A Jet stream anomaly caused a deadly cold snap in Europe, described the worst in several decades has taken nearly 200 lives leaving thousands trapped. Many of the dead from one of the harshest European winter in decades are homeless. Meanwhile, the same Jet stream anomaly caused temperatures further north near the Arctic Circle and the US to be much warmer than normal. Countries from Italy to Ukraine on one hand and on the other hand, upto to Greece and Turkey on the East struggled to cope with temperatures that reached record lows in some places.UKRAINE: Tens of thousands of people have headed to shelters trying to escape the freeze that the emergencies ministry said has now killed nearly 100 people. Most of them literally froze to death on the street, with only a handful making it to hospital before succumbing to hypothermia, the ministry said. Shivering and hungry, tens of thousands of Ukrainians have sought help in the more than 2,000 temporary shelters set up by the authorities to help the poor survive the fearsome spell of cold weather.ROMANIA: Many people died overnight because of the cold, bringing the overall toll to 22, the health ministry said. Schools remained closed in some parts of the country as temperatures reached minus 31 degrees Celsius.
BULGARIA: Mercury dipped to lows not seen in a century.LATVIA: 10 people have died around the capital Riga alone, with no figures available for the rest of the country.LITHUANIA: A 55-year-old homeless man found in the ruins of an abandoned house in the port city of Klaipeda became the ninth victim of the chill.ITALY: hundreds of people were trapped overnight on trains as freezing temperatures and heavy snowfalls in the centre and north caused widespread disruptions on roads, railways and at airports.SICILY: The cold has so far killed an infant in and a 76-year-old pensioner in Parma during what forecasters say is the coldest weather in Italy in 27 years.AUSTRIA: An 83-year-old woman was found frozen to death in the woods after apparently slipping on her daily walk and not managing to get up again, becoming the country's second victim of the cold snap, officials said. In Serbia, the cold has killed six people and trapped some 11,500 others, mostly in remote mountain villages inaccessible by road.SERBIA: Homeless people unable to secure one of the 140 spots in the capital's sole shelter took refuge in trolley buses and trams.FRANCE: Several regions have been placed under "deep cold" watch; authorities banned trucks on several major highways where the risk of snowfall and ice remained high.UK: The Met Office has issued its most serious cold weather alert of the winter so far after overnight temperatures dropped to -9C in parts of the UK, with chilly conditions set to continue into the weekend and some snow forecast.GREECE: Forget the usual images of Greece basking in hot sunshine reflecting on blue seas, and imagine snow-covered mountains and sub-zero temperatures. Greece is in the grip of arctic weather which has seen temperatures plummet well below zero. The ice on the ground and the snow covered orange trees glimmer in sunlight which belies the freezing conditionTURKEY: Extreme winter conditions have brought life to a standstill across Turkey. The biggest freeze since 30 years has grounded 180 flights on Tuesday, and on Monday 200 flights were cancelled. The daily life of the European side of Istanbul was mainly paralyzed today and snowfalls are predicted to last until the weekend, with icy temperatures as low as Minus 27° Celsius in Southern Turkey. Meteorology officials have warned that snowfall and blizzards are likely to continue uninterrupted until February 7.
So why this cold burst in February?
In general, the La Niña causes radical Jetstream changes and you can click the arrow in the video to watch Accuweather’s explanation. Moreover, the Arctic Oscillation (AO) which was strongly positive till mid January overwhelmed the La Niña’s cooling effect by keeping the winds spinning fast in the Arctic, not allowing the cold southwards. But for last two weeks, the AO has flipped to its strongly negative mode as shown below which unleashed the arctic blast into Europe.
The cold jet stream dipped in Europe and Asia, but is still bottled up over North America. That's because another weather phenomena, called the North Atlantic Oscillation (NAO) is playing oddball by staying positive and keeping the cold away from the rest of North America. About 90 percent of the time, the North Atlantic and Arctic oscillations are in synch. But not this time, so much of the United States is escaping the winter's worst. But this can change soon. The NAO index looks as if it is going to soon flip strongly negative too.
India: Another Western Disturbance underway, temperature to drop early next week
Taken from http://devconsultancygroup.blogspot.inIndia’s North-West, is right now receiving an active western disturbance (WD) with rough weather implications for not just the higher reaches but also the plains. On Thursday, an India’s Met Office update confirmed the WD located the weather-making westerly system lying over north Pakistan and adjoining Afghanistan. The system would start affecting the western Himalayan region and adjoining plains from Friday onwards. As it happened mid January, there is as simultaneous wave from exactly the opposite direction (easterly wave) moving across the seawaters of the Bay of Bengal aiming to hit south peninsular India from around the same time today.The IMD has forecast heavy rain or snow at one or two places over Jammu and Kashmir and Himachal Pradesh on Friday and Saturday. Importantly, the forecast also mentions about the possibility of hailstorms lashing one or two places over Punjab, Haryana, north Rajasthan and west Uttar Pradesh on Saturday. A two-day forecast said that rain or snow would break out at a few places over Jammu and Kashmir and at one or two places over Himachal Pradesh and Uttarakhand on Friday and increase thereafter. From early next week, temperatures in India should experience a significant dip
Wondering why Mysore registered the coldest minimum temperature in 120 years recently? Steven Goddard who administers the bog Real Science give us a clue: "Global temperatures are plummeting, and the temperature recorded by AMSU satellite of 251.858K on January 19 was the coldest of any day since at least 2002.”
It’s all happening. The Arctic Oscillation (AO) has finally flipped to its strongly negative mode and if it stays that way, a deep freeze is on its way that would plunge global temperatures to lows, last seen during the 1945-77 global cooling cycle the very least. A foretaste of winter to come during February is already indicated by some of these very recent events:
Snow in Sahara Desert
Snow fell Tuesday in the province of Bechar in the Sahara Desert in western Algeria. A 24-hour cold spell brought snow and rain to the region. Strong wind blew the snow across roads and buildings in the province of Bechar. The weatherman at the National Centre of Meteorology and Seismology (NCMS) recorded sub-zero temperatures at Jebel Jais area of Ras Al Khaimah and forecast that these conditions are set to continue for the rest of the week. People who live in the region said the snow was good for the palm trees because it killed parasites. Bechar is located in the northern Sahara, about 36 miles south of the Moroccan border. Click arrow to watch video.
Extreme Cold Wave in the Gulf countries
According to the National Centre of Meteorology and Seismology (NCMS) forecast for today, minimum temperatures are set to dip to 0°C in the UAE’s mountainous regions while internal areas could see temperatures dipping to a nippy 5°C and coastal areas could see minimum temperatures of 13°C.
The NCMS forecast reads: “Cold weather during day times to very cold during night. The cloud amount will increase at times, especially over the northern areas, with chance of light rain. Winds will be west to northwesterly, moderate to fresh in general. Sea will be moderate to rough with wave height 3 - 5 / 6 ft offshore.”Unaccustomed to the chill, UAE residents are putting up a brave front as a cold wave continues to spread across the length and breadth of the country, with extreme weather conditions sweeping mountainous regions and the country recording its lowest temperatures for the year yesterday. Rough weather has prompted a warning to beachgoers across the UAE to refrain from venturing into the sea. The UAE’s met department has predicted that the rough weather will continue until Friday
Leh: minus 22.2 degrees Celsius
Leh town in Ladakh recorded the coldest night of this season as mercury settled at a low of minus 21.8 degrees Celsius, an official of the Met department said. Nearby Kargil town recorded a low of minus 21.0 degrees Celsius, making it the second coldest place in the state.In Kashmir Valley, Pahalgam resort was the coldest place at minus 16.5 degrees followed by Gulmarg Skiing resort at minus 16.2 degrees Celsius, the official said.Qazigund, the gateway town to Kashmir, recorded a low of minus 12.4 degrees Celsius followed by Kokernag resort at minus 9.9 degrees Celsius.Srinagar city, the summer capital of the state, saw mercury dipping to minus 5.0 degrees Celsius last night.
An Igloo Village in Davos
The Occupy protests that blossomed across the globe in the fall of 2011 are popping up at the annual meeting of the rich and powerful in Davos Switzerland. Using the weather to their advantage, protesters are carving out blocks of snow and shaping them into igloos that are surprisingly warm, if not an effort to make. They hope to make develop an "igloo village" near the Davos train station.Deep freeze kicks in as Arctic Oscillation turns strongly negative
The first half of winter has clearly been much milder than the last couple of winters, as a very strong polar vortex has controlled the pattern, and shielded Europe from any sustained cold. Recently, the vortex has weakened and the AO turned strongly negative as seen above, which would allow seasonably cold weather across much of Europe in February if not earlier.
According to NOAA as seen in the above diagrams the AO index describes the relative intensity of a semi-permanent low-pressure centre over the North Pole. A band of upper-level winds circulates around this centre, forming a vortex. When the AO index is positive and the vortex intense, the winds tighten like a noose around the North Pole, locking cold air in place.A negative AO and weak vortex … allow intrusions of cold air to plunge southward into North America, Europe, and Asia. … the index has been mostly positive in wintertime since the late 1980s. The Arctic Oscillation has strengthened in recent decades, contributing to the unusual warmth over the Northern Hemisphere land masses.
The first sign of a much weakened polar vortex is that the Arctic Oscillation (AO), also referred to as the Northern Annular Mode (NAM) has recently switched to a strongly negative mode - the first time in four months.Britain blasted by snow & ice yesterday is example of this. Read here.
The AO is an atmospheric circulation pattern in which the atmospheric pressure over the Polar Regions varies in opposition with that over middle latitudes (about 45 degrees North) on time scales ranging from weeks to decades. The oscillation extends through the depth of the troposphere. During the months of January through March it extends upward into the stratosphere where it modulates in the strength of the westerly vortex that encircles the Arctic polar cap region.
The NOAA's AO prediction for the next two weeks shows a strong negative trend which typically in the past has brought colder weather for Europe. The bottom chart for Europe shows the anomaly for the coming week. The middle chart shows the foret.cast for the week after. It’s going to get even colder. Europe this year may get a hard winter after all – it may be just arriving late. The lower chart of central Asia shows below normal temps are forecast for almost every region for the coming week, and the middle chart shows even deeper cold for the week after, as we saw is the case for Europe. In fact it’s rare to see that much cold over such a vast continent
However, AO's cousin the North Atlantic Oscillation (NAO) sill remains weakly positive (graph to right) but ensemble mean (graph to the left) suggests models are indecisive which mode NAO will go by February. But since the polar vortex is rapidly giving way, the odds favour the NAO too slipping into strongly negative mode sometime in February or even earlier.
Atlantic over the past 50 years,. h Other studies have found correlations between NAO and Indian monsoon. “Interannual and long-term variability in the North Atlantic Oscillation and Indian summer monsoon rainfall” (Dugam, Kakade and Verma, Indian Institue of Tropical Meteorology, 1997 [http://cat.inist.fr/?aModele=afficheN&cpsidt=2068184]) investigated 108 years of NAO / monsoon data and found that:
“The decadal scale analysis reveals that the NAO during winter (December-January-February) and spring (March-April-May) has a statistically significant inverse relationship with the summer monsoon rainfall of Northwest India, Peninsular India and the whole of India. The highest correlation is observed with the winter NAO. The NAO and Northwest India rainfall relationship is stronger than that for the Peninsular and whole of India rainfall on climatological and sub-climatological scales.”
Atmospheric Blocking
When the polar vortex weakens, the polar jet stream slows and meanders in a form that allows the extension of low pressure lobes much farther to the south. These can become stationary for days and block the normal circulation of the atmosphere. The negative AO/NAO is associated with a slowed polar vortex and polar jet stream. When the jet stream slows, it meanders in a waveform pattern (Rossby waves). The general effect is illustrated below:
Taken from >> http://devconsultancygroup.blogspot.comBlocking has a lot to do with the severity of winter weather in the Northern Hemisphere, and the AO has a strong ability to control blocking. A blocking event can be defined as a week or more of excess pressure in the mid-troposphere together with an anticyclone at the surface. … blocking occurs preferentially during the low AO phase in Alaska, the North Atlantic, and Russia. [http://www.jisao.washington.edu/wallace/ncar_notes/] Barriopedro et al (“Solar modulation of Northern Hemisphere winter blocking”, Journal of Geophysical Research, Vol.113, 2008 [http://idl.ul.pt/davidbarriopedro/2008%20Barriopedro%20et%20al.pdf]) found that:“Solar activity modulates the preferred locations for blocking occurrence over both Oceans, causing local frequency responses therein. Over the Pacific Ocean high/low solar activity induces an enhanced blocking activity over its eastern/western part. Atlantic blocking occurrence increases for both (high/low) solar phases, with a spatial dependent response confined to western/eastern Atlantic. … Low solar Atlantic blocking episodes last longer, are located further east and become more intense than high solar blocking events.”
Our December 15th post Winter may have had a mild start but likely to be progressively harsh appears to be turning out prophetic. Big pattern changes in the global weather are on the way and we in India during the last few days got just a small taste of things to come during the last few days.
A strong western disturbance over the western Himalayan region caused cloudiness over northwest and adjoining central India. If snowfall played truant in Himachal Pradesh on Christmas and New Year's Eve, then it made up for the lapse with a vengeance. Snow walloped Shimla, Kufri , Narkanda , Chail , Manali , Chamba and Dalhousie.In fact the entire tribal belt of Kinnaur, Lahaul and Spiti, Kullu and Chamba districts witnessed heavy snowfall. Shahpur and parts of Hamirpur among other places also experienced snowfall and sleet after a gap of more than three decades. And it's snowing in 'Queen of Hills' Shimla as well. This after 8 years! The minimum temperature recorded in the hill station fell to minus 0.8 degree C.Dharamsala received snow after a gap of 35 long years. Located at a height of only 1,350 metre and the abode of Tibetan Buddhist spiritual leader the Dalai Lama, Dharamsala was totally covered in white, making the town more picturesque. In fact the snowfall was unusually heavy with McLeodganj, its tiny hamlet, known for its strong British heritage, receiving some of the heaviest snowfall on record.
Even Nurpur experienced snow. This after 45 years. But what really took weather forecasters by surprise was heavy snow lower down in Kangra town. This was after a gap of a whopping 67 years! The peculiarity of Kangra, Nupur and Dharmasala are that these are foothills where snowfall is not normally expected because of their low elevation. But Himachal Pradesh is not complaining. Good amount of snowfall has not only rejuvenated its glaciers, but also proved beneficial for its tourism industry, with scores of tourists making a beeline to the hill state. Hotel accommodation and flights are reportedly fully booked.It gets even better. Probably for the first time in the recorded history of Punjab, several villages of Pathankot and Hoshiarpur districts experienced snowfall on Saturday morning. The two districts normally experience maximum temperature of up to 45 degrees Celsius in summer. The Met office however dismissed the event as a 'freak' happening due to change in wind directions.Last Friday, parts of New Delhi and Amritsar woke up to be greeted by a hailstorm. It is not that hailstorms are a rarity in these parts of the country. It usually takes place during the transition period where winter gives way to spring. This is when temperature rises initially in the southern parts of India, giving rise to thunderstorms and squally weather, including hailstorms in Northern India. The problem is that we are not in this transition period and in fact only now entering into the peak winter season.So what could have triggered the hailstorms? My friend, Rajesh Kapadia who administers the blog Vagaries of the Weather explain that conditions for snow are a) surface temperatures are below freezing upto 2 deg C b) atmospheric temperatures are below freezing c) air contains a minimum moisture level. Atmospheric temperatures were below freezing but conditions of surface temperature and minimum moisture levels for snowfall were not meet to create snow and so the western disturbance impact on New Delhi and Amritsar probably took the shape of hailstorms. This of course remains a logical conjecture.Meanwhile, more than 3 feet snow received over the past two days closed down Kashmir's main highway, stranding hundreds of travellers. The snowfall on either side of the Jawahar tunnel, blocked the only road link, connecting Kashmir to rest of the country, and traffic has been suspended. Trucks carrying supplies to Kashmir haven't moved a bit in the past three days because the Jammu-Srinagar highway that connects the Valley with the rest of India is closed due to heavy snowfall and landslides.The heavy snowfall also knocked out power and telephone lines after the 220 KV-Kishanpur-Pampore and 400 KV Kishanpur-Wagoora transmission lines snapped on other side of Jawhar Tunnel due to snowfall. Against the required 950 MW of electric power being supplied to the valley, the availability this time is pegged at 120-150 MW. Among the available power, 40-50 MW is being supplied to consumers while rest is being used for running essential services. The plight of residents made worse as J&K is already facing shortage of fuel- LPG and kerosene- for cooking and heating purposes.Temperatures at Srinagar plummeted to minus 5.5 degree C, the coldest night in the city this winter. Due to the extreme cold, water taps in most areas of Srinagar were frozen in the morning. Picturesque tourist spot Gulmarg recorded a low of minus 16.5 degree C. Qazigund’s low dipped to minus 8.4 degree C followed by Kokernag (minus 6.3 degree C), Pahalgam (minus six degree C) and Kupwara (minus 5.6 degree C).The Dal Lake was frozen at many places too. Kulgam town in south Kashmir received 2 feet of snow while Srinagar, around 5 inches of snowfall since last evening. High-altitude areas including the ski resort of Kupwara district which recorded night temperature of minus 0.3 degrees Celsius, had 14.4mm of fresh snow till early morning.Pahalgam, received fresh snow of 8cms during the time while the world famous hill resort in south Kashmir, recorded a low of minus 1.8 degree C. Kargil district in Ladakh witnessed the first heavy snowfall of the season with Kargil town recording 2 inches of snow while Drass had about 3.5 inches on the ground this morning. Taisuru and Rangdum also recorded 2 inches snowfall. In Leh, temperatures plunged to minus 18.8 deg C.India is experiencing a harsh winter characteristic of a La Niña winter. So how does rest of the world shape up this winter?GLOBAL WINTERLet’s look at the latest satellite temperature imagery for today.From these temperature maps it is evident that most of the extreme cold is confined to Canada, Russia and Northern China. Winter by and large had been mild in most other areas within the Northern Hemisphere. So mild that huge swathes of Northern India are currently colder or at comparable temperature to much of Western Europe.
The table illustrates that El Niño-Southern Oscillation (ENSO) by itself is not sufficient conditions to determine the character of winters within the Northern Hemisphere. More important is the Arctic Oscillation (AO) Index. The erratic AO can generate strong shifts in the climate patterns that could overwhelm or amplify La Niña's or El Niño’s typical impacts.
Technically, the Arctic Oscillation is a measure of atmospheric pressure variations at sea level north of 20N latitude. Whenever an Arctic high or low develops, it affects weather thousands of miles away.
Last year the so-called "Arctic fence" that keeps cold air penned up in the north broke down, allowing frigid air to spill south. So far that's not happening this winter which should explain the mild winter at the mid latitudes. However, the AO is a fickle—not seasonal—phenomenon and can switch erratically between the two modes.
As seen in the NOAA graph, the AO has been in its positive phase for the last 4 months, being particularly very strong all through December and first week January this year. The exception was a couple of days around the middle of October and before Christmas when it briefly flipped to its weakly negative mode. But each time it showed a strong streak of resilience - rebounding quickly to its strongly positive mode again.But yesterday, it flipped back to its weakly negative mode again as that Northern India and Pakistan received a snow packing wallop. At the same time, in Europe, Austria found itself buried under 4 feet of snow, creating chaos and disruption of traffic and power supply. Snowfall trapped some 15,000 tourists at ski resorts on the Arlberg Mountain on Friday, and while some roads are open there, others remain closed. High winds are also whipping the nation, and closed an important rail line. Most snow has fallen in the western states of Tyrol and Vorarlberg. 52 people were rescued by an army helicopter there. An important rail line that connects Vienna and Innsbruck with western Austria and Switzerland was to be closed until Sunday. Two rail lines that connect western Austria with Germany were also closed.These two events may look unconnected but they need not. They occurred the same time as the AO flipped to it weakly negative mode. But the moot question is whether a negative AO is just a blip or something longer in duration?
So what do weather ensemble models indicate? As seen in the above graph, some show the AO index rebounding and going positive while others (the majority) have it trending negative and ending below zero.Two weathermen think on similar lines. On Twitter, former Accuweather and now with WeatherBell, legendary weatherman Joe Bastardi observed: “10mb [stratospheric] warming on European [model] over the pole by 360 hrs reaches 50C!!!! This is a huge event and will have [northern] hemisphere cold implications…By that I mean, something major is about to happen.”Henry Margusity Accuweather also anticipating a major change similarly observed: “This is such an amazing weather pattern evolving. I told all the [meteorologists] that we have a lot of winter ahead of us.”It was left to Dave Tolleris of Wxrisk to make a more nuanced statement about a possible pattern change. He stated: “All this being said this does NOT mean the winter of 2011-12 is about to turn nasty for everyone and or the Northeast is going to see big snows or noreasters. …It might turn that way but we don’t know that yet. But the old winter pattern of 2011-12 that has featured sustained warm/ mild dry pattern is going to end soon. And whatever the new pattern … won’t be the same as what the last 45-60 days have been.”The Washington Post’s blog, Capital Weather blog reacting to these twitter posts:“Much of the excitement by Bastardi and Margusity probably stems from a strong stratospheric warming event that is now showing up on the model guidance and how it might lead to more blocking and a negative Arctic Oscillation (AO). Remember, a negative AO means a cold and sometimes snowy weather pattern over the eastern U.S...The pattern change ideas stem from research by Baldwin and Dunkerton published in a 2001 “Science” article which documents how there is coupling between the stratosphere and troposphere and that sudden stratospheric warming events can have an impact on the AO (by helping modulate the strength of the polar vortex), flipping it negative...That research notes that once the warming propagates down sufficiently to produce a weather pattern favouring a negative AO (lots of high latitude blocking), the pattern tends to last for about two months. That probably explains why some forecasters think that if the AO goes negative it might stay that way through much of the remainder or the winter....The potent polar vortex event and positive AO that has been going on for over two months already appears to be on the wane with or without help from the stratosphere. This strong vortex event has lasted longer than most such events so the forecasts of it weakening may have some merit.”
What all this means is that a big pattern change in winter outlook is due in the next 7-14 days and the odds favour a strong negative AO. If Europeans and Northern Americans have put away their woollies and not stocked up on their heating oil, then it is time they did so in a hurry as a harsh winter is speeding their way and when it does will probably not go away for the next 2-3 months.
In India, if you thought that winter would have peaked by month end, you could be likely to be wrong. Instead, the cold wave could turn even harsher. Much of the cold wave and snow in the country is linked to what called western disturbance (WD), which is a term used in India, Pakistan, Bangladesh and Nepal to describe an extra-tropical storm, originating in the Mediterranean that brings sudden winter rain and snow to the northwestern parts of the Indian subcontinent.This is a non-monsoonal precipitation pattern driven by the Westerlies. The moisture in these storms usually originates over the Mediterranean Sea and the Atlantic Ocean. Extra-tropical storms are a global, rather than a localized, phenomena with moisture usually carried in the upper atmosphere (unlike tropical storms where it is carried in the lower atmosphere). Once their passage is hindered by the Himalayas, they are unable to proceed further, and they release significant precipitation over the southern Himalayas. In winter it brings snow and sleet.
As a strong negative AO brings cooling to the Mediterranean Sea and the Atlantic Ocean, this in turn creates stronger WDs that in turn create higher likelihood of snow, sleet and plunging temperatures.
Then again, the AO is so unpredictable and could prove everyone wrong.taken from http://devconsultancygroup.blogspot.com
