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iapennell

Winter 2017/2018-Stormy December, Two Severe Wintry Spells January/February.

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13 minutes ago, Nick L said:

Hell of a stormy winter so far? Seriously? 13/14 was a stormy winter. This has been nowhere near a stormy season. There have been a few storms, nothing out of the ordinary. 

Quite agree - this has not been a stormy winter at all. 

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22 minutes ago, Radiating Dendrite said:

Quite agree - this has not been a stormy winter at all. 

Agreed. No where near stormy. I'd call it a typical North/South split Winter....if u see what i mean

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2 hours ago, Nick L said:

Hell of a stormy winter so far? Seriously? 13/14 was a stormy winter. This has been nowhere near a stormy season. There have been a few storms, nothing out of the ordinary. 

Quite.

I was beginning to think I was in my own microclimate and had missed the stormy December. :D

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I think it's been a good, typical winter. We've had cold, mild, a few storms, settled spells and many areas have had decent snow. Nothing extreme or particularly severe/prolonged but something for everyone. I'm not holding out much hope for a severe cold spell but I'm hoping iapennell is right, that's for sure!

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I suppose with iapennel predicting a cold spell it's a good test for the way he predicts the weather . First time I think he has predicted a proper cold spell since he has been doing lrf,s. And his lrf,s have been overall the probably the most accurate compared to others since he has been doing them these last few yrs. So end of Jan/start of Feb will be his biggest test. I will be well impressed if he turns out to be correct.

Edited by sundog
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2 minutes ago, sundog said:

I suppose with iapennel predicting a cold spell it's a good test for the way he predicts the weather . First time I think he has predicted a proper cold spell since he has been doing lrf,s. And his lrf,s have been overall the probably the most accurate compared to others since he has been doing them these last few yrs. So end of Jan/start of Feb will be his biggest test. I will be well impressed if he turns out to be correct.

The ten day very cold spell at the end of Jan doesn't look like happening sadly, so onwards to Feb. Let's hope we can get a good cold blast before the sun strength starts ramping up.

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Personally I don't think we will get a real proper cold spell tbh,never really did regards this winter. Not until next yr at least or the yr after imo 

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10 hours ago, Nick L said:

I think it's been a good, typical winter. We've had cold, mild, a few storms, settled spells and many areas have had decent snow. Nothing extreme or particularly severe/prolonged but something for everyone. I'm not holding out much hope for a severe cold spell but I'm hoping iapennell is right, that's for sure!

Largely agree with your sentiments and has been better than any winter since 2012/13, mixed as you put it with a bit of everything (particularly December). Not so sure on the 'many areas' seeing decent snow - I should guess that many areas in the south west, south, parts of the Home Counties and many parts of East Anglia and the East have seen not much at all in the way of settling snow (experienced 2 mornings myself with slushy stuff, near 1 inch on the first morning).

Wouldn't at all be surprised to see this winter though end up somewhat warmer than average.

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Late January cold spell looking unlikely now (it looks now like the short spell of easterlies that brought widespread night frosts around 7th and 8th January was it!).  Outlook into early February has persistent deep depression track across the North Atlantic close to 60N, short spells with colder north-westerlies over the UK followed by milder south-westerlies. An big area of high-pressure comes on the scene by early February but (as yet) in the wrong place to deliver frigid easterlies.  Its what is known as a Bartlett High!

image.thumb.png.87bcd98bef66dd9e6a2f09071ce202a8.png

The extreme cold over the north-eastern USA and Canada combined with warmer-than-usual temperatures further east in the NW Atlantic has generated the necessary baroclinic gradients for some big storms to cross the North Atlantic- much of North West England has had wind gusts up to 60 mph over the last 24 hours causing ferries to be cancelled, disruption on roads, etc. The North Atlantic flow has been strong through most of January and is liable to win out against cold high-pressure from the east for longer than I predicted in my original forecast, but I still expect a spell of very cold easterlies to materialise and last 10 days to a fortnight during February. 

High pressure looks set to be being in charge as we go into February and this will mean drier weather for the south and east of the country (as per my forecast for next month).  The 10 mb forecast for 60N is for the mean wind-speed to drop below 30 m/s and there is a strong likelihood that high-pressure gets established over northern Europe- particularly as the active phase of the MJO moves into the tropical Atlantic.  In February the Circumpolar Vortex usually weakens dramatically and with an easterly QBO, a weak La Nina bordering on ENSO-neutral and there being a lack of significant Sunspot activity or Solar flares,- various parameters are in place to encourage much weakening of the Circumpolar Vortex as the Sun returns to warm the Arctic Stratosphere by the end of this month.

I did make clear in my original forecast that I was not expecting a colder than normal winter for the United Kingdom, only that it would be colder than the last few winters have been (this now looks like it will be the case) and that two cold spells from the east would occur between late January and the second half of February. I was also clear that these very cold spells would come from the east or north-east; the transient cold spells from the north-west (such as we have at present) do not really bring snow and freezing temperatures to the south and the strong winds accompanying these transient cold spells are indicative of a strong Circumpolar Vortex.  The strong Polar Vortex will certainly become weaker as we hit February (and longer-range weather charts are starting to show this), don't give up hope for those frigid easterlies yet!

 

Edited by iapennell
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15 hours ago, BLAST FROM THE PAST said:

Not a good update Ian.....why should it change using your method? Indeed that becomes the fate of all of us and we try to see why

 

BFTP

Strange comment. Ian has laid out why the forecast has changed... and anyone claiming that a forecast has to stay fixed in stone whatever the medium range developments is wanting more than any forecast can give!

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strange for you Catacol......not for me.  When one sets out the plan..the idea is the plan verifies and as one progresses the verification gets better and better....and that nothing should override in a big way what is forecast.  It isn’t a criticism but that what Ian relied on was misread or was overridden.....something experienced by all

 

BFTP

Edited by BLAST FROM THE PAST
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Well for snowfall this winter is behind 2009-10 by just 5 inches.

Had to wait till February 1st for the next measurable snow in 2010.

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On 1/19/2018 at 22:43, BLAST FROM THE PAST said:

Not a good update Ian.....why should it change using your method? Indeed that becomes the fate of all of us and we try to see why

 

BFTP

@ BFTP,

When I make my seasonal  prediction I use the global patterns of Arctic ice-cover, Eurasian snow-cover, the ENSO Cycle and the Quasi Biennial Oscillation (the pattern of alternating easterly and westerly winds in the Equatorial Stratosphere) and sea-surface temperature anomalies at the time I make the predictions.  Other factors such as Sunspot Activity (the Sun is entering a quiet phase) also have an influence on likely weather-patterns  I use my understanding in meteorology (which I studied at university 25 years ago) to put these together to work out the likely trajectory of the prevailing weather-patterns.  Conditions around the UK, such as sea-surface temperatures around and to the west of Britain also have a strong bearing on likely weather-patterns going forwards.  I also make references to what other professional forecast companies are predicting, and if (say) a number of them predict something significantly different I modify the outlook;  I am of the opinion that trusted forecasting companies might pick up something different, like variations in tropical convection- that I might miss in my assessment that could substantially alter the outlook.

For the first month into a forecast, I use the 16-day forecast charts, Arctic Stratospheric outlook (which gives a strong indication of conditions for a further two to three weeks' ahead) and I make reference to the Met Office and Accu-Weather extended outlooks  and I use that, as much as my own understanding of how all the factors are liable to play out.  However, even the Met Office with their super-computers are only totally reliable out to about five days and if you are familiar with the concepts of Lorenz Theory you will understand that small perturbations, such as a depression forming over Newfoundland and racing eastwards can completely alter a weather-pattern over the medium term.

However, certain macro-scale conditions do have a tendency to support certain prevailing weather conditions.  A warmer  than usual North Atlantic with very cold conditions over Canada and Greenland create stronger atmospheric temperature gradients and these would spawn deeper depressions and stronger westerlies coming into Western Europe and these conditions between the North Atlantic and Canada/Greenland were the basis of my prediction that December through mid-January would be Atlantic-dominated but with short cold snaps- which has largely come to pass. 

I did also predict two very cold easterly-dominated spells for late January and early February on the basis of the easterly QBO, weak Lá Niná, excessive snow-cover over Eurasia at the time of my forecast and a quiet Sun that would lead to a weakening of the Circumpolar Vortex and the strong (baroclinic-related) Westerlies coming across the North Atlantic being pushed back.  I don't think this analysis is wrong as there is plenty of evidence that no Sunspots, greater snow-cover over Eurasia and easterlies high over the Equator along with cooler-than-normal Equatorial waters weakening the Intertropical Convergence Zone (and with it lessening the creation of Westerly AAM that fuels the Circumpolar Vortex)- lead to weaker Westerlies and a greater extent of blocking in higher latitudes. It takes a lot to convince me of the likelihood of high-latitude blocking and the occurrence of severe cold in Britain (indeed I did under-estimate the extent to which cold Arctic air would reach Britain during December, even though it was still an unsettled month with storms Caroline and Dylan).  The stormy pattern I predicted for early January has merely continued longer than I originally predicted, however that will change as a big anticyclone appears in the pressure charts for ten days' time and the intensity of depressions over the North Atlantic look weaker!

As to the reasons for the failure of the late-January frigid spell with easterlies there are a few candidates to blame:  There has been a little more solar activity in the terms of Solar Flares that was not anticipated back in November, snow-cover over Eurasia has been pushed back to the Russian border by mild south-westerlies over the continent and the exceptionally cold conditions over Canada and the north-east USA during December and this month have led to a reduced predisposition towards blocking in high-latitudes and a stronger North Atlantic flow than was anticipated by this point in time. 

However, the Circumpolar Vortex does normally weaken in early February as the Sun returns to the Arctic Stratosphere:  As the Arctic Stratosphere warms in consequence that does help tip the balance in favour of weaker Westerlies and high-latitude blocking.  I am still confident that this, in addition to the factors highlighted above -snow-cover over Eurasia (which is increasing again), cooler than normal oceanic waters overall and the easterly QBO will be enough to tip the balance at some point in early-mid February.  Note too that the Met Office is now predicting " drier spells", "that will be colder" by mid-February in their 16 to 30-day outlooks:  See here- https://www.netweather.tv/forum/topic/75951-met-office-16-to-30-day-outlook/?page=70.

I trust this helps clarify how I make my predictions and my own analysis of why the January bitter-cold spell -that I predicted back in November-has failed to materialise.

 

 

Ian Pennell

 

 

Edited by iapennell
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So basically there is still a chance of easterlies developing just not at the end of January, more like the start of February.

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6 hours ago, lassie23 said:

So basically there is still a chance of easterlies developing just not at the end of January, more like the start of February.

February 1986.:yahoo:

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08:50 and temps are widely in double figures across Northern Ireland, ROI, southwest Scotland, southwest England and parts of Wales

40ba4fce-1ce0-4176-870d-fb346f9cae9e.thumb.png.6ad064000455ec334bf3c1b01edece0d.png

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8 hours ago, Summer Sun said:

08:50 and temps are widely in double figures across Northern Ireland, ROI, southwest Scotland, southwest England and parts of Wales

40ba4fce-1ce0-4176-870d-fb346f9cae9e.thumb.png.6ad064000455ec334bf3c1b01edece0d.png

This thread is about a winter forecast and an analysis of it

I don't understand why this was posted in here especially when we have such a thread for current conditions which your goodself posted. :wink:

Edited by Weather-history
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1 minute ago, Weather-history said:

This thread is about a winter forecast and an analysis of it

I don't understand why this was posted in here especially when we have such a thread for current conditions which your goodself posted. :wink:

Nor do I actually I've got the wrong thread the forum loads up I scroll down and sometimes it jumps up once it has fully loaded which sometimes results in me clicking on the wrong thread this time I genuinely didn't realise

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On ‎22‎/‎01‎/‎2018 at 18:26, Snowyowl9 said:

February 1986.:yahoo:

Yes I remember it well,forgotten by many but still the coldest of any month in the last 55 years !

Edited by hillbilly

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On 18/12/2017 at 20:01, iapennell said:

@karyo, I'm glad you found the forecast.  I do indeed remain confident that there will be high-latitude blocking during late January and in February, which will result in a spell of much colder weather across the country courtesy of east or north-easterly winds from Russia. 

It's not just that we have a La Nina episode in the Equatorial Pacific but the equatorial waters across much of the Atlantic and Indian Oceans are also cooler than normal, whilst sea surface temperatures are a little above normal over the Northern Hemisphere subtropical oceans- cue a weaker Hadley Circulation and slacker NE'ly Trades that add less Westerly Atmospheric Angular Momentum to the Northern Hemisphere circulation than normal for the time of year. 

The QBO is now firmly Easterly, the Sun is very quiet and snow-cover is well-established over the Eurasian landmass: All of which point to a strong likelihood of high-latitude blocking, particularly when the Julian Madden Oscillation gets into the right phase to enhance that possibility (which it will in late January and early February). 

Ian, any thoughts today? Looks like you may have called it once again, give or take a few days :)

 

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@karyo, It does look like the promised easterlies will be materialising over the next fortnight,  although rather than being one continuous spell it looks like high-pressure over northern Europe will deliver two or three short spells with easterlies each lasting two or three days. The first of these looks set to occur around 5th/6th February. 

And this is the forecast chart for 14th February:

 

EUROPE_PRMSL_HGT500_336.jpg

Edited by iapennell
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So there we have it folks,after a lot of doubters and people saying in ain't gonna happen another box for Ian can be ticked. After a stormy December and Jan ( for me wnyway) after a 12 foot sand wall was produced by storm laden seas battering the southwest coast  (I've lived here for 15 years and never witnessed this before) right on cue, as if by magic we have a bitter start to Feb 2018 and where's the cold coming from?? Yes, the East. Hats off to you Ian calling it almost to the day and from so far out!!! I'll tell you something if this was netweather's forecast certain people would be all over it!!

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11 hours ago, iapennell said:

@karyo, It does look like the promised easterlies will be materialising over the next fortnight,  although rather than being one continuous spell it looks like high-pressure over northern Europe will deliver two or three short spells with easterlies each lasting two or three days. The first of these looks set to occur around 5th/6th February. 

And this is the forecast chart for 14th February:

 

EUROPE_PRMSL_HGT500_336.jpg

Thank you, it sounds good to me.  A very much improved February compared to previous years.☺

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