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A Winter's Tale

The Seasonal Forecast Thread

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My forecast has been hampered by the excessive moisture flow from early June to mid-July. Since then it has begun to phase more with the actual pattern. By mid-July I could see that extremely high temperatures would be difficult to achieve but the Olympic period has been notably warmer and drier than both average and the recent past. So I feel good about that. By the way, congrats to all in "Great Britain" or whatever you call your country, the Olympics have been a great organizational success and a big spectacular sports-wise, almost everything has been quite exceptional. Including the weather (can you imagine certain two week periods in the previous six?)

*shudders*

We have been enjoying the coverage, even the cross-country bike track looked like the ground was quite dry which is amazing given the rainfall anomalies previously.

Team GB on a roll, our own performance rather "up and down" but about what was expected.

I'm sure the LRF assessments at end of season will be cruel enough, but I happen to be reasonably pleased with the pattern outcome at this late stage, sort of like the winter, the best part of the forecast is the last part, oddly enough.

Aye, you always seem to be there or there abouts Roger....same goes for GP. You can't beat experience Posted Image

What's annoying me is the fact I didn't do a formal forecast for summer as (by complete luck) my thoughts in early spring were dead on what actually occurred in a broad sense. Very wet June with prevalent northern blocking, an improving July with warmer weather last week into August. Believe it or not, I simply based a lot of this on the long range CFS model which IMO spotted the wet trend from as early as March. The point of this post is not to blow my own trumpet in any way but to highlight the usefulness of this model.

'I am seeing a signal for a very wet May/June period so this may ease the drought situation......summer may improve progressively throughout July into August.

A very generalised view, but it's how I expect pressure patterns to play out based on current stratospheric conditions and various model indications including CFS and a general hunch.

Edited by CreweCold, 24 February 2012 - 17:02'

Edited by CreweCold

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Posted Image

What's annoying me is the fact I didn't do a formal forecast for summer as (by complete luck) my thoughts in early spring were dead on what actually occurred in a broad sense. Very wet June with prevalent northern blocking, an improving July with warmer weather last week into August. Believe it or not, I simply based a lot of this on the long range CFS model which IMO spotted the wet trend from as early as March.

Aye Crewe, I follow the long range CFS maps closely too and have been very impressed with their accuracy regarding the general pattern this year. As long ago as late winter they picked up the pattern of a warm and dry regime for the far north west of Britain and a very wet start to the summer over Wales and central and southern England, and they stuck with it.

Contrary to the opinion of a few posters in the model thread the CFS maps are indicating September will be slightly wetter than average, apart from eastern coastal areas, with temperatures not far from, or a little above, average.

Edited by Terminal Moraine

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My first attempt at a different format; 2nd and final version of summer forecast:

ASWT'S SUMMER FORECAST 2012

JUNE ... mostly warm and dry, with short unsettled interludes. Temperatures 0.5 to 1.5 above normal. CET 15.3C. Rainfall 55% south east to 75% north west, storms and occasional fronts providing most the rain for the SE, a mixture of fronts and showers providing rain from the NW during unsettled interludes. Sunshine 15-20% above normal.

Wrong. Mean temperatures were -0.5 to -2.5C below the seasonal norm, for the vast majority June was a wet month. CET was around 13.6C. Rainfall 20% of the average in the NW and 200% above average in some southern and eastern areas. There were storms and in particular, deep atlantic fronts brought a lot of rain to most of us. Sunshine 10-50% below the norm.

JULY ... cool and wet periods likely at times with warm, dry conditions and some heatwaves likely too. Temperatures 0.5 to 1.0 above normal. CET 16.6C. Rainfall 60% south east to 85% north west, atlantic lows, showery and storms providing rainfall, driest towards the SE. Sunshine 5-15% above normal.

Wrong but not entirely so. Cool and wet periods dominated, particulary the first half and some warmer, dry conditions did occur for a time. Temperatures were 0.5 to -3.5C of the norm, CET 15.5C. Rainfall around 20% in the NW and 200% in some eastern areas. Atlantic lows and precipitation associated with low pressure provided rainfall, driest towards the NW of Scotland. Sunshine 10-50% below the norm.

AUGUST ... changeable, mainly warm and dry start mixed with cool and wet blips, cooler and wetter end with some warm and dry periods. Temperatures 0.0 - 1.0 above normal. CET 16.3C. Rainfall 80% south east to 90% north west with atlantic and channel lows, showers and storms bringing rainfall. Sunshine 5-15% above normal.

As of the 15th of August, there have been changeable conditions, mainly warm, some dry weather around a third of the way through the month. It seems like a warm spell is heading our way so probably by the 20th we'll be looking at the warmest month of the summer, a wet month in some places with lows, showers and storms, possibly sunnier than the average too. However the final third could indeed be cooler aswell as an unsettled regime continuing.

Overall, an inaccurate forecast as of yet with June and July being responsible for inaccuracies. July's forecast was probably more accurate than June. August at the moment isn't looking too bad but I'll wait till the end of the month before I can review on the august and indeed summer forecast as a whole.

I inted to continue using this format of forecast for the future. By the end of this month, I shall complete and publish my forecast for Autumn 2012. My aims are to have of course a more accurate forecast but between now and the end of the month I would like to gather a variety of links and information that could provide signals and signs for the season ahead which may contribute to a more accurate forecast.

In this moment of time, my current thoughts on autumn 2012 are:

September:- Overall, an above average month with a mixture of dry and wet periods. Some windy conditions likely on occasions. Sunshine generally above the norm away from the NW, rainfall around average for most, below average in the SE and above in the NW.

October:- Slightly above average on the whole with some warm spells at times, particulary earlier in the month. Some dry weather could be likely but atlantic lows and hurrican remnants could bring heavy and widespread rainfall throughout the month aswell some winds. Showery interludes also possible aswell as some brief colder spells in the latter half of the month contributing to hill snow and the first frosts. Rainfall above average and sunshine varying between below and above the average.

November:- Average to slightly above average, mild, windy and wet start with atlantic lows and showery conditions. Possibly more settled conditions mid month with average to below average temperatures, some sunshine and cloud cover and some frosts. A return to Atlantic lows followed by showers later in the month, some sunshine in showery spells, mixture of mild and cold spells. On the whole, rainfall above average, and sunshine on the average or slightly below.

That's my thoughts on autumn at the moment. If anyone could provide any useful links to improve on the theory behind long range forecasts then that would be a great help.

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AWT'S Autumn 2012 Forecast


SEPTEMBER ... quite warm and changeable with good periods of both dry and wet and windy autumnal weather. Temperatures 0.0 to 1.0 above normal. CET 14.0C. Rainfall 110% in the north/west to 60% in the south east, spells of active atlantic weather. Sunshine 5-15% above normal.

OCTOBER ... warm start, cooler end and wet, windy and changeable at times. Temperatures 0.5C below to 0.75 above the normal. CET 10.8C. Rainfall 120% in the north west to 75% in the south east, depressions and showery precipitation bringing rainfall. Sunshine 5-10% above normal.

NOVEMBER ... cool and mild spells, average overall and quite wet and windy. Temperatures 0.5C below to 0.5C above normal. CET 7.1C. Rainfall 110% in western and northern areas to 70% in the south and east. Sunshine 0-10% above normal.

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I always read this thread with interest, but have to say a statement such as this really covers everything

"....quite warm and changeable with good periods of both dry and wet and windy.....

I understand how difficult and challenging it is to forecast, but really wonder if we as a forum add credibility by outputting a coverage that just about covers everything

Like I said I'm no expert and I not bemoaning those prepared to go for it, but I was wondering just how valuable the statement is and how it adds value to any short seasonal forecast.

AWTS this is NOT aimed at decrying your output, it more about do we as a forum really add value in outputting this type of forecast?

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That's a fair question DB...But, that said, don't more than 9/10 UK summers deliver just that?

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Heres a video I've created just exploring some of things I like to keep an eye on through the autumn in terms of creating a winter forecast;

What Goes Into A Winter Forecast?

http://www.gavsweath...m/seasonal.html

Hope you all find it informative. Posted Image

Edited by Gavin P

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@gavin p hey gavin every time i go to your website i cant play the video and if u dont mind me saying this can u make your website a bit v.i friendly thanks man.

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@gavin p hey gavin every time i go to your website i cant play the video and if u dont mind me saying this can u make your website a bit v.i friendly thanks man.

Are you trying to watch on an i-phone? I have has some feedback that the vids are hard to play on i-phones. Unfortunately thats YouTube's fault and theres nothing I can do.

I may launch an app next year though.

Edited by Gavin P

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Oh, I'm not sure what the problem is then? YouTube vids should play on all PC Browsers?

I've found Google Chrome to be the most stable browser, but YouTube videos should play on all PC's and browsers.

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Hi Gavin

I think Syed is saying that navigating to the video and playing it is difficult for the visually impaired,

Ian

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Hi Gavin

I think Syed is saying that navigating to the video and playing it is difficult for the visually impaired,

Ian

Ah I'm with you now. Thanks Ian.

Sorry Syed. I hope you don't mind if I PM you?

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thanks ian. Of course gavin thanks.

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E S S's - autumn and early winter forecast 2012/13 - mid-September, October, November, and December, with thoughts on early January.

Wet and wild with some Arctic elements.

Main Factors:

La-Nina and El-Nino.

Sea surface temperatures.

Hurricane season.

Solar activity.

Long range forecast models.

Forecast for mid September onwards -

Highest rainfall - North and West

Driest - Southeast and EA

Mild month for all, some cold nights.

Temperatures - above average

Rainfall - average north and west, below average south and east.

Deep low pressure systems with Ex-hurricane or tropical elements are quite likely to influence our weather, most highest risk for these Atlantic storms to affect are the far North UK, they could affect Western and Northern parts depending on how far south the track they take is, i expect the SE to be mostly little affected by the wind storms or low pressures although rain here at times to , southern areas especially the SE seeing warm days and cool maybe quite chilly nights, thunderstorms could become a feature as warm and cold air gets in the mix, and low pressure being nearby to the North then thunderstorms most likely to affect here. The further south and east the driest weather is expected, although some shower type downpours are always a risk.

Forecast for October -

Highest rainfall - far North and Western areas where low pressures from the Atlantic are most likely to move through.

Driest - Southeast where ridges of high pressure are expected.

Mild month for all areas, some cooler days and some cold nights though, especially in the SE.

Temperatures - average

Rainfall - average

This month the Atlantic gates open wider, the flow of wet and wild weather quite frequent for the NW, i expect Ex-Atlantic hurricanes and Tropical storms to take a journey up towards the Northwest UK and far North as deep lows, with low pressures systems moving through here quite often bringing wet and windy weather and quite mild air, one or two of these lows becoming deep and into potentially storm force systems. Most of England, Wales and Ireland seeing rainfall at times most likely in Western and Northern areas as the lows pass to the northwest. Quite a mild month for most areas, with a very mild Atlantic air flows at times, and in southern England we could see some warm feeling days. The most likely area for ridges of high pressure being the Southeast, and where this happens there will be cold nights and a risk of some ground frost.

There is a small risk of a deep low sweeping through southern areas if an ex-tropical storm or hurricane tracks further into the south and mid Atlantic then would be expected.

Forecast for November -

Highest rainfall - South and West where low pressures from the Atlantic are most expected to move through.

Driest - Far North and NW UK as Atlantic lows expected to be further south.

Mild at times with short cold periods with some wintry weather on the hills and mountains.

Temperatures - below average.

Rainfall - above average mostly but slightly below far NW.

The Jet stream moving south bringing with it very wet and wild conditions across all areas, this month i expect deep low pressure systems to move right across England and Wales rather than just Northwest UK bringing very windy and wet weather with a risk of a damaging storm, mild Atlantic air at times with some cold air on the backs of the low pressures systems, this bringing a risk of something rather wintry with snow falling over Northern hills, i don't expect any snow in the far South, although higher Southern hills may just see something wintry as the cold air mixes in, this all depends on the track of the weather systems.

Forecast for December -

Highest rainfall - Western and Northern areas - Atlantic weather systems most likely to affect here.

Driest - Southern and eastern areas - high pressure most likely.

Temperatures - below average.

Rainfall - average

Generally a cold month.

As we enter this month we could have the Jet stream hanging around and not really moving south at this stage but across the southern coast UK, or north France, I expect there to be low pressure systems still affecting all areas, some wet and very windy weather around as this systems sweep through, mild air at times within the systems but cold air sweeping down on the back edges of the lows and with some cold days and nights i expect some sleet and snow over the hills in the north and a risk on southern hills, I’m expecting the Atlantic to slowly settle down with less activity reaching our shores, high pressure moving in to affect most areas from around mid-month, although some fronts affecting the far north and western areas early in the month it shouldn't be as wet, as we move towards late month high pressure sitting right over us, much calmer and much colder conditions result, i expect sunny cold days and frosts for most.

Early January - early thoughts

Cold, possibly a very cold month.

A long way off so confidence is low at this stage, i am expecting a cold month with blocking high pressures and a North-easterly at times bringing snow, a blocked month for cold and with lots of heavy snowfall.

General thoughts:

This Autumn and winter is likely an El-Nino, this usually brings mild and wet weather with an Atlantic flow, and less risk of prolonged blocked cold spells, Solar activity has increased from being very low, there is likely a delayed affect with solar activity to how it affects weather patterns, the Jet stream this summer has been further south bringing very wet periods at times with low pressure, the Jet Stream usually moves north of Scotland during summer to allow high pressure to build from the south and bring settled weather to all areas, the Jet has not really got it's normal pattern in order, the reason for this is likely due to the solar low affecting the Jets normal pattern, for this reason i do not expect El-Nino to affect how would be expected under a normal Jet pattern, and even if it did it is not certain of a mild winter. I am expecting a cold winter for 2012/13, by late December i expect the Atlantic to settle down and the Jet to move south, a strong area of high pressure building to our NE, this being the forerunner of what could be a very cold winter.

Other factors:

Imported thunderstorms in relation to winter cold and snowfall:

Once again during spring and summer we did not import continental thunderstorms, i see that there is possibly a connection with more prolonged winter snow and very cold weather and lack of imported summer storms and plumes, for example, Southeast England has had increased snowfall over the last few years and decreased imported thundery weather, this could mean that weather patterns are moving south, we can look at the Jet stream pattern to see this, the Jet should sit to our far north during summer and over southern England, the Channel, or North France for winter, the last few years the Jet pattern has changed, with it being more south than normal, this means it has a head start in moving south for winter, taking lows across South France and Spain and allowing cold blocking highs to form further north feeding in cold air from the Arctic or Siberia. This is what i expect to happen this winter, so i will be looking north and keeping watch on the Jet Stream.

ESS.

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Interestingly ESS i think your December forecast is a fair shout at the minute- depicting a fairly typical +NAO with LP steered far enough N to allow a pressure rise over the UK. Although I personally have a sneaking suspicion that it'll be a month dominated by quite an active Atlantic.....no December 2010 I think....thus I can't see an early start to winter. Also, Jan/Feb have been shown consistently by the CFS to feature blocking to the N which allows an easterly airstream to dominate in quite a few of the recent runs. Whether this bears any weight we'll have to wait and see but you've certainly gone to town with your early look at January.

Edited by CreweCold
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Apologies if this point has been aired before, but I was wondering if this potentially northerly set up, with a MAH/Greenland was common this early on in the season, I seem to remember a slow change from summer to winter through September and October with HP influencing the south for a lot longer than the models are indicating at the moment.

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Apologies if this point has been aired before, but I was wondering if this potentially northerly set up, with a MAH/Greenland was common this early on in the season, I seem to remember a slow change from summer to winter through September and October with HP influencing the south for a lot longer than the models are indicating at the moment.

I might sound stupid but i have seen you mention MAH a few times, what does this mean? thanks.

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I might sound stupid but i have seen you mention MAH a few times, what does this mean? thanks.

Hi Mark, its abbreviation for a Mid Atlantic High and quite often it can ridge northwards (retrogress) and merge with the Greenland high to bring us a cold northely in Winter. Some more abbreviation that are sometimes use are GH Greenland High, AH Azores High, One abbreviation witch had me guessing fora long time was the GIN sea, witch turned out to be the Greenland, Iceland, Norway sea.

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Hi Mark, its abbreviation for a Mid Atlantic High and quite often it can ridge northwards (retrogress) and merge with the Greenland high to bring us a cold northely in Winter. Some more abbreviation that are sometimes use are GH Greenland High, AH Azores High, One abbreviation witch had me guessing fora long time was the GIN sea, witch turned out to be the Greenland, Iceland, Norway sea.

Thanks i have heard of GH & AH, before, but had never known what MAH meant glad to know now, thanks for the reply, much appreciated :)

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I will not bother posting an autumn seasonal forecast in part due to the late date but I expect OCT to be near normal in temperature and NOV to be quite mild.

Meanwhile, here is my winter seasonal forecast. I have posted this also in the winter 2012-13 thread so kindly don't block copy it and post it there again ...

Winter 2012-13 Forecast Summary

Based on my usual methodology and a consideration of the unusual ice-free anomaly expected to start the season, the following is my expected temperature and precipitation trend for DEC-JAN-FEB (following a November with expected mild temperatures by 1-2 C deg, and near normal in precip).

DECEMBER looks fairly close to normal with a roughly equal mixture of mild and cold days. There may be one relatively severe cold spell of 2-4 days around the middle of the month towards the 20th. The period 7th to 13th is expected to be quite mild, and the run up to Christmas increasingly mild with rain replacing sleet or snow in most areas but there would be a better chance for snow in north-central parts of the U.K. around Christmas. A stormy interval may develop just around or after Christmas Day.

JANUARY looks relatively mild but with severe cold forming gradually off to the north and east of the U.K., some intervals of modified cold could intrude. The month may also become rather stormy at times especially in periods around the 10th and 25th. A trend to much colder weather is likely near the end of the month although mild weather could hold on in the southwest.

FEBRUARY is expected to be much colder than average by 2-4 degrees with considerable snow and frequent easterly winds. This will develop because of massive blocking to the north of the U.K. extending from Iceland to Scandinavia. There is some indication of a very severe period of wintry weather. This severe cold may last some time beyond the end of the month.

... Will update into early November before launching this for better or worse, but don't expect any big changes to this outlook, the signals I have in my research model are quite strong concerning a downward trend in anomalies from NOV to FEB. Comparisons to 1946-47 are not ruled out by the numerical output. ...

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I am sure this will get lots of 'likes' Roger as it is what most folk are hoping for.

Not that I am implying in any way your forecast is skewed for them-as ever you produce reasoned outlooks from your system which still mystifies me but both short and longer range you have had some pretty good successes.

many thanks for your time and the forecast.

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Roger - your Jan and Feb forecast looks like an almost carbon copy of the forecast (from memory) you came up with last year. Is there any particular recurring reason for this, or just chance? Last year the Siberian High got close - ever so close - but was constantly blocked and bent the wrong way by the ridging Azores High. Do you see the Azores High playing such a large role this Jan/Feb?

Edited by Catacol_Highlander

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