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South West and Central Southern England Regional Weather Discussion 22/02/2018 Onwards


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Sod the snow, Tom Baker is trying to steal your car. 

I want to see this in the morning.  

Good afternoon all ,with the passing of my beautifull wife last Autumn things have been rather busy at home but now starting to quieten down ,so today i,v been for a great walk up local woods .with th

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  • Location: Barton on Sea, Hampshire
  • Weather Preferences: Snowy winter, warm/hot summer with the odd storm thrown in
  • Location: Barton on Sea, Hampshire
    1 minute ago, TheHumph said:

    We're still sizzling here CE.

    Same over here although heavier snow reported a few miles to the west of me. 

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  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL

    Getting heavier, some decent drifting happening in a strengthening wind!!

     

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  • Location: Wellingborough, Northants
  • Weather Preferences: Heat and thunderstorms, snow in winter
  • Location: Wellingborough, Northants
    13 minutes ago, matt111 said:

    I don’t think I can ever remember seeing -3°C at lunchtime let alone in March. 

    Yes was -4 at midday here, incredible. For me the cold has been more notable than the snow (so far)!

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  • Location: W. Sussex, E. Hants & Portsmouth
  • Weather Preferences: Storms, snow and ice. The usual.
  • Location: W. Sussex, E. Hants & Portsmouth
    1 minute ago, TheHumph said:

    We're still sizzling here CE.

    Keep the faith TH, it's heading your way, hopefully. Actually pretty decent now and the wind is back with a vengeance.

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  • Location: Weston-S-Mare North Somerset
  • Weather Preferences: Hot sunny , cold and snowy, thunderstorms
  • Location: Weston-S-Mare North Somerset

    Still at work, thinking of booking the afternoon off....

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  • Location: The Purbeck Microclimate, Dorset.
  • Weather Preferences: Gales, T-storms, Heavy Rain, Heat, Cold - Love it all.
  • Location: The Purbeck Microclimate, Dorset.
    2 minutes ago, karlos1983 said:

    Getting heavier, some decent drifting happening in a strengthening wind!!

     

    Is this really happening here??

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    Posted
  • Location: Warminster, Wiltshire
  • Location: Warminster, Wiltshire

    Radar suggests Mother Nature may be about to even things out after 5 largely snowless winters!

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    Posted
  • Location: Reading
  • Location: Reading
    1 minute ago, TropicThunder said:

    Yes was -4 at midday here, incredible. For me the cold has been more notable than the snow (so far)!

    Could it end up being the coldest day in Southampton since 1987? I lived there in January 1987, when the temperature on the 12th didn't get above -5.

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    A POSSIBLE HISTORICAL WEATHER EVENT - PART 3:  PROS AND CONS

    In part 1 (buried on page 170) I examined the early set up and re-conditions to today's event and in part 2, I focused on temperatures and winds. In this part, I'll look at some of the other factors and consider the "pros and cons" on terms of what can go wrong, what can go right going forward from today and through to the weekend.  I will do the first bit of this now and finish it off later today in part 4. 

    Before I get going, I need to point something out that some of you might not realise. I just stated in my interim update this morning (on page 199) that the current (mostly light) snow is not the main event. It was part of the snow that pushed up over France yesterday and overnight well ahead of storm Emma. It then moved across the Channel and engaged with the remains of our Channel streamer. The whole band then pushed northwards. There is some additional residual moisture in the Channel now and the surface flow remains (more or less) easterly with the dense cold air still well in place. This recipe might beef up some of the Channel snow and sustain some more light snow during the next few hours. There are also a few other patches of snow moving north out of France that will top this "early" snow up. There may then be a lull for several hours. None of this is associated with the main event. Do not be surprised to see only a little more snow showing up over much of France during the day. Our "blizzard" will start to form much closer to us. The less cold air associated with storm Emma tracking northwards will (already has been for over 24 hours) will over ride the frigid surface flow ahead of it. As the frontal systems associated with Emma approach our cold block, snowfall should develop very rapidly and expand and intensify as it (at least initially) makes very slow and erratic progress northwards. It is this "mild over cold" air that generates the perfect conditions for exceptional snow events.  The radar echoes may look quite benign even after midday. I believe that many of us will be gobsmacked by how rapidly things develop early this afternoon.

    I'll post the usual "key" live charts here to keep an eye on: 

    lastsnowradar_uk.gif  lastsnowradar.gif  anim_ir.gif  anim_ir_color.gif  pression2_eur2.png 

    I need to keep reminding a few of you that the colours in the (4th) "infra red" chart represent areas of thicker cloud, the reds and purples (and whites when they appear) being the thickest cloud. This does not always relate to precipitation but it's safe to assume that on this occasion it does.  The strong under cutting remains intact. That is the frigid surface layers still in place under much of the upper flow from north-west France, the UK northwards and further west and then south-westwards right down to the west of Biscay. This is one mammoth battle will probably be fought out right over much of southern and south-west England over the next few days. We have merely seen the very early skirmishes so far. This takes me on to the main point of this post, the pros and cons.

    What Can Go Wrong and What Can Go Right? 

    Many of us (including me) would imagine that with such a massive deep cold block in place it will be very difficult to displace and that it will put up one hell of a fight. Although the deep cold is an important ingredient, it is the pressure patterns and what drives them that are key. I will keep this very simple so that those of you who perhaps only take a passing interest in the weather can understand (and I am NOT an expert but someone whose lifetime hobby has been learning about some of the processes and studying maps and charts all the time and I'm not experienced enough to go into too much technical detail). You do not need to understand all of it to get a general idea of what's going on. 

    This exceptional cold spell all started with a record strength sudden stratospheric warming event  several weeks ago. This impacted on the Arctic and caused the flow at the surface to reverse with HP forming close to the pole and spreading out from there. These HLB "blocking" patterns then set up around the high latitudes of the northern hemisphere. Much of the Arctic cold was displaced towards the middle latitudes.  On this occasion we had the almost perfect pattern for cold here in the UK. The Siberian HP extended westwards through Russia, Scandinavia and on towards Iceland and Greenland. The dense and very cold air over Siberia surged westwards right across Europe , the UK, Ireland and way out into the Atlantic. Such was the expanse of this dense cold air mass that it reached into much of central and southern Europe too with snowfalls in parts of Italy and Spain that rarely see them. The near record low temperatures that we have seen would be very unusual even for a mid January cold spell and today is the first day of meteorological Spring!  The sheer depth of this cold is also exceptional. The upper flow has seen temps last night fall to below -14c over the entire country and below -16c in a few spots. Even in many of our severest winters we do not see values as low as this. i did a post on the MOD thread several weeks ago comparing this spell to previous winters and this one ranks around the tenth coldest. So, we have both deep surface cold and deep upper cold in place right now over the whole of the UK.

    So what can it take for this cold block to be displaced or to weaken? With a normal cold spell (without a pattern reversal) the jet stream usually changes course and strengthens and pushes much milder air straight through our country and well into Europe. The charts below show that the main branch of the jet stream has been pushing from west to east well to our south through southern Spain, the Mediterranean and even north Africa.. There is a very weak breakaway streak that's pushing up towards southern and south-eastern England. Just 48 fours later this has dissipated. To me this seems to be too weak to displace the block very far at all (but time will tell). 

            GFS 6z T+6 for 1300, Mar 1st                     GFS 6z T+54 for 1300, Mar 3rd 

    gfsnh-5-6.png?6       gfsnh-5-54.png?6

    Now, we need to see the predicted surface pressure charts for the next couple of days. Pick any model or any ensemble chart and you'll find a huge range of solutions. This is the micro scale pattern that we're talking about over 2 days and simply demonstrated that this set up is the most complex one with such enormous opposing forces, that nobody knows the outcome beyond today! I'll stick with the "normally" much more reliable (for 1 to 2 days ahead) Met O fax charts which were updated earlier this morning (and subject to updates soon but part of the Met O is slow to update due to the huge volume of viewers):.

         Met O Fax for 0600 Thur Mar 1st            Met O Fax for 0600 Fri Mar 2nd               Met O Fax for 1200 Fri Mar 2nd              Met O Fax for 0000 Sat Mar 3rd  

    20180301.0725.PPVA89.png  20180301.1049.PPVE89.png   20180301.0530.PPVG89.png  20180301.0549.PPVI89.png

    The first chart has already passed but shows Emma off north-west Spain and Portugal and throwing up a succession of fronts towards the UK. The "ghost" (not blacked out) warm front) which is over riding the deep surface cold.is approaching us. That produced the first impact with the mixing of some "French" snow with our Channel streamer remnants (the barbed trough on the chart). There is a further pulse of snow pushing now and it looks like this will beef up the snow before the main event. In fact it's snowing steadily here now (1230). By tomorrow morning Emma has split into a complex group of LPs. The initial cell is now over the Breast peninsular. The very cold easterly flow is still entact and it looks like the less cold air has yet to penetrate down to the surface. The snow will probably be changing from dry and powdery to wetter with bigger flakes as the air aloft will be closer to freezing.  So either more very heavy snow (blizzards with severe drifting in the strong winds) or possibly some freezing rain or even an alternating snow to rain to snow sequence but still sub zero at the surface (I should imagine). By later tomorrow (3rd chart) Emma has hardly moved and the fronts are stalling and queuing up in the Channel - perhaps an even more severe blizzard by then OR temps just above zero and some more rain or drizzle and a gradual thaw. By Saturday evening the now occluded front has pushed up to the Midlands with the flow over the south coming up through France from the south but this will still have a south-easterly wind blowing towards us. Will the less cold air have reached the surface by then? We'll need to watch the charts and monitor the temps etc..  

    Remember other models and solutions are available. I must get to the Post Office before I get snowed in - so I'll post this now and get on with part 4 later on.  Enjoy :)

    David

     

    Edited by Guest
    Correct typos and check charts
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    Posted
  • Location: Anglesey, Gosport, Hampshire
  • Weather Preferences: Lightning and Snow
  • Location: Anglesey, Gosport, Hampshire

    Light powdery snow falling in Gosport. It's been snowing most of the morning but intensity seems to have increased within last 30 mins. UKMO have upgraded their forecast to heavy snow for 2100 and 2200 tonight preceded by 3hrs of light snow. My own forecast on my website which appears to have stuck to it's guns for the past 24 hrs (after a week of flip-flopping and upgrading / downgrading) is forecasting 80% chance of snow tonight which is in agreement with the UKMO.

     

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  • Location: Cottingham
  • Weather Preferences: Cold Snowy Winters, Hot Thundery Summers
  • Location: Cottingham

    Some bigger flakes within the drizzly snow now, looking forward to the arrival of the snow blob in the channel :D

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  • Location: Barton on Sea, Hampshire
  • Weather Preferences: Snowy winter, warm/hot summer with the odd storm thrown in
  • Location: Barton on Sea, Hampshire

    A few bigger flakes starting to fall here. 

    @Climate_Eyes I’m guessing the snows come a day too late for your exam? 

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  • Location: Poole
  • Weather Preferences: Snow and Hot Sun (but not at the same time!) 57m asl
  • Location: Poole

    Moderate snow now here in central Bournemouth. Great to see. Himself is home and the baby is home from nursery. Now just need more to settle so I can take her out on the new sledge. 

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  • Location: W. Sussex, E. Hants & Portsmouth
  • Weather Preferences: Storms, snow and ice. The usual.
  • Location: W. Sussex, E. Hants & Portsmouth

    Sorry  @TheHumph

    Just realised I've mixed you up with Kold, who I believe is north of me.

    :oops:


     

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    Posted
  • Location: Isle of Wight
  • Location: Isle of Wight

    I know I sound pessimistic but really poor here in Shanklin iow Can’t even call them snowflakes they so tiny ? met o reduced us from 3 hours heavy snow to 1 hour at 8 tonight it just doesn’t happen for us down here ??

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    Posted
  • Location: Lydford
  • Location: Lydford
    15 minutes ago, Polar Bear said:

    I know and its the whole bare hands on metal frozen gate we casually do! Ha hab  - tell you what has made poo picking outside easier! Come up in one go! ha ha. Ours at my friend's home as they are hers. School though is frozen, and no access to paddock but they have their "sun terraces" so to speak outside the stables so they can have some outside walk about..all has been plenty gritted and they have loads of haylage. Both were clipped a while ago and both like yours regulating temps well.

    Ps don't know if you do this or are doing it or can practically do it, but we gave ours a bucket of really warm water as well  - drank that in seconds.. so maybe worth taking up some when you go as some tend to not drink so much water if it is too cold.

    I broke ice in troughs at 9 a.m. this morning. By 1230 it had refrozen too hard for them to get through.

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  • Location: Southampton, UK
  • Weather Preferences: Hot, hot, hot! Or cold, cold, cold!
  • Location: Southampton, UK
    5 minutes ago, Mapantz said:

    That's pleasing to see! 

    Corfe Caste in view with snow..

    http://www.swanagerailway.co.uk/corfe-castle

    My dad loved snow, and the castle is overlooking him. :)

    It's where the Auld Fella and I had our first kiss! (Under the Castle, not the station.)

    Max temp today -3.4C.

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