An unusually low pressure recorded in Iceland

During the night and morning of 30 December 2015 an unusually deep low crossed Iceland. The minimum officially recorded sea level pressure was 930.2 hPa, measured at the station Kirkjubćjarklaustur in the Southeast at 5am. This is the lowest sea level reading in Iceland since 24 December 1989 when the pressure at Stórhöfđi in the islands of Vestmannaeyjar measured 929.5 hPa. On 5 January 1983 the pressure at Stórhöfđi was down to 929.9 hPa. 

During the morning hours the low crossed the country from the south to the north. The map below shows the situation at 9 am.

islandskort-2015-12-30_0900

The lowest reading in the North was at Akureyri at 8 am, 932.0 hPa, the second lowest ever recorded there, exceeded only by the 931.4 hPa measured on 3 January 1933. At that occation the lowest pressure in the country was 923.9 hPa (Vestamannaeyjar). 

The lowest pressure ever recorded in Iceland is 919.7 hPa, measured at Vestmannaeyjar 2 December 1929. However, the reading was made during strong winds, Bf 11. This throws some doubt on the exact value of the pressure, but it was certainly lower than the 1933 reading (when the wind was not a problem). 

There is also a measurement of 929.0 hPa made at Vestmannaeyjar on 27 December 1914. 

There are two (or three) measurements of below 930 hPa pressure in Iceland during the 19th century. Two are considered quite sound, but the exact hPa values can be debated. The third one was made, but later retracted by the observer after an inquiery, however, there are some doubts remaining, because of wind damages that occurred on the same day. 

As seen on the map above the wind was strongest on the eastern side of the low pressure centre. Hurricane force winds (10-min sustained >32.7 m/s) were recorded on 7 stations, the maximum being, 43.9 m/s at the mountainpass Vatnsskarđ in the east, the highest sustained value at a coastal station was 38.6 m/s, at Papey. A gust of 63.8 m/s was recorded at the station Steinar in the south, but has not been ratified at the time of writing.

There was considerable local wind damage in the east, but the main damage was caused by an unusually high sea level inside the eastern fjords where a few seaside houses are probably beond repair. No human injuries were sustained by the weather. 

This was the second great storm to hit Iceland this Deceember. The first one [on 7 and 8 December] was worse in terms of wind and damage, affecting more than 2/3 of the country, blowing cars of roads and destroying houses. Hurricane force winds (sustained) were then measured on 33 stations (compared to 7 now, as mentioned above), the maximum being 50.9 m/s. 


An unusually warm year in Iceland, 2014

The Icelandic Meteorological Office has issued its official statement of the climate in Iceland in 2014 in English. In the Eastern part of the country and in some of the northern areas as well it was the warmest year ever measured and in the rest of the country it was generally the second or third warmest, slightly exceeded by the temperature in 2003 or 1933.

It was the 19th consecutive year of above normal annual temperature in Reykjavík (vis. 1961 to 1990). The annual temperature in Surtsey, 7.2°C is the highest annual mean temperature ever registered at an Icelandic weather station, exceeding the temperature at the same site in 2010 by 0.1°C.

In spite of the high temperatures the weather was changeable and often dull. The first months of the year were especially wet in the North and East and the weather was difficult. In the west it was very dry at the same time with favorable weather conditions. The summer was warm and considered fine in the North and East but in the south it was very wet and dull. The autumn was fine, November extraordinarily warm, but the year ended with an unruly and a rather cold December.

The precipitation in 2014 was above normal at most stations, as was the number of days with precipitation. Snow was light in Reykjavík, as generally in the South and West. Snow covered the ground in Reykjavík for 41 days during 2014, 24 days less than average. The snow was heavy in Akureyri in and covering the ground for 133 days during the whole year 2014, 16 days more than average.

There was less sunshine in Reykjavík and Akureyri than during the recent years, about 100 below the 1961 to 1990 average at both locations and 200 below the average of 2004 to 2013.

The average sea level pressure in Reykjavík was 1001.7 hPa, 4.2 hPa below the average 1961 til 1990. In the long term it is rather low, but the annual pressure in 2011 was lower still.

The wind speed was close to the average for the year as a whole, but December and February were very windy, June was unusually calm. Easterly and Northerly winds were unusually persistent in January and February, westerly and southerly winds were prevalent in September and easterly in November.


An unusually warm November in Iceland

The year 2014 will be one of the warmest ever measured in Iceland. It has a real chance of becoming the warmest of all along the northern and eastern coasts. The odds of a new temperature record is lower in other areas.

November became the fourth month of the year to exhibit an overall anomaly larger than +2 degrees C [the others are: January, June and September]. The table shows the November temperatures and anomalies for selected stations all over Iceland. The month was the warmest ever in Grímsey off the N-coast, measurements have been done there for 140 years. It was also the warmest at Teigarhorn at the Eastern coast, where measurements have been made for 142 years. The station Árnes in the Southern inland also shows its highest November value ever, but as the station has not been located at the same farm throughout the period the rank is slightly more uncertain than at the other stations. The same uncertainty also applies for the rank at the station Bolungarvík at the extreme Northwest tip of the country.

stöđmeananomaly 1961-1990rankof

anomaly

2004-2013

Reykjavík5,54,421443,2
Stykkishólmur4,33,431692,7
Bolungarvík3,72,97 til 81172,8
Grímsey4,33,711402,9
Akureyri3,43,761333,1
Egilsstađir3,94,63602,2
Dalatangi5,73,92763,0
Teigarhorn5,54,111423,3
Höfn í Hornaf.5,83,9   
Stórhöfđi6,23,821382,7
Hveravellir-0,34,52503,1
Árnes4,64,811343,7

 


A remarkably warm June in Iceland

The first six months of 2014 have been very warm in Iceland, overall the second warmest to fifth warmest of all time at stations with long measurement series. At many stations the warm anomalies have culminated in June.

 
In Stykkishólmur in W-Iceland the temperature records go back to 1845. June 2014 ranks as the warmest of the whole period. In Akureyri in the north (records back to 1882) it is the second warmest, exceeded by June 1933 with the closest possible margin, 0.1°C. The average temperature in Reykjavík in June ranks at number four (records back to 1871).


The average temperature at the station Torfur located inland in a valley near Akureyri in the north was 12.7°C. This is equal to the highest monthly average June temperature ever recorded in Iceland. The earlier instance of 12.7°C (Húsavík 1953) has been considered to be dubious because it was 0.4 degrees higher than the second highest June average in the country (Akureyri 12.3, June 1933).

This was also the warmest June ever recorded in Grímsey, an island at the Arctic Circle off the North coast of Iceland. The new record is 0.7°C higher than the earlier maximum and also almost four degrees higher than the 1961 to 1990 June average at the station. This must be considered remarkable at an oceanic site as Grímsey. The sea surface temperatures around Grímsey have also been very high. During the last week of the month the ecmwf sea surface temperature analysis showed an area near Grímsey with an anomaly of +6°C. This area was also very warm last June (2013) and highlights the general anomalous oceanic conditions off the North coast of Iceland prevailing during the last 15 years or so. Even so – this great culmination of warmth is unexpected.

June was generally on the wet side in the Western part of the country, especially in Reykjavík where the month was the second wettest in a series that extends back to 1885 – with a large gap from 1907 to 1919.

 

This was nominally the calmest month of June in the country since 1963 – but the confidence in the homongeneity of the wind speed series low when it comes to a close absolute ranking of mean speeds over a long period.

In spite of this exceptional warm conditions the absolute maximum temperature recorded in Iceland during June 2014 was "only" 23.1°C. But at the same time the temperature in the inhabited areas of the country never dropped below freezing. In the recent record (comparable station network density) this also happened in June 2003 - but before that only in June 1933 (slightly less dense network), June 1909 and 1880. The station density in 1909 and 1880 was much lower than later so these years are not quite comparable to the other three (1933, 2003 and 2014) in this respect.


A January without freezing temperatures

The absolute minimum temperature at Vattarnes in the Eastern Fjords area in Iceland remained above 0.0°C during the whole month of January 2014. This is the first time that this happens at an Icelandic weather station. The final minimum of the month was 0.4 °C (measured at 10 and 14 utc 14 January).

At the nearby island station at Seley (less than 10 km distant) the January minimum was 0.0°C. A few other stations in the country registered their highest January minima ever.

On the whole the temperature variability in Iceland during this month was unusually small. The absolute maximum temperature in the entire country was only 10.1°C, the lowest since 1994 and the lowest minimum in the inhabited areas was -16.4°C, the highest in the books since 1990. The total range (maximum - minimum) was thus only 26.5°C. It was the same in January 1990 but one has to go back to January 1947 to find a lower value. Then the station density was much lower than now and comparison is open to question.

There were very few observations in the highlands until about 1995. In most months the lowest temperature in the country is observed at the highland stations - this time -19,0°C at the Brúarjökull glacier. This is about 6°C higher than the average of the last 10 years.

The absolute temperature range in Reykjavík has only once been as small in January as now (in 1987) and it has by a large margin never been as small in Akureyri (since reliable maximum registrations began there in 1935).

Overall January was warm in Iceland. In the country as a whole it is about the 10th warmest of the period 1874 to 2014, but at some of the stations in the East - both coast and inland it was the second warmest of all time. This was the case at Teigarhorn which has continuous observations back to 1873, only January 1947 was warmer than now.

In Reykjavík it was the 12th warmest (starting in 1871) and 11th warmest in Akureyri (starting in 1882).

The Vattarnes automatic station is located on a low promontory at the mouth of Reyđarfjörđur, the largest fjord in Eastern Iceland:

Vattarnes          64°56.22'N; 13°41.086'W; 5.0 m.a.s.l.  began in 2000 

A synoptic station was in operation there during 1931 to 1943 (no minimum thermometer).

A web search for the name will return some photographs (mainly the lighthouse) and a map search should find the Vattarnes promontory.


A new highland maximum temperature record in Iceland

Iceland was favored by high temperatures during the last part of July. The maximum temperature in the country exceeded 20°C for 14 days in a row. The maximum length of a period with maximum above 20 degrees is 23 days (recorded last year 2012) but warm periods (in this particular sense) of two weeks or more are unusual.

The highest temperature in the country in July was recorded on the 21st, 26,4°C at the station Ásbyrgi in the Jökulsá national park in the northeast.

The headline news of the month, however, was the 25,9°C measured in Veiđivatnahraun in the southern highlands on 24 July. This is the highest temperature ever recorded in Iceland at a station above 400 m a.s.l. The Veiđivatnahraun station is located at the height of 647 m above sea level in a semi-desert area. At the time of observation the relative humidity was extremely low, only 13%.

The station has been in operation since 1993. There were practically no meteorological observations in the highland until the lone all-season manned station was established at Hveravellir in the central highlands in 1965 (640 m a.s.l.). After 1993 an increasingly dense network has been established, mainly at the effort of the Landsvirkjun (national power company).

The earlier maximum temperature registered in the highlands was only exceeded by 0,1°C, 25,8°C , measured at Upptyppingar - in the northeastern highlands.

A table of monthly temperature maximum records in the Icelandic highlands:

 

idyrmondayhrmax °C station name
401920101251712,5 Upptyppingar
401920062211811,1 Upptyppingar
401920003281313,2 Upptyppingar
401920074301718,0 Upptyppingar
401920074301818,0 Upptyppingar
401920005111319,0 Upptyppingar
401920006301424,1 Upptyppingar
665720137241525,9 Veiđivatnahraun
401920048131825,8 Upptyppingar
59702009913919,8 Hallsteinsdalsvarp
597020099131119,8 Hallsteinsdalsvarp
5943200310261317,4 Eyjabakkar
5943199911191016,8 Eyjabakkar
594320101215112,5 Eyjabakkar

All of the station names are googleable.

This is an extract of the icelandic version:

http://trj.blog.is/blog/trj/entry/1307122/

hungurdiskar blog:

http://trj.blog.is/blog/trj/


A new absolute minimum record for May in Iceland

On 2 May the automatic weather station at Brúarjökull registered a minimum temperature of -21.7°C. This is the lowest temperature ever measured in Iceland in May. However, it should be kept in mind, that this station has only been in place since 2005 and it is one of the coldest measuring sites in the country.

This cold spell is probably the most intensive one in May throughout the period of automatic observations in Iceland. The network was established in 1993 to 1998, becoming more dense since. New station minimum temperature records for May were registered at the majority of the automatic stations during the present cold spell.

The number of manned synoptic stations measuring temperature has decreased rapidly after 2004. A few of the remaining stations registered new minima for May during the present cold spell. These stations, except one, have only been in operation since 1988 or later. At the older synoptic stations the present minima did not exceed earlier records, except at one station. Most of these originate in a cold spell in early May 1982. One station which has been in operation since 1924 (not quite continuously, however) registered a new absolute record on 2 May this year.

The present cold spell seems to have been the most intensive in May in Iceland since at least 1982. Nobody knows how low the temperature at Brúarjökul was at that time.

On the measurements of minimum temperature in Iceland

At the “manual” stations the minima are measured with a traditional alcohol minimum thermometer. Readings are made two times per day, at 9 utc and at 18 utc The lower of the two readings becomes the minimum of the day. In the middle of winter the daily minimum is quite often recorded at 18 hrs, but during the other seasons most often at 9 in the morning.

At the automatic stations the minimum of the day is the lowest 2-minute average temperature during the 24 hour period from 00:01 to 24:00. At most of the automatic stations the temperature is registered every 10-minutes (a 2 minute mean) along with the highest and lowest 2-minute averages during the preceding 10 minutes. The automatic instruments have a somewhat faster response time compared to the traditional minimum thermometers placed in thermometer screens. In calm situations fluctuations of the minimum temperature are common as the temperature inversion nearest to the ground strengthens and mixes at irregular intervals.

This fluctuating behavior of the minimum temperature has not been examined systematically in Iceland.

The validity of the new record
The old record May minimum in Iceland was registered at the manned station Möđrudalur on 1 May 1977, -17.4°C. The new record is more than 3 degrees C lower than this and must be considered unquestionable even though the new record is made at an automatic station with different attributes than the traditional measurement.

The Brúarjökull station is located at 845 m above sea level at the snout of a very large and flat outlet glacier of the icecap Vatnajökull. This is well within the highlands of Iceland and almost 400 meters above the location of the earlier record station Möđrudalur.

The first all-year highland station in Iceland was established in 1965 and a few others were in drift for a few years or seasons until the advent of automatic stations. It has been customary to distinguish between the highland stations on one hand and the stations in the inhabited areas on the other in the listing of weather records. However, regarding the minima, the inhabited stations in the very flat northeastern highlands have been almost on par with the higher level highland stations proper during winter. The earlier May minimum record had thus persisted for 36 years even though many automatic stations have been in operation at higher levels for more than 15 years.

A new absolute minimum for the inhabited stations was also registered at the same hour as the new whole-country record. The minimum at the automatic station at Grímstađir (another northeastern inland station) plunged down to -17.6°C, 0.2°C lower than the old record.

The automatic station at Grímsstađir is new, however, established last autumn only. There still are ongoing measurements at the old manual station there. The in-screen minimum thermometer registered “only” -14.5°C on the morning of 2 May. The distance between the two stations is less than 100 meters.

The registrations at the new automatic station at Grímsstađir have not been compared to the manual registration in a systematic manner and a post-installation calibration has not been made. Until that is done the new record will not be formally confirmed.


August in Iceland

August was a very warm month in the northern, western and southwestern parts of Iceland. In Reykjavík it was the fourth warmest since the official beginning of observations in 1871. August of 2003, 2004 and 1880 were slightly warmer. The temperature was above average in the whole country but not much above in the southeast.

The highest temperature of the month was recorded at Eskifjörđur in the Eastern Fjords area on the 9th, 28.0 degrees C. This is the highest temperature measured in Iceland since 2008. The last week of the month was rather cold with overnight freezing temperatures at many inland locations. The lowest minimum of the month was -5.3°C registered at Brúsastađir in a valley in the north.

It is unusual that the maximum temperature of the country stays above 20 degrees C for more than a few days in a row. But this summer saw a new record in this respect, the period from 27 July to 19 August had an unbroken chain of country maxima above or equal to 20 degrees. During the warm period the overnight low temperatures were also unusually high and the minima close to being record high.

The precipitation was at average in Reykjavík but in most parts of the country it was drier than usual. In Akureyri the total of the month was only 8.4 mm, the driest August since 1960. The sunshine hours in Reykjavík were close to average but Akureyri has only once enjoyed more sunshine in August since the beginning of registration in 1928.

The first eight months of the year have been unusually warm in Iceland. This period of the year has only once been warmer in Stykkishólmur (in the west), that was in 2003. The record goes back to 1846.


July - a warm and sunny month in Iceland

July was both warm and sunny in most of Iceland. A small part of the East had temperatures just above average, in most other areas the month was one of the 10 warmest months of July.

In Vestmannaeyjar off the southern coast this July was the warmest since the station was moved to its present location in 1921. Temperature measurements, however, were done at another location at a lower elevation prior to that from 1877. And during 1869 to 1877 (unofficial) measurements were made at the third location. Older measurements exist for Vestmannaeyjar (during the 1840s) but they were clearly contaminated by the exposure of sunlight during summer. Since 2003, measurements have been made at two locations allowing the calculation of a site adjusted series back to 1877 (and unofficially back to 1869). This shows that July 1880 was probably about equally as warm as July now (2012).

The sun has been shining in the west and north as never before. The number of bright sunshine hours was well above average in Reykjavík and within 1 hour of the July record in Akureyri. But a look at the sum of the last three months reveals an exceptional situation at both stations. This period is the sunniest at both stations since the beginning of registration, in Reykjavík in 1911 and in 1928 in Akureyri. In Akureyri the old record (from 1939) was exceeded by 120 hours of sunshine and the total for the first seven months of the year is already close to the average annual total.

The precipitation in July was below average in all districts but not quite so as in May and June.

Even though the weather has been warm, days with maximum temperature above 20 deg C have been few and the Reykjavík absolute maximum of the summer is still below 19 deg C.

The month also brought the lowest July pressure ever recorded in Iceland (see a separate entry). Even so, the average monthly pressure was above the long-term mean.


A new low pressure record for July in Iceland

A remarkably deep low developed to the southwest of Iceland on 19 and 20 July 2012. According to the analysis of the ECMWF the central pressure in the low dropped to 966 hPa. This is amongst the lowest values ever observed in the North Atlantic in July.

After the low reached its maximum intensity it moved towards Iceland and filled gradually. In the evening of Sunday 22 July the pressure was at minimum near the south coast of Iceland. The lowest mercury barometer reading was 972.8 hPa, first at Vestmannaeyjar at 21 pm and then again at Kirkjubćjarklaustur 6 hours later. The lowest value at an automatic station was reached in Vestmannaeyjar during an extended period of one hour, 21:30 to 22:30, 972.4 hPa.

The pressure in Iceland has only on three occasions dropped down to 975 hPa or lower in the entire record extending back to the 1820s. These cases were 974.1 hPa in Stykkishólmur on 18 July 1901, 974.3 hPa in Stykkishólmur on 19 July 1923 and 975.0 hPa in Reykjavík 11 July 1912. It should be kept in mind that even the pressure was recorded at a few stations all over the country during the period from 1874 onwards, longer intervals passed between readings than now. Three readings per day were typical, but eight readings have been made at most of the barometric stations since the mid-1940s.

The low has brought rain to most of the country. Some parts have been experiencing an unusual drought since May. If the rain will alleviate the low water levels in the non-groundwater-fed rivers remains to be seen.

The country more or less escaped the high winds associated with the low as the centre passed just south of the country. The wind was strongest to the south of the low, as well as in the Greenland Strait (Denmark Strait) to the northwest of Iceland. The strongest gust associated with the low was measured 39.5 m/s at the station Steinar at the southern coast.


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Iceland Weather blog

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Trausti Jónsson
Trausti Jónsson
Senior meteorologist at the Icelandic Met. Office. Speciality: Climatology
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