Jump to content
Snow?
Local
Radar
Cold?
IGNORED

Short range model discussion - into 2018


Paul

Recommended Posts

Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

With regards to thundersnow, already this evening been some off the Essex and Suffolk coast over south North Sea and also eastern Ireland off the Irish Sea

archive_2_image.thumb.png.aad4785a603a36a482c9a53df8b8f0eb.png - since 1800hrs

  • Like 2
Link to comment
Share on other sites

Posted
  • Location: BS15 8bx
  • Location: BS15 8bx
2 minutes ago, Nick F said:

Synoptic analysis 22:00 27/02/2018

Wednesday

Pretty impressive 500mb upper low and associated cold pool moving SW across the N Sea from Denmark tonight and moving over northern Britain Wednesday morning. EC indicating 500mb temps as low as -46C, this will create very steep lapse rates and the intense upper low will create large scale ascent – which will both support vigorous convection off the North Sea over northern UK, bringing some significant snowfall to eastern England north of Lincolnshire and eastern Scotland over the next 12-24 hours. Could be frequent snow showers affecting Norfolk, Suffolk, Essex and perhaps north Kent too overnight as flow veers from northeasterly to easterly, hence upgrade to Amber warning for these areas this evening.

Weds_loop.thumb.gif.f0741ebc69f9740438d3d1b2f2b1a1bf.gif

So frequent snow showers for eastern Scotland and northern England on Wednesday - giving 5-10cm widely, 15-25cm over higher ground, locally up to 40cm. Further south across England and Wales, like today, surface shallow warming in sunshine under deep cold air characterised by steep lapse rates will generate snow showers or flurries inland and further snow coming in off North Sea.

ecmwf_tsnow_britain_7.thumb.png.60eba09af92d43fa677a4e5073cbbdd4.png

Thursday

Thursday sees further frequent snow showers pile in through the day across Scotland, getting well inland, could pose a problem through the central belt – with the straight easterly flow funneling a streamer through here perhaps – giving some large local accumulations to this more populated area of central Scotland and likely causing further travel disruption.

ecmwf_tsnow_britain_10.thumb.png.d61ba4b08d1629082704cdd824c888de.png

48.thumb.png.abe8f767d46c1f05170f44666162def3.pngec48.thumb.png.d5f08a5b522d62848e255d229d93c304.png

Further south, brief lull in the south continues Wednesday night into Thursday morning, but trouble is lurking to the south, as Storm Emma, named by the Portuguese weather service, lurks off NW Spain by 12z Thursday and pushes fronts north across France toward southern England, bringing a spell of snow north across southern areas through the morning, turning heavy across SW England and Wales in the afternoon and evening, as Emma moves north across Bay of Biscay then turns NW toward SW Ireland by midnight. The low deepening as it moves toward Ireland. 972mb off SW Ireland for 06z Friday, so some strong winds developing across SW England, Wales and particularly Ireland – giving blizzard conditions over higher ground.

Friday

Friday sees Emma just off SW Ireland by Midday before pulling away west over the Atlantic and filling. Associated occluding front, behind warm/upper warm fronts bringing snow on Thursday, looks to being another band of snow northeast Friday afternoon and evening, before slowing and fizzling out over central parts as per 12z EC – though where exactly it stalls and weakens still uncertain, maybe central maybe further south.

60.thumb.png.dccbcdce792748cde575f356c9eb66bf.pngec60.thumb.png.ca2311681b82db2c48052e451ae675ba.png

72.thumb.png.21c48fd67efec8e4355b16d6cbf7912b.pngec72.thumb.png.07c60bf696ddbf4022c47e9ce67ba1fd.png

 

What's your best guess on snowfall totals on the front from the SW Nick?

Link to comment
Share on other sites

Posted
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
  • Weather Preferences: Winter: Snow>Freezing Fog; Summer: Sun>Daytime Storms
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness

Faxmania time again:

Thursday:

T+96: 20180225_2132.PPVM89.thumb.png.aacc4d5b5aefb6234bbe4bb62515cef2.pngT+84: 20180226_0520.PPVL89.thumb.png.3afa386eec66483a48ee502df9dd2496.pngT+72:20180226_1755.PPVK89.thumb.png.301a781788674e7478f99797c0839bdf.pngT+48:20180227_1723.PPVI89.thumb.png.e84d175684622a380b1f042997208c7e.png

Friday:

T+120:20180225_2132.PPVO89.thumb.png.148cc7cde04bfa7cb04bbf7076651381.pngT+96:20180226_2205.PPVM89.thumb.png.05d0a0f9d4681121ff8f61f67606487f.pngT+84:20180227_0521.PPVL89.thumb.png.6544026f236ff73dbdf458c0bc7c2894.pngT+72:20180227_1805.PPVK89.thumb.png.793dbb59a0a55c48a60aa4133f1ed03d.png

Saturday:

T+120:20180226_2205.PPVO89.thumb.png.b1511cf1335b380c5ab62d894ffe66a9.pngT+96: 20180227_2255.PPVM89.thumb.png.07fb85b9086b7b9ba3b5f9ab4d5b1189.png

Sunday:

T+120:20180227_2313.PPVO89.thumb.png.91938db2045a2444f8ccdd7839e28076.png

 

Commentary: Tendency for warm fronts to make less northward progress before occluding and fading. Surface pressure charts for Saturday looking more similar to a repeat of Friday.

 

Edited by The Enforcer
Link to comment
Share on other sites

Posted
  • Location: Llanharan, South Wales
  • Location: Llanharan, South Wales
20 minutes ago, West is Best said:

Devon and Cornwall will be in the firing line Thursday and should accordingly be under a Red warning. Whether this pushes east I'm doubtful, but the second wave on Friday might.

So should south east wales including Cardiff and Newport. 

  • Like 3
Link to comment
Share on other sites

Posted
  • Location: Camborne
  • Location: Camborne
11 minutes ago, ajkwilson said:

@knocker How do you think things will pan out tomorrow and Friday regarding this low in your own opinion? 

Ajk, further to my post above I bow to the expert opinion of Exeter and thus the recently updated fax charts. Against that my opinion is not worth a candle :)

PPVG89.thumb.gif.90f4534e69ade66a7d686ac9325c6b49.gifPPVI89.thumb.gif.c0eff7f0c0e81863e5634627b6d24e58.gifPPVJ89.thumb.gif.004beb8087e03ac335bc34d3e34f8209.gif

PPVK89.thumb.gif.ec0226ca54315b01922999b3c2d07846.gifPPVL89.thumb.gif.64dc3b1efe568ac7e0dc8d7d05dc1733.gif

Edited by knocker
  • Like 1
Link to comment
Share on other sites

4 minutes ago, knocker said:

Ajk, further to my post above I bow to the expert opinion of Exeter and thus the recently updated fax charts. Against that my opinion is not worth a candle :)

PPVG89.thumb.gif.90f4534e69ade66a7d686ac9325c6b49.gifPPVI89.thumb.gif.c0eff7f0c0e81863e5634627b6d24e58.gifPPVJ89.thumb.gif.004beb8087e03ac335bc34d3e34f8209.gif

PPVK89.thumb.gif.ec0226ca54315b01922999b3c2d07846.gifPPVL89.thumb.gif.64dc3b1efe568ac7e0dc8d7d05dc1733.gif

Well noted :) been fasinatng watching how these models have unfolded and I'll keep an eye on this thread for your updates .I appreciate the reply :)

Link to comment
Share on other sites

Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
22 minutes ago, knocker said:

It never ceases to amaze me that that some on this forum feel qualified enough to advise the professionals at Exeter on what they should, or not, be doing regarding warnings, particularly as the current system was initiated by the latter. I'm sure they will issue the appropriate warnings when, and if, they think it necessary.

Quite agree, a RED warning is pretty unheard of, not sure if it has ever been issued. Some very clever folk about.

  • Like 4
Link to comment
Share on other sites

Posted
  • Location: Bedworth, North Warwickshire 404ft above sea level
  • Location: Bedworth, North Warwickshire 404ft above sea level
2 minutes ago, johnholmes said:

Quite agree, a RED warning is pretty unheard of, not sure if it has ever been issued. Some very clever folk about.

Didn't we have one in either 2010 or 2013? I'm sure I remember one red warning to do with snow?

  • Like 4
Link to comment
Share on other sites

Posted
  • Location: Bollington
  • Location: Bollington
1 minute ago, johnholmes said:

Quite agree, a RED warning is pretty unheard of, not sure if it has ever been issued. Some very clever folk about.

We have had a red warning once for snow here and it was on the day. It means ‘take action’ which would be too early now anyway. 

Anyway. That cold pool coming over in the night has really made that cold bite. I wouldn’t be surprised if a lot of areas got some pretty heavy snow today. They seem to be quite readily pushing across the Pennines now.

Link to comment
Share on other sites

Posted
  • Location: Brynmawr 1300ft asl
  • Weather Preferences: sun and snow
  • Location: Brynmawr 1300ft asl
6 minutes ago, johnholmes said:

Quite agree, a RED warning is pretty unheard of, not sure if it has ever been issued. Some very clever folk about.

We had a red warning in South Wales in 2013. Had nearly 2ft of snow over night that night.  Started as heavy rain too. 

  • Like 3
Link to comment
Share on other sites

Posted
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
  • Weather Preferences: Winter: Snow>Freezing Fog; Summer: Sun>Daytime Storms
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
14 minutes ago, johnholmes said:

Quite agree, a RED warning is pretty unheard of, not sure if it has ever been issued. Some very clever folk about.

January 2010, Central Southern England.

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
54 minutes ago, knocker said:

Some impressive minTs and Tgs this morning

http://www.met.reading.ac.uk/~brugge/06.html

 

Wow what a list, enough for a coffee break later I think!

Link to comment
Share on other sites

Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

Wow what a list, enough for a coffee break later I think!

Thank you also to those correcting my mistake re red alerts, however my comments about the actual posts I replied to remain.

5cm here and -3.3 C with snow on and off 

off to look at when I last had this much snow and so many consecutive air frosts, currently on 7

I tried to add the last 4 lines to the first and got told not allowed as too long since last post!!

If Paul reads this can you see what this is about please-thanks you

 

  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Crymych, Pembrokeshire. 150m asl
  • Weather Preferences: Extremes of all kinds...
  • Location: Crymych, Pembrokeshire. 150m asl

Looking at the detailed charts for the period out to about +65h there is a distinct wedge of less cold uppers shown forming across the SW and then making an arrowhead into south and west Wales.  The difference in temperature of this air is quite marked compared to the surrounding air and is modelled to considerably restrict the amount of snow falling over central Wales over the next three days.  This is the WRF but all high res models show this feature:

image.thumb.gif.8a6bac0e1b505d2c365d9056ccd0894f.gif

Is this the result of a geographical feature (Bristol channel, or Dartmoor perhaps?) or is it simply the dynamics of the low pressure system?  It stands out on the line of upper temperatures as they move north across the British Isles and it would be interesting to find out the reason for it.

 

Edited by Sky Full
..
  • Like 1
Link to comment
Share on other sites

Posted
  • Location: Nymburk, Czech Republic and Staines, UK
  • Weather Preferences: Sunny and warm in summer, thunderstorms, snow, fog, frost, squall lines
  • Location: Nymburk, Czech Republic and Staines, UK
2 hours ago, knocker said:

It never ceases to amaze me that that some on this forum feel qualified enough to advise the professionals at Exeter on what they should, or not, be doing regarding warnings, particularly as the current system was initiated by the latter. I'm sure they will issue the appropriate warnings when, and if, they think it necessary.

Absolutely. The key word here is ‘professionals’.

Link to comment
Share on other sites

Posted
  • Location: Hadleigh, Suffolk
  • Weather Preferences: An Alpine climate - snowy winters and sunny summers
  • Location: Hadleigh, Suffolk
21 minutes ago, Sky Full said:

Looking at the detailed charts for the period out to about +65h there is a distinct wedge of less cold uppers shown forming across the SW and then making an arrowhead into south and west Wales.  The difference in temperature of this air is quite marked compared to the surrounding air and is modelled to considerably restrict the amount of snow falling over central Wales over the next three days.  This is the WRF but all high res models show this feature:

image.thumb.gif.8a6bac0e1b505d2c365d9056ccd0894f.gif

Is this the result of a geographical feature (Bristol channel, or Dartmoor perhaps?) or is it simply the dynamics of the low pressure system?  It stands out on the line of upper temperatures as they move north across the British Isles and it would be interesting to find out the reason for it.

 

With the easterly flow over Wales it could be the air descending and warming (adiabatic compression) on the leeward side the Welsh mountains? You'll often see it in the Alps where it's referred to as the Foehn effect.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

Posted
  • Location: Irlam
  • Location: Irlam
1 minute ago, Blessed Weather said:

With the easterly flow over Wales it could be the air descending and warming (adiabatic compression) on the leeward side the Welsh mountains? You'll often see it in the Alps where it's referred to as the Foehn effect.

I think you see that in the US, Appalachian mountains?

  • Like 3
Link to comment
Share on other sites

Guest
This topic is now closed to further replies.
  • UK Storm and Severe Convective Forecast

    UK Severe Convective & Storm Forecast - Issued 2024-03-29 07:13:16 Valid: 29/03/2024 0600 - 30/03/2024 0600 THUNDERSTORM WATCH - FRI 29 MARCH 2024 Click here for the full forecast

    Nick F
    Nick F
    Latest weather updates from Netweather

    Difficult travel conditions as the Easter break begins

    Low Nelson is throwing wind and rain at the UK before it impacts mainland Spain at Easter. Wild condtions in the English Channel, and more rain and lightning here on Thursday. Read the full update here

    Netweather forecasts
    Netweather forecasts
    Latest weather updates from Netweather

    UK Storm and Severe Convective Forecast

    UK Severe Convective & Storm Forecast - Issued 2024-03-28 09:16:06 Valid: 28/03/2024 0800 - 29/03/2024 0600 SEVERE THUNDERSTORM WATCH - THURS 28 MARCH 2024 Click here for the full forecast

    Nick F
    Nick F
    Latest weather updates from Netweather
×
×
  • Create New...