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The Atlantic is showing off some classic visible cloud features of cyclone birth and decay today.  Systems labelled 1-4 on the satellite photo above show different features including stages of cyclone / mid-latitude depression formation and decaying high pressure ridge all on one satellite picture.  The chart below shows the same view with fronts.

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Starting with LOW number #2 (why not?!): the spectacular classic cloud spiral of LOW #2 indicates a mature low occluding and filling.

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This maturing occluding LOW has a couple of interesting extra vortices near the low core.

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Despite their angry look, classic cloud spirals like this on satellite photos are actually decaying and filling lows, losing their strength as pressure rises in the low core.  This particular LOW has a spectacular cold front of over 1500 miles stretching from 60N to the sub-tropics. The red colours on the RGB false colour eumetsat image below shows the cold continental polar air surging in behind the cold front.

Low #1 is a rapidly intensifying LOW off the coast of Labrador.  It looks harmless as a smudge of cloud but this shape … a so called “baroclinic leaf” indicates the birth of an angry developing storm: rapid cyclogenesis.

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This will deepen and pressure will fall rapidly in the next 24 hours as frigid continental air collides with humid maritime air under the influence of an active 200mph jetstream.

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LOW #1 is expected to form a big storm in the Labrador Sea by Wednesday. The fronts on this storm are then forecast to stretch clean across the Atlantic and bring the SE our first frontal rain for over a week by later Thursday.

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System #3  on the top satellite photo shows the HIGH pressure lingering over the South of the UK but regressing into the Atlantic.  This ridge has dominated mid to late March weather in the UK but brought a lot of anticyclonic gloom to the SE.  The deflating ridge will allow a more unsettled Atlantic westerly regime to dominate late March and early April weather.

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Low pressure #4 is an interesting developing depression in the Mediterranean, courtesy of a southward limb of the jetstream. Currently a disturbance dumping snow over the N Atlas in Morocco, this LOW is set to deepen across the Mediterranean through the week.  It will track directly ENE through the Med and bring snow to the Atlas mountains, rain to N Algeria and foul wet, windy and wintry conditions to Italy and then more snow and wintry weather to the Balkans.

Finally, for the UK our weak ridge is deflating to the SW and this will open the door to zonal westerlies and frontal systems bringing rain and wind from later Thursday and into the weekend.  Ensembles below show the dry spell ending this week and some notable rainfall spikes in the days to come, especially over the weekend.

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High pressure has dominated the last week of our weather but it has turned out disappointing here due to cloud cover lingering under a persistent temperature inversion, not unusual for this time of year.  Lingering decaying fronts have caused drab stratocumulus cloud to spread out beneath an anomalously warm upper air mass causing anticyclonic gloom for much of the SE.

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Any convection has been limited to the lowest 1km and been unable to break the inversion, so cloud, unable to rise into cumuliform tufts associated with the stronger sunshine in April, simply spreads out into a boring grey blanket, especially when the flow arrives from the North Sea bringing additional moisture in the lower layers. An inversion is when temperatures increase with height through a part of the atmosphere, usually referring to a lower layer.

So, whilst upper air temperatures have been anomalously warm, the surface temps have been kept disappointingly low.  Somewhat “upside-down” weather.

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This is because the Spring sunshine has been unable to break through the cloud and warm the surface.  The exception has been the north and west of the country, especially the hilly parts of Wales and NW England, which have enjoyed more sunny days.

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anticyclonic gloom

Today it was the turn of the E/NE coast to get the sunshine as weakening fronts shifted south around the high.

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The coming week sees the HIGH slowly deflating, like a sad party balloon, into the sub-tropical Atlantic.  A couple of powerful late winter storms emerging out of the NE US and Newfoundland start the onslaught to break a westerly unsettled flow back across the Atlantic by Easter.

For us in the SE this change to unsettled conditions happens slowly but ensemble runs are showing around 20mm of rain is possible before the end of March. So we might expect some wet and windy days before the end of March, including a risk of a wet bank holiday period.

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A return to more mobile frontal conditions is not all bad news, especially in the SE.  A westerly flow with weakening Atlantic frontal systems will break the gloomy cloud cover and bring sunny intervals and showery episodes to clear the pollution phase we have experienced lately.  The risk for us is any fronts stalling over the SE in front of a European HIGH – this situation can dump fairly large amounts of rain. Chart below shows wind speed and an active cold front for Sunday, too far off to be reliable but worth watching.

 

The multi-model charts below show this change from HIGH to LOW during the next week.

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Note the model agreement below by Saturday for SW winds, bringing temperatures up possibly into the mid-teens in the SE.

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In short, we can expect the weather to turn the “right way up” again and we should enjoy more mobile, fresher, brighter conditions, albeit with breezy episodes of potentially heavy rain at times. The charts below show temperatures rising in the SE but rain returning by Friday.

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Further into April there are hints that pressure rises across the Pole which will bring the potential for further unsettled cooler conditions during the school holiday period. RGSweather is off to Iceland (East fjords) again so this could mean some nice cold conditions for our trip there as the AO is expected to turn negative and the flow northerly, at least for the N Atlantic.  The UK appears to get stuck in an unsettled trough for early-mid April. Worth watching as JMA and CFSv2 both agree on this blocked pattern.

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February 2016 weather statistics for Reigate, Surrey, England.

  • Tmax 13C
  • Tmin -3C
  • T Average 5.3C
  • Rainfall total (CoCoRaHs) 48.2mm
  • Sunshine 99.6hours
  • Average MSLP 1010mb
  • rain days 18

Feb CET 4.9C (anomaly +1.1C)

Mean UK temp 3.9C

Storm Henry opened February weather with inclement wet windy conditions for the far NW but no significant impact here in the SE.

Storm Imogen on the 8 Feb impacted Wales and the SE more with the highest gusts of the month exceeding 41mph here in Reigate, with a max gust of 81mph on the Needles, Isle of Wight.

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February was another mild winter month, though not on the scale of record breaking December 2015.  February UK average was 3.9C, the Central England temperature (CET) for Feb was 4.9C, an anomaly +1.1C above the long term average. Locally our February average was 5.3C showing that the SE was warmer than the rest of the UK.

February was the sunniest winter month with nearly 100 hours of sunshine, compared to 94 hours in January and a dull 80 hours in December.

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The mean 500mb heights for the month (above) shows a trough placed over the UK for much of February and an overall Atlantic flow bringing milder than average temperatures, mainly to the south and SE. The continent was even warmer with some anomalous temperatures exceeding 10C in E Europe and Russia.

Rainfall for February was about average for the month at 48.2mm, similar to the MetOffice official SE England precipitation figure of 49mm.

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Global mean temperatures turned out warm again for February, in fact 0.47C warmer than the previous record.

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stratospheric warming February 2016

A notable atmospheric event that went mostly unnoticed at the surface was a significant stratospheric warming in February (and March).  The sudden warming of temperatures high in the stratosphere, much anticipated by the weather community and long range forecasters as a key tool to forecast winter conditions in the Northern Hemisphere, came too late to cause much cold winter weather in Europe.  El Nino winters are often accompanied by Sudden Stratospheric Warmings (SSW) events in late winter.  Such events can cause cold weather in mid latitudes as pressure eventually rises in the troposphere some 2 weeks after a SSW.  The warming during an SSW is truly remarkable, with temperature rises exceeding 80C in a matter of days at 10hPa (30km), from -80C to +10C in some SSW events.

An SSW is like inflating a balloon in the high atmosphere, pressure is expected to propagate down and eventually rise in the lower atmosphere some weeks after an SSW. Importantly, the pressure rise often disrupts the zonal westerly flow of the jetstream.  This appears as negative anomalies on the zonal wind chart below (blue colours). Unfortunately for this winter, the SSW came too late for much significant winter cold to penetrate into Europe.  You can spot that the anomalous easterly winds only got going in March… too late for deep cold to push into Europe.

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The JMA snow charts below also show how February came out as an anomalously un-snowy period for much of Europe.

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http://www.metoffice.gov.uk/climate/uk/summaries/2016/february

 

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After a pleasant dry and sunny day in the SE, the satellite photo from this evening spells trouble ahead for mid-week with a deep depression over Iceland and an increasingly active Atlantic with a long frontal boundary trailing across the ocean into thick bands of cloud.

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Reigate and the south of England are set for a potentially very wet day on Wednesday as shown on the Euro4 chart below showing just 12 hours of rainfall during the morning.

Unusually high rainfall totals could mount up, possibly to around 30mm for the day on some models. However, models usually exaggerate rainfall totals but it is likely to be soggy!

A strengthening Atlantic jetstream is causing the convergence of moist sub-tropical and polar air at the Polar Front over the Atlantic Ocean.  The winds can be seen converging on the Atlantic chart below.

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The convergence of Polar and Tropical airmasses can also be seen on this chart showing the trajectory of winds arriving in the UK on Wednesday.  Note the surface tropical airmass circulates round the Azores high and meets the incoming Polar air from Canada.  It’s the less dense moisture laden maritime tropical air which is lifted over the cold, enhancing rain on frontal boundaries.

The 850hPa (15oom) temperature chart below shows the steep temperature gradient between contrasting airmasses across the Atlantic.  The water vapour Meteosat satellite picture shows a broad sweep of moisture laden air crossing the Atlantic from the Sargasso Sea.

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The boundary of the contrasting moist Polar and humid Tropical airmasses causes lift and this is set to rapidly form a depression over the UK later on Tuesday into Wednesday courtesy of a jetstreak to the west of the UK.

Large amounts of Atlantic moisture are set to converge in this low pressure as airmasses meet at frontal boundaries.

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The result over SE England is an unsually steep rise in dew point to 6-7C, indicative of increasingly moist air.

The atmospheric column looks to become exceptionally moist on Wednesday and saturated through to a height of 25,000 feet.  Cloud depth will make it a very dull day.

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Rainfall charts look impressive and, at the moment, show the rain arriving on Wednesday morning. Here is a medley of rainfall charts from 3 different models showing the potential for a deluge, though do note that models tend to exaggerate these totals this far out.

The 6 hourly total chart from GFS shows an extraordinary 26mm over parts of SE on Wednesday morning.  This would lead to local surface flooding on roads.

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Note this is not a convective event so no thunderstorms are likely, which makes such high rainfall even more unusual. It could be the biggest daily rainfall total for quite a while, over 36.6mm of rain in a day was recorded on 24 August 2015. Keep posted on twitter and check MetOffice forecasts for updates if travelling.  Some disruption could occur if this comes off as models suggest.  Milder and settled conditions are expected into the weekend after our mini-monsoon!

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8-10 day mean upper air chart

The most wintry set-up of the “winter” has decided to arrive at the start of Spring! High pressure over the Pole is still keen to push out polar air into mid-latitudes as the meteorological Spring starts tomorrow.  The Arctic Oscillation shows this tendency as it has been dipping negative, showing relatively high pressure over the Pole and lower pressure in mid-latitudes. The belated rise in Polar pressure has been attributed to the stratospheric warming which occurred around a month ago.

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Unfortunately, for most of late winter the jetstream has remained strong enough to push a predominantly Atlantic flow into the UK and breach any blocks attempting to drag in sustained cold air. This is shown by the slight but persistently positive North Atlantic Oscillation below: this set-up spoilt any chance of proper cold this half of the winter.

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However, this week the wind is expected to turn more northerly as pressure lowers first over the North Sea and then the Channel / N France. By the weekend the UK will be in a cold Arctic flow courtesy of the same LOW lingering over Europe and a blocking Atlantic ridge. Between them and the jetstream they will do a good job of pulling down a cold Arctic flow this weekend. Spot the cold anomalies in the chart below. Lots of lying snow is not likely but some wintry precipitation is possible at times here, especially a marginal chance on Friday am.  Things change though, so check weather professionals like the MetOffice to make any weather related decisions.

Here is the story of how we get to some belated cold by this weekend.  Tuesday sees an end to the cool clear HIGH that brought Spring-like sunshine to Reigate and Tmax 9C.  A warm front will sweep in tomorrow morning and bring rain for most of the day for the SE.  It will be breezy, though relatively mild in the warm sector shown below, Tmax 10C.

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warm sector Tuesday

Things cool off into Wednesday as an active blustery cold front ushers in colder polar maritime air through the morning.  Any snow is restricted to the NW of the UK.

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The flow swings increasingly to the north west during the day with the possibility of showers later here, some quite heavy, maybe even with the outside chance of hail and thunder thrown in.  Tmax 6-7C.  Update: The video below shows how that showery trough passed through Reigate during Wednesday:

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Thursday is the crux to building a set-up capable of producing any snowfall at all for the SE.  A LOW is forecast to develop from a system off Greenland and cross the Atlantic smartly from the NW.2016-02-29_19-50-10

This low, with rapidly occluding warm sector, will deepen slightly and meet the cool pool sitting over the UK from Wednesday’s Polar attempt. The LOW is expected to arrive late Thursday and track south east overnight into Friday bringing in a cool NE flow capable of wintry precipitation for a while on Friday morning.

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The latest charts suggest the track into N France will result in NE winds which could bring snow for a time in the SE on Friday morning.

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meteoearth Friday ppt

It is all rather marginal for us in the SE and Reigate though. A rain / sleet event with a possible wintry mix at times is more likely and nothing much is expected to settle.

By Saturday and into the weekend a cold northerly / NE flow sets as the “Greenland” LOW settles over Europe. Wintry showers could develop across the SE, especially in any distrubances in the Arctic flow.  However, pressure is likely to be on the rise as the Atlantic ridge creeps in from the west under an increasingly anticyclonic jetstream.

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How long any early Spring cold lasts is not certain, the Atlantic ridge looks like toppling over to bring in warmer conditions later next week.

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The UKMet analysis chart for today shows a building ridge in the Mid-Atlantic and a complex large LOW over Scandinavia.  This is dragging down a cold Arctic airmass, which will usher in progressively colder upper air each day through to Thursday.  The low NW of the Azores is drifting ESE but filling and can be ignored for now.

Air at 850hPa, roughly 1500m up, is used to judge airmass characteristics because, at this height, the airmass is not affected by diurnal and surface changes like sea, forest, mountain, towns, which can create big temperature variations near the ground.  The 850hPa temperature by Thursday could dip as low as -8C over Reigate.  Whilst this is not extra-ordinary it is about the coldest and most sustained chilly dip we have seen so far this winter.  Skies will be mostly clear and nights will turn frosty with day Tmax struggling to 5-6C. Wind chill will make it feel more like freezing for most days this week.

High pressure nudging in from the Atlantic will keep any precipitation light and restricted to coastal areas.  Friday sees things get interesting and unusual.

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A southerly diving jetstream gets into action on Friday and is set to amplify the 500mb trough and deepen a low off the west coast of the UK and develop it further into Biscay into Saturday and create a cut-off feature by Sunday.

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The Atlantic / Biscay LOW is unlikely to impact us in the SE much directly but, as it passes south of us through the weekend into Europe it will drag in cold easterly and then NE winds.  Our own mini-Nor-Easter!

Nor-Easters are famous powerful winter storms in the USA.  Our own version this weekend is a rather tame feature in comparison but notable because it is relatively unusual and has potential to bring a more sustained wintry feel to the SE through the weekend and maybe into next week.

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This southerly tracking LOW will move NE through the continent and will set up a cool Easterly then NE wind over the SE. Nothing outrageously cold for us because the coldest air is likely to stick further to the north east in Russia and Scandinavia.  Nevertheless, by Sunday a brisk NE wind with upper air of -8C or so will continue to make it feel chilly, after a cool week.

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The winds over the SE will therefore swing from  Northerly mid-week through to Southerly on Friday and thence to Easterly and finally Nor-Easterly / Northerly by Sunday. This anti-clockwise rotation is called backing and often ushers in cold air.  This is despite the wind turning through a seemingly mild southerly direction.  Remember we are sitting well north of the jetstream this weekend, which is somewhere in the Mediterranean, thus all airmasses are relatively cold and polar.

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Pressure stays relatively high throughout this “mini-nor-easter” episode and so this will limit chances of any snow unless the low decides to track further north nearer the UK OR we pick up sea effect snow as winds turn NE over a relatively warm North Sea.

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Snow showers are theoretically possible near the North Sea coast if Sea Effect / Lake Effect snow can be kicked off.  Such sea effect snow occurs when (very) cold air masses cross warm sea surfaces.  This can trigger lines of convective showers that dump lots of snow in places like the Great Lakes in the US.  Sea Effect snow occurs best when there is a temperature contrast of at least 13C between 850hPa (which must be well below freezing of course) and a warm sea surface.

The charts above show the North Sea is anomalously warm at more than 8C across a large area, although cooler near UK shores.  The upper air temps this weekend are around -8C, making a potential 16C contrast in temperature, theoretically sufficient to trigger showers. Unfortunately the airmass seems to be dry and, at this stage at least, rather stable. Looking ahead the cold spell could last into next week. Check our twitter account @rgsweather for local updates but always check professional weather forecast providers for decision making, of course.

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Reigate, Surrey January 2016 summary weather statistics

  • Tmax 12.8C
  • Tmin -5.1C
  • T av 5.2C
  • Total rain 137.2mm
  • sunshine hours 94.1 hours
  • mean pressure  1009mb
  • max gust 35mph

January 2016 was a modestly unsettled month in Reigate with frequent wet days (21 in total with >1mm) and total rainfall amounting to 137.2 mm, this was some 160% of normal expected rainfall totals for the SE as a whole for January.  This caused some surface water flooding and soggy fields but, whilst a few flood alerts were issued, the River Mole behaved itself as no one rainfall event occurred with sufficient intensity to cause significant flooding problems in the Mole catchment.

In comparison with recent years, January 2016 turned out moderately wet sitting between the very wet January 2014 183 mm and the drier Jan 2015 69mm.  Of note locally was a spectacular display of mammatus cloud on 10 January as a squall line brought a thundery trough that passed over the area bringing some hail and cumulonimbus cloud.

It was a mild month with average temps 5.2C, Tmax 12.8C and only 7 days with minimum temperatures dipping to or below freezing. The highest January max temp ever recorded occurred in N Ireland. Whilst no weather record was broken in Reigate it was still a mild month with about average sunshine.

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sunshine Reigate January 2016

At 5.4C the CET temperature for the UK was 1.6C above the long term average. At 1.13C the global average January temperature turned out to be another record breaking warm month.

Returning to local events, one brief marginal wet snowfall event occurred in Reigate and Surrey overnight 16-17 January.

Snow lay during the morning of 17 January and was just sufficient to allow families to enjoy sledging and snowman building in Reigate and Priory Park for a few hours before it all melted by midday.

 

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The mean 500mb pressure anomaly pattern for January shows the UK in a mostly stormy Atlantic regime with storms rattling through especially the NW bringing high rainfall totals there. Storm Gertrude at the end of the month did not impact the sheltered SE much. As usual the SE was relatively protected sitting nearer the higher pressure over S Europe.

Imogen is the ninth named MetOffice storm this winter.  She formed in the Atlantic in an area of steep temperature gradients under control from an active jetstream.

 

Storm Imogen is deepening rapidly today to 953mb, though on arrival in the UK she will be occluding and filling gradually to above 960mb on her track over N Scotland into the North Sea on Monday. The exact track makes a big difference to where the strongest winds are.  Current trends are for the storm to pull wind fields further north so impacts could be less than expected. Keep an eye on the MetOffice forecast as things are likely to change. Below is an outline of Imogen’s likely activity:

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Unlike the previous eight named storms, Imogen has a more southerly track, guided by a more southerly tracking jetstream, and the field of strongest winds and heavy rain are possibly set to impact the densely populated southern part of the UK, including the SE. High waves are also expected on the Channel coast.

 

Strong winds on Sunday night will be associated with Imogen’s fronts running ahead of the depression.  The cold front is an active kata-front, associated with descending cold dry air from the stratosphere running ahead of the surface front and enhancing lift and potentially generating heavier rain and gusty conditions (image and info courtesy UKweatherworld).

On Monday gusts up to 80mph on the Channel coast are possible, while inland the MetOffice consider 60mph possible in exposed places.  Around Reigate and sheltered parts of Surrey, 40-50mph gusts are more likely.  The North Downs could see gusts approaching 60mph. The strongest winds for the SE are likely to be through midday and in the afternoon.

Yellow warnings apply to inland parts of Surrey and SE England while the entire Channel coast has an Amber MetOffice warning. The first impact will be frontal rain tonight.  Fronts passing through overnight into Monday could drop over 20mm of rain in places particularly linked to the occluding “triple point” forecast to cross the SE overnight.

 

Monday is likely to see showers, some heavy, appearing through the day.  Warm sea surface temps in the Channel are likely to cause more on the coast but the brisk winds could bring them inland as the day progresses.

The cause of the strong winds behind the cold front on Monday is a steep pressure gradient.  On Monday tightening isobars show the steep pressure gradient bringing gusty showery conditions in unstable Polar Maritime air behind the cold front later on Monday.

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The Wight-Wash Oscillation (WWO) measures the pressure difference between The Wash and the Isle of Wight and is designed as a guide to wind speed in the SE corner of the UK. The WWO on Monday shows a significant 16mb gradient between The Wash and the Isle of Wight on the WRF model.  The Euro4 model has a more modest 12mb WWO.  16mb would be the largest WWO pressure gradient recorded and greater than St Jude, which was 12mb.

On Tuesday models show a wave depression bringing more rain to the SE, some even show fleeting wintry precipitation on the back end of this low as colder air ingresses from the north.  This is unlikely to be significant, at least on Tuesday, as upper air temps remain mostly too high for snow in the SE.

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ECM colder flow mid-week

Colder conditions are preferred by the ECM as northerly winds bring cool polar air further into the country through mid-week.  The Arctic Oscillation is again going negative which shows pressure rising over the Poles trying to push Arctic air south into mid-latitudes.  However, the NAO remains positive so Atlantic depressions will continue to bring frontal depressions for this week.

The 8-10 day mean shows a deep trough over the UK meaning low pressure and unsettled conditions remain likely into half term.

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The ECM builds heights over southern Greenland which links with higher pressure over the Atlantic, a more northerly feed of cold polar air is likely in this scenario into half term . The ECM has been outperforming the GFS so the more Atlantic driven GFS chart would be the less favoured option.

The Sudden Stratospheric Warming going on over the Pole is another astonishing feature of weather at the moment.  Today (Sunday) temperatures in the stratosphere over Siberia has got up to an amazing +12C from a more usual -70C.  SSW events often build pressure over the Polar troposphere a few weeks later which can cause cold incursions into mid-latitudes.  This is by no means certain but is perhaps our last chance of any sustained cold this winter… if it were to happen it would be late Feb/March. One to watch!

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Jonas to UK this week

The phenomenal winter storm Jonas brought NE USA to a standstill over the weekend as more than 20 inches of snow fell on Washington and New York.   Jonas was a truly massive storm and broke regional snowfall records with up to a metre of snow in places, and brought a record storm surge of 9.27 feet on the Delaware coast with significant coastal flooding (beating Super Storm Sandy surge in places*). Weather Underground reported…

This nor’easter, dubbed Winter Storm Jonas, was one for the ages–among the most powerful and far-reaching in regional history.  Jeff Masters Weather Underground

Jonas threw blizzards, storm surge, heavy snow, icy rain and thundersnow at the US over the weekend.  Here is a brief outline of the storm and a look at where it is headed next.  It is worth noting that potentially another Nor-Easter snow storm is possible for this part of the USA later this week, although less likely to be as powerful.

New York had it’s heaviest daily snowfall total on record on Saturday courtesy of Jonas. Forecasters started warnings several days out and the National Weather Service made people aware of the seriousness of this storm in the lead up.

Jonas was a classic and historic “Nor-Easter” storm albeit with the potential added spark of warmer than usual Gulf Stream temperatures.  The system was well forecasted by the NWP models from several days out.  An insignificant low pressure disturbance entered the NW Pacific coast of the North America earlier last week, traversed the continent and emerged out of the SE dragging cold continental air to interact with warm Gulf moisture.

This explosive mix was exacerbated because both the Gulf of Mexico and Gulf Stream sea surface temperatures were anomalously high adding to the moisture and energy available for this storm.

“Take unusually warm Atlantic ocean surface temperatures (temperatures are in the 70s off the coast of Virginia), add a cold Arctic outbreak (something we’ll continue to get even as global warming proceeds), mix them together and you get huge amounts of energy and moisture, and monster snowfalls, like we’re about to see here” Michael Mann, climate researcher who directs Penn State University’s earth systems science center.

The storm got hooked up by a strong jetstream and traveled rapidly north over Friday 22 Jan, hugging the east coast and intensifying as pressure fell into Saturday 23 Jan and leaving the coast by Sunday 24 Jan.

The chart below shows the jet during the lead up to the storm on Tuesday 19 Jan.  Spot the LOW mid-west, this was Jonas in the making.

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jetstream emerging out of Gulf of Mexico… perfect Nor-Easter set up, spot LOW Jonas over MidWest

Another important element making this one of the top two most intense Nor-Easter winter storms on record was HIGH pressure lodged over NE Canada which intensified the pressure gradient and increasing those north-easterly wind speeds.  These strong winds drove ice and snow across a vast swathe of the NE and dumped 2 feet of snow as far north as New York city.

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In addition to large snowfalls the low pressure and strong on-shore winds also created a storm surge risk on high tides.  The coastal impact was recorded by a series of video cameras placed along the New Jersey coast by Hurricane Track’s Mark Sudduth.

Jonas is now forecast to track across the Atlantic, riding the jetstream and deepening on approach to the UK by Tuesday.

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Jonas GEFS tracks set to cross near NW Scotland

Through Tuesday and Wednesday Jonas will bring some stormy and wet but mild conditions especially to the NW of the UK.  Nevertheless potentially 70mph gusts are forecast for parts NW Britain.  Gusty conditions on associated fronts are likely at times here in the SE as well, but nothing like the intensity or disruption of the US version.

Further ahead, at least this week, the NAO and AO are both trending positive and this is set to bring further unsettled conditions across the Atlantic separated by drier periods of higher pressure, but mostly staying a good deal milder than average.

The pressure over the Poles has weakened and the Icelandic low has deepend, both indicating a lack of sustained cold potential in the near future for the UK.  Nevertheless, action in the stratosphere is hotting up with a forecast sudden stratospheric warming afoot.  Sudden warming events in the stratosphere can build pressure over the Poles and increase the chance of sustained cold weather, sometimes, over Europe.  This occurs several weeks after an SSW and the forecast SSW, if it occurs, is still at the end of model runs so… any chance of sustained cold risk can most likely be reserved for several weeks ahead as things stand. The temperature and pressure anomaly scene in the Post – Jonas world looks like this: a warm NW Europe, warm Pole and cold NE USA.

 

Winter storm Jonas References

http://www.wunderground.com/blog/JeffMasters/colossal-noreaster-dumps-record-snow-from-maryland-to-new-york

http://www.realclimate.org/index.php?p=19070

http://mashable.com/2016/01/22/causes-of-east-coast-blizzard-global-warming/#ZQIP9mQOOmqb

2016-01-15_22-13-03

Hurricane Alex and the UK 14/01/2016

Satellite pictures have emerged showing how truly amazing Hurricane Alex really was. These satellite pictures (courtesy MeteoSat, Dundee sat.dundee.ac.uk and eumetsat/eosdis) show that Alex is one of the most northerly and easterly forming Atlantic Hurricanes (second ever, in any month to form north of 30N) and rare for January at this extreme northerly and easterly location.  In typically understated fashion, the official National Hurricane Center tropical discussion hinted at the astonishing nature of this event as the diminutive storm transitioned to a Category 1 hurricane on 14 January.

“Remarkably, Alex has undergone the transformation into a hurricane. A distinct eye is present… ” (11am 14 jan 2016)

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Hurricane Alex (Cat1), just before downgrading to a Tropical Storm, near the UK 15/01/2015

Alex is very likely to be the closest January hurricane to UK shores but Fran and Hannah were Cat 1 hurricanes that came closer, albeit both in October.

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Hannah and Fran Cat 1 hurricanes tracked close to the UK

It is quite common for ex-hurricanes to track across the UK (e.g. Bertha Aug 2014) each year as extra-tropical storms but usually these happen in late summer and Autumn, at the mature end of the hurricane season.  Nevertheless, a hurricane (Category 1) forming on the European side of the Atlantic so far north and east in January, with snow clearly visible on the UK hills is truly amazing.

Some meteorologists think that a hurricane visiting Britain is possible before 2030.

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Alex becomes a hurricane 14 Jan 2016 (image EUMETSAT)

Alex is the first Atlantic hurricane to form in the month of January since 1938 and is the first Atlantic hurricane to exist during January since Alice in 1955.

Hurricane Alex, located in the sub-tropical Mid-Atlantic south of the Azores at approximately 30N 30W, was named on Wednesday by the National Hurricane Center as a sub-tropical storm lingering in the tropical Mid Atlantic took on more hurricane characteristics.

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Hurricane Alex 14/01/2016

Despite sea surface temperatures of only 20C, wind speeds in excess of 80mph started circulating around a tight hurricane eye.  The notable northerly formation would be remarkable in summer, let alone January.

So Alex is certainly remarkable but not entirely unique because two other hurricanes have occurred in January since records began in 1851.

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Hurricane Alex’s eye 14/01/2016

Hurricanes usually form June 1 to November 30, the official “hurricane season”.  This is towards the end of long hot summers, when Tropical seas are at their warmest. Hurricanes are named starting from “A” as the first one of the season.  It is extremely unusual for hurricanes to form in January, and making landfall over the Azores so far north will almost certainly be a first for any hurricane.

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How freaky is Hurricane Alex?

A key ingredient of hurricane formation is a warm sea surface, usually at least 27C to at least 60 metres.  Warm waters fuel the energy hurricanes feed on and, through evaporation of vast quantities of sea water and release of latent heat into the atmosphere, convection is caused and wind speeds increase to a sustained 74mph into a hurricane eye.

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Hurricane Alex, spot the eye (image EUMETSAT)

Alex has formed over relatively cool SSTs, around 20C, which would usually not give birth to a hurricane.

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usual hurricane formation

Meteorologists suggest that unusually COOL upper air temperatures in an upper trough over have assisted convection and the uplift of air to create thundery conditions around a hurricane eye.

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sea surface temperature anomalies Alex

Like other recent remarkable weather events, Alex’s special early arrival is not quite unprecedented and two hurricanes have occurred in the Atlantic in January.  An unnamed hurricane formed in 1938 in the tropical Atlantic, with winds of 70 knots, but only lasted as a Cat 1 hurricane for one day.

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In addition, Hurricane Alice formed on December 31 1954 and lasted as a Cat 1 for 5 days into Jan 1955 before weakening to a tropical storm.  She had a slightly strange SW track towards Venezuela.  Also, interestingly, 1954-55 was a weak La Nina year, strengthening to a moderate La Nina year.  La Nina years are more conducive to Atlantic hurricanes whereas our current very strong, but gradually declining, El Nino state is associated with fewer Atlantic hurricanes.

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Geographically, both Alice and “the unnamed one” formed much further south (around 20N) in the tropical Atlantic than our Alex (around 30N).  So Alex can certainly claim to be an unusual storm because it is so far North AND so far out of the hurricane season.  This might even qualify him as “freak” status.

Currently, Alex is a small storm with a tight hurricane eye where sustained winds exceed 85mph.  It is not expected to strengthen much or last more than a few days as a hurricane system because the track is northerly and this will take it over ever cooler Atlantic waters.  The Azores is on the track of Alex and is likely to experience a highly unusual January hurricane in the next 12 hours.

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Hurricane Alex intensity Cat1

The storm will lower intensity and dissipate over cooler than average North Atlantic waters before making “landfall” most likely somewhere near the southern tip of Greenland.

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Hurricane Alex track January 2016

Here’s some expert explanation of the development of Alex from the very excellent Mark Sudduth of hurricanetrack.com

Alex started life as a tropical disturbance near the Bahamas over unusually warm sea surface temperatures emanating out of the Gulf.

The sub-tropical disturbance never threatened land, except momentarily to risk a nor-easter for the Atlantic US coast.  His track took him safely into the Atlantic.

However, despite his remote location, Alex did impact our European weather indirectly. Earlier this week a trough disruption took some of his tropical energy into Europe via the Bay of Biscay.

This lowered pressure over Europe sufficient to allow an Arctic plunge to push further south across the UK and into the continent.

Warm air from Alex’s sub-tropical source has also possibly helped build pressure to the north over the Atlantic that assisted a tighter pressure gradient over the UK allowing a more brisk Arctic wind chill to build.  This same high pressure will keep him stuck in the Atlantic until he dissipates near southern Greenland.

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Hurricane Alex and HIGH pressure to the North

However, the existence of Alex has possibly thrown weather prediction models into a spin because the forecasts from models, even short term, are now in a good deal of disagreement about next week.

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models completely disagree… Alex’s influence?

So perhaps Alex has broken more things than just weather records!

and finally… is global warming to blame for Alex?  Well, typically, the answer is both Yes and No!

Read this interesting article below here to get the idea why..

http://www.cato.org/blog/buzz-alex-global-warming

http://mashable.com/2016/01/14/hurricane-alex-forms-january/?utm_cid=mash-com-Tw-main-link#i2kSmA3cnGq1

https://xmetman.wordpress.com/

http://www.wunderground.com/blog/JeffMasters/alex-becomes-the-atlantics-first-january-hurricane-since-1955

Hurricane Pali has also been setting records in the Pacific http://www.aljazeera.com/news/2016/01/hurricane-pali-sets-pacific-record-160113090131993.html