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Met Office predicting very cold weather in 3 weeks time.
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<blockquote data-quote="Eildon Hill" data-source="post: 5800358" data-attributes="member: 244"><p><a href="https://www.gavsweathervids.com/flash.html" target="_blank">https://www.gavsweathervids.com/flash.html</a></p><p><span style="font-size: 18px"><strong>UKMO Contingency Planners Guidance: Jan-Mar 2018</strong></span></p><p></p><p>[Updated - 20/12/2018]</p><p></p><p></p><p>The excellent UK Met Office Contingency Planners Guidance has been released today.</p><p></p><p>This update covers the three monthly period January to March 2019 - Late Winter 2018/19 - You can read the UK Met Office Contingency Planners Guidance for yourself <a href="https://www.metoffice.gov.uk/publicsector/contingency-planners" target="_blank">here</a></p><p></p><p>For tonight's blog update we're going to review the UKMO contigency planners guidance for Jan-Mar 2019.</p><p></p><p>The headline for this months updated is that a colder than average Winter is expected!</p><p></p><p></p><p></p><p><span style="font-size: 15px"><strong> For January and January-February-March as a whole, below-average temperatures are more likely than above-average temperatures. The likelihood of impacts from cold weather is greater than normal.</strong></span></p><p>So we're channeling a cold January and a cold Jan-Mar but this doesn't show why the next three months are likely to be colder than average. However the "context" part of the guidance adds a little more "flesh to the bones"</p><p></p><p></p><p></p><p><span style="font-size: 15px"><strong> A moderate El Nino event is likely over the coming months. This increases the likelihood of the negative phase of the North Atlantic Oscillation (NAO), implying an increased chance of colder-than-average conditions.</strong></span></p><p></p><p></p><p><span style="font-size: 15px"><strong> The Madden-Julian Oscillation (MJO) is an area of enhanced thundery activity that moves eastwards through the tropics over a period of several weeks. It has recently been active and is forecast to enter a phase that often leads to negative NAO. This implies an increased chance of lower-than-average temperatures in early- to mid-January.</strong></span></p><p></p><p></p><p><span style="font-size: 15px"><strong> The stratospheric polar vortex (SPV) has recently weakened. It is influenced by various factors, including the sun, which is approaching a minimum in its 11-year cycle of activity. This increases the likelihood of a weak stratospheric circulation in late winter. On the other hand, the westerly phase of the Quasi-Biennial Oscillation (QBO) of the equatorial winds in the stratosphere tends to favour a stronger SPV.</strong></span></p><p></p><p></p><p><span style="font-size: 15px"><strong> In spite of this, long-range forecasting systems are confidently predicting further weakening of the SPV over the coming weeks, possibly cumulating in a sudden stratospheric warming event (SSW) in late December or early January. These events disrupt the SPV and substantially increase the chances of a negative phase of the NAO, implying colder-than-normal conditions during the outlook period.</strong></span></p><p></p><p></p><p><span style="font-size: 15px"><strong> For both January and January-February-March overall, the Met Office long-range prediction system, alongside systems from other prediction centres, shows an increase in the likelihood of negative NAO consistent with these global influences. Consequently, the probability of below-normal temperatures is increased compared to normal. The chances of disruptive cold weather, such as snow, are also higher than usual.</strong></span></p><p>So very, very interesting. Most of the main "drivers" of the weather are pointing us to not only cold weather in January but also cold weather in the late Winter - January to March period.</p><p></p><p>The QBO isn't favourable but otherwise things are strongly pointing towards a colder than average period - Long range computer models are still forecasting large amounts of northern blocking through this Winter - Something we've been seeing within the seasonal model output for quite some time.</p><p></p><p>As far as precipitation is concerned the headline summary of the Contingency Planners Guidance says a drier than average late Winter period is likely:</p><p></p><p></p><p></p><p><span style="font-size: 15px"><strong> For January and January-February-March as a whole, below-average precipitation is more probable than above-average precipitation.</strong></span></p><p>The "context" part of the guidance adds a bit more detail:</p><p></p><p></p><p></p><p><span style="font-size: 15px"><strong> There is an increase in the likelihood of negative NAO in this period. Conventionally, this would be associated with a greater likelihood of drier-than-average conditions at this time of year, as moisture-bearing Atlantic depressions deviate towards Southern Europe.</strong></span></p><p></p><p></p><p><span style="font-size: 15px"><strong> In this instance, the extent of this deviation is predicted to be less extreme with an increased likelihood of weather systems moving over France and giving precipitation over the southern half of the UK. For UK-wide average precipitation, therefore, this results in only a small shift in the probabilities towards below-normal precipitation.</strong></span></p><p>So this adds even more interest, A colder than average late Winter is likely but the jet stream and storm track may not be as far south into southern Europe as might be expected. This means we could conceivably see low pressure bumping into cold air and bringing an increased risk of snow - And this would be particularly focused on southern parts of the country!</p><p></p><p>A wintry start to 2019? It certainly sounds like it.</p><p></p><p>Vert interesting times ahead. Keep checking back for more and GWV will keep you posted...</p><p></p><p><span style="font-size: 18px"><strong>Previous Blog posts:</strong></span></p></blockquote><p></p>
[QUOTE="Eildon Hill, post: 5800358, member: 244"] [URL]https://www.gavsweathervids.com/flash.html[/URL] [SIZE=5][B]UKMO Contingency Planners Guidance: Jan-Mar 2018[/B][/SIZE] [Updated - 20/12/2018] The excellent UK Met Office Contingency Planners Guidance has been released today. This update covers the three monthly period January to March 2019 - Late Winter 2018/19 - You can read the UK Met Office Contingency Planners Guidance for yourself [URL='https://www.metoffice.gov.uk/publicsector/contingency-planners']here[/URL] For tonight's blog update we're going to review the UKMO contigency planners guidance for Jan-Mar 2019. The headline for this months updated is that a colder than average Winter is expected! [SIZE=4][B] For January and January-February-March as a whole, below-average temperatures are more likely than above-average temperatures. The likelihood of impacts from cold weather is greater than normal.[/B][/SIZE] So we're channeling a cold January and a cold Jan-Mar but this doesn't show why the next three months are likely to be colder than average. However the "context" part of the guidance adds a little more "flesh to the bones" [SIZE=4][B] A moderate El Nino event is likely over the coming months. This increases the likelihood of the negative phase of the North Atlantic Oscillation (NAO), implying an increased chance of colder-than-average conditions.[/B][/SIZE] [SIZE=4][B] The Madden-Julian Oscillation (MJO) is an area of enhanced thundery activity that moves eastwards through the tropics over a period of several weeks. It has recently been active and is forecast to enter a phase that often leads to negative NAO. This implies an increased chance of lower-than-average temperatures in early- to mid-January.[/B][/SIZE] [SIZE=4][B] The stratospheric polar vortex (SPV) has recently weakened. It is influenced by various factors, including the sun, which is approaching a minimum in its 11-year cycle of activity. This increases the likelihood of a weak stratospheric circulation in late winter. On the other hand, the westerly phase of the Quasi-Biennial Oscillation (QBO) of the equatorial winds in the stratosphere tends to favour a stronger SPV.[/B][/SIZE] [SIZE=4][B] In spite of this, long-range forecasting systems are confidently predicting further weakening of the SPV over the coming weeks, possibly cumulating in a sudden stratospheric warming event (SSW) in late December or early January. These events disrupt the SPV and substantially increase the chances of a negative phase of the NAO, implying colder-than-normal conditions during the outlook period.[/B][/SIZE] [SIZE=4][B] For both January and January-February-March overall, the Met Office long-range prediction system, alongside systems from other prediction centres, shows an increase in the likelihood of negative NAO consistent with these global influences. Consequently, the probability of below-normal temperatures is increased compared to normal. The chances of disruptive cold weather, such as snow, are also higher than usual.[/B][/SIZE] So very, very interesting. Most of the main "drivers" of the weather are pointing us to not only cold weather in January but also cold weather in the late Winter - January to March period. The QBO isn't favourable but otherwise things are strongly pointing towards a colder than average period - Long range computer models are still forecasting large amounts of northern blocking through this Winter - Something we've been seeing within the seasonal model output for quite some time. As far as precipitation is concerned the headline summary of the Contingency Planners Guidance says a drier than average late Winter period is likely: [SIZE=4][B] For January and January-February-March as a whole, below-average precipitation is more probable than above-average precipitation.[/B][/SIZE] The "context" part of the guidance adds a bit more detail: [SIZE=4][B] There is an increase in the likelihood of negative NAO in this period. Conventionally, this would be associated with a greater likelihood of drier-than-average conditions at this time of year, as moisture-bearing Atlantic depressions deviate towards Southern Europe.[/B][/SIZE] [SIZE=4][B] In this instance, the extent of this deviation is predicted to be less extreme with an increased likelihood of weather systems moving over France and giving precipitation over the southern half of the UK. For UK-wide average precipitation, therefore, this results in only a small shift in the probabilities towards below-normal precipitation.[/B][/SIZE] So this adds even more interest, A colder than average late Winter is likely but the jet stream and storm track may not be as far south into southern Europe as might be expected. This means we could conceivably see low pressure bumping into cold air and bringing an increased risk of snow - And this would be particularly focused on southern parts of the country! A wintry start to 2019? It certainly sounds like it. Vert interesting times ahead. Keep checking back for more and GWV will keep you posted... [SIZE=5][B]Previous Blog posts:[/B][/SIZE] [/QUOTE]
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