On 1 August 1674 an active cold front moved over the Low Countries. The
accompanying thunderstorms along the squall line were abnormally active,
leading to large-scale damage in Europe, from northern France to the northern
parts of Holland where damages were particularly severe. Using reported and
pictured observations of damages and modern meteorological concepts, the
reconstruction of the storm points to an exceptionally severe squall line.
The orientation and the velocity of the squall line are reconstructed and
shows a developed bow-echo structure. An estimate of the strength of the
strongest wind gusts is
Wednesday 1 August 1674 (new/Gregorian calendar) ended in thunder and
lightning over the Netherlands, which is not uncommon for a typical warm and
humid Dutch summer day. Different from other days was that the meteorological
conditions of this day led to the formation of a line of thunderstorms along
the cold front which developed to extremely severe levels. During the passage
of this line, wind gusts caused severe damages over an area from northern
France, into (what was called in the 17th century) the Spanish Netherlands
and the Dutch Republic. The passage of the front was noted as far east as
Hamburg (northern Germany; see Fig.
Using modern insights in mesoscale meteorology and by gathering impact-related evidence and accounts from various sources, we take a fresh look at this day, analyse the event and make an estimate of its severity in terms the strength of the wind gusts and its return period. Here we argue that this event is characterized by strong straight line winds resulting from downbursts. This contrasts with the popular view that a single tornado caused this damage. However, we argue in this study that vortices, embedded within the frontal structure, are likely to have been present. In addition to a description of a historic event, the reconstruction and analysis of this summer storm event illustrates the impact of a storm of this ferocity that is rare enough not to be captured by the modern weather radar archives (which are a few decades long) but apparently not unlikely to occur. The quantification of the strength of the wind gust associated with this event may provide a perspective on the disruption to society in case such a rare event would occur again.
Cities, towns and villages mentioned in the text. The numbers in the map refer to (1) Alkmaar, (2) Amsterdam, (3) Antwerp, (4) Brussels, (5) Delft, (6) Fontainebleu, (7) Frankfurt am Main, (8) Haarlem, (9) Hamburg, (10) Hilversum, (11) Ilpendam, (12) Koog aan de Zaan, (13) Leiden, (14) Neerkant, (15) Strasbourg, (16) Texel, (17) Utrecht, (18) Vethuizen.
A summary of the storm event is given by the newspaper “The Dutch
Mercurius” of August 1674 On the first day of this month, in the evening around 8 o'clock nearly
throughout all of Holland a terrible thunderstorm passes, mixed with Thunder
and Lightning, Winds, rain and hail. Severe damage in Amsterdam occurred,
where the powerful winds overturned most of the trees, many ships broke
adrift from the quay of which nine sunk and several houses lost their facades.
Hardly any house was found that had no damage to its tiles, windows or
something else. Several windmills were overturned by the wind (…) As it
was all prayers day, many men were outside, and many of them were never seen
again. Several other towns in Holland suffered damage as well, though not as
much as Amsterdam. On the island of Texel, the furious winds drove many ships
on the beach or were sunk. The largest damage happened in Utrecht because in
a quarter of an hour most of the houses lost their facades and roofs.
(…) These thunderstorms were not only in Holland but also in other
provinces. In Brussels, hail stones fell which were as large as marbles, many
trees were removed from the Earth, but also many house facades were
overthrown. The bridge in Antwerp, which lay over the river Scheld, was
destroyed by the strong winds, and the ships drifted away on the river. In
Hamburg and in the area of the river Elbe this thunderstorm was felt as well.
In Strasbourg, hailstones fell as large as a baby's head.
Drawing of the ruin of the Dom cathedral following the 1674 storm by Herman Saftleven (Utrecht City Archive no. 28635). The viewpoint of the artist is from the undamaged part of the Cathedral overlooking the area with the collapsed nave towards the Dom tower.
The storm caused an enormous amount of damage in the Dutch provinces of
Holland and Utrecht (located in the west and central parts of the
Netherlands). Especially Utrecht city and surrounding villages were hit hard,
where church towers from five surrounding villages were partly or completely
destroyed based on newspaper accounts
The Dom cathedral in Utrecht probably suffered most from the storm.
Although the church had seen storm damage from earlier storms, this time the
nave of the church, between the tower and the transept, collapsed (Fig.
There are several newspapers and a pamphlet which provide descriptions of
this storm and its damage
The exact circumstances during and after the storm are well known due to the
publication of Gerrit Jansz. Kooch (1674), skipper and merchant (1597/98–1683).
Drawings by the landscape painter Herman Saftleven (1609–1685) were
commissioned by Utrecht city council to record the damage in and around
the city in great detail. The sheer amount of drawings depicting the damage
of the storm in the vicinity of Utrecht (over 25 are available in the Utrecht
city archives
In the summaries of local histories of all Dutch cities and villages compiled
by
In a historical description of events by Joh. Lodew. Gottfrieds
Finally,
The short duration of the storm is made clear in Kooch's account of the
damage in Amsterdam. His personal experience was that the storm passed in a
short half hour (strophe 10). Later, one of his sources claims that the storm
passed over Amsterdam in a quarter of an hour (strophe 80 and 81) and that no
house would have been undamaged if the storm were to have lasted a full hour.
The passing of this system saw unusually strong gusts which are described in
Kooch's report, accounting numerous cases of people, small boats and
carriages taken up into the air. The impact of the storm on the landscape is
also made clear by
The destructive force of the gusts was illustrated by the nature of the
damage: churches collapsed, church choirs and spires were damaged or
destroyed, wind mills were overturned, pieces of lead used as roofing (some
of them 150 pounds in weight) were blown off completely and roofs of houses
were ripped off. One account from the city of Hilversum
There are several reports from the water-rich province of North Holland about
boats that did not survive the storm. An example from the area near Ilpendam
(north of Amsterdam), was of two farmers who were first blown out of the boat and
then the boat was taken up by the winds, flying “over several fields”. The
boat was shattered to pieces when the farmers found it again
The amount of rain
Damage reports compiled from various sources related to the 4 August 1674 storm.
Drawing of the ruin of the Dom cathedral following the 1674 storm by Herman Saftleven (Utrecht City Archive no. 28637 and no. 28630, both views from the southeast).
A compilation of all damage reports is shown in
Fig.
It is interesting that in the westernmost parts of North and South Holland
almost no damage was seen (Fig.
At smaller spatial scales, the contrasts in damage are also striking. Kooch (1674,
strophe 110) notes that in Amsterdam harbour the ships broke from their moorings
and drifted away, while empty barrels on the quay were
unaffected. What is striking about the drawings of Saftleven
(Fig.
The thunderstorms produced a long track of massive destruction through the province of North-Holland, without losing strength. Damage was reported as far as the northern part of Holland at Texel Island.
The widespread damage in the east–west direction and the rapid passing of the storm point to a narrow frontal structure passing over the Low Countries. Such cold fronts are common in the summer season, replacing warm humid air with cooler air.
A few sources match the passage of the front to the time of day. Between
18:00 and 19:00 LT (local time) the storm passed Antwerp
Decomposing these estimates into the direction parallel to the movement
of the squall line and one perpendicular to it, the average speed of the
frontal system on the west side of the front (passing through Antwerp) is
about 60 km h
The distance between Amsterdam and Koog a/d Zaan is too small (
An accelerating central part of the squall line and an area west of the
squall line without significant damage point to the existence of a bow echo.
A bow echo is formed when the band of convective thunderstorms is combined
with a rear-inflow jet. When this rain-cooled downdraft of a thunderstorm
reaches the Earth's surface, it spreads horizontally and most rapidly in the
direction in which the front progresses, producing straight-line winds. The
rear-inflow jet advects high-momentum winds from aloft, further enhancing the
wind speeds at the surface. Within these areas of convective downdraft, or
downbursts, smaller pockets of intense winds exist which are referred to as
microbursts. Microbursts are characterized by spatial scales of approximately
4 km. Still smaller areas of extreme wind within microbursts are called burst
swaths, which range from 40 to 140 m
Left panel: drawing of the ruin of the Pieterskerk with the spires
and part of the church towers removed by the storm. The direction of the fall
is into the church. Drawing by Herman Saftleven (Utrecht City Archive
no. 28644). Right panel: plan of the Jacobikerk, showing in blue the
reconstruction of the direction in which the spire fell in the 1674 storm. In
purple, the carillon is shown in its separate spire east of the main spire,
with the position of the bells on the church floor after the collapse of the
spire. In red, the destroyed arches are shown (which have never been
repaired). Figure from
When the rear inflow jet bends the frontal system, bookend vortices develop on either side of the jet which are advected along with the front. The cyclonic vortex in the west will be strong due to the interaction with the Coriolis force, making the winds on the west side of the vortex much weaker, explaining the absence of damage in towns like Haarlem and Alkmaar (which are to the west-northwest of Amsterdam close to the North Sea coastline). The stronger winds due to the bookend vortex at the west end of the squall line could have contributed to the vast damages in Holland. The bookend vortex at the eastern end lacks the interaction with the Coriolis force and is much weaker, making the distinction between areas with or without damage further inland less clear than at the west side of the bow echo.
Apart from the bookend vortex of the squall line, the straight-line wind
associated with the bow echo may have embedded vortices which are produced by
horizontal shear. There are no observations of a whirlwind in the accounts of
Kooch (or elsewhere). However, the direction in which church spires fell in
the city of Utrecht may indicate embedded vortices. While the nave of the Dom
cathedral and the towers of the Nicolaaskerk fell in a northerly direction (in
the same direction as the movement of the front), the drawings of Saftleven
show that the two towers of the Pieterskerk (200 m to the ENE) were blown down
in the direction of the nave and choir of the church (Fig.
The Jacobikerk, about 680 m northwest of the Dom cathedral, had a spire
of nearly 80 m height in 1674.
Embedded vortices are also observed in the damage analysed
by
Compiled damages to larger structure in the city of Utrecht. The
numbers in blue circles refer to Table
There are no direct measurements of the strength of the mean winds and wind
gusts at the surface generated by the downbursts of the storm. In order to
make an assessment of the strength of this storm and a provisional estimate
of its return period, two approaches are tried. One relates the observed
damage to a wind strength via the Fujita scale
The accounts of the storm from the newspaper reports, the drawings of
Saftleven, and especially Kooch's rhyme are detailed to the point that a
Fujita damage scale
In Kooch's rhyme are several accounts, mostly from the water-rich northern
parts of Holland, of prams being taken up into the air to be transported (in
one account) “over several fields”. A pram is a light tender with a flat
bottom and a bow formed from the ends of the side and bottom planks meeting
in a small raised transom. The common size of these barges in the province of
North Holland was typically 6.6 m
Detailed damage reports within the city of Utrecht and its immediate
surroundings. Numbers refer to locations on the map of Fig.
There are numerous accounts of uprooted or snapped trees from Utrecht (such as
from the St Jans churchyard) and Amsterdam where on the Nieuwe Markt (New
Market) a heavy tree (“too large to embrace”) was uprooted and transported
across the market for 180 feet (
Of the seven windmills on the city wall of Utrecht, perhaps one survived the
storm
In Kooch's poem we find two accounts of objects which are propelled at high
speed. One is in Amsterdam, where the lead roofing of the corn exchange was
stripped off (estimated to weigh nearly 2000 kg;
Selection of drawings of Herman Saftleven following the storm
of 1674.
The drawings made by Herman Saftleven of the destruction in and around the
city (Fig.
The description of the Fujita scale for F2 includes “roofs torn off frame houses”, “large trees snapped or uprooted”, “light-object missiles generated”, and “cars lifted off ground”. With the lighter carriages and prams replacing the description of cars, these descriptions match the accounts of the 1674 storm damage. The F3 scale for “severe damage” describes “roofs and some walls torn off well-constructed houses”, “most trees in forest uprooted” and “heavy cars lifted off the ground and thrown”. In the heavier-hit areas, like the city of Utrecht, such damage to roofs and walls is evident in the drawings of Saftleven. The provinces of Holland and Utrecht were almost completely deforested in the 17th century, probably explaining the lack of accounts of large-scale damage to forests, but the account of uprooting of all trees in the St Jans churchyard and elsewhere in and outside Utrecht resonate with this description.
There are insufficient grounds from the damage reports of the 1674 storm to related widespread damage to the stronger F4 and F5 ratings. The damage descriptions relating to the F4 rating are “well-constructed houses levelled”, “structures with weak foundations blown away some distance”, and “cars thrown and large missiles generated”. Although many houses have been severely damaged in the 1674 storm, the qualification above is too strong. Similarly, there is evidence that missiles were generated, but all these relate to planks or a piece of lead roofing which do not qualify as “large missiles”.
The Enhanced Fujita scale
Note that the Fujita scale relates to rotational winds and may not be directly applicable to straight-line winds.
The severest damages caused by this storm are from the wind gusts and a return period estimate should be based on the strength of the wind gusts. However, a climatology of wind gusts related to downdrafts is not available in the Netherlands or surrounding countries. As an alternative, we turn to hail stones for an estimate of the return period.
There are frequent observations of severe hail and massive hail stones.
Maximum observed hail size (one value per year, minimum value 2 cm)
from Finland
The modern equivalent of the “pound” mentioned in these reports is difficult,
and the weight of a pound varied from region to region and depended on the
goods to be weighed (butter having for instance a special “butter
pound”)
The largest hail observed during the 1674 event was the hail in northern
France, estimated to be somewhere between 15 and 20 cm. This account seems to
be a single observation and one source reported this. However, reports of
extreme hail (both size and quantities) are mentioned by several sources for
many other places, making the possibility to observe extremely large hail
stones less unlikely. Nevertheless, the uncertainty on this observation is
considerable. Hail of this size (20 cm) has earlier been observed in South
Dakota (USA)
The Netherlands has no climatology of hail, so the accounts of the size of
hail stones cannot be compared to modern measurements. A climatology of
severe hail, covering the period 1930–2006 is available in
Finland
An estimate of the return times of severe hail can be obtained by fitting a
Gumbel distribution to the maximum observed hail size per year (one value
each year). Figure
Using the Finnish data as a proxy for the circumstances in the Low Countries,
the return time of hail with a diameter between 15 and 20 cm is estimated to
be more frequent than once every 10
A modern – but much less devastating – equivalent to the summer storm of 1 August 1674 is the squall line with an embedded bow echo that occurred on 14 July 2010 and passed over Belgium, the westernmost part of Germany and the southeast of the Netherlands.
The most active part of this frontal system was part of a long squall line which extended into Switzerland and it caused severe wind damage in the Netherlands, particularly near the villages of Vethuizen, 85 km ESE of Utrecht, and Neerkant (60 km SSW of Vethuizen). The storm caused two casualties in Vethuizen.
The Vethuizen storm is described in some detail in this section based on an
earlier technical report
The progression of the squall line is shown in Fig.
An onsite survey was carried out by a team of the Royal Netherlands
Meteorological Institute
Weather chart of 14 July 2010, 18:00 UTC. The chart shows the low-pressure system south of Ireland and the cold front, displacing the warm continental air with cooler air from the Bay of Biscay, as a blue line with closed triangles.
In the village of Neerkant, the damage consisted mostly of snapped or uprooted trees. It was estimated that about 75 % of the trees in this area had been damaged, mostly oak with an approximate age of well over 50 years. Greenhouses in this area were also destroyed; one greenhouse lost all its glazing while another was detached from its foundations and moved for about 8 m. Observations of trees falling in other directions than the direction of the movement of the frontal system were made.
European weather maps (Fig.
The centre of this heat low was present in Belgium at 15:00 UTC (Coordinated
Universal Time, Fig.
The track of the frontal system was in the NNE direction and its speed
decreased gradually. At 14:00 UTC, the speed was about 85 km h
Synoptic analysis of 14 July 2010 15:00 UTC. Isobars are solid black lines, dashed red and blue lines are isallobars, showing pressure drops and pressure increase respectively. Station observations indicate wind direction and strength and the (partly) filled circles show the cloudiness.
Rainfall intensity from radar images on 14 July 2010, from 15:00 to
18:30 UTC. Red denotes precipitation intensity of over
30 mm h
The radar image of 16:30 UTC (Fig.
The horizontal shear causes rotations which are sometimes referred to as gustnados.
A theoretical estimate of the maximum possible wind gust, under the most ideal
circumstances, gives a value of 50 to 55 m s
From the meteorological perspective, many similarities can be observed
between the 1674 and the 2010 situation. The direction of movement of the
squall line, from SSW to NNE, is similar
and matches the direction of movement of the strongest squall lines in the
modern climatology of the Netherlands. The velocity of the squall line in the
1674 situation is perhaps a little slower (
Figure
The theoretical maximum of wind gust strength in the 2010 event
(
While both the difference in max wind gust and the speed at which the squall line passed will have contributed to the less extensive damage in the 2010 case as compared to the 1674 situation, the possible development of multiple segments with a bow-echo structure along the squall line in the 1674 case will have made the area over which violent wind gusts develop much larger. However, the lack of sufficient detail in the observations prevents confirmation or reconstruction of these structures.
Estimates of the number of people severely injured or dead due to this storm
are lacking. There are anecdotes mentioning people getting injured, like hail
stones bruising people caught in the fields
A cultural-historical perspective of this storm is provided
by
It has been argued that the nave of the Dom cathedral might have been more
vulnerable because of the lack of flying buttresses and because of having a
roof supported by a wooden structure rather than an overarching stone
structure
A comparison with a modern bow-echo event from 2010 shows many similarities
in terms of the meteorology. The severest of summer storm events in the past
century in the Netherlands occurred in the early evening of 10 August 1925 in
the town of Borculo
Although direct meteorological measurements of the events of 1 August 1674 are
lacking (the earliest instrumental weather observations were made in 1697), the
meteorological interpretation of the contemporary reports indicates that the
widespread damage from northern France into Holland was caused by an
exceptionally active cold front. Strong downbursts generate straight-line
winds where the strongest wind gusts are estimated to have a speed of
up to 90 m s
An important source for this study is the poem by
The authors declare that they have no conflict of interest.
The authors wish to thank René de Kam and Frans Kipp for their enthusiasm and in-depth knowledge of the history of Utrecht. Jari Tuovinen (FMI) is thanked for making available the hail climatology of Finland and Henk van den Brink (KNMI) is thanked for his assistance in making the Gumbel plot. Marja Goud (National Maritime Museum) is thanked for her information on the prams of North Holland. Edited by: V. Kotroni Reviewed by: A. De Kraker, P. Brohan, and one anonymous referee