Tuesday 6th January
Latest: Met Office at 12.46
Warning of multi-hazard event Thursday into Friday from Storm Goretti.
We could have disruptive event from snow or rain or high winds, or a combination, dependent on position of incoming depression. More detail tomorrow.
However, rain late tonight with icy conditions possible tomorrow.
Although we had another very sunny day on Monday it did nothing for any increase in warmth under the continuing flow of Arctic air. It is interesting to see that over the last four consecutive days the ‘High Solar’ value has been almost identical with 237W/m2, 230W/m2, 229W/m2 and 236W/m2 respectively, whereas the the maximum for the those four days has steadily fallen with 3.4C, 2.9C,3.0C and 1.6C respectively.
I mentioned yesterday the problem of measuring the content of frozen precipitation in an automatic rain gauge. The early morning snow eventually melted in my automatic rain gauge at 11.16 whilst the snow in my copper gauge turned to liquid quite soon after being brought indoors then slowly warming the funnel to melt the ice in a few minutes with a result soon after 08.00, before any more precipitation fell.
The past night has been cold, very cold. The sky remained clear until just after 03.00 that allowed any residual warmth in the ground to escape into the atmosphere, exacerbated by calm conditions, the last air movement was logged at precisely 00.28. A minimum of -7.2C was logged at 02.51 being a significant 8.4C below my long-term average. It was the coldest night since 5th January 2025 when -7.5C was logged. There was a slight rise in temperature due to thin cloud drifting across, seen on the back track of the cloud radar, from the northwest before dropping back to -6.6C at 06.00.
Tuesday at first light revealed a line of clear sky on the eastern horizon, just about to be overtaken by the advancing thicker cloud. At 08.00 the thermometer read -3.9C, the advancing thick cloud cover allowed the rise in temperature or any increase in a temperature drop. At 08.10 very light powdery snow was observed falling from a narrow band of cloud that had been advancing from the northwest over the previous three hours seen on the back track of the relevant rain radar. This quickly turned into a very brief modest fall of heavier snow.
The advance of a low-pressure system from the north towards the end of the week, that I mentioned yesterday, could bring some interesting weather depending upon its exact position over southern England. The most likely position is for our area to be on the border between snow and rain, a little further south in its position overhead the English Channel could produce disruptive rainfall, a littl further north could produce disruptive wind.
It is ironic that with the first morning when the sun began to rise earlier, by one minute from 08.12 to 08.13, having been at 08.12 since the 26th December, it was dark with snow falling.
I thought it appropriate to attach a recent article from the Met Office regarding the difficulties of forecasting the arrival of snow over the UK.
Snow forecast difficulties – Met Office
The UK’s maritime climate plays a big role in limiting snowfall. In winter, land cools quickly, but the surrounding seas remain relatively warm. This moderates the air temperature as it approaches our shores, often turning what could have been snow into rain or sleet. While inland areas of large continents experience prolonged cold spells, the UKs exposure to milder Atlantic air means that snow is usually confined to short-lived events or higher ground.
The most common wind direction for the UK is southwesterly, bringing moist, mild air from the Atlantic. This typically results in rain rather than snow. For snow to occur, we need a combination of cold air and moisture, two ingredients that don’t always align in our climate. If we have a flow of colder from Continental Europe this will increase the likelihood of snow, especially when combined with high-pressure, which allows temperatures to fall steadily over several days.
Moisture is another key factor. For snow to form over the UK, cold air must either meet a rain-bearing weather front or pick up moisture during its short journey across the North Sea. This can lead to showers that fall as snow if temperatures are low enough.
Topography also plays a role. When air rises over hills and mountains, it cools and condenses, forming cloud and precipitation. Whether this falls as rain or snow depends on the freezing level, the altitude at which temperatures drop below zero.
How far ahead can we predict snow?
Unlike regions with more stable winter climates, the UK’s variable weather means snow cannot be forecast with high confidence weeks in advance. While long-range models can indicate colder spells, pinpointing snowfall requires short-range analysis. Typically, confidence increases within a few days of an event, and severe weather warnings are issued when there is a significant risk of impacts.
The Met Office uses a combination of model data, radar observations and expert judgement to refine forecasts. When snow is likely to be impactful, National Severe Weather Warnings are issued to help people prepare for potential disruption.
How the Met Office communicates snow warnings
When snow is expected, the Met Office issues warnings through its National Severe Weather Warning Service. These warnings are colour-coded, yellow, amber and red, based on the likelihood and potential impact of the event. Yellow warnings highlight the need for awareness, amber warnings indicate increased risk and potential disruption, and red warnings are reserved for the most severe conditions where immediate action is required.