SEASONAL PREDICTION FOR WINTER 2014-15 FOR NORTHERN BRITAIN BASED ON LARGE-SCALE SST, SEA-ICE ANOMALIES IN AUTUMN 2014

[Hocus Pocus]

Note for Mr Pennell: Include Newton, Bowland in to next years forecast.

[draztik]

I wouldn't call this forecast a home run, and obviously many more weeks to go.

But certainly, as things stand and as we move into January proper.... this forecast, tho painful, is looking much closer to the mark when compared to others.

[Daniel*]

Ian Pennell you are doing exceptionally well compared to some many were going for a cold hearted winter and all the background signals supported this, the damn PV needs to be nuked. I'd love you to be wrong every inch of me wants you to be wrong - but at this precise time you stand alone, in your initial thoughts and they're being transpired. Still 2/3 of the Winter to go. If next year you forecast a bitterly cold winter I will take be up on four paws. (December) "There is confidence that almost all of England will come under the influence of a cold, dry high-pressure system from Europe for more than a week" close to the mark indeed.

Edited January 2, 2015 by Daniel*

[Bristawl Si]

But the December forecast predominately south westerlies and they were not v common last month

[The PIT]

But the December forecast predominately south westerlies and they were not v common last month

They were dominate direction here accounting for 20 days. However it wasn't a stormy month here and high pressure didn't dominate until the last few days of the month when the cold spell arrived.

Edited January 2, 2015 by The PIT

[iapennell]

I wouldn't call this forecast a home run, and obviously many more weeks to go.

But certainly, as things stand and as we move into January proper.... this forecast, tho painful, is looking much closer to the mark when compared to others.

 

First up, Happy New Year to all Weather Enthusiasts!

 

On balance I am pleased to note that my predictions for mild wet conditions in October and November were bourne out, the December cold snap did occur.  It was cold over much of England (and Scotland) early in December and (especially) around the 12th and 13th of the month; also just after Christmas (28th to 30th) it was cold over much of the country with frosts and freezing fog in places.  There was a weakening in the strength of the prevailing southwesterlies reaching the UK during these times, but I see that I was wrong about the details of how the cold spell would develop.  I was not, therefore, predicting severe cold in Scotland in December (it dropped to -9C in the Highlands at one point, they also have more snow in the Cairngorms and NW Highlands together than in the Alps according to a recent news report!).

 

The cold spell I predicted would happen was to be a result of high-pressure building over Europe and extending over England; this would have brought cold easterlies or SE winds to England and a good deal of dry and frosty weather; I predicted Scotland would remain firmly under the influence of south-westerlies and stay mild (but wet and stormy).  This has not happened because the high-pressure cells developed further west and the cold spells were the result of cold north-westerly airstreams from the sub-arctic.  Following these north-westerlies high-pressure has tended to sink south across the UK with milder westerlies to the north moving in from the northwest across the whole country as the ridge of high-pressure moved south; then a few days later another incursion of cold sub-arctic air would arrive behind a depression and the whole pattern would repeat. 

 

So this meant the whole country was cold at times; with the cold being the result of cold and unstable north-westerly airstreams sleet and snow fell widely (though it was seldom cold enough for it to lie for long periods).  If the cold had been a result of high-pressure from Europe the weather would have been cold and frosty but the high-pressure would have supressed any precipitation (including, of course, snow).

 

As we go into January, and certainly looking at the BBC's long range forecast, they are predicting unsettled and stormy conditions but with short, colder interludes with snow showers in the North and night frosts.  I predicted that, overall, January and February would be dominated by strong westelies, gales at times and wet (particularly in the North West).  I also predicted a few sharp short-lived cold snaps that would being much colder conditions with snow in the North and Scotland and some sharp night frosts.  Overall I predicted mean temperatures for both months would be a degree milder than usual in the South but near normal in northern Scotland. That this pattern looks likely to play out according to the BBC and Met Office forecasts is encouraging.

 

Ian

[John Badrick]

First up, Happy New Year to all Weather Enthusiasts!

 

On balance I am pleased to note that my predictions for mild wet conditions in October and November were bourne out, the December cold snap did occur.  It was cold over much of England (and Scotland) early in December and (especially) around the 12th and 13th of the month; also just after Christmas (28th to 30th) it was cold over much of the country with frosts and freezing fog in places.  There was a weakening in the strength of the prevailing southwesterlies reaching the UK during these times, but I see that I was wrong about the details of how the cold spell would develop.  I was not, therefore, predicting severe cold in Scotland in December (it dropped to -9C in the Highlands at one point, they also have more snow in the Cairngorms and NW Highlands together than in the Alps according to a recent news report!).

 

The cold spell I predicted would happen was to be a result of high-pressure building over Europe and extending over England; this would have brought cold easterlies or SE winds to England and a good deal of dry and frosty weather; I predicted Scotland would remain firmly under the influence of south-westerlies and stay mild (but wet and stormy).  This has not happened because the high-pressure cells developed further west and the cold spells were the result of cold north-westerly airstreams from the sub-arctic.  Following these north-westerlies high-pressure has tended to sink south across the UK with milder westerlies to the north moving in from the northwest across the whole country as the ridge of high-pressure moved south; then a few days later another incursion of cold sub-arctic air would arrive behind a depression and the whole pattern would repeat. 

 

So this meant the whole country was cold at times; with the cold being the result of cold and unstable north-westerly airstreams sleet and snow fell widely (though it was seldom cold enough for it to lie for long periods).  If the cold had been a result of high-pressure from Europe the weather would have been cold and frosty but the high-pressure would have supressed any precipitation (including, of course, snow).

 

As we go into January, and certainly looking at the BBC's long range forecast, they are predicting unsettled and stormy conditions but with short, colder interludes with snow showers in the North and night frosts.  I predicted that, overall, January and February would be dominated by strong westelies, gales at times and wet (particularly in the North West).  I also predicted a few sharp short-lived cold snaps that would being much colder conditions with snow in the North and Scotland and some sharp night frosts.  Overall I predicted mean temperatures for both months would be a degree milder than usual in the South but near normal in northern Scotland. That this pattern looks likely to play out according to the BBC and Met Office forecasts is encouraging.

 

Ian

Hi Ian, your forecast is an interesting read and going quite well so far however you did say south/ south west would have very little cold and snow. Coming up to the Half way mark of proper winter and down here in Cornwall we have had around 6 days of severe frosts. A couple of days when it didn't get much above freezing so frost lingered all day. We had a covering of snow last night and looking at the charts there may well be more to come next week. Do you think the cold we are seeing in the charts now will be prolonged going in to February or will we see a milder outlook shortly? (i.e. mild/ warm spring)

[iapennell]

Hi Ian, your forecast is an interesting read and going quite well so far however you did say south/ south west would have very little cold and snow. Coming up to the Half way mark of proper winter and down here in Cornwall we have had around 6 days of severe frosts. A couple of days when it didn't get much above freezing so frost lingered all day. We had a covering of snow last night and looking at the charts there may well be more to come next week. Do you think the cold we are seeing in the charts now will be prolonged going in to February or will we see a milder outlook shortly? (i.e. mild/ warm spring)

 Hi John:  What exactly is your definition of a "severe frost"?  Where I live in the North Pennines I have yet to record anything colder than -4C; in December much of the country (inc Midlands and SE) got down to about -3C to -5C during the coldest nights:The North Pennines missed a lot of the clear sky and calm that would have resulted in lower temperatures.  However, under such conditions (particularly as westerlies held up for much of the month) I would be surprised if air temperatures ever got much below freezing point at all in Cornwall (certainly not enough to freeze wet ground rock hard- my definition of a severe frost).

 

We could well have such a hard frost nationwide this week as winds are forecast to go round to the north towards the weekend.  This is probably the first of the short arctic cold snaps of January that I predicted, in what I still maintain will be an overall slightly milder than normal, rather wet and windy winter:  The overall pattern is much as I predicted it would be, the "cold patch" in the NW Atlantic leading to the prevailng winds being SW to NW rather than south to west (as was the case last winter).  This leads to more opportunity for short cold snaps from the northwest as deep subarctic depressions pass eastwards (the coming cold snap will result from the passage east- of the vicious depression crossing Scotland tonight\tomorrow that is causing havoc across much of Britain today).

 

Ian

Edited January 14, 2015 by iapennell

[Hocus Pocus]

If the models verify for next week then I'm struggling too see how your forecast will be right, as I can't find anything in there about a cold/ very cold 7-10 day period with the potential for lowland snow.

Edited January 14, 2015 by Hocus Pocus

[John Badrick]

Hi John:  What exactly is your definition of a "severe frost"?  Where I live in the North Pennines I have yet to record anything colder than -4C; in December much of the country (inc Midlands and SE) got down to about -3C to -5C during the coldest nights:The North Pennines missed a lot of the clear sky and calm that would have resulted in lower temperatures.  However, under such conditions (particularly as westerlies held up for much of the month) I would be surprised if air temperatures ever got much below freezing point at all in Cornwall (certainly not enough to freeze wet ground rock hard- my definition of a severe frost).

 

We could well have such a hard frost nationwide this week as winds are forecast to go round to the north towards the weekend.  This is probably the first of the short arctic cold snaps of January that I predicted, in what I still maintain will be an overall slightly milder than normal, rather wet and windy winter:  The overall pattern is much as I predicted it would be, the "cold patch" in the NW Atlantic leading to the prevailng winds being SW to NW rather than south to west (as was the case last winter).  This leads to more opportunity for short cold snaps from the northwest as deep subarctic depressions pass eastwards (the coming cold snap will result from the passage east- of the vicious depression crossing Scotland tonight\tomorrow that is causing havoc across much of Britain today).

 

Ian

More frosts and heavy snow in Devon (admittedly on the moors but still heavy snow in the West Country) so a lot better for cold and snow this year

[iapennell]

More frosts and heavy snow in Devon (admittedly on the moors but still heavy snow in the West Country) so a lot better for cold and snow this year

 

@ John Baldrick

 

The cold "north-westerly" snaps seem to be somewhat longer and more entrenched through late January and Arctic airstreams are set to remain into the first week of February.  That said, I am encouraged that the basic forecast for January 2015 (at least for the North Pennines)- stormy, wet and with a cold snap later in the month has come to pass, even though the "cold snaps" (there were two, not one) have been longer in duration than I predicted (leading to mean temperatures near-normal rather than a degree above). 

 

On a more serious note, a look at the weather maps for Europe/the North Atlantic seems to indicate some weakening in the overall strength of the higher-latitude Westerlies coming into NW Europe going into February.  The weather chart today shows no depression deeper than 970 mb in the sub-arctic and there is a ridge extending from Iceland to the Azores; this means a more north to south airflow with Arctic air reaching most of the UK.  The weather at Nenthead (the village near where I live) has become very cold with a number of days not exceeding freezing point and I recorded -6C last night.  We also have over eight inches of snow lying (it was ten the other day).

 

In the light of recent developments I would shave a couple of degrees' Celcius off the February 2015 mean temperature prediction and assert that there will be more than a couple of short cold snaps from the north-west:  Northerlies are likely over the next couple of days and I would assert that at least one more "direct hit" from the Arctic (at its coldest in February) will occur before the month's end.  This means daytime temperatures near freezing point (with snow-showers) even in the South and hard night frosts in the clear night skies following these cold snaps.  

 

That aside I still think mild, strong west/SW winds (with high rainfall but further snow on high ground in Scotland and the North) will dominate in between so this means near-average February temperatues for the South but fractionally colder than normal for Scotland and the North (i.e. mean daily temperature about 3C in the lowlands of Scotland).  It will still be substantially wetter (and windier) than normal over most of the country (the SE of England being the possible exception where near-normal rainfall is likely and with a little more sunshine than the February norm).  The sea-surface temperatures over the North Atlantic and temperature regimes over both Greenland/Canada and NE Europe do not suggest anything other than continued strong westerly/northwesterly airstreams for February as a whole.  The patch of seasonally colder-than-normal waters in the mid North Atlantic near 45N is sufficient in intensity to put high-pressure there and encourage an anomalous north-westerly flow for points further to the north-east; this does not, in itself, point to a change to prolonged blocking in high-latitudes with frigid northeasterlies for the remainder of the winter.

 

Ian   

[John Badrick]

@ John Baldrick

 

The cold "north-westerly" snaps seem to be somewhat longer and more entrenched through late January and Arctic airstreams are set to remain into the first week of February.  That said, I am encouraged that the basic forecast for January 2015 (at least for the North Pennines)- stormy, wet and with a cold snap later in the month has come to pass, even though the "cold snaps" (there were two, not one) have been longer in duration than I predicted (leading to mean temperatures near-normal rather than a degree above). 

 

On a more serious note, a look at the weather maps for Europe/the North Atlantic seems to indicate some weakening in the overall strength of the higher-latitude Westerlies coming into NW Europe going into February.  The weather chart today shows no depression deeper than 970 mb in the sub-arctic and there is a ridge extending from Iceland to the Azores; this means a more north to south airflow with Arctic air reaching most of the UK.  The weather at Nenthead (the village near where I live) has become very cold with a number of days not exceeding freezing point and I recorded -6C last night.  We also have over eight inches of snow lying (it was ten the other day).

 

In the light of recent developments I would shave a couple of degrees' Celcius off the February 2015 mean temperature prediction and assert that there will be more than a couple of short cold snaps from the north-west:  Northerlies are likely over the next couple of days and I would assert that at least one more "direct hit" from the Arctic (at its coldest in February) will occur before the month's end.  This means daytime temperatures near freezing point (with snow-showers) even in the South and hard night frosts in the clear night skies following these cold snaps.  

 

That aside I still think mild, strong west/SW winds (with high rainfall but further snow on high ground in Scotland and the North) will dominate in between so this means near-average February temperatues for the South but fractionally colder than normal for Scotland and the North (i.e. mean daily temperature about 3C in the lowlands of Scotland).  It will still be substantially wetter (and windier) than normal over most of the country (the SE of England being the possible exception where near-normal rainfall is likely and with a little more sunshine than the February norm).  The sea-surface temperatures over the North Atlantic and temperature regimes over both Greenland/Canada and NE Europe do not suggest anything other than continued strong westerly/northwesterly airstreams for February as a whole.  The patch of seasonally colder-than-normal waters in the mid North Atlantic near 45N is sufficient in intensity to put high-pressure there and encourage an anomalous north-westerly flow for points further to the north-east; this does not, in itself, point to a change to prolonged blocking in high-latitudes with frigid northeasterlies for the remainder of the winter.

 

Ian

Thank you for the update Ian and it will be interesting to see how things pan out in the next couple of weeks. Thinking further afield, what are your thoughts for March? Do you think the dominant mild westerlies will continue to dominate? Or will there be a change in pattern to something colder? (i.e March 2013