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Tracking the potential Polar Low - Thursday into Friday


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Is it only me, or are the 'is it a/isn't it a Polar low' reamrks just plain old semantics.........as long as I get a dumping of snow, you can call it a lesser spotted chocolate teapot if you want    

Hi all.  Had great fun following this brilliant forum last night.  Just to introduce myself; I was senior forecaster at Manchester Weather Centre for 20 years, now retired.  I think that it was defini

so then....members in the west believe it'll track down the irish sea giving the action in the western regions...... members in the east believe it'll track though northern england and the SE giving s

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Posted
  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

    Just seen Ians Forecast and was surprised to hear a Polar Low mentioned, didn't realise there was a dedicated thread lol been out all day. Ian highlighted "risk" of 5cms on higher ground, 1-3 at lower levels for our region ie Westcountry.

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  • Location: leicester
  • Location: leicester

    So ecm gfs and nmm have it battering the east midlands and Euro4 and meto model have it further west!! I guess the middle route would be central midlands!!

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  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)
  • Location: Llanwnnen, Lampeter, Ceredigion, 126m asl (exotic holidays in Rugby/ Coventry)

    Not convinced, a polar low proper would be sat in at least sub -5c 850s and be an all snow event. This will be a wintry mix event, it has a mild sector within it.

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  • Location: LEVEN, Fife
  • Weather Preferences: snow, thunderstorms and extremes
  • Location: LEVEN, Fife

    I don't think it is a true Polar Low. A polar Low is a sub-synoptic feature which will not show up on a synoptic chart. I remember reading an article in Weather magazine about the Shetland Polar Low in February 2001. 500Hpa temperatures need to be below -52C. Forms in a strong baroclinic flow. Warm cored like it's tropical cousin. Centre filled with Nimbostratus producing heavy snow with gale force 8+ force winds at the surface.

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  • Location: CARDIFF
  • Location: CARDIFF

    Here in the west temperatures have dropped nicely below what was forecast

    Also dew points are dropping again so if this is widespread the mixing could bring a surprise covering to many more people.

    Better still this is just one of many chances over several days and the models continue to prolong the spell with possibly a disruption to polar vortex to kick it all off again around 7th Feb

    I feel the polar low will follow pretty much track North Wales to East Anglia but with two bands of precipitation of interest on its East And North West. Most of Wales away from Coast and far west should get Snow, The Swansea and Cardiff area Probably marginal with dew points, but close call. 

    Same for South Coast England and Far South East

    In between those areas the other band should give a nice few Cm's

    The other factor is the winds, which will be very strong, Drifting of snow could be a further hazard. These winds may make the dew points to high, however they could mix the air significantly to just put things on right side of marginal. The other thing is convection over the Irish sea. A plus now would be to see some sferics in the bands of heavy precipitation. Marginal can become quite optimum with evaporative cooling. 

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    Posted
  • Location: Irlam
  • Location: Irlam

    Not convinced, a polar low proper would be sat in at least sub -5c 850s and be an all snow event. This will be a wintry mix event, it has a mild sector within it.

    Will someone clear something up for me.

    Is a mild/warm sector, the area that is bounded between a warm and cold front?

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  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

    Will someone clear something up for me.

    Is a mild/warm sector, the area that is bounded between a warm and cold front?

     

    Yup?

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  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral

    I don't think it is a true Polar Low. A polar Low is a sub-synoptic feature which will not show up on a synoptic chart. I remember reading an article in Weather magazine about the Shetland Polar Low in February 2001. 500Hpa temperatures need to be below -52C. Forms in a strong baroclinic flow. Warm cored like it's tropical cousin. Centre filled with Nimbostratus producing heavy snow with gale force 8+ force winds at the surface.

     This used to be the case.. not anymore, Polar Lows can be adequately forecast by models, though like todays they will be most likely to shown as a wave, or a general disturbance. I believe -35C is the absolute least to have technical Polar Low capable of delivering snow. 

     

    However, a Polar Low could technically occur in summer given the right set up.. what then? This will lose Baroclinic elements as it moves south, and will become something akin to a polar low. 

     

    Do all Polar Lows initiate by baroclinic means?

    Edited by SP1986
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  • Location: East Lothian
  • Weather Preferences: Not too hot, excitement of snow, a hoolie
  • Location: East Lothian

    Will someone clear something up for me.

    Is a mild/warm sector, the area that is bounded between a warm and cold front?

    Yes, warm sector

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  • Location: Swansea South West Wales
  • Weather Preferences: Cold and Snow in winter Warm Sunny Summer
  • Location: Swansea South West Wales

    An occluded front is even more complex contains both warm and cold air which makes it difficult to forecast and this is what looks like is happening to the polar low its occluding so could be a headache to forcast snow and rain id imagine.

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    Posted
  • Location: Liphook
  • Location: Liphook

    Its not even as simple as temperature. For example you could have upper temps near -40 but because the sea is too cold lapse rates arent high to drive the convective process. Equally if you get -32c but the seas are a solid 2-3c warmer than average then you will have a better shot at having enough instability to develop it than if the temps were -32 but normal ssts.

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    Posted
  • Location: LEVEN, Fife
  • Weather Preferences: snow, thunderstorms and extremes
  • Location: LEVEN, Fife

     This used to be the case.. not anymore, Polar Lows can be adequately forecast by models, though like todays they will be most likely to shown as a wave, or a general disturbance. I believe -35C is the absolute least to have technical Polar Low capable of delivering snow. 

     

    However, a Polar Low could technically occur in summer given the right set up.. what then? This will lose Baroclinic elements as it moves south, and will become something akin to a polar low. 

     

    Do all Polar Lows initiate by baroclinic means?

    In the summer it would be rain, not snow. What are the wind speeds around this so-called Polar Low?

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    Posted
  • Location: Winterbourne, South Glos
  • Location: Winterbourne, South Glos

     A plus now would be to see some sferics in the bands of heavy precipitation. Marginal can become quite optimum with evaporative cooling. 

    There have been some sferics associated with the feature:

     

    http://www.blitzortung.org/Webpages/index.php?lang=en&page_0=12

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    Posted
  • Location: Bedworth, North Warwickshire 404ft above sea level
  • Location: Bedworth, North Warwickshire 404ft above sea level

    Looks like the thing is following the same path as the showers presently crossing the Midlands?

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    Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral

    In the summer it would be rain, not snow. What are the wind speeds around this so-called Polar Low?

     My thoughts exactly, which qualifies the temperature doesn't matter.. it's simply a cold core depression driven (eventually) by the thermal properties of the ocean. 

     

    Not sure.. but the north-western side of the low, in NW Ireland, generally sustained 25-35mph and gusts around 40-60mph currently. Must lower to the east of the low.

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  • Location: Stroud, Gloucestershire
  • Weather Preferences: Extreme!
  • Location: Stroud, Gloucestershire

    PPN really getting going around the Polar Low!

     

    polarlowppn_zpsdf8f93a5.png

    Edited by chris55
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    A YELLOW FLASH warning of Snow has been issued for parts of Northern Ireland.

    A polar low has developed near Scoland and is expected to track over eastern areas of NI this evening, this was unexpected hence a flash warning has been issued. This is likely to bring an area of snow for Co Antrim and Co Down, which could be heavy. Accumulations of 2 - 5 cm are likely in a short space of time and accumulations of up to 10cm locally and over the hills.

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