A quick look at the objective LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. data from 1871 to find the most anticyclonic November reveals that 1942 and 1988 (60%) are at the top of the pile. Not a lot of people know that. 🙂
November 1988November 1942
As you might expect, November 1942 and 1978 were both quite dry and cold months.
I have no idea if this is an analog for the coming winter, but I’ll do a bit more digging and see what I can find out what the following winters were like.
A month of mixed weather types, a negatively zonal start gradually became more zonal, with alternating cyclonic and anticyclonic spells through the month, which gradually became more anticyclonic in nature as pressure gradually rose.
I had previously plotted correlations between LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. and CETCETCentral England Temperature, so the obvious thing to do now was to plot correlation charts using daily LWT types and daily rainfall from the UKPUKPUKP is a gridded datasets of UK regional precipitation. regional rainfall series, which I download from the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy. It turned out to be even less exciting than a lot of the climate statistics I’ve produced before, in that it just confirmed what you could easily deduce by using a little common sense in that anticyclonic weather types are drier than cyclonic types. 🙂 Generally westerly types come in second wettest, using an average for the whole year. Depending on what region you look at, easterly & northerly types are sometimes drier than anticyclonic types. The reason for that is that the results are likely skewed for easterly and northerly types because they occur much less frequently than do anticyclonic types. Westerly types in Scotland (see below) seem to peak in January, at close to 2 mm per day, but fall to a low of 0.4 mm in May, again a fairly obvious correlation.
I wrote some code a long while ago now that correlated temperatures in the Central England with the corresponding weather type from the objective Lamb Weather Type series. I compared just the six pure types, anticyclonic, cyclonic, northerly, easterly, southerly and westerly. The application allows you to correlate using the mean, maximum or minimum temperatures with the LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. on that day. I may have published these charts in a previous blog but I forget, so here they are again 😉
Cyclonic types, whatever the time of years generally seem to be associated with colder anomalies.
Mean temperatures in anticyclonic types are generally only warmer in the months of June or July, otherwise they are invariably colder. See below for charts of maximum and minimum CETs.
As you would expect northerly LWT types always produce colder mean temperatures in central England.
Not surprisingly E types are much colder from October to May, but a little warmer in the extended summer months.
Southerly types are warmer from around April till the end of October, otherwise they produce lower than average mean temperatures.
Westerly types in contrast to N, S, and E types are usually a little colder in the summer, from mid-April to the start of October, in winter they are nearly always milder.
Above are charts for mean maximum and mean minimum temperatures for anticyclonic types, the results of which are a little surprising to me, in that the maximum correlation in summer months is much lower than I imagined it would be, because of course you naturally assume the A type, must be the one favoured for many of the very warm spells in summer. I calculated all the anomalies in the correlations using the 1878-2023 long-term averages, which I thought was the fairest way of doing things, but maybe I was wrong. Perhaps if I revisit this code again I’ll add the frequency each weather type occurs. 😜
I’ve added some code to my LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. application to display graphs of 365 day moving averages for some of the daily indices that the objective series generate. I thought it might be easier to pick out trends using an extended period like this, although the application is flexible enough to allow shorter periods. At a glance you can see that mean MSLPMSLPMean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature. over the last 10 years across the British Isles is currently at its lowest at the moment, and positive cyclonic vorticity has also been at a ten year high in 2024 as well. What it all means remains a mystery but it kept me busy this afternoon. 😜
Circulation wise September was a rather blocked and meridional sort of month, with winds from N or E. Mainly anticyclonic from the 12th to the 19th, otherwise rather cyclonic at times, especially during the last week.
MSLPMSLPMean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature. was below average for much of the summer [JJAJJAMeteorological Summer comprising the months June, July & August] with a strong mobile W or SW flow with an above average GIGIGale Index. Brief anticyclonic interludes that got briefer as the summer went on. The NW flow in June backed into a SW’ly from the middle of July.
July 2024 was a very zonal month, and cyclonic at times, with below average MSLPMSLPMean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature., but a little more anticyclonic towards the end. It looks like I’m going to have to search for missing charts on the 10th and 11th. Sunday the 28th looks a rare day when the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy couldn’t find a single frontal structure or trough near IONAIONAIslands Of North Atlantic.
Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK..
A mobile, and at times a quite cyclonic month for June across IONAIONAIslands Of North Atlantic.
Yes I know there's an island called Iona, but this is so I don't have to use the term 'British Isles' when referring to the whole of Ireland and the UK. started anticyclonic enough, but the flow steadily veered more northwesterly up until the 11th, when a low tracked slowly eastward from the 14th to the 18th leaving a northerly behind it. The circulation gradually became more southwesterly until the 24th, when a brief anticyclonic couple of days gave way to a low that tracked northeastward across the northwest of the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. on 27th & 28th, with winds veering more northwesterly, as high pressure built in from the southwest.
May was a generally quiet month with four or more cycles of cyclonic and anticyclonic spells, as much positive meridional than it was negative, with more negative zonality than positive. It’s no wonder that the mean pressure pattern for the month was slack.
A fairly cyclonic start and end to April 2024 in the objective LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. indices, with an anticyclonic spell in the fourth week. There was a fair spread of wind directions during the month, but the second and third weeks were zonal W or SW’ly.
March 2024 was a mobile affair, and often quite cyclonic, with only brief anticyclonic interludes between before the arrival of the next low. MSLPMSLPMean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature. during the month was well below the LTALTALong Term Average. This is usually defined as a 30 year period by the WMO., particularly in the last week.
February 2024 was a rather cyclonic month and a zonal westerly flow for much of the time. Despite this the gale index remained fairly subdued for most of it.
The CRU at the UEA have updated their LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. data series and here’s a look back at how the winter of 2023-24 is shaping up.
A strange old month with some rapid switches in cyclonicity. Mostly zonal but an anticyclonic second week and three named storms. The Gale Index in the objective LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. that I calculate from reanalysis data is not the same as the GIGIGale Index that I generate from SYNOPSYNOPSYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. observations.
It looks like this January (2024) could turn into a very anticyclonic month from this weekend, so I thought I would take a look back in the objective LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. records, which started in 1871, and found that January 1992 was the most anticyclonic on record., although despite it being so anticyclonic, it never really managed to generate more than a few easterly days at the start of the third week.
MSLPMSLPMean sea level pressure is the pressure at sea level, or, when measured at a given elevation on land, the station pressure reduced to sea level assuming an isothermal layer at the station temperature. that month across the UKUKThe United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and Northern Ireland. got close to 1050 hPahPaA Hectopascal is the SI unit of pressure and identical to the Millibar on the 26th as you can see from the chart for 12 UTCUTCCoordinated Universal Time or UTC is the primary time standard by which the world regulates clocks and time. It is within about 1 second of mean solar time (such as UT1) at 0° longitude (at the IERS Reference Meridian as the currently used prime meridian) and is not adjusted for daylight saving time. It is effectively a successor to Greenwich Mean Time (GMT)., the highest on that chart was 1049.0 hPa at Cynwyd in Denbighshire. I only have main synoptic hour data so it may have broken through 1050 hPa. Notice that they’re also plotted SYNOPSYNOPSYNOP (surface synoptic observations) is a numerical code (called FM-12 by WMO) used for reporting weather observations made by manned and automated weather stations. SYNOP reports are typically mad hourly and consist of groups of numbers (and slashes where data is not available) describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. reports from Cape Wrath, Butt of Lewis and Binbrook on that chart, those were the days 😉
One other point about January 1992 is that it was also a El NinoEl NiñoEl Niño 'The Boy' is the warm phase of the El Niño–Southern Oscillation and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific month.
December 2023 ended up being a mobile month with the jet stream for much of it south shifted, which made it more cyclonic than normal, and hence a rather windy month too with four named storms. The LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. zonal index was negative for the first week or more, but went positive in a big way from the second week onward. Quite a few classic analyses from the UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy during the month ranging from a plethora (thanks CK) of troughs on the 1st & 2nd to multiple occlusions on the 31st (thanks Mr Occlusion).
Meteorological Autumn 2023 has seen some quite varied weather types, predominantly anticyclonic until mid October and then full on cyclonic. It also contained four named storms, some of which were more deserving than others for being named. I can’t even remember them all, only Ciaran and Debi stick out. Zonality also did a couple of about faces during October and again towards the end of November.
What a month. The Icelandic low decided to move 700 miles further south for a change of scene. It started well enough, but became cyclonic from the 19th onward.3 Aug-1 Nov 2023 50N 5W Pseudo Barograph Anomalies of -40 hPahPaA Hectopascal is the SI unit of pressure and identical to the Millibar in the last week close to the Lizard.
Summer started in a very anticyclonic mood with negative zonality (E’lies). The rot soon set in, and by the 19th of June the summer had turned when positive zonality (W’lies) was restored, and that’s basically where we’ve been since then. The meridional index has switched between spells of negative and positive, as it tends to do across our part of the world, and generally cyclonic. There were a couple of days with a gale index above the threshold of 30, but neither tie in with the named storms of Antoni (5 Aug) or Betty (18-19 Aug). The UKMOUKMOThe Meteorological Office is the United Kingdom's national weather service. It is an executive agency and trading fund of the Department for Business, Energy and Industrial Strategy, in their wisdom, decided not to name the deep low on the 15th of July that produced a GIGIGale Index of 40.5, but I reckon it was the equal of either of the two that were named.
You may have noticed that I’ve put some work into smartening up the front end of my application that visualises objective LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types., the data for which I download from the CRU at the UEA. I’m quite proud of the app, and it works very well. I am so glad that the CRU have kept the objective series going after H.H.Lamb’s death in 1997. I do have the objective LWT algorithm, which I run on six hourly gridded reanalysis data in a seperate application as well , which gives a more detailed view of how weather types unfold.
The anticyclonic spell that lasted 25 days and began on the 15th of May 2023 and ended on the 8th of June, was fourth longest in the Objective LWTLWTLamb Weather Types are often used in UK-based analyses, with individual weather patterns based on the eight primary cardinal directions (N, NE, E, SE, S, SW, W, NW) plus cyclonic (C), anticyclonic (A) and unclassified (U) types. series that began in 1871 (the total includes all hybrid ACACAltocumulus clouds are generally associated with settled weather and will normally appear white or grey with shading.
Height of base: 7,000 - 18,000 ft
Shape: Bands or areas of individual cells
Latin: altum - height; cumulus - heap
Altocumulus clouds are small mid-level layers or patches of clouds, called cloudlets, which most commonly exist in the shape of rounded clumps. There are many varieties of altocumulus, however, meaning they can appear in a range of shapes. Altocumulus are made up of a mix of ice and water, giving them a slightly more ethereal appearance than the big and fluffy lower level cumulus. types). From the 28th of May the flow was generally easterly. Not a lot of people know that.
