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Whilst Storm Katie was not a record-breaker by any means she did provide some evidence of stingjet winds in the wrap-around feature that showed up especially on IR satellite photos and rainfall radar in the later stages of her track across the SE and UK.

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Here is some analysis from local Reigate Surrey records of these winds to explore this feature more. Stingjets can be the most damaging winds, in this case they were not especially strong.  Professionals, like Matt Hugo (NorthWstWx services) and Simon Lee (MMetReading), saw hints of stingjets during the passage of the storm but what evidence of stingjet winds is there “on the ground” and how can amateur observers watch out for these potent weather features in future?

Katie’s rapid cyclogenesis prior to landfall over the UK was a precursor to the formation of stingjet winds.

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Stingjets are associated with vigorous bomb-depressions developed in a process called rapid cyclogenesis: in RaCy depressions central pressure falls very rapidly and slows the horizontal surface speed of the cyclone.  A stingjet is a narrow band of gusty winds that descend from high altitude in the latter stages of RaCy depressions.  They arrive from some 3-4km above the ground and are associated with descending stratospheric air into the low core.  Ironically stingjets are associated with weakening fronts and aging cyclones.  This descent of upper air pushes the jetstream lower and this can deliver extremely gusty conditions to the surface in a narrow band that is shown by a cloud hook and matching rainfall pattern.

Watervapour satellite loop from 00hrs to 8am showing dry descending stratospheric air forming a dark slot – dry intrusion – that wraps into the developing low core: a sure signal of rapid intensification.

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The hooked rainfall signature below matched a marked increase in the strength of wind and the modest strongest gusts of the whole event of 52mph in Reigate. In exposed places like Redhill aerodrome this exceeded 60mph and over the North Downs at Kenley 68mph was recorded with 70mph in places. 2016-03-28_07-32-34 Arriving from high altitude, stingjet winds are unsurprisingly cold with low dew points. So you’d expect a dip in temperature at the surface.  Parts of Wales and Shropshire had snow in this airstream wrapping round the back of the low as it moved into the North Sea. Stingjets match the mature stage of the Shapiro-Keyser cyclogenesis model.  In all respects, they are aptly named as the “sting in the tale”.

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metoffice stingjet info

Storm Katie had some generally strong winds (for the SE of the UK!) associated with the southern edge of this cyclone where the tightest pressure gradients developed as pressure fell across the SE: in the narrow warm sector especially.  The lowest central pressure was 971mb.  Our Wight-Wash Oscillation reached 16 or 17mb at one stage: the difference between the pressure over the Isle of Wight and the Wash.

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Most significant storms to impact SE England have similar NE tracks through the Bristol Channel and exiting through the Wash. This was certainly the case with October 1987, St Jude 2013 and Storm Katie March 2016.

A complex warm sector and bent-back wrapped occlusion make it tricky to identify the normal Norwegian model of warm-cold frontal passage.

It is more likely that Katie, like other RaCY depressions, developed according to the Shapiro-Keyser model of rapid cyclogenesis which involves a break away cold front fracturing away from the depression core: T-bone.

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The wrapped rainfall radar and cloud hook above both suggest a stingjet feature associated with this kind of development.

Now, onto evidence stingjets… the passage of the strongest gusts shown below do not match the passage of a “normal” cold front but suggest some other process was at work to deliver the strongest gusts.  The strongest winds occurred 3 hours after the passage of the front that started to deliver the expected colder polar air behind the wrapped occlusion. This can be seen from the chart of Reigate wind speeds and temperature below. 2016-03-28_22-25-38 The chart shows the persistent warm sector gales proceeding from midnight on 28 March through to about 5am.  These gales do not exceed 80kmh but they modestly peak just before the passage of the front, an expected pattern.  Fronts then pass through Reigate at about 5am and temperatures fall as expected, as do gusts.  However, from 7am gust strength sharply increase, this matches the timing of the sting jet cloud feature on satellite photos.  This increase in wind speed had no front associated with it and therefore suggests evidence of a stingjet process: arriving out of the blue!

Note the temporary drop of temperature to a minimum and recovery after the departure of strongest winds.  This again suggests these winds are not frontal in origin but are part of the stingjet process.  Are they associated with a sting jet of descending high altitude air originating some 3-4km in the troposphere?  I’d like to think this is a sting jet signature but will need confirmation from official sources to pin this down. 2016-03-29_07-29-56 For comparison shown above is a “normal” cold front passage from the previous weekend when a cold front squall line of some note passed through.  Note there is no dip to minimum temperature associated with the maximum gusts and temperatures remain cold after the passage of the front because of the insurgence of cold polar air.   This is more typical behaviour when it comes to frontal passage.

 

 

Other charts and references support this idea, but some not unfortunately not quite with same timings.

http://www.metoffice.gov.uk/media/pdf/2/p/Sting_Jet_Flyer.PDF

A system stirred up by a low pressure tracking out of Mexico into the Gulf of Mexico this week is on track to bring unsettled conditions for part of the weekend to the UK.  It’s nothing too severe for most but is an interesting feature that will bring some wind and rain everywhere.  Below is a satpic showing the development of this system as it interacted with a lively jetstreak on Saturday 28/02/2015.

development of LOW on jetstreak

development of LOW on jetstreak

 

This LOW illustrates nicely how extra-tropical systems can rattle clean across the Atlantic in a few days if they are picked up by an active jetstream.   This one does precisely that.  Spot the system leaving Florida on the chart below for today and the sat pic.  This system started as a low pressure crossing from Mexico into the Gulf of Mexico mid-week, so for weather systems it will be an aged fellow on arrival here in the UK.  Its’ longevity is partly due to the exceptional COLD over NE US which interacts with the warm tropical air and causes further deepening.

The Gulf low pressure is tracking quickly NE skirting the US east coast before being picked up and deepened further by an active jetstream.  The jetstream itself is particularly powerful at the moment due to intense cold spilling out of an exceptionally wintry NE USA meeting warm tropical air issuing from a strong subtropical Azores HIGH pressure converging with the moist Gulf airmass.  A result of the powerful jetstream is a positive North Atlantic Oscillation: the NAO is a measure that indicates the difference in pressure between Iceland and the Azores.  In positive NAO conditions the jetstream is often active, producing a strong westerly zonal flow keeping Europe mild and unsettled especially in winter, or early spring!

Our Gulf LOW is due to pass over Reigate fairly rapidly through Saturday pm and overnight into Sunday am and bring some moderately wet and windy weather, likely to go unnoticed because of the nocturnal transit.  Winds gusting in excess of 40mph are possible for Reigate into Sunday am in exposed places.  Notably, due to the TROPICAL origins of this airmass the temperature overnight Sat-Sun could climb to double figures in Reigate.  Tropical air crossing the Atlantic also picks up a tremendous amount of moisture so attendant fronts are likely to bring a lot of rain too, possibly exceeding 10mm overnight, which is a moderately wet night.

Here are the synoptic charts showing the Gulf low progress across the Atlantic, deepening and occluding into the North Sea.  Note the secondary wave which could bring additional rain later on Sunday to the South.

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The additional rain later Sunday afternoon / evening looks potentially heavy for the South and SE.  It’s a rapidly developing wave feature that needs attention as, on the northern edge, it looks to raise the possibility of snow across the Midlands.  Heavy rain is possible for the SE and #Reigate with a period of gales on the south coast.

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The outlook for next week is for the Azores HIGH pressure to extend a ridge to the north and cause a NW then northerly airflow for the UK.  This will bring cooler temperatures to the UK.  Whilst it is likely to be mostly dry for Reigate and the SE with pressure rising, wintry showers especially on east facing coasts of the North Sea could be possible depending on how the HIGH develops.  Frost is likely with temperatures dipping below freezing at night from mid-week.

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Atlantic ridge builds to the west and brings in northerlies

How long this Atlantic block persists, and the cooler weather, is uncertain.  The coldest scenario would depend on the HIGH moving north and east and building over Scandinavia to pull in easterlies from a cold continent.  This scenario is preferred by the ECM by later next week whilst the GEFS topples the high to the SE and brings back a zonal mild westerly flow from the persistent Icelandic LOW pressure that erodes the edges of the HIGH from the NW.  The charts below show the uncertainty as a wide spread of possible pressure and temperature towards the end of the first week in March.

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Gulf low for the weekend, then pressure builds

The cool start to March is shown below.  The overall outlook is for a persistent positive NAO and Arctic Oscillation to persist and this would suggest a brief cool epsiode without the formation of a persistent Scandinavian High.  Models have flirted with possible easterly winds by the end of next week but the outlook is for the positive NAO to persist and this rather suggests a quick return to milder zonal westerlies.  As the high builds in early in the week various troughs and fronts could even push some wintry precipitation as far as the SE on Tuesday (spot the pink on the rainfall chart below for Tues)

First week of March starts cool: MetOffice synoptic chart for mid-week shows Azores high briefly ridging north to block mild zonal westerlies and usher in a cold polar airmass, albeit briefly as this ridge looks to topple SE and by next weekend we could be in a pretty mild SW flow hitting mid-teens possibly.  So a cool, mostly dry middle part of the week for Reigate and much of S England but precipitation, some even wintry, pulling in on NW / N winds is not ruled out with a North Sea low possible.  As the Atlantic is likely to push westerlies back in later in the week we can expect more purposeful frontal rain pushing east across the whole country.

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link to accuweather take on this system

http://www.accuweather.com/en/weather-news/winds-to-whip-uk-north-sea-coa/43063930

 

Quick update here focusing on SE especially: please note this applies mainly to Reigate in Surrey and is an amateur analysis for educational purposes.  For updates through the storm please see @RGSweather on twitter for the Bertha story as it unfolds for us in Reigate and SE.  This is called NOWCASTING (as opposed to “forecasting”).

Ex-Bertha is turning out to be rather interesting meteorologically!  A convective potential has emerged today, which means there is more possibility of thunderstorms of some significance as the LOW passes across the UK, especially to the south of the system.  Convective gusts of 50-60mph could be possible and the odd tornado cannot be ruled out, though no need to panic because these are quite common and not usually powerful or damaging in the UK.  So it is still the case that the overall impact of this storm is still not likely to be extra-ordinary or wreak widespread havoc Daily Express style.  It is more likely to be underwhelming for most.  Nevertheless, rainfall totals in a short space of time for some places might be high and there could be some interesting weather phenomena associated with active fronts.

UPDATE Sunday 7:30am

Estofex and TORRO have issued severe convective weather warnings for the S UK. Estofex Level 2 storm warning is most unusual for the UK and TORRO do not issue tornado watches lightly.

(back to yesterdays update:) The UKMO fax chart below for Sunday midday shows a “triple point” of three fronts meeting near the SE (warm front, cold front and occlusion) Between the warm front and cold front the warmest humid air is wrapping into the centre of the LOW in the warm sector: this contains much of the moisture to fuel the storm as condensation releases latent heat driving up parcels of air.  On top of this a conveyor of cooler drier Polar air that flows over the cold front and warm sector and this increases lapse rates further encouraging lift throughout the system. The warm air eventually flows to the core of the storm as it occludes.

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All the time the jetstream to the south is lifting air off the ground (by a process called divergence in the upper atmosphere) and lowering the central pressure causing air to converge into the centre of the LOW… this results in the surface wind rushing into the centre.   Converging air at the surface has nowhere to go except up.  Rising air, especially where tropical air meets polar air at the fronts, creates condensation, thick cloud and potentially plenty of rain.  The potential water available in this storm is large.  In addition, cloud top temps, with the influx of cold air aloft, are likely to be as low as -50C causing ice to form in turbulent air that can create charge up thunderstorms.  Such storms are only a risk and may not happen at all.2014-08-09_20-59-21

For Reigate and the SE it seems we can expect more rain during the morning than was previously the case in earlier models and forecasts.  Latest models suggest widepsread rain in the SE of up to 20mm and discrete patches of high totals possibly exceeding 50mm in the SE.  This is about a month of rain in one day, so local flooding could be a problem.

Rain will arrive tonight, after midnight, and persist throughout the morning.  Wind speeds, probably 30-40mph max gusts inland, possibly more gusty in any thunderstorms, will increase towards the middle of the day and potentially be highest as the cold front moves away which, on current models looks like early afternoon.  Strongest gusts will be associated with any thunderstorms.  The good news is that by pm the cloud should break rather rapidly, however, scattered showers could follow in the brisk westerly. This regime will continue for much of the early part of the week.

Needless to say, apart from the rain potential, Reigate is less at risk from tstorms than further N during this episode (Reigate storm shield!)

Even now much still remains uncertain about this storm and it is causing lots of interest and headaches for both professional and amateur meteorologists.  The nature of the fronts may produce some organised squall like features and some organised thunderstorms for places but predicting these is extremely difficult.  Any such storms can have the potential to deposit a lot of rain in a short space of time.

Late this afternoon Saturday Bertha split in two: one rain system moving north, the other pushing more ENE.  This was unexpected.  Currently the rain moving north across Ireland is the more significant but things can change.

 

Let’s finish with the UKMO forecast for Reigate.  It shows lots of rain, potential for thunderstorms and some unsually strong winds for the time of year.  As leaves remain on trees this might cause loose branches to fall and peak rainfall totals, if met, could cause some local flooding.  Certainly nothing to panic about but do look out for any interesting weather features and send them in to @RGSweather!  Sadly for @ridelondon the prospects are not terriibly nice in the morning.

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Photo mosaic of the squall line that passed over Reigate on 10 Aug afternoon: quite a feature!

and tornado reports of damage from various locations including Hull, plus other news here:

http://metofficenews.wordpress.com/2014/08/10/sundays-rain-and-wind-data/

http://www.bbc.co.uk/news/world-europe-jersey-28746723

 

 

A ridge of HIGH pressure brought excellent fair weather cumulus cloud formation over the SE today.  The sat pic shows cloud streets of cumulus over the SE where local convection, capped by an inversion at 5000 feet created beautiful fluffy bubbly cumulus for much of the day. This came after the “coldest” night of the year at -1.2c in Reigate and -6c in the far north of the UK under clear skies and polar air.

Another point to note was the opposite wind directions at different altitudes today: surface SE flows giving way to NW flows above 7000 feet.  The skew-t chart below illustrates these features of a super-lovely day here.  The fairweather Cu convection was surpressed later in the day as an advancing occluded front spread high level cirrus and cirrostratus across the sky thereby creating an enormous regional inversion of warmer upper air that effectively stopped further convection and the cumulus gradually faded with incoming cirrostratus and altostratus later in the day.

 

skew-t chart fair weather CU formation

skew-t chart fair weather CU formation

 

The rest of the week for Reigate deteriorates and becomes cooler and damper and more gloomy.  A large cut-off low is set to form over the continent, while a HIGH over Scandinavia will combine with this COOL-POOL to drag NE and easterly winds over the UK.

Usually such winds bring cool, damp and showery weather across the East and SE, including Reigate, with moisture picked up from the N Sea and temps from a cool early spring-time continent often creating layers of cloudy gloomy stratocumulus widely.  Thurs/Fri may see brighter spells with showers.

A LOW from Denmark mid-week is modelled to drift across the N Sea and this is likely to exacerbate the cold by bringing an extra-cool shot of cold continental air (-6 at 850hPa) over the UK mid-week: snow is possible over high ground of the Pennines and NE at this time.

Later in the week and at the weekend a subtle shift in the location of the Scandi HIGH and Euro-low could allow warmer SE winds sourced from the Mediterranean to filter into SE UK edging temps to the upper teens once again.  This is a fair way off still but will make the weekend a more pleasant prospect if this comes off.

Model predictions for the start of April look uncertain still with ifs-and-buts over how settled it will be.  Several sugges high pressure building at times early on but other models put a LOW over the UK for this period… so charts definitely worth watching for Easter school hols.

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High pressure persists this week over the UK as shown by the chart and the amazingly clear satellite pic showing great swathes of clear skies over a remarkably snow-free Europe today 11 March. It’s worth remembering that on this day last year we saw the lowest wind chill temps of the year in Reigate at -11.9c early on 12 March with -10c at 9:30am on 11 March during an episode of extremely cold NE winds which brought a blizzard to the Channel Islands.

Back to this week… the high pressure has brought delightfully sunny days and Tmax temps to Reigate over 19c last weekend , especially warm and spring like on Sunday. Since then a cooler NE/E breeze around the edge of the high as it slipped north and east has kept us cooler and occasionally more gloomy with anticyclone gloom and stratocumulus blanket on some days.

The outlook this week remains settled but with a distinct drop-off of temps over the weekend and especially into next week.  This is due to the HIGH slipping west and the jetstream dragging down cooler NW winds fresh from Greenland.  A LOW moving across N Scotland and over to Scandinavia this weekend will start the process of dragging down NW winds that will make next week cooler, especially further east where it looks like the N Sea will get a full blast of chilly air at times.

Nevertheless, it is unlikely to become terribly unsettled down here in the SE as the longer term picture looks like high pressure hangs on in the south keeping us mostly dry.  The north of the UK might see more frontal action as LOWS bring fronts across more northerly parts.  Models seem to be keeping the south relatively dry for another week to 10 days.

After the wettest winter on record, groundwater levels in the chalk aquifers are the highest EVER in the SE and the Mole Valley particularly.  There are still 50 flood warnings in the SE and locally flood water continues to pour across the A25 between Reigate and Dorking near Brockham.  This groundwater flooding, though of course nothing like as damaging as the fluvial river flooding during the winter along the R Mole and the Thames, could last for some months yet as the winter rain continues to percolate into the chalk water table and flows out along geological boundaries at inconvenient locations such as normally dry river beds and bournes and across impermeable surfaces such as roads. The map showing soil moisture below shows how wet the soil remains after this extremely wet winter.

Weather is chaotic and numerical weather models are not perfect. The forecast for Reigate today went rather awry, though not completely.  It was forecast to rain heavily, perhaps on and off, but the forecast was for heavy rain more or less throughout the day. Check UKMO forecast from yesterday below.  Some models brought 24 hour totals of 20-30mm to SE at points on the lead up to the event.  The cause of the forecast deluge: a small scale low tracking NW to SE with a tightly wrapped occluded front crossing the area once, then lingering nearby to deposit more rain during the day before drifting off southeast. Once the front had passed through early am, it turned out to be a splendid day with sunshine and bright spells throughout, until rain later.  So what went wrong/right?

The front passed over as forecast during early am dropping 6mm on Reigate before 8am.  It then sat N of London most of the day while further south convection over Sussex caused significant Cb clouds and showers (some thundery) to spark off from midday.  For us in Reigate, we had a splendidly bright day with glorious sunshine by 8am and bubbly cumulus clouds thereafter, the odd spot of rain but nothing significant until early afternoon when the front migrated south east.  So for most daylight hours Reigate was dry, quite the opposite of the forecast.

The photos above and graphics below suggest a possible reason for this.  Reigate sat in a sort of “Goldilocks Gap” between the persistent frontal rain further north and convective rain nearer the LOW further south. It is notable that the convective showers built mostly over the land, showing almost April-shower tendencies to build on warmer land surfaces than the now-cooler sea. The occluded front sat close to Reigate, frontal wave clouds and cirrus were visible above and to the north for most of the day.  This may have helped suppress convection.  As warm tropical air is lofted over an occluded front it spreads out and forms a cirrus veil, this often suggests a broad inversion of warmer air aloft that effectively suppresses uplift of thermals: the cirrus acts like a lid.  So cumulus clouds over Reigate and the N Downs stayed small and harmless.  Not far south, in Sussex, thundery downpours developed as the buoyant air lofted uninhibited by any inversion.  You can see this on the radar image below.

Reigate was therefore dry for most of the day perhaps because of our location in a sort of Goldilocks Gap (our word) that was just far enough from the occluded front to avoid persistent rain and just near enough to benefit from the inversion to prevent convective showers. Met-Magic!  The graphics and photos try to explain this further.

This is just one possible reason why slight changes in the tack of a LOW will render a forecast completely wrong, even in the middle of a LOW pressure when all hope of a nice day might be thought lost.  Further ideas are most welcome to extend this.

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Four days of UKMO weather warnings and this hasn’t been unusual this winter!

Unsettled is an understatement, the weather is still on over-drive! Here’s a quick update on rain and storm events upcoming this week for Reigate, as the weekend summary didn’t quite do it justice!  The jetstream is still blasting across the Atlantic and giving birth to storm after storm.  Causes of this extraordinary jetstream are complex, but most “local” to the UK is the extreme contrast in temperature across North America with a buckling jetstream dragging frigid conditions across much of that continent.  This creates a steep temperature and pressure gradient that kick-starts a powerful jet across the Atlantic.  Storm force lows are being created amazingly quickly and most of them are being directed at the UK.

So, here’s a summary of storms on offer this week for Reigate and Surrey…

Tuesday: active front with cold air behind sweeps across the UK and arrives in Reigate am for heavy rain at lunchtime with gusty winds for a time. 10mm is possible in a short space of time which could lead to local FLOODING.  The front will whizz through quickly by the afternoon and leave a brighter but cooler feel pm even with possible wintry showers on a brisk cool W/NW wind.

Wednesday: looks grim… another tight storm approaches from the SW.  This one brings more gales to the SW, Wales but also pushes them further inland across the Midlands.  The south coast and the NE coast (on departure) will also see gales.  Wind for the SE will be pushing in off the Channel at possibly 50-60mph with 40mph gusts inland for inland places Reigate, peaking pm.  Rain is due to be heavy, especially pm and early evening and it will be cloudy all day.

Thursday… looks like a brighter showery day with possible heavy thundery showers at times. Friday / Saturday brings in the next storm with high rainfall totals adding to already saturated ground.  The likelihood of more flooding seems high at this stage which is terrible news for those places along the Thames that have been so badly hit today.

No, not a record low pressure this one but the stormy weather continues for the UK with another deep area of low pressure sweeping up past the NW of Scotland tomorrow, Friday.  This one, called Anne, has violent storm force westerly winds out in the Atlantic building high waves and matching high tides, causing unusual storm surge conditions for the west coast. It is the orientation and track of this storm that appears to be causing most trouble: spot those isobars directed straight at the UK and building high seas with those high tides.  The distance which wind travels over the sea is called FETCH and the longer the fetch the greater the possible wave height.  Note also the waves and wind that build in the Channel.

There are currently 17 severe flood warnings from the Environment Agency for the west coast of Wales and SW England.  The River Severn estuary is also at risk as as it faces the SW winds, funnels tides and has high river flows all to contend with.

Envt Agency are even warning people to evacuate if possible from vulnerable locations on West coast.  N Ireland also adopting this too.

http://www.bbc.co.uk/news/uk-northern-ireland-25580692#TWEET1001676

http://www.bbc.co.uk/news/uk-25572390

For Reigate and the SE (inland) heavy overnight rain will pause for a while in the morning only to resume as winds increase to gusts possibly 30-40mph, gusting higher on hills, and with possible heavy showery rain.  Rain totals for Fri-Sat 48 hours could amount to 30-40mm, but more likely 10-20mm for Reigate and Mole Valley.

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rain totals fri – sat

Is there any sign of improvement? Met experts watch the high atmosphere for some long range forecasting. In particular, the stratospheric Polar Vortex is a a possible indicator of how the tropospheric jetstream might be acting in weeks to come.  The stormy weather we have been experiencing has been “caused” by an extremely powerful polar vortex: a great contrast in temperature difference between high and low latitudes sets up high winds in the stratosphere which act like a belt to hold in cold air to the Pole.  The North Pole stratosphere is extremely cold this winter and this has encouraged a powerful polar vortex.

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You can see from the chart below that the vortex is forecast to change shape: split or squeeze, meteorologists are watching for this to tell them if the jetstream will weaken, and there are signs that it will in mid-Jan.  This may also have the effect of allowing polar leaks of cool air to reach the UK: so maybe less stormy but a tad cooler. Check these guys for further details: http://www.weatherweb.net/wxwebchartsecmopmsl.php

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Finally, the Express is unusually conservative with this article: the wind speeds are too low!

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The 2013 December 5-7 North Sea storm caused “the biggest UK storm surge for 60 years” (UK Environment Agency).  With associated gales across Scotland, coastal flooding in North Wales, Merseyside and the UK East coast, tidal river flooding in Hamburg, the closure of all major North Sea coastal surge barriers and disruptive snow further south in Europe, this storm system was arguably more powerful than StJude back in October.  Thankfully, this storm only killed 7 people across Northern Europe (http://www.bbc.co.uk/news/world-europe-25243460).

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Essentially a storm surge is a higher-than-normal sea surface caused by low air pressure coinciding with high tides which, when thrown into shallow coastlines by winds, can produce exceptional coastal flooding.  A surge can also include associated lower-than-normal water levels with off-shore winds pushing water away from the coast at low tide.

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This post outlines the factors that makes the North Sea so vulnerable to storm surges and, further down, there is a summary of some impacts and a quick resume of the successful responses to this hazard event with some useful links.  Finally, before we get too smug and chill out entirely about future storm surge hazard…will development land lapped-up on exposed coasts, for example in the Thames Gateway, increase our future vulnerability in the face of sea level rise and climate change?  Is it sensible to build in these locations?

Animation shows storm surge rolling round the coast and into the North Sea.

http://www.bbc.co.uk/news/uk-25229885

Causes

The North Sea is particularly vulnerable to storm surges because of an unlucky combination of factors that come together to occasionally make the “perfect storm”.  Fortunately, not every North Sea storm produces a surge!  Remember that Tacloban in the Philippines was hit by an even bigger storm surge generated by Typhoon Haiyan due to similar forces and a funnel shaped bay.  Compare videos on this blog to see the difference between Tacloban and North Sea surges. So what comes together to produce the most significant storm surge hazards in the North Sea? There are at least 6 factors that combine to produce the biggest storm surges: here they are:

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1. Sea shape and low lying coastlines: The North Sea is particularly prone to dramatic storm surges because it is open to the North Atlantic and then tapers towards the south in a funnel shape. This funnel shape has the effect of allowing strong northerly winds to direct storm surges towards cities like London, Amsterdam and Hamburg and surrounding vulnerable low lying coastal areas including Norfolk, Lincolnshire, Essex, Kent and the Netherlands. Some of these areas are at or below sea level and require sea walls and dykes and barriers to protect them during storm surge events otherwise they will be flooded. The 1953 storm surge broke the rather primitive sea walls of the time and flooded large areas of Essex and even more of the Netherlands causing the worst European peace-time disaster since the war and killing 307 people in the UK and thousands in the Netherlands (see you tube documentaries below)

TechsmithWor6C52.png

2. Sea depth/ bathymetry: the North Sea gets shallower towards the bays and wetlands towards the south.  These shallows have the effect of increasing the height of tides and surges as they are forced up over submerged shelves into narrowing bays.  This is possibly why Boston, Lincs and Hamburg suffered some of the worst flooding because surges were forced up bays and rivers.

3. Intense low air pressure: A 1 millibar reduction in air pressure allows sea level to rise by 10mm.  This effect can be replicated by sucking water up through a straw. The storm that crossed to the north of Scotland on 5 December had a central pressure of 976mb that deepened to 968mb over the North Sea. This is a similar central pressure to the storm that caused the 1953 storm surge that killed 307 people in the UK and 1800 people in the Netherlands.

4. Storm track: the LOW pressure has to track east over north of Scotland, which will drive a surge of water into the North Sea that is then pushed south by vigorous onshore Northerly winds into the low lying east coast of UK.  Ideally, the storm should deepen on its’ track across the North Sea, thus allowing northerly winds to gain in strength driving the surge and associated wind waves south.

LOW track

LOW track

5. High tides: high spring tides are the final requirement for the biggest surges.  Tides migrate as a bulge of water around the coast and, for the worst impacts, any surge travelling south down the North Sea must match the dome of the highest tide to produce the highest water levels in any one place. Since high tides occur twice a day it is quite likely that high elements of the surge will match a high tide level somewhere down the east coast.

6. Wind driven waves: Finally, surge and tide heights can be increased yet further by strong on-shore winds producing locally high wind driven waves that can over-top sea walls.

Warnings and impacts

The impacts of the 2013 storm surge included flooding in coastal towns on the east coast of the UK with perhaps worst hit being Boston in Lincolnshire. Houses on some vulnerable stretches of coasts such as Hemsby were washed into the sea as waves eroded sand dunes.  There was also significant flooding in Rhyll, North Wales and along the Merseyside coast at New Brighton (note: not Brighton!) where a Morrisons supermarket was flooded. The worst impacts on major populations and cities were avoided by the raising of the Thames Barrier to defend London and the closure of the flood gates on the Delta Scheme in the Netherlands.

The storm was modeled over a week prior to impact.  Initially GFS and UKMO models were seeing a cold surge as the main factor bringing possible snow across the UK but from about 6-7 days out it became increasingly obvious that the exact track and orientation of the LOW meant that powerful northerly winds and a possible storm surge were the greatest risk.  The UK Met Office, with Environment Agency, then started preparations for warning those at risk from flooding.  Most news channels were airing significant coverage from 24 hours out.

http://www.hulldailymail.co.uk/Yorkshire-Wildlife-Trust-blamed-flock-sheep/story-20301801-detail/story.html

Responses

Significant flooding did occur along the East coast, notably in Scarborough in Yorks, Boston in Lincs and Hemsby in Norfolk. In Hemsby some vulnerable houses located on the sand dunes were washed into the sea. Bridges near the sea were shut for a time, like the Humber Bridge; and rail services in some eatern counties were disrupted for a time.  Power was cut to homes in Scotland due to high winds.  Hundreds of residents were evacuated prior to the floods in various locations but some claimed to have little warning.

The worst impacts were successfully controlled by the massively impressive engineering schemes built since the devastating 1953 floods.London has nearly 200 miles of flood walls and 8 barriers holding back the tidal Thames. The Thames Barrier was opened by the Queen in 1982.

The Eastern Scheldt storm barrier was closed for the first time since the 1970’s.  The Netherlands barriers are built to withstand a 1 in 10,000 year storm surge event so it is perhaps unsurprising that they easily saw off this event.  It is also noteworthy that the Dutch have great faith in their storm surge protection barriers.

These measures, along with warnings and on the ground assistance for places that were flooded, proved extremely effective.

http://www.bbc.co.uk/news/uk-25272050

http://www.bbc.co.uk/news/world-europe-25242991

Further useful links on 1953 and 2013 storm surges:

1953 storm surge: original newsreel and timewatch documentary

http://www.metoffice.gov.uk/news/in-depth/1953-east-coast-flood

The sting in the tale?

London is sinking into clay and, along with the rest of the SE, it is tilting into the sea partly due to an epeirogenic / isostatic adjustment taking place since the glaciation released the north of the country from the burden of millions of tonnes of glacial ice causing positive isostatic rebound in the north and related subsidence in the south.

Flood plains and reclaimed land exposed to storm surges are still being lapped up by hungry developers as places ripe for building, like the Thames Gateway in London.  But is it sensible to concentrate massive new urban development in low lying areas vulnerable to coastal flooding when we have sea level rise and climate change?

http://www.deeestuary.co.uk/news1.htm

ONGOING UPDATES ADDED TO THIS PAGE: THIS IS NOW THE MOST INTENSE TYPHOON TO MAKE LANDFALL IN HISTORY WITH 230MPH GUSTS MADE LANDFALL ON THE PHILIPPINES COAST FRIDAY 7 OCTOBER 2013… THINK OF PEOPLE THERE AND HOPE THEY ARE MAKING THEMSELVES SAFE.

STORM STATS TO DATE…(10/11/2013) President declares “state of national calamity”

Latest 15/11/2013 PH Gvt website and BBC  5000 dead; 3853 injured; 921,000 displaced; 243,000 homes destroyed

At least 2 million families (11.8 million people) in 51 cities; 1444 evacuation centres. Estimated $4billion damages to PH

http://www.humanityroad.org/situation-report

LATEST FROM BBC NEWS

http://www.bbc.co.uk/news/world-asia-24878801

This page has essentially become a chronological scrap-blog of emerging information from the pre-storm warnings to the immediate post-disaster phase. Scroll down for maps, sat pics, videos and photos and links as they were forthcoming during the storm.  Live information from web sources including twitter and facebook direct from chase teams and embedded weather journalists as well as local Philippino sources traversed by the eye wall are included. This video was shot for CNN by storm chaser James Reynolds @typhoonfury who went to Tacloban knowing the eye wall would cross directly over.

This is an historic tropical cyclone: a truly huge storm and the strongest in recorded history with devastating impacts emerging from the areas hit by the hurricane eye, such as Tacloban City, Leyte and S Samar.  (Typhoon Tip was the previous record breaking strongest storm). Several extreme storm chasers and journalists embedded themselves into the path of the EYE WALL including James Reynolds @typhoonfury and Jim Edds @ExtremeStorms bringing up-close and personal stories of the true horrifying nature of the storm and the terrible aftermath now unfolding.

(LIVE now a recording offline COVERAGE OF LANDFALL http://www.youtube.com/watch?v=SrEVLCbAfys&app=desktop)

LIVE BBC COVERAGE http://www.bbc.co.uk/news/world-asia-

http://www.youtube.com/watch?v=WCiYEBAooZo

http://www.theguardian.com/world/2013/nov/08/typhoon-haiyan-batters-philippines

https://www.facebook.com/iCyclone

A major super typhoon with winds gusting more than 200mph has emerged out of the NW Pacific and is on track to cross the Philippines at the end of this week. With 175 mph sustained maximum winds this is the most powerful storm this year and, were it an Atlantic Hurricane, it would be about the most powerful on record. Although it will weaken slightly when it crosses land, it is still an exceptionally dangerous storm and a great threat because the Philippines is a densely populated country and, while the capital Manila will not receive a direct hit, some 10 million people in Luzon are in the area predicted for Haiyan to make first landfall.  The storm is then predicted to track rapidly across to Vietnam where it will arrive on Sunday, possibly still as a strong typhoon.

Update: poss most powerful landfall typhoon ever: off the NOAA Dvorak instensity scale http://www.ssd.noaa.gov/PS/TROP/CI-chart.html

It was a FAST moving storm and the eye passed over Guiuan district and Tacloban City in just a few hours but the impact was immense.

“The typhoon moved fast and didn’t last long– only a few hours– but it struck the city with absolutely terrifying ferocity.”

The last tweet from storm journalist Jim Edds in Tacloban was sent just before the eye wall hit and then..nothing. He and other extreme film makers were reported safe and evacuated later

http://stormvisuals.com/florida-weather/2013/11/7/video-storm-photographer-awaits-super-typhoon-haiyan-in-the.html

http://stormvisuals.com/florida-weather/2013/11/10/video-storm-photographer-shares-experience-with-deadly-typho.html

http://www.accuweather.com/en/weather-news/super-typhoon-haiyan-a-serious/19561621


http://www.news.com.au/world/super-typhoon-haiyan-gaining-strength-set-to-hit-philippines/story-fndir2ev-1226755411772

http://news.sky.com/story/1165530/super-typhoon-haiyan-hits-the-philippines

IF the typhoon had passed over Europe… how big would it be?

09-11-2013 10-52-55

http://www.independent.co.uk/news/world/asia/typhoon-haiyan-most-powerful-storm-to-ever-hit-land-batters-philippines-with-235mph-winds-8926719.html

http://www.wunderground.com/blog/JeffMasters/show.html

Instagram videos of destruction in Tacloban http://instagram.com/macmaloon



http://www.rappler.com/nation/43285-initial-reports-damage-tacloban-city
http://www.weather.com/news/weather-hurricanes/super-typhoon-haiyan-latest-news-20131108?hootPostID=de00db08af5507b1944839bc6c86d92a
http://www.westernpacificweather.com/2013/11/08/typhoon-haiyan-photo-and-video-gallery/

http://www.aljazeera.com/news/asia-pacific/2013/11/thousands-feared-killed-philippine-typhoon-2013119131138727893.html

09-11-2013 11-57-16


http://www.dailymail.co.uk/news/article-2494635/Philippines-super-typhoon-Haiyan-powerful-storm-history.html?ITO=1490&ns_mchannel=rss&ns_campaign=1490&utm_source=twitterfeed&utm_medium=twitter

Morgerman posted this harrowing report on Facebook:

First off, Tacloban City is devastated. The city is a horrid landscape of smashed buildings and completely defoliated trees, with widespread looting and unclaimed bodies decaying in the open air. The typhoon moved fast and didn’t last long– only a few hours– but it struck the city with absolutely terrifying ferocity. At the height of the storm, as the wind rose to a scream, as windows exploded and as our solid-concrete downtown hotel trembled from the impact of flying debris, as pictures blew off the walls and as children became hysterical, a tremendous storm surge swept the entire downtown. Waterfront blocks were reduced to heaps of rubble. In our hotel, trapped first-floor guests smashed the windows of their rooms to keep from drowning and screamed for help, and we had to drop our cameras and pull them out on mattresses and physically carry the elderly and disabled to the second floor. Mark’s leg was ripped open by a piece of debris and he’ll require surgery. The city has no communication with the outside world. The hospitals are overflowing with the critically injured. The surrounding communities are mowed down. After a bleak night in a hot, pitch-black, trashed hotel, James, Mark, and I managed to get out of the city on a military chopper and get to Cebu via a C-130– sitting next to corpses in body bags. Meteorologically, Super Typhoon HAIYAN was fascinating; from a human-interest standpoint, it was utterly ghastly. It’s been difficult to process.


http://www.washingtonpost.com/blogs/capital-weather-gang/wp/2013/11/09/disaster-in-tacloban-philippines-chasers-document-ghastly-scene-from-typhoon/
https://docs.google.com/forms/d/16aq0AH-OnEE_bM53iL5qInqHPZ28lntEXPs-rS01a88/viewform

http://www.abs-cbnnews.com/nation/regions/11/09/13/massive-destruction-tacloban-city
http://www.itv.com/news/story/2013-11-07/super-typhoon-haiyan-philippines/
http://www.rappler.com/nation/43311-diary-tacloban-death-anarchy
http://www.cbsnews.com/8301-202_162-57611622/typhoon-haiyans-death-toll-rises-in-philippines/

http://newsinfo.inquirer.net/524159/1200-believed-dead-in-philippine-typhoon-red-cross

http://www.washingtonpost.com/world/asia_pacific/one-of-worlds-strongest-storms-lashes-philippines-but-nation-appears-to-avoid-major-disaster/2013/11/08/2d7c164e-48d8-11e3-95a9-3f15b5618ba8_story_1.html
09-11-2013 19-16-12

09-11-2013 16-19-09

Damage far worse than people thought: http://www.weather.com/news/weather-hurricanes/recent-tropical-cyclones-killed-over-one-thousand-20131109?hootPostID=774277f3e615bfd5c5f0a71157fbfab7
http://earthsky.org/earth/incredible-images-and-video-of-super-typhoon-haiyan

http://ph.news.yahoo.com/super-typhoon-haiyan-hits-philippines-230815112.html


Massive online efforts from PH govt to help aid and search and rescue efforts: http://www.gov.ph/crisis-response/updates-typhoon-yolanda/
http://www.gov.ph/crisis-response/updates-typhoon-yolanda/
http://www.bbc.co.uk/news/world-asia-24887337
http://www.itv.com/news/story/2013-11-07/super-typhoon-haiyan-philippines/
http://edition.cnn.com/video/data/2.0/video/world/2013/11/10/natpkg-philippines-typhoon-storm-chaser.james-reynolds-uncut-productions.html
http://www.gov.ph/2013/11/10/ndrrmc-data-report-per-province-november-10-2013/
http://anc.yahoo.com/video/pnp-explains-why-looting-never-015407805.html
600,000 people evacuated from Vietnam and Hainan as Yolanda Haiyan arppaches Sunday 10/11/2013
2 months to fully restore power as 90% poles lost in storm surge https://donate.oxfam.org.uk/emergency?pscid=ps_ggl_Emergencies_Philippines_GDN

http://anc.yahoo.com/video/first-aid-tips-during-supertyphoon-083020305.html

http://reliefweb.int/sites/reliefweb.int/files/resources/OCHAPhilippinesTyphoonHaiyanSitrepNo.4.10November2013.pdf

doc02382320131110212404

11/11/2013 Tacloban now officially placed under a state of emergency

Red Cross report “absolute bedlam”

11-11-2013 19-16-15UK Govt promises £10 million

http://www.independent.co.uk/news/world/asia/typhoon-haiyan-every-single-building-every-single-house-destroyed–governments-pledge-millions-but-tacloban-is-still-waiting-8933515.html