Archives For November 2013

STORM SURGE WARNING FOR NORTH SEA COASTS WIND and North Sea storm surge update later today: check twitter @RGSweather for updates!

Check environment agency website for flood warnings

Point to note: the original weather forecast (below) for Thurs-Sat dec5-7 emphasised a plunge of cold Arctic air on the back of the low passing across N Sea.  However, in the event, as things quickly transpired nearer the time the strong northerly winds became the focus and the storm surge down the east coast on the back of it. 528 dam (coldest air) stayed well to the east of the SE and so we had squally showers on the cold front with no wintry ppt.  

Express meaning rapid / short-lived icy blast for later this week is firming up in most model runs now, though with differences in arrival, departure and intensity (especially the GFS which is least chilly, but I understand this is not deemed as performing well on this event).  Anyhow, it would be sensible to assume that it will be chilly or cold to very cold for early December across much of the UK from Thursday onward and through much of next weekend with the North and coastal areas, especially North Sea coasts, getting some really icy gales at times, particularly Thurs-Fri/Sat.  

30-11-2013 22-29-39Some snow is likely for north facing coasts both East and West and Scotland and parts of Northern England.  Reigate and the more sheltered SE will, as usual, be protected from the worst but we can still expect cold blustery conditions at times with such a cold upper Arctic airmass incursion. Air mass temps are usually measured at 5000ft (850hPa) (to avoid surface interference and changes day/night, urban/rural etc above the so-called boundary layer). Currently our 850hPa temp is around 0c, by the end of this week they will drop to -8c or even -10c.  

30-11-2013 22-16-20

Include the wind expected, especially Thursday – Friday and this will feel cold if you are out and about, watching football matches on the touchline for example: much colder than this weekend!  Air temps may struggle to reach 2-3c in Reigate on Friday and the 15-20mph wind will make it feel well below freezing.  An interesting additional feature is a possible LOW forming in the southern part of the North Sea on those icy northerly gales.  If this occurs it might bring snow to the far SE of the UK and certainly into Netherlands and, later, the rest of N Europe. 

However, it is likely that this episode will be a brief SHOT of cold as a high pressure stirs in some warmer air later next weekend and the winds also die down making it feel more tolerable, though an anticyclonic gloom is more likely than sparkling sunshine. Latest Aus model shows an easterly picking up sustaining some cool conditions in SE in the week after this cold shot…check below…

01-12-2013 08-56-03

but a tad warmer later

but a tad warmer later

The culprit is the jetstream which is looping wildly around the Northern hemisphere at present.  The jetstream acts as a kind of “belt” around the Poles holding the cold Arctic air in.  If the jet starts weakening and wiggling from North-South it allows cold air to leak out from the Poles and plunge south in huge swoops of icy air.  The Arctic swoop expected later next week is going to inject icy weather to much of Europe from Greenland and the North Pole  The UK, being on the western edge of this swoop, will miss the most intense cold (that’ll hit Netherlands and Germany and, eventually, get as far as E Europe and the Alps).   The lead-up to this event is pretty benign with a high pressure giving calm cool cloudy conditions early in the week, turning into a more westerly zonal flow for a time before the northerly plunge hits from Thursday. More on this later in the week as more details emerge.

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A current picture of Greenland shows conditions this weekend.  Think of air leaving here this week and reaching the UK by Thursday: thankfully, it’ll warm up from around -40c on the ice sheet to about +4c by the time it reaches Reigate high street.

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Latest update Saturday 30/11: confidence really building for this event: cold shot end of week Fri 6- Sat 7 / Sun 8 Dec but not lasting long.  Could be some threat of snow / wintry ppt for SE but most likely just rain/sleet but with a cold wind.  More details later but end of next week CHILLY! An additional feature on ECM model is a wave depression on the northerlies running down the north sea arctic winds: could introduce snow to North Sea coasts esp Netherlands/Germany but also potentially E / SE UK. The episode will be short-lived though. stay tuned!

While this weekend will be cool and dry, things might possibly be hotting up for a more significant cool-snap end of next week and into next weekend (7-8Dec). Some models show an attempt at an early December cold snap possibly developing later next week Thurs/Fri 6 Dec and over the weekend with a cold Arctic flow across the whole of the UK and reaching the Weald / SE.  (when) If this comes off, the Arctic flow will be brought to us by a LOW moving over Scandinavia and a HIGH nuzzling in from the Atlantic. The two closing up will squeeze the pressure gradient urged on by an active jetstream plunging in from Greenland which will increase the northerlies to make things feel chilly, especially on the coast and anywhere exposed to the wind. So… it could be a proper cold snap if models come into agreement: currently they are not really coming into line and, while the ECMWF looks dramatic (see chart below), the GFS is keeping the cold further north only skirting Scotland with snow while the South stays in a relatively milder flow: so one to keep in mind but it’s not certain, yet! Latest ECM run still showing significant chilly plunge from late next week/next weekend … but high topples in quickly (see ebelow)

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29-11-2013 07-39-08

If it does happen, typically an Arctic airmass brings snow to Scotland, snow showers and cold and blustery conditions down the North Sea but probably just bright breezy and cold conditions to Reigate. Occasional wintry showers cannot be ruled out for us, though.  At this stage it really does look like a brief episode with a HIGH building over the UK the following week (by 11 Dec) but a cool frosty theme is likely to continue under clearer skies as a high builds in encouraging a cool northerly regime to persist.  This is all worth keeping an eye on but the set-up is not primed yet for a sustained wintry blast because:

  • the Atlantic block isn’t strong enough and a toppling high is likely to spill over the UK shutting the door on any sustained Polar air.
  • the jetstream is predominantly over or even north of S England and this keeps us in westerly or slightly milder conditions.
  • the NAO is weakly positive which means more westerly winds and stormy, milder conditions with HIGH pressure to south and LOW to north.

28-11-2013 22-21-44

Despite these indicators of benign winter weather for the UK, there is a huge mass of extremely COLD air on the threshold of spilling across the UK at any moment.  It is never very far away and, with the jetstream wildly migrating north and south, it is quite likely that some intense cold shots are possible as we push further into December.  All a mixed bag: the HIGH forecast should keep us dry, cool and frosty into mid Dec but expect the odd cold incursion as a distinct possibility.

The US and Canadian winter storm is dominating weather headlines with London in Ontario, for example, recording -10c and plenty of snow. The jetstream looped wildly down across the US and Canada due to an “omega” blocking pattern in the Pacific causing a plunge of Arctic air to flow across the entire continent, almost reaching Florida at one point (but not quite!).27-11-2013 17-41-10

For the UK things are more benign.  This Friday 29 Dec sees a cool NW upper flow reaching the UK with a LOW moving over Scandinavia bringing down cool bright Arctic air for the weekend.  This is a rather interesting “cross-polar flow” which sees surface winds flowing right across the North Pole from Siberia / Pacific and reaching Reigate via N Greenland! It will warm up considerably over the N Atlantic waters which are still around 10c surrounding the UK but still only allow Reigate weekend temps of Tmax 5-7c with a cool breeze making it feel like 3-4c at best. Wrap up!

27-11-2013 07-38-06

After the weekend the HIGH keeps the south dry and relatively mild humid air (so cloudy) for the start of next week but it slips south allowing an increasingly brisk W/NW air flow. The main news is a possible significant cold shot from around Friday 6 Dec which will bring in much colder air across the whole country.  Models are currently coming into line on this and it is not certain how long or deep any cold snap will be but it seems likely that a cold snap will bring snow across northern and east coast regions while Reigate and SE will get some cold conditions with possible snow showers but cold wind and rain and sleety icy / wintry episodes are more likely for us. In any case, significant snowfall is not expected in the SE currently but periodic and overnight dusting on the hills in some v cold air temps is likely.  Frosty and icy conditions are coming for a while. Check back for updates though!

Dec 6-7 arrival of colder air

Dec 6-7 arrival of colder air

Update Friday: end of this week looking like a cooler shot from North: cold front to bring wet conditions across UK during unsettled Friday with jetstream dragging in colder northerly winds from Pole behind for weekend (after a mild-ish period mid-week as warm air incorporated into system).  Not snowy or outrageous, just cooler for Reigate. SE could win out at weekend as a bright, showery regime is possible on this NW airstream. Also, a possible “chilly” snap early/mid-dec appearing on charts now but not a major winter event likely at present, worth checking back for updates. No US winter storm for us, yet!

If this was July it would be all fine. The HIGH building from the SW sitting over the UK this week will do its best to deliver some nice weather but, for the SE especially, it “could do better” with some cloud and drizzle sometimes spoiling the potential for a glorious end to Autumn.  Nevertheless, there will be predominantly calm light winds and dry weather this week so nothing to complain about and no wintry weather on the cards for us in the SE at least.  The south-east and Reigate sits in between a cold plunge over the East of Europe driven by a LOW drifting over Scandinavia and a HIGH to the SW of the UK driving upper air on a long circuitous route from the SW Atlantic, over Iceland and then down the N Sea.

HIGH pressure sitting to the S and SW will build as a warm flow of SW upper air flows to the NW of the UK. This will, oddly, bring warmer conditions to the North of the UK initially than the South in the first part of the week. Initially a cool flow from the N and NE will keep the SE cool and with possible frost early in the week where temps will struggle to Tmax 6c and fall to freezing at night. Conditions warm through a little from weds onward and frosts become less likely as the warm air is stirred into the system and brings up temps day and night.  It also delivers more humid air which usually means more cloud for SE rolling in off NSea. 

Later in the week the jetstream is predicted to pull down cooler air flow from the north again, especially for E and SE England and, whilst there is no risk of wintry weather for us, this will cause another dip in temps with a spell of wet weather spilling down on a cold front towards Fri / next weekend, though nothing out of the ordinary.  It remains edgy but snow lovers will have to be patient, the air we are getting simply isn’t cold enough… yet!

When you are out and about this week: consider a global weather picture: a long haul jet from Deep South of USA delivers a warm Tropical airmass over the North Atlantic to build the HIGH this week which is making our UK weather, albeit it may not feel like it!…

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24-11-2013 21-37-38

Don’t worry, no icy blasts for SE and Reigate this week. Some cooler weather certainly arriving Tues (but dry and bright initially) and a slight possibility of snow flurries for Weds night/ Thursday am across the Downs for a little while but sleet more likely and rain either side of this momentary event, which most will miss anyway by being in bed. It’s interesting weather nonetheless. A LOW is developing rapidly as we speak between Greenland and Iceland. Freezing air off the Greenland ice cap is meeting warmer air brought north by a brisk jetstream and the two are colliding at a development zone for storms on the pole-ward side of a very frisky jetstream blasting west to east across Greenland from  Canada. The jet is in a meridional / wildly loopy phase and is directing this LOW pressure with attendant cold polar air straight across Iceland, across the North of Scotland and then down the North Sea brushing very close to the East coast and SE of England on Weds- Thurs.  

In Reigate this will bring chilly / “icy” rain overnight and a brief low risk possibility of dusting snow over the Downs. The LOW drifts off down to the continent where it brings snow and very cold conditions to the Alps: -25c is predicted on some models for the high Alps. So, there will be icy blasts here and there associated with this LOW but you’ll have to pop to Greenland or Iceland, possibly the mountains of Scotland or the Alps this weekend to experience this!  

For the UK a HIGH pressure builds through to NW later this week / weekend so things look to be staying cool but rather settled with a N/NE wind dominating.

Weds night into Thurs: looks to be that wintry ppt on the way 🙂

check out latest radar 21:00hrs weds: please follow our twitter feed for latest updates on local winter weather @RGSweather

20-11-2013 20-59-32

next update: Sunday 24 Nov…

The well-advertised cool-off this week arrives in Reigate late Monday and through Tuesday with the coolest days being mid-week: some remarkably cold upper air temps are due to cross the SE this week. While Tuesday will be cold and bright under a brief ridge of high pressure over SE, the coldest feel will be in more windy and damp conditions Weds night – Thurs am.  Whilst this is far from an early winter-Armageddon we are certain to see chilly temps during the day staggering to maybe 5 or 6c Tmax with night temps dropping below freezing: car scraping, road gritting with cold days and chilly nights, if you happen to be out, will be the norm in Reigate from Tuesday on wards, but must stress nothing outrageous, just chilly, especially when wind picks up with arrival of a LOW skirting down from N of Scotland and journeying south down the North Sea mid-week: sticking tightly to the East coast.  This will eventually introduce a COOL POOL low over the near continent which will form the basis of weather in the SE for later this week and into the weekend with cool and, usually gloomy, NE and E winds off N Sea, whilst a frosty HIGH builds over the north of the country. 

A meridional (wiggly) North-South jetstream is responsible for dragging down frigid air from the Poles… the distance from the Greenland Ice sheet to Reigate is some 2000 miles, so this Polar air will warm up over the comparatively warm North Atlantic Ocean courtesy of the warm ocean current, North Atlantic Drift. Nevertheless, a series of cold fronts Monday and then again Weds will introduce successively colder air from N-S down the country, with accompanying rain (snow for north and northern hills).  These fronts will also bring down rain, occasionally “icy” / sleety mid week, possibly with dusting of snow too for higher ground locally.  The complicating factor in this Arctic plunge scenario is a vigorous area of LOW pressure regressing down the North Sea, driven by the northerly jetstream, which has some cold polar air from Greenland wrapped into the circulation.  The North Sea is about 9c so this will have warmed up considerably since its departure from the Ice Sheet but the warming from below could invigorate wintry showers for the East coast. The GFS model has the additional possibility of the cold front dusting the SE with snow overnight Weds into Thursday am as this cold air sweeps over and freezing levels touch down on the Downs. As usual, check back for updates as this interesting wx takes shape this week as models are hinting at further COLD for next weekend. Follow @RGSweather on twitter too! 

So, prepare for the arrival of the Queen of Freezer!


14-11-2013 19-53-00Whilst extreme weather scare stories in the press can be ignored as hot air, there is real confidence growing for a quick icy plunge of Arctic air visiting UK and reaching SE and Reigate next week. This is the first Autumnal cold snap of upcoming winter 2013 so heads-up to dig out the woolly hats and thermals, at least for a good part of next week until it probably warms up to autumnal average again over next weekend.  It is a well within the “normal” for late Autumn cold conditions so nothing to get too excited about; in fact, it resembles a similar Omega Block from exactly this time last year (see below).  Nevertheless, it will bring the usual frisson of excitement as some substantial snow is due for the hills of N England and Scotland and possibly flurries of wintry weather reaching the Midlands and even over the Downs to as far south as Reigate and SE (though here sleet is more likely but cool certainly). A regressing HIGH in the Atlantic moving to NW of UK will drag in this chilly NW Arctic air courtesy of a northerly blast from the jetstream: this arrives in SE from Monday on ward and reaching Reigate properly by Tuesday, lasting through much of next week. The upper air temps will plunge well below -30c at 5000m above the UK next week – and the “thickness” of the air will fall to below 528dam (decametres) which is a critical threshold for snow and wintry weather.  (Warm air masses are “thicker” than cold; warm air takes up more depth in the atmosphere and, rather like a warm fluffy thick duvet, keeps the surface warmer, and usually builds a higher pressure.  Imagine thinner cold air-masses as a thin duvet lacking the insulating capacity of warmer thicker air. This is a simple interpretation of “thickness”: warm and thick or thin and cold)

14-11-2013 07-05-19

Daytime temps will be above freezing, but not much… perhaps 4-5c and a significant windchill on occasions will make it feel distinctly colder than it has been.  It will feel chilly at night, down to -2 or -3c. Any precipitation during this time will be wintry.. i.e. snow or sleet.  Not much ppt is forecast for us in the SE during this time except possibly for places near the east coast but check back for updates on this.

14-11-2013 22-17-41

Meanwhile, it is usually safe to ignore alarmist headlines… check below and confirm that we are still here, despite the dire warnings from the past!

13-11-2013 07-10-03

The initial Arctic blast does not last that long: a toppling HIGH moves over from Iceland and across the N of Scotland later next week to effectively shut the door on the direct Polar air.  This pattern of weather can persist and is called an “OMEGA BLOCK” after the similarity in pressure pattern and upper wind flow to that of the Greek letter omega.  Unfortunately, this pattern is likely to leave a large cut-off COOL POOL of frigid air over the UK and the near continent which can bring cool easterlies to the east coast which may penetrate inland across the SE giving Reigate continued cool weather through to next weekend 23-24 Nov .  COOL POOLS usually warm up slowly but this can spark showers and later lead to slack gloomy conditions weather for the East coast.

14-11-2013 19-34-24A very similar pressure pattern built this time last year Nov 2012: so this is not an unusual or especially extreme weather pattern.

14-11-2013 21-35-29On the other hand, the chart below shows a really strongly negative Arctic Oscillation building up and this would usually mean a strong blocking pattern where Arctic air is allowed to leak periodically from the Poles because of a weaker pressure gradient in the Atlantic and a correspondingly weak jetstream.  The jetstream acts like a belt holding cold air into the Polar regions, if it slackens off it can allow the cold air to escape more easily.  Cold end of November persisting is a possibility looking at the chart below.

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Haiyan officially deadliest storm in Philippines history with 5209 people killed.

Some 30 storms of varying intensity have formed in the Western Pacific region in 2013 and nearly 10 of these have crossed the Philippines or come near. People in the Philippines and this part of the Pacific are entirely used to tropical cyclones which is perhaps why so many so sadly did not heed warnings this time, choosing instead to sit it out in their homes. It is also dreadfully ironic that perhaps the welcome recent expansion of a more populous middle class in LIC’s such as the Philippines meant that people may possibly have felt safer in their new concrete homes than they may previously would have done in simpler shacks or self-built dwellings.  The storm surge would have meant they were trapped in a deadly and terrifying “washing machine” inside their own home rather than making the journey to shelters on higher ground given the warnings to evacuate low lying coastal districts. This, of course, is unsupported conjecture but was mentioned today by a previous resident of Tacloban interviewed on BBC Radio 4.

Haiyan was spotted before the 3 November when a cluster of intense thunderstorms began to rotate near the central Pacific Micronesia islands. At this point it became a Tropical depression, the weakest status for a cyclone. Rotation is the precursor for hurricane formation which is why hurricanes / typhoons never occur on the Equator due to the zero Coriolis (spinning effect) near the low latitudes.
During the next 3 days the storm traveled 2000 miles to the west, varying in intensity but staying below supertyphoon status. Nevertheless, the Joint Typhoon Warning Centre based in Pearl Harbour was monitoring it and several storm chasers and camera crews chose to fly direct to the line of fire in Tacloban. 

So, the Philippines may have been unlucky this time because the Haiyan / Yolanda reached maximum intensity as a Cat 5 supertyphoon just before it made landfall and, due to the very warm sea surface temperatures to the east of the Philippines at the end of the summer, it did not weaken at all.
This led to the ferocious winds exceeding gusts of 200 mph and massive storm surge of some 6m that hit Tacloban and regions around there.

On the other hand, if Haiyan had been a terrorist attack: we knew his precise location, direction and potential threat several DAYS beforehand and we knew that Tacloban was staring down the barrel of this most unprecedented attack at least 48 hours before Haiyan unleashed with such ferocity.

With masses of technology already invested in weather prediction, the challenge for this century is to get appropriate, meaningful and timely warnings to people on the ground so they can react accordingly.  This will mean education and responsible leadership.

Tacloban and the Philippines more widely, is known to be exposed to the potential for typhoon damage, they experience storms frequently. Nevetherless, it is the lack of human planning and preparation that made her so vulnerable this time.

The picture below of the father carrying his child is so distressing that it should perhaps not be on this blog, but it might help us to understand the immeasurable impact this massive storm has had on real people.  Social media has made the world SO small now, allowing us to communicate with and get to know more about individuals who live across the planet than sometimes live across the street. It means that the people in these photos should, more than ever, be seen as our neighbours.

Here is an excellent explanation from the BBC

More on hurricane / typhoon formation here: this is old but a good outline of hurricane formation:

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Notes and links on RESPONSES and more long term impacts

6 days later:

PH Govt now facing criticism as “despair and chaos” descend over Tacloban and effected areas.

Tonnes of aid remains undelivered due to Govt inefficiency? No large scale food distribution until now.

US Military / US Marine Corps arrive in force with aircraft carrier George Washington and other vessels with helicopters to rapidly deliver aid.  US have taken control. There is a dramatic change on the streets with dead being collected now, 6 Days later.

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$5m Canada

$10m UK

15-11-2013 06-58-54 15-11-2013 07-00-06

A superb article here : are events like Haiyan just “acts of God” or partly “acts of Man”?

16-11-2013 10-24-05Fear of disease: mass vaccination program of 33000 children started in Tacloban amongst fears of cholera epidemic threat in devastated city.

Psychological damage

Good summary on management of aftermath and aid and reconstruction:

storm surge science

Reigate will see a wet, miserable start to the week, albeit a warmer day than the cool weekend due to the warm sector bringing in tropical air.  Rain is due to arrive for Monday morning journey to work and thereafter remain pretty drizzly and on and off all day with some heavier showers poss around midday and pm, including rain clearing on Tuesday morning.  The rest of the week looks drier and, whilst not bone dry, a high pressure edging into the SW from the Atlantic will inhibit the sort of rain and storms we have seen recently and push them way up north to Iceland.  

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For us it will be much calmer and drier with Tmax around 9c and cool nights down to 3 or 4c air temp, staying mostly frost-free unless cloud cover clears overnight. Further ahead models want to push down November temps from mid November onward, including a precursor of something briefly colder towards the end of the week as the HIGH shifts west and north of the UK and a LOW slips south down the North Sea: this could drag in some chilly winds.