Date 4 May 2018

Version 1.0

Authors Dennis Schulze, Agnieszka Glowacka, Evelyn Müller, Reinout van den Born, et al

Winter 2017/18

European End-of-Season Report

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Executive Summary

Accidents caused by icy roads account for more fatalities than all other weather-related hazards combined.1 Winter road maintenance services have the demanding task of ensuring road safety in the most economical way with the least environmental impact.

The amount of effort winter road maintenance services need to exert naturally depends on the weather conditions itself. But also on the accuracy of weather information services they consult to plan their activities. MeteoGroup has been a provider of this consultancy for many years and has developed several models and tools supporting road services.

The winter of 2017/18 affected road services in many different ways. In most European countries the winter season started relatively mild, was turbulent mid-season and then ended unusually cold. It was also notable the record amount of snowfall seen in the alpine regions, leading in part to severe flooding when the snow melted in early spring.

Our customers benefited from excellent forecast quality which was delivered through our meteorological experts in weather rooms in eight European countries. In many cases our success rate for the prediction of the minimum road surface temperature was well above 90%.

Table of Contents 1. WEATHER CONDITIONS ........................................................................................................................ 3

2. FORECAST PERFORMANCE ................................................................................................................... 5

3. HOW METEOGROUP SUPPORTS WINTER MAINTENANCE SERVICES ................................................. 8

ANNEX: HIGHLIGHTS OF WINTER 2017/18 IN KEY EUROPEAN COUNTRIES ......................................... 10

1 Data for USA via USDOT Federal Highway Administration and NOAA, National Weather Service

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1. Weather Conditions

November 2017 to January 2018 will be recorded as having a warmer than climate

average. The end of the last winter season was characterized by unusually low

temperatures.

Surface air temperature anomalies summary2

November and December 2017 were warmer than the 1981-2010 average over

eastern Europe and January was warmer over most of Europe. The most spectacular

warming was observed in December over the Arctic in which the monthly

temperature was more than 6°C above average over parts of Svalbard. On the

contrary, November was cooler than average over large parts of the west of the

continent and December over the south-west of the continent. January 2018 was

warmer than the 1981-2010 average over almost all of Europe. It was especially

warm over a belt from France eastwards and over the far north and north-east. Only

a few areas of the continent experienced a cooler average than normal.

February 2018 was colder than the 1981-2010 average for the month over much

of Europe. It was only warmer than average in the far north and over the south-east

of the continent. The latter part of the month was characterized by the intrusion of

very cold temperatures from the east. This was in stark contrast with daily

temperatures in parts of the Arctic more than 30°C above the daily average. March

2018 was colder than the 1981-2010 average over almost all of Europe. It was only

warmer than average over the far north and over the far south-east of the continent.

Abundant snowfall in the Alps

Several cases of cold air mass intrusion from the North, which met with much

warmer humid air masses in central Europe, resulted in some massive snow events.

This effect was enhanced by the highest mountains in Europe, the Alps, and brought

record snowfall last winter.

Strong winds

January stood out due to several significant storms. In the beginning of January the

storm Burglind caused severe damages, especially in Germany. In mid-January, a

low-pressure center in the North Atlantic developed into a severe storm named

2 All maps on this page are courtesy of the Copernicus Climate Change Service (C3S) funded by the European

Union

Nov 2017

Dec 2017

Jan 2018

Feb 2018

Mar 2018

Nov 2017

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Friederike. This storm hit the British Islands on the night of January 17/18th and continued into Germany,

Benelux and Central Europe countries on the following day.

Know-How: Sudden Stratospheric Warming, the most characteristic feature of the last

winter in Europe

Every winter, as polar latitudes receive little or no sunlight, the air in the stratosphere above the Pole

cools rapidly and a strong westerly wind flow develops around this ‘cold pool’. This is called the polar

vortex. However, the natural variability and fluctuations in surface weather across the globe can

sometimes generate large vertically moving waves in the atmosphere. As these waves travel up

towards the stratosphere they tend to increase in strength. At times they can slow down the polar

vortex; similar to a brake being applied to a fast-moving wheel. If the waves are strong enough, then

the westerly vortex can distort and even break down completely, with the wind direction reversing

and becoming easterly. This change in wind direction is also accompanied by a rapid rise in

temperature in the stratosphere, called a sudden stratospheric warming (SSW). SSWs tend to occur

about once every 2 or 3 winters, normally between mid-January and mid-March. After a strong SSW,

the weather patterns over Europe can become more conducive to allowing colder wind flows to

develop from the north and east, with high pressure over the north Atlantic, Scandinavia and Iceland

blocking the mild westerly winds.

That is exactly what happened in February 2018. It caused a freezing cold end to a rainy and mild

winter.

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2. Forecast Performance

To measure our forecast quality, we take a strict user perspective. We apply scores which are

scientifically sound while still being intuitively understandable. We inspect weather situations where

road services are most vulnerable. We accept the limitations of road weather observations for

verification purposes. Following the suggestion of the Institution of Civil Engineers,3 we compare the

forecasted road frost against the actual observed. This is applied during critical nights with minimum

road surface temperature below 3 °C, in a contingency table as given in Table 1.

Frost forecast No frost forecast

Frost occurred F/F (Protection cost) NF/F (Damage cost)

No frost occurred F/NF (Protection cost) NF/NF (Correct rejection)

Table 1 Two-by-two contingency table as suggested by Institution of Civil Engineers

The contingency table provides input for quality scores like

• Percentage Correct = [(F/F + NF/NF) / (total number of critical nights) * 100]

• Miss Rate = (NF/F) / (F/F + NF/F) * 100

• False Alarm Ratio = (F/NF) / (F/F + F/NF) * 100

Figure 1 gives a high-level summary of MeteoGroup’s road frost forecast accuracy during the challenging

road winter season 2017/2018. Averaged over all countries, more than 94% of our road frost forecasts

were correct. Figure 3 shows the distribution of these results over the total number of investigated

stations.

In detail, evening forecasts as issued between 1 October 2017 and 1 April 2018, have been compared

with observations made by more than 1.500 road weather stations. One third of these stations is located

in the UK, another 400 in Germany, and about 200 each in the Netherlands, Switzerland, Liechtenstein,

and Spain. Additionally, a smaller set of 60 French stations was used for our quality assessment.

Regional performance is of course impacted by local specifics, as well as by the dominant weather

patterns of the past season. In Spain, most road weather stations are located on the Iberian plateaus at

elevations between 800 m and 1500 m above sea level. Up to 145 nights have experienced critical road

frost conditions. Our forecasters supported road services during several major snowfall events, which

brought up to 70 cm of fresh snow and hauled long into late April. In Switzerland, most road stations are

located in narrow Alpine valleys which are between 400 and 700 m above sea level. Local micro-

climates have a strong influence on the forecast performance and resulted in up to 160 critical nights

during the past season. In the Netherlands, MeteoGroup provided excellent forecast accuracy, this past

3 Highway Winter maintenance: Ice Design and Practice Guide (2000). Institution of Civil Engineers (ICE), Thomas

Telford Ltd, ISBN-10 0727729578.

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winter. This is only possible with expert knowledge of local wind systems alongside the shores and the

specifics of bridges, as well as a close monitoring of clearing clouds. Figure 2 shows detailed results for

the Netherlands, where on average 97% of the 80-100 critical nights were forecasted correctly. In

Germany, potential forecast accuracy is determined by mountainous terrain. Half of the German road

weather stations are located at elevations over 200 m above sea level, a quarter over 400 m above sea

level. Additionally, a high number (nearly 40%) of road weather stations are installed on bridges, which

react more sensitively to unforeseen changes in the atmospheric conditions. In the UK, both mountains

and sea, and some of the most challenging weather patterns of the past decade, had an influence on the

forecast accuracy during this winter season. Depending on the location, 65 to 140 nights have had

critical road frost conditions. Only an excellent forecasting model and expert forecasters could achieve

an average accuracy of 95% correct forecasts; with less than 5% missed road frost nights and only 6%

of false alarms. On March 1st, 2018, the storm Emma brought widespread heavy snow and drift into the

south-west England, followed by and alternating with freezing rain. it gave our weather rooms the chance

to prove high forecasting skills and accuracy. It has already entered the annals of British road services.

Figure 1. MeteoGroup Road weather forecast accuracy during season

2017/18. On average, 94% of MeteoGroup’s road frost forecasts for

the next night were correct, with a false alarm ratio of less than 5%.

Figure 2. Percentage correct road frost forecasts by MeteoGroup during the 2017/18 season in the Netherlands. Between 80 and 100 nights during the season were critical for road frost (including

bridges), and on average 97% of them were forecasted correctly. The average false alarm ratio was less than 2%.

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Correct forecasts distribution

Figure 3. Distribution of correct forecast percentage amongst the inspected ~1500 stations.

For resource scheduling by winter road services, the major decision support is provided by the noon

forecast issue. MeteoGroup updates forecasts every hour, incorporating fresh precipitation radar

soundings as well as new reports from thousands of weather stations and many more observations to

capture the latest atmospheric development. Until the evening, an average gain of 1% in temperature

forecast accuracy is achieved. For snowfall and freezing rain, the accuracy gain is even higher,

particularly during capricious atmospheric conditions.

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3. How MeteoGroup supports Winter Maintenance

Services

About MeteoGroup

MeteoGroup is the global weather authority which combines accurate science with advanced technology

and local expertise with global reach. MeteoGroup is trusted by hundreds of government agencies,

thousands of companies and millions of consumers. MeteoGroup is ISO 9001 and BS OSHAS 18001

quality certified.

MeteoGroup RoadMaster

RoadMaster is the world’s leading winter road weather solution. And it’s easy to see why. It provides the

most reliable forecasts, delivered on the best platform – making it the most cost-effective solution.

RoadMaster combines everything you need to minimize costs and limit your environmental impact

without jeopardizing safety on the road.

An Expert Weather Room Team

MeteoGroup’s Road team of over 150 meteorologists is recognized worldwide for its expertise and

predictive accuracy. This team includes dedicated RoadMaster weather experts with extensive road-

specific experience – including knowledge about the emergence of different types of road slipperiness.

This experience, combined with their understanding of weather patterns and anomalies, allows

MeteoGroup to support you with unrivalled expertise and 24/7/365 weather room support.

Mature, Road-Specific Weather Models

MeteoGroup RoadMaster is powered by proprietary, road-specific weather models which have been

refined over the past three decades. Our mature physical and statistical modelling techniques combine

the best available weather models with data collected from road weather information stations (RWIS),

historical predictions, and records of actual weather conditions to generate the most precise location-

specific forecasts available. Our unique weather model has consistently proven to be more accurate and

reliable than any alternative.

Constantly Monitored for Quality

As conditions change, you need weather information that’s accurate and up to date. We constantly

monitor the quality of our forecasts by having meteorologists correct them 24/7 as needed and

benchmarking against alternatives. Constant monitoring of factors such as road-surface temperature and

conditions, combined with our capacity to incorporate live weather observations into our model, ensure

that our forecast is of the highest quality in changing conditions. Analysis of radar and satellite images

further refines our forecasts and nowcasts. Benchmarking has consistently shown that our forecasts

outperform both raw weather models and the competition.

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Clear, to-the-point user interface

MeteoGroup RoadMaster’s clear and to-the-point user interface simplifies decision making by giving you

the most relevant information first. You can easily drill down to important details. Get effortless access

to short-term and long-term road specific forecasts. Easy-to-read color-coded tables identify the most

relevant information. The hazard table alerts you to any upcoming road weather hazards such as hoar

frost, snow, ice, and freezing rain. RoadMaster’s platform gives you a clear overview of road-surface

temperatures and data from RWIS sites. You can also view real-time observations, forecasts for the

coming 3 hours and animated precipitation type radar to distinguish between rain, hail, snow and

freezing rain. RoadMaster provides you with animated satellite images to determine cloud cover.

RoadMaster’s premium Decision Support System (DSS) can even advise you on the optimal time window

for salting and the latest safe time to carry out the gritting action.

Integration with your systems

Would you also like to visualize our forecasts your way? MeteoGroup’s weather API lets you incorporate

information from RoadMaster into your existing systems and be displayed through the interface that you

are most familiar and comfortable with. Integration can also be a two-way street. MeteoGroup applies

the data from your RWIS in location specific forecasts and displays the measurements and forecasts in

RoadMasters’s web-based platform. Whatever you choose, MeteoGroup’s professional services can help

you carry out a smooth and successful integration.

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Annex: Highlights of winter 2017/18 in key European

countries

Spain

Unlike in most parts of Europe, the recent winter season was longer and more active with some heavy

snow events in Spain. Especially compared to the relatively calm winters of the last 5-6 years.

January and February were unusually snowy months; March subdued to normal while the winter

weather remained in the highlands and in the mountains.

Seventy centimeters snow on roads

The most severe snowfall events took place on January 6th-7th in the northern half of Spain, with large

amounts of snow and reaching up to 70 cm in some areas. Roads around Sistema Central and Sistema

Ibérico, the northern plateau and even in the Ebro valley were heavily affected. Lots of roads were

closed because snow plows could not work and vehicles becoming stranded in traffic jams. The

snowfall event was of particular importance because the impact was massively amplified by the

media. Finally, it generated a high amount of comments and complaints including at high levels of

government.

Severe combination of weather at the end of the season

February 27th-28th, after a cold intrusion from Europe (“Beast from the East”), a low-pressure system

which developed just west of the Iberian Peninsula pulled warm and moist air from the tropical

Atlantic which met with colder air masses previously advected from the east. As a result, snow fell

even in the lowlands and on the coast, as the warm air gained terrain from south to north (later

reaching the British Isles). More than 10 cm fell on the northern coast of Spain. Associated with the

warm front, scattered cases of freezing rain were also observed at some locations on the northern

plateau.

In summary, January and February were months with severe winter weather while the rest of the

winter season was average.

United Kingdom

As with Spain, Britain went against the norm, with a colder than average winter. The temperature

was ~0.5°C below the average over England and Wales and ~1°C below the average over Scotland

when compared to a climatology of the last 10 years. January was the only month where there was a

monthly averaged mild anomaly over a sizeable part of the UK (southern half of England and Wales),

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while February was a colder than average month over all parts, especially in the south. The coldest

weather of the winter came at the very end of February (and into early March), when a major sudden

stratospheric warming in the polar stratosphere in mid-February triggered the development of

intense high pressure over Scandinavia and the Arctic. This brought Siberian air rapidly south-

westwards over the UK, with widespread snow and severe wind chill and frost.

Lows changed their tracks

A low-pressure track frequently displaced to the south of climatology resulted in a drier than normal

winter over most of Scotland and northern England. We saw far fewer mild and wet spells sweeping

across these areas than in a typical winter. Locations such as Cumbria and Lancashire, which have

suffered severe and damaging flood events during several winters in the past decade, did not have

to endure these conditions this winter. Meanwhile, over southern and western areas of the UK,

rainfall amounts were near or slightly above normal, with most of the wet days occurring in

December and January. February was a drier than normal month over all of the UK, while March was

very wet with more than twice the monthly rainfall falling in some southern areas.

The southerly displaced low-pressure track also resulted in a calmer than normal winter over

Scotland and the far north of England. Nearly all of the deep low-pressure areas that crossed the UK

between October and January produced their strongest winds over central and southern parts of

England and Wales. From late January through to March, an increase in high pressure blocking

weather patterns over northern Europe saw a distinct lack of strong and damaging wind storms over

the UK.

The road salting crews were very busy last season, as there were plenty of nights with road surface

temperatures below zero and quite a lot of precipitation as well.

Snow, snow, snow

On Sunday December 10th, 2017 an area of low pressure moved eastwards across the far south of

England. Just to its south, strong westerly winds, up to 70 mph (113 km/h), caused a few problems.

However, the main issue was the heavy snow which fell on the northern side of the system, across

parts of Wales and the Midlands. 10-20 cm of heavy, wet snow fell in just a few hours, which caused

a lot of travel problems, despite the forecasts giving generally very good guidance. This was partly

down to the intensity of the snow, as well as low traffic volume as it was a Sunday morning (so the

salt doesn’t mix in so well with the snow). On January 15th-18th 2018, a strong west to north-westerly

flow brought frequent snow showers to Scotland and parts of northern England. 20-40 cm of snow

fell in places, with drifting in the strong winds. Lightning was an additional hazard.

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Siberian cold and …. snow

Late February into early March 2018: The Beast from the East. After a major Sudden Stratospheric

Warming event in mid-February, a bitterly cold airflow from Siberia swept in from the east across

northern Europe, including the UK. It was the coldest spell since December 2010, with some places

having their coldest days since February 1991. Almost everywhere in the UK had snow, which was

dry and powdery, and drifted a lot in the strong easterly winds. Storm ‘Emma’ (named by the

Portuguese Met. Office) moved towards southern England and brought more widespread heavy snow

(as opposed to snow showers in the preceding days), especially to south-west England. Devon, a

normally mild county, experienced drifts 3-4 metres deep. Additionally, slightly less cold air moved

in for a time just above the ground, creating conditions favourable for freezing rain in parts of

southern England. This added to the widespread travel problems.

Belgium

The meteorological winter in Belgium lasts from December until February and the average weather

conditions very much approached the climatological mean. In other words, when studying the

weather parameters, the winter appeared “normal” for Belgium. Nevertheless, there were some

considerable differences between the months with periods of weather that certainly deviated from

the norm.

December and January were very dark months with temperatures higher than average. During those

two months we had almost 70 hours less sunshine than normal. You would have to go back to 1915

to find similarly dark and warm months. February, on the other hand, was dominated by northern

high pressure and thus produced a significant cold spell in Belgium. The average temperature

dropped 3 °C below the climatological mean.

Freezing Rain

On Friday March 2nd a long cold spell was ended by a low-pressure system that approached Belgium

from the South. The atmosphere was still very cold, however, and the arriving warm front in

combination with a layer of very cold air near the surface, created conditions favorable for freezing

rain. For a couple of hours freezing, supercooled rain was falling all over Belgium. This generated icy

conditions on roads in the whole country. The forecasts were accurate though and the main airport

in Brussels was able to continue normal operations for most of the day. Once the cold front set in,

snow started falling and accumulating in vast areas of Belgium. Despite all efforts, the airport had to

cancel most of the flights for that evening.

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The Netherlands

Similar to the previous four years, the winter of 2017-2018 as a whole went quite smoothly.

However, the differences between the individual months were large. The top ten warmest months of

January in De Bilt were followed by the coldest February since 1996.

Quick start of the winter

Already on the night of November 6th/7th the temperature declined to below freezing on a large scale,

for the first time in the season. Later in November it came to light frost a few times during the night.

Mixed feelings about December

The first days of December brought considerably colder weather. On December 1st, the temperature

in Gilze-Rijen fell to -5.6 °C in the evening. The day after, the eastern regions experienced the first

ice day in many places (maximum temperature below 0 °C), due to persistent fog. Then, after a milder

intermezzo, colder air began to flow again on the 7th December leading to significant snowfall on

December 10th and 11th, in most of The Netherlands. The biggest amount, more than 30 cm of snow,

was reported locally on the Veluwe. Eventually, the soft air won the battle again and the remainder

of December was mostly non-wintry and varied weather. On New Year's Eve the temperature reached

14.5 °C in Arcen!

11 Beaufort

In January temperatures remained above zero most of the time. The lowest national temperature in

January was -3.1 °C, in Nieuw-Beerta in Groningen on January 8th. The most significant weather

events that month were two very heavy storms on the 3rd and 18th of January. The second one was

the heaviest since January 1990. At sea, hourly average wind force 11 Beaufort was reported, and

also deep inland, local force 9 Beaufort was achieved. In addition, wind gusts up to 124 km/h were

observed in Enschede and 143 km/h in Hoek van Holland. Apart from the storms, very spring-like

weather came on January 24th is worth mentioning, with maximum temperatures up to 14.7 °C in

Woensdrecht.

Freezing in February

The weather pattern changed in February. Frequent easterly winds allowed colder and drier air to

enter the country. That gave the sun a lot more room and frequent frost in the nights. During the last

days of February and the beginning of March it was icy cold. Due to strong easterly winds extremely

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cold air from Siberia was transported, the temperature remained negative for five days in a row, at

some locations. It was extremely cold, especially on the last day of February. During the day the

maximum temperature in Enschede was only -6.0 °C. The lowest winter temperature was measured

in Woensdrecht, on February 28th (-10.5). At the same time, there was a wind force 5 to 8 beaufort

lowering the perceived temperature down below -15 °C. On top of that, at the end of February snow

showers spread over the German Bight into the Wadden Sea region, resulting in more than 10 cm of

local snow.

From cold to warm and back again

March started quite winterly with ice days and a cold east wind. Ice-skating was possible in many

places, even in Amsterdam. On March 3rd soft air from the south attacked the cold air mass, resulting

in more than 5 cm of snow on the frontal zone in some places in the south. The mild air eventually

conquered the entire country. From one day to another the cold was gone. On March 10th it was even

16.7 °C in Ell. However, the winter cold came back. As a result of an icy easterly wind, it remained

freezing in many places during the day on March 17th. March was again a clearly cold month and

was even colder than December and January.

February saved the sunny image of the winter

Despite a very dark December and January, the winter appeared to be sunnier than average, largely

due to a record-breaking February. On average, the sun shone 48 hours more than usual during the

three winter months. In February, the number of hours with sun (162 hours in average for the

country) was about twice as much as in December (32 hours) and January (50 hours). Also, in March

sunny weather was more frequent than the long-term average.

December was particularly wet with 112 mm precipitation on average over the country. January was

also slightly and overly wet with 89 mm, while February was considerably drier, by 23 mm on

average.

Switzerland

Last year’s winter was somewhat warmer than usual overall in Switzerland, only in the mountains it

was slightly colder. It was grey and brought a lot of snow. December was colder than average, with

early snowfall in low-lying areas and frequent snow showers, which were difficult to forecast well

enough in advance for our winter-service clients. January was very warm with a record high mean

temperature of 6°C in Geneva. Frequent storms caused some severe damage, especially storm

Burglind on January 3rd.

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Snow records

Several times last winter, strong westerly winds brought very humid Atlantic airmasses to the Alps

("atmospheric rivers"), resulting in excessive precipitation in the Western Alps in January and a lot

of snow in the higher Alps: Simplonpass (2000 m amsl) got 90 cm of fresh snow within 24h and on

January 23rd a new record of snow depth of 239 cm was established!

Never-ending snow? Where’s the sun?

February was very dull (less than 50% of sun duration hours, especially in the north of the Alps) and

cold. March as well brought cold weather with frequent snowfall and a lot of work for our weather

room in Appenzell. Geneva reported a snow height of 17 cm on the 3rd (new record), and low-lying

Basel in northern Switzerland noted 10-15 cm snow on March 18th.

Even the last day of March 2018 brought 60cm of fresh snow to Göschenen (~1000m amsl) on the

northern side of Gotthard tunnel and located on an important south-north freeway. The snowfall

was associated with a low-pressure center over Italy and so called “diabatic cooling-effect”.

It was very difficult to make thermal mappings in Switzerland and France this year due to unsettled

weather conditions in February and March.

Germany

December was gloomy and wet while January was flooding and very mild. The end of season was icy

with lots of sun and snow in the Baltic Sea region. Last winter offered a great snow season in the

Alps, but also unfortunately brought with it a lot of dangerous avalanches. In general, the winter was

mild, and warmer by 1.4°C than the climate on average.

Christmas without snow

December started promising with snowfall. Not only in the Alps but also in lower parts of Germany

and far up North. Mild weather around Christmas caused thawing and led to floods in the West and

Southwest of Germany.

Dynamic weather

In February it was sunny, but there were heavy snow showers towards the Baltic Sea and in the North

of Schleswig-Holstein. Snowbanks also occurred due to gusty easterly winds.

Windy anniversary

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On January 18th, exactly 11 years after the Kyrill storm, the Friederike low hit Germany. Maximum

wind gusts reached 203 km/h on Brocken (the highest point in Middle/Northern Germany). Another

storm Burglind brought not only gale force winds but also mild temperatures. On January 3rd, 2018

the temperature reached the highest value in this winter season in Rheinfelden, 16.2. Lowest

temperature, -40.3°C, was observed on February 28th, 2018 in Funtensee, a high valley in the

Southeast.

More facts:

It is worth mentioning widespread freezing rain covering the area from the North Sea via Hamburg

to Berlin, on the morning of February 5th, 2018 caused a lot of traffic problems. Furthermore, the

period from February 26th to 2nd of March brought a lot of snow with a maximum of 38 cm in

Bordelum, on February 28th.

Poland Above the average

Last December and January were significantly mild. During Christmas the deviation from climate

values reached up to over 10°C in some locations, with maximum temperatures up to 12°C. On the

other hand, February and March appeared to be much colder than usual, especially in the end of

February and beginning of March, with minimum temperatures around -15°C in the prevailing area

and below -20°C in some places in eastern Poland.

Peculiar snow record

Although December was warm with hardly any snow, a snow depth record was reached! On the

December 24th on Kasprowy Wierch, one of the highest Tatra Mountain summits in Poland, the snow

layer reached 210 cm, and that is the highest ever reported value.

White locally in February

Snow cover usually did not last for many days in a row because of frequent temperature changes.

However, on February 2nd, in south-east Poland, 20 cm of fresh snow fell in 10 hours, followed by

25 cm more in the next few days. That was associated with an atmospheric front dividing warm and

moist tropical air from much colder polar masses. As it happened in the highlands area with naturally

lower temperatures, the snow remained during the whole month.

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The last snow event was observed on April 1st and 2nd, but on the very next day the maximum

temperatures reached 17-20°C in many locations.