end up close to final April CET. Scotland will, on the whole be just a little warmer than the long-term normal there (I predicted a mean temperature for lowland Scotland of 7.0C), given the mild start to April this allows plenty of scope for chilly wet weather later in April (as predicted) and for the month to still end up a little warmer than average. Some of the modelling is showing plenty of indications of cold, wet weather late in April- such as this for the 25th: The pattern there is cold, showery and (over Scotland) cyclonic. And this for just six days' time: Quite a vicious little depression there off north-west Scotland driving what looks to be a chilly unsettled Polar-Maritime westerly airstream over Britain. Yes, I could yet be wrong, as I mention in my prediction (above) as the Circumpolar Vortex weakens in springtime it becomes susceptible to alteration by quite localised mesoscale weather conditions (i.e. heavy snowfall over Sweden or a depression moving over Germany) and can therefore change at short notice into a pattern of ridges and troughs quite unlike the one predicted a week earlier. However, on the basis of the record Westerly QBO circulation high above the Equator, the extent of Arctic sea-ice and pattern of sea-surface temperature anomalies around Britain across the North Atlantic (the so-called "Cold Blob"- that area of the North Atlantic that is unusually cold for the location and time of year is south of Greenland- and it will tend to induce an upper trough somewhat downwind of it- i.e. nearer the UK), combined with a look at what the main weather-charts predicted for a few weeks' hence led me to conclude that the most likely outcome this April and May was for a good deal of unsettled weather- in the North and Scotland in particular but with seasonal temperatures on the whole a little above average. Sea-surface temperatures around Britain are running at around 2C above the seasonal norm and I anticipated that this would moderate the predicted northerlies over the next week and cool westerlies later and that, despite their frequency, temperatures would still be above normal for April on the whole. With a warmer sea and with deep cold Arctic air travelling over it you also make for a more convectively unstable air-mass (translating to heavier showers and thus higher rainfall where such an air-mass moves over land). P.S. Not to worry for those living in the Midlands, southern England, South Wales and Yorkshire I do expect the second half of May to be very warm and settled in these locations as the subtropical high asserts itself over Europe and the storm-tracks over the NE Atlantic migrate to the Iceland area! Even Manchester and Liverpool will probably get a good deal of warm dry weather then.