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

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1 minute ago, Nights King said:

Hard to say if that is good news for west country or not..?

100% good

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Just now, MidnightSnow said:

Whats changed for tomorrows event mate? App still shows plenty of snow

I thought models showed our area (Bristol) to only get patchy snow later tom, before main stuff Friday.

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Just now, Nights King said:

Hard to say if that is good news for west country or not..?

Nice upgrade from the NMM Mully, it has me down for 15cm tomorrow and another top up on Friday.....similar amounts, if not more, for you

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1 minute ago, Nights King said:

Hard to say if that is good news for west country or not..?

Personally to me looks less marginal for us and more comfortably within the band of snow rather than the edge. Really now any eastward shift won't affect us with all that snow to our west.

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Just now, ajpoolshark said:

Nice upgrade from the NMM Mully, it has me down for 15cm tomorrow and another top up on Friday.....similar amounts, if not more, for you

Cheers I looked at it but not properaly I asumed they were two time frames etc of latest but my beer googles skewed it :oops:

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8 minutes ago, cazbym said:

Can't find it..  I've been lurking in long range model and short range model.  Is it one of those?

Try this one,

 

 

 

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8 minutes ago, Bristle boy said:

I watch Only Fools on Gold all the time. Some episodes i reck i've watched 50 times! Chain Gang is an all-round classic- saved on my Virgin v6 box.

Anyway, light flurry here now. Was hoping for main event tomorrow but looks like Friday is main action

Ian, BBC and Metoffice all singing from same hymn heavy snow starts around 4pm tomorrow afternoon and stays heavy until early hours Fri morning. 2nd less intense band comes through Fri am and PM. No delay.

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1 minute ago, Smiler1709 said:

Hi nick

how do you reckon West Sussex will fair tomorrow?we seem to be on the boarder of the amber warning. Thanks 

The problem is the models still disagree even at this late stage. 

Its really going to come down to a nowcast on the day , you will see snow but as for amounts still hard to pin down .

There are several bands moving through and then a slow moving occlusion later on Friday.

 

 

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5 minutes ago, Jayfromcardiff said:

Accuweather have me down for blizzards tomorrow day and night with up to a foot of snow lol.

Sleeping s going well then Jay :rofl:

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The stuff in France is NOT the main low, it is convection and a weaker front ahead of it. That band may give snow slightly further East than was expected but to put your minds at ease the 18z Harlem, the same model everyone on other side of the A3 are raving about shows this:

 

hirlamuk-1-25-0.png?28-22

That was always the main event, anything earlier is bonus, anything after is a bonus (and I wil probably be banking on the bonuses rather than the main event).

 

People will always post the chart they want to see....well, most do.

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6 minutes ago, Jayfromcardiff said:

Accuweather have me down for blizzards tomorrow day and night with up to a foot of snow lol.

ha, if 'inaccuweather' are forecasting that, then I;d expect temps in the 80's with wall to wall sunshine....lol

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All that snow over the north of France and sliding NE. Surely that's not part of our main event?

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I have been trying to sleep for the past 1.5 hours. Between himself snoring his bloody head off, and checking the radar I well and truly have insomnia. 

 

 

Edited to add: although the radar seems to be trolling me. It was so close and now so far away. 

Edited by divadee
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If I focus long and hard enough at the lamppost outside I can definitely spot a flake or two hurtling by in the raw Easterly wind. That counts as snowfall here in Weymouth.

it really is time to sit back and enjoy the final aperitif before the main course is served up shortly. Just remember, this setup is nigh on perfect for a huge dumpings of snow in this region . I think by the weekend there will be many happy people on here. I say enjoy it as it may be many years before we have something as good for us as this on our doorsteps again.

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Just now, divadee said:

I have been trying to sleep for the past 1.5 hours. Between himself snoring his bloody head off, and checking the radar I well and truly have insomnia. 

Sneak downstairs and pour yourself a drink!:D:drunk-emoji:

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2 minutes ago, kent said:

All that snow over the north of France and sliding NE. Surely that's not part of our main event?

No it’s not, our main low is still down in northern Spain I think! However if that does hit you beforehand, happy days!

Edited by dec10snow
Actually checked the satellite instead of guessing 😂
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A POSSIBLE HISTORICAL WEATHER EVENT - PART 2: TEMPERATURES AND WINDS

I think I'll break this into 4 parts, as it's so busy and if I take more than hour (or even 2 hours) the early "non live" charts are already out of date!. Part 1 was back on page 170, where I posted the live radar and satellite charts  + pressure with an analysis of the current snow position and chances for tonight and tomorrow morning prior to the much anticipated arrival of the "big one"!   I'll focus on temperatures and winds in this part. In part 3 I'll examine what we need to see and want we do not want to see and what is actually hinted at by any of the evidence available. I'll also look at the jet stream and broader pattern set up. In part 4 I'll draw it all together. These will both be tomorrow.  

Before I go any further, there are three Live charts which I'm going to repeat with each part. They are so important in monitoring developments and I can see them while I'm writing this - I don't want to miss anything. 

lastsnowradar_uk.gif       lastsnowradar.gif      anim_ir_color.gif   

The snow shower activity is increasing steadily as the wind increases (I'm writing this part at 10 pm). Rather than die down in southern areas they are really getting going. The Channel streamer is healthier than ever and is once again moving closer to the coast and it's tail could be traced back to south-east Kent - longer than ever at 10pm. There's another line of quite beefy snow showers (which I'll nickname the A30 streamer for obvious reasons :D) stretching  from the Thames estuary though London and south-westwards through Hants, Wilts, Somerset, north Devon and Cornwall. Meanwhile I'm still sandwiched in between the two as I'm sure many others are too. The full France radar (doesn't pick up the Channel streamer so well) shows that the snow is making steady progress north and north-eastwards and turning to rain in south-west France. The infra red is simply remarkable, even more so than 2 hours ago. Just look at the enormous undercutting. Almost all that cloud and less cold air is been lifted well above the surface flow. If that profile continues as it tracks closer to us, something has to give and by then it'll be approaching the massive cold block. Can someone post a chart showing the temperature profile with altitude and the lapse rate? If I wasn't writing these reports, I'd be glued to these three charts :) 

I've just skimmed through the 12z model output and looked at the Met O fax charts and I'm none the wiser. What a mixture of outcomes. Even the GEFS ensemble panel starts to show a fair spread at T+72. I completely agree with what some on here have said, that even the T+0 nowcasts may not nail this one. Let's get a better idea of the progress of the less colder conditions. All times in headings adjusted to GMT. 

 France temps:   1148 Feb 28th                                                 2048 Feb 28th                                GIF 24 hours to 2148 Feb 28th                                        Live

       temp-12.png         temp-21.png       tempresult_ilz7.gif      temp.png

We need to take account of the usual min/max changes in the GIF chart. The start period is around this time last night. The less cold green colours have reached southern France today.

       France winds:  1148 Feb 28th                                           2048 Feb 28th                                  GIF 24 hours to 2048 Feb 28th                                      Live 

       vent-12.png        vent-21.png       tempresult_imk4.gif      vent.png

Explanations:
This map shows the average wind in real time recorded by weather stations in France and neighboring countries. The red arrows represent the direction of the wind of the stations, and the white arrows represent the direction of the wind calculated at any point of the map according to that of the stations. The color represents the average strength of the wind. These are the most recent observations of the present time and not forecasts. You can also see a ranking of the average wind values in France or see the wind information archive for the past hours or days by clicking on Classification or Archives above this map. You can also have more information about stations by hovering over the map.

What we need to focus on is the point where the winds veer from the east or north-east to a milder more southerly or south-westerly point. We can see that at 2048 this evening that the winds over much of France were still more or less from an easterly point and only in the extreme south of France were they more south-easterly and then in north Spain and south-west Biscay they are due south. The winds are much stronger further north and in the UK.

Now just a quick look through some UK and Europe view charts:

UK Live:    Surface Temps                                           Dew Point Temps                                         Windchill Temps                     GEFS 18z T+0 850 Temps for 2200 Feb 2th  

temp_uk.png       pointrosee_uk.png      windchill_uk.png      gfs-1-3-3h.png?18

Euro Live:    Surface Temps                                         Dew Point Temps                                         Windchill Temps       

temp_eur2.png       pointrosee_eur2.png      windchill_eur2.png  

With the stronger winds and cloudier skies the min temps may not be quite so low tonight but the maxes tomorrow will be well below zero in many parts, probably some sub -5s around - a nippy start to Spring :DWe should beat the UK's lowest max record set on 2nd March 2001 (at Cassley in Sutherland) with a max temp of -4.6c. The lowest in England was -3.3c at Spadeadam on 2nd March 1965 matching that on 5th March 1942 at Buxton (-4.4c in Wales and -1.2c in N.Irleand). The lowest min temp of -22.8c was on March 14th 1958 (at Logie Coldstone, Aberdeenshire) may survive unless we get some calm clear conditions over the Scottish snowfields.  

The coldest 850s are just about over us right now. Sub -14s everywhere and pockets of sub -16s just north of our region. This is an amazingly deep and extremely cold block. 

There is plenty of very cold air over Europe to continue to tap into.

Finally tonight - I promised to give my take on tomorrow's snow event and I will now, trying to take wishful thinking out of the process. After some snow in many parts of our region tonight and tomorrow morning - the main event should kick off some time tomorrow afternoon. The snow will start off as the dry powdery stuff for several hours with temps falling even further initially - perhaps below -5c even in our neck of the woods. Then as the flow comes more and more from the south-east it will warm up closer to -1c or even a balmy 0c and the snow will become much wetter and very sticky. There will be widespread blizzard conditions for quite a few hours but perhaps not for the 48 hours suggested by some. I also see a period of freezing rain for some hours as the milder air aloft just cannot penetrate the dense surface cold. Then I see the LP stalling and splitting but no really less cold air making it in. One LP cell will run east under the block and bring back the cold on a north-easterly. The Scandi HP will re-build and the cold spell continues but not quite so extreme as right now. On the other hand we might see some early Spring warmth :D. Frankly, it's pretty ridiculous to make any forecast in the most uncertain set up we've (perhaps) ever had. I'll examine all the pros and cons in part 3 tomorrow morning and give a few reasons why I really do think that the cold will continue. . 

Edited by Guest

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3 minutes ago, kent said:

All that snow over the north of France and sliding NE. Surely that's not part of our main event?

When are you gonna change your name to Dorset? :D

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Just to clarify things a bit more , the main uncertainty isn’t with the low itself.

The expansion east in some models isn’t because the sw is being downgraded in terms of snow .

Its in relation to the strength of some fronts ahead of the main low.

I think what’s happened is some mixed messages so as some members further east have been happy to see that expansion the impression might have been it’s because of a change in the track of the low .

 

Edited by nick sussex
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Well, no more snow here apart from the brief shower last night (apart from a dandruff flurries). Had some light stuff pass slightly north of me earlier.

However, models and forecasts seem to have upgraded precip for me tomorrow, many show 10-20cm.. With the wind.. blizzard like conditions with exposure especially in the evening.. could be the event we've been waiting for, I'm almost going into ramp mode!

Also just a thought, I wonder if the possible freezing rain tomorrow night could be ice pellets for some if the cold layer is deep enough... I'm not knowledgeable enough or do I have the right charts.. but I've done a brief search that suggests it might be possible if the warm layer is only around 850hpa and above.. the temp only rises to -5C on the forecast for Yes Tor at this time (620m high).

Either way, looks interesting!

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6 minutes ago, nick sussex said:

Just to clarify things a bit more , the main uncertainty isn’t with the low itself.

The expansion east in some models isn’t because the sw is being downgraded in terms of snow .

Its in relation to the strength of some fronts ahead of the main low.

Couldnt have put it better myself

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15 minutes ago, john w said:

The stuff in France is NOT the main low, it is convection and a weaker front ahead of it. That band may give snow slightly further East than was expected but to put your minds at ease the 18z Harlem, the same model everyone on other side of the A3 are raving about shows this:

 

hirlamuk-1-25-0.png?28-22

That was always the main event, anything earlier is bonus, anything after is a bonus (and I wil probably be banking on the bonuses rather than the main event).

 

People will always post the chart they want to see....well, most do.

Hi everyone, Long time lurker here, this is my first post despite years of forum and chart watching. I agree with this comment. What we are seeing on radar isn't Emma. Here is the latest IR sat image. I have circled the low which is due to arrive tomorrow which currently looks like it's going to be a direct hit to me. Can't wait. Before that my eyes are on that streamer looks like it's going to be 100+ miles wide by 4am looking at some of the models. Happy days!

image.thumb.png.ad87b75cfc8ccd620003b26227b1675e.png

Edited by SNMartyn
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