UK meteorology

Members will no doubt be glad that the cold period is on the way out, though it has given us 2 inches of snow overnight!
Here's Malcolm's usual post from Netweather for today:
We are slowly coming to the end of, understatement of the year, a period of very interesting weather, and slowly moving into a period best described as more mundane albeit, being the weather it will not be without interest. A quick and very short overview. Our weather in the medium term will be dominated by a complex upper trough fed by energy running east from the south east US seaboard under the high pressure to the north.



Back to more detail. It looks like the UK is entering into a N/S split period and at 00 the low and wrap around occlusion were over the south west and central England whilst the north still in the cold showery easterly. This regime will continue during today whilst further south one occlusion will weaken whilst a band of snow, sleet and rain associated with the second will push north, mainly affecting the west, from the south. It is this that finally introduce warmer air generally and initiate the beginning of the thaw during the day in the south (The sat image is for 0400)







So in a nutshell tonight pretty cloudy in England and Wales with patchy rain and sleet in the south and snow further north in Wales and the Midlands and snow showers continuing in the north east and Scotland.



By Sunday the N/S split is quite marked with low pressure dominating the UK with the centres to the south west. This leaves Scotland, N. Ireland and the far north of England still in the showery south easterly whilst the rest of the country is under a patchy rain, sleet and snow regime with the slow thaw continuing.



Keeping in mind the opening comments of this post vis the upper trough this is essentially where we stand Monday-Wednesday with low pressure influencing proceedings, Colder with snow showers in Scotland and the snow, rain and snow mixture continuing elsewhere as the slow thaw continues. The detail of this will vary but these are the gfs spot charts for the three days



I've mentioned a slow thaw a few times and temps are certainly creeping up but realistically Spring is not yet bursting forth and temps are still below average.

 
Can they be seen as reliable 72hrs ahead ?
Yes - he wouldn't post if he wasn't confident in the accuracy of the models. They struggled in the run-up to this cold period as an historic Sudden Stratospheric Warning collapsed the vortex and reversed the stratospheric winds very rapidly, but, most of the time, the models can be analysed by those who are used to doing so in order to work out where consensus lies between the models out to 72 hours with good accuracy.
 
Yes - he wouldn't post if he wasn't confident in the accuracy of the models. They struggled in the run-up to this cold period as an historic Sudden Stratospheric Warning collapsed the vortex and reversed the stratospheric winds very rapidly, but, most of the time, the models can be analysed by those who are used to doing so in order to work out where consensus lies between the models out to 72 hours with good accuracy.
Thanks Chris, thing's have moved on over the last few years . Yes of some interest . Paul.
 
Last night's anomalies:
Pretty good agreement on the overall pattern with tonight's anomalies but disagreement on the intensity and alignment of the ridge/trough combination in the arena of the amplified Atlantic.

Essentially still a secondary lobe NW Greenland and a trough over the south east US with the ridge/high cell in between around the Labrador Sea area. Thus two energy flows, one around the ridge to the north and the other stronger one exiting the seaboard of the south east United States, The two flows coalesce in mid Atlantic but there is no agreement on this because of the varying configurations of the trough in the eastern Atlantic as previously mentioned. Until this is sorted the detail of the evolution will be problematic as the area of the coalescence is an environmentally friendly zone for cyclogenesis Suffice it to say at this stage looking like an unsettled period with the upper flow from the westerly quadrant, perhaps quite windy, with temps average or a little below.

 
Today's deterministic run discussion as usual:
The slow change to a different pattern continues with low pressure dominating our weather for the foreseeable with upper troughs and associated surface lows being the guiding feature. It's been awhile since we had to look W/SW for developments.



So today with low pressure and a couple of occlusions drifting north sees patchy rain sleet and snow doing the same over England and Wales and N. Ireland leaving heavy rain showers in the south west Further snowfall expected in Scotland particularly the north east The 'warmer' air and slow thaw also moves slowly north and has already reached the south Midlands this morning but Scotland will remain cold.

https://wow.metoffice.gov.uk/





The snow showers will persist overnight in north east Scotland whilst elsewhere will be partly cloudy with mist and fog patches developing and this will be the general theme through Monday with persistent snow still across NE Scotland with showers developing across England and wales. But later in the day a band of more concentrated rain rain will track north affecting the western side of England and Wales and by now temps have recovered to be near average.



At the risk of sounding like a stuck record this relatively mundane weather will be the order of the day through the middle of this week; Namely scattered showers with some longer periods of rain and still a chance of snow on the higher ground, some mist and fog overnight and in the mornings and temps still recovering.




Obviously the detail will vary but the ecm on the same page as the GFS so just some spot charts.



 
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