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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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21 minutes ago, offerman said:

No chance I’m afraid!  To mix with us mere mortals peasants ..... 

 

Dafty! He’s a lovely bloke, just doesn’t need the grief of certain types of posters who think they know more than him. ?

I’ll ask him 

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Fergie's just slapped down a tweet stating that Thursaday and Friday is going to be a non-event. The end of the week is still a long way off and any outcome is still possible.

 

Edited by TheLastMinute
Tweet didn't embed correctly
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1 minute ago, TheLastMinute said:

Fergie's just slapped down a tweet stating that Thursaday and Friday is going to be a non-event. The end of the week is still a long way off and any outcome is still possible.

<blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">Hmmm. Premature. Check eg DWE-ICON 18z deterministic (an important model alongside ECMW/UKMO/GEM). This saga is far too early to call... &amp; crazy to do so one way or another at this range. A very, very complex evolution.</p>&mdash; Ian Fergusson (@fergieweather) <a href="https://twitter.com/fergieweather/status/968250500268388353?ref_src=twsrc%5Etfw">February 26, 2018</a></blockquote>
<script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>

 

Sorry but where does that say non-event?

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I think Ian is saying at the very least this is far from over. If you look at the model corrections South over the last 24 hours then this is going to be a close one. I Woulden't like to be responsible for calling this correct and personally I believe there will be more corrections. The ICON has done well with this difficult period it was the first to pick up the trend and has run with it so its latest output is worth a look.

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Just now, kumquat said:

I think there's a bit of a misunderstanding here. When @TheLastMinute said Fergie "slapped down a tweet" - he meant that Ian dismissed the tweet that he was replying to - which was calling the Thurs/Fri event a damp squib.

Yep - fair enough; I get ya ?

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1 minute ago, kumquat said:

I think there's a bit of a misunderstanding here. When @TheLastMinute said Fergie "slapped down a tweet" - he meant that Ian dismissed the tweet that he was replying to - which was calling the Thurs/Fri event a damp squib.

Yes, @kumquat's correct, that's what I intended to say. It perhaps would have been clearer if I had embedded the tweet correctly, sorry.

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12 minutes ago, TheLastMinute said:

Yes, @kumquat's correct, that's what I intended to say. It perhaps would have been clearer if I had embedded the tweet correctly, sorry.

Not your fault ? and I apologise for taking it the wrong way. There have been a few posts over the last few days that have been underhand and I reacted too quickly ??

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Good evening everyone. I was intending to provide an update this afternoon but an urgent business matter cropped up that was even more important than monitoring this historic cold spell. It delayed my MOD post on the possible freezing rain event until 6pm. Right let's try to make some sense of all of this. I have some good news for all the snow starved south-westerners :) 

The snow that some of us saw today (just a few flakes here in Exmouth) was a bonus coming some 12 to 24 hours earlier than had been expected (for the south-west). The rare Channel streamer has been developing nicely. The wind started off this morning from an east to east-south-easterly direction but the flow backed very slightly this afternoon to a more direct easterly or even just north of east. This has kept the streamer tantalisingly close but for most just off shore. The streamer is steadily expanding (in width) and intensity especially in the western Channel. I had better provide (and repeat some) of the charts as my first post was buried quickly on page 80. In fact it will get a lot busier on here as the week progresses as snow chances increase further - so I'll repeat the key charts with each update (several times a day). I do not pay too much attention to weather warnings, especially for many snow events. Please note that sometimes the live charts get stuck. Just click on the image ans press "refresh" (or F5) and that should nudge it into action. 

        LIVE (RAIN) SNOW RADAR                        LIVE ANIMATED INFRA RED SATELLITE                     LIVE STANDARD SATELLITE

  lastsnowradar_uk.gif              anim_ir_color.gif                 anim_ir.gif

The snow radar confirms what i said about the streamer. It is expanding in the west and generally intensifying - look at those white colours developing which are pockets of heavy snow. For now, the streamer is off shore (more below on that). Now the second chart. As I said this morning , those bright colours are areas of much thicker cloud and not necessarily precipitation bearing. in this case it is. It is linked to that small area of LP moving south-west from Scandinavia. I simply cannot understand why the MetO decided that this will now move just to the north of us and miss us. The radar only picks up rain/snow about 40 to 50 miles off shore. Now look at that band just about to hit the north-east and east. That is heading straight towards the centre of the west country. So on exactly the right trajectory. My only concern this morning was that we might be on the tail end of it as it fizzles out. Well it looks pretty well defined. Back on the snow radar you can just see the snow reaching the east coast. Radars are fickle things and not completely reliable but the NetWeather radar shows the same snow band. The Meteoceil charts all have French times (an hour ahead of GMT) but they are 10 to 20 minutes behind the NetWeather updates. The snow looks to be light to mostly moderate intensity but with some heavier echos. I feel pretty confident that this will pass over us later tonight and give most of us at least a slight covering (more than a dusting but probably less than 5 cm). Looking at the third chart, the cloud area is showing little sign of dispersing. Downside risk: there could still be a change in direction (further north) and intensity.

LIVE PRESSURE (10 MIN UPDATES)                    GIF PRESSURE 24 HOURS TO 2220                   FRONTS & TROUGHS AT 1900 26.2.18              MET O FAX FOR 0000 28.2.18     

pression2_eur2.png                tempresult_yia5.gif                  analyse-2018-02-26-18.png        20180226.1651.PPVG89.png

This is good news all round. Our Scandi HP is continuing to intensify and look at the improving flow alignment. I mentioned this this morning. The flow is veering very slightly back to east and then fractionally south or east. I posted that Met O fax chart this morning and referred to the trough close to the south coast. That's our faithful Channel streamer. Some have said that it's not close enough. You need to realise that it's the precise flow and wind direction that is key. I think Knocker and several others also commented on this earlier and Knocker showed us an ECM chart with a comment which he later clarified. The snow showers on the streamer will be blowing inland.perhaps up to a good 20 to 30 miles from the coast. This should start during tomorrow and peak during Wednesday before the flow backs to just north of east again. With the streamer likely to intensify and expand further during the next 24 to 48 hours, even more us are likely to benefit from this. Some may well see some large accumulations from later tomorrow and into Wednesday with almost continuous shower activity. I would estimate around 5 to 15 cm for a lucky few and 2 to 5 cm for others on the margins. These are purely guesses based on my experience of studying low level easterly convection and snow streamers from the 1960s. Downside risk: the flow might not quite veer sufficiently. The streamer might weaken. The former needs to be monitored (I'll update this tomorrow morning), the latter seems unlikely.   

         LIVE UK  TEMPERATURES                             LIVE EURO TEMPERATURES                          GIF EURO TEMP 24 HOURS TO 2300

temp_uk.png               temp_eur2.png               tempresult_fbc8.gif 

        LIVE UK  DEW POINTS                                          LIVE EURO DEW POINTS                         GIF EURO DEW POINTS 24 HOURS TO 2250  

pointrosee_uk.png               pointrosee_eur2.png              tempresult_lpm8.gif

         LIVE UK  WIND CHILL                                            LIVE EURO WINDCHILL                           GIF EURO WINDCHILL 24 HOURS TO 2310  

 windchill_uk.png              windchill_eur2.png              tempresult_gif5.gif

It's getting late and it has been a long day, so just a brief comment on the temperatures. The coldest air is still 24 to 36 hours hours away.  As that LP or wave moves through tonight and tomorrow morning, it should be introducing even colder air behind it. Then as the easterly flow strengthens further on Wednesday, even colder air will move in and this roughly coincides with the lowest 850s too. I'll discuss those more tomorrow as well as focus on the possible disruptive snowfall for Thur/Fri/Sat (timing uncertain and snow amounts very uncertain). I did provide some comment on it and on a possible freezing rain event in my MOD post (on page 20 of that thread).  I feel that temperatures in these set ups are usually pretty well understated. They will only rise to 0c or just above if you get some longer sunny intervals.with the sun getting higher in the sky now but if it remains much more cloudy and in any snow showers, it'll drop to around -1c to -3c for many of us. Just look at those exceptionally low temperatures and dew points moving in across Europe. -41c in Russia today and -49c dew points. The wind chills are perishingly low too and when we get that stronger easterly on Wednesday, expect those to drop to -15c or lower!

Overall there are so many snow chances, that even the most unlucky of us should get a decent covering with the majority getting some very large accumulations.

Good night..  David.  

Edited by Guest
Correct typos and check charts
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