Latest Winter Synoptic Analysis courtesy of Paul Blight (For the latest up to date analysis click)

This will follow the synoptic evolution of the upcoming colder spell of weather...

As we go through the week, the High and its assoc upper blocking ridges NE towards the Faeroes as the cold block slips South over Scandinavia, then into Germany and the Netherlands.  There is considerable variation in the shape, speed and orientation of this trough as it disrupts.  A quick study of the EPS and GFS Ensemble postage stamps indicates the spread in solutions which mean detail differences in the actual weather even though the overall trend is clear.  There is reasonable agreement from the main deterministic models of the GFS, UKMO GM and High Res ECWMF, of the trough coming SSW into the Netherlands and Western Germany, then it slips South, with an arm reaching NW and rotating SW across the UK with an easterly airflow becoming established after that.  The ECM has been insistent that the build of pressure to the North of the UK (to the rear of the confluent part of the trough) will be greater than the UKMO, with the GFS somewhat undecided about exactly how much it wants to build pressure.  The 06Z and 12Z Operational Runs have seen lower pressures than their corresponding 00 and 18Z Runs.   The ECMWF was somewhat at the top of Its ensemble range with the pressure build - though it would not surprise me to see the ECM being proved correct, but perhaps a compromise of 4-5mbs off the ECM would be more appropriate. 

Sunnier weather comes SW into most parts mid week, but with increasing Snow Showers in eastern parts.  Cold in these areeas, and feeling cold everywhere - though in the sun, numerically it wont be that low 3-5C in most places, though over higher ground 1-4C and generally colder later in the week as the lower level airmass comes from a less maritime source.  Frost occurring overnight where skies are clear- dropping to nr zero where cloud persists.

Risk of more significant Snow across the SE and East Anglia later on Weds and Thursday as the cold pool arrives and swings forcing SW towards these areas. Snow becoming heavier and more persistent leading to some accumulations in places with a cold wind.  Kent and E Anglia seeing potential for more Sig Snow. A colder end to the week - Daytime Maxes largely 1-3C, though a little milder in the Western and Northern Areas and sub-zero over High Ground.

The cold pool sinks SE away for Friday with a cold Easterly, the 12Z GFS brings another cold pool west into the Weekend as does the ECMWF (though the ECM is much slower with the 1st one so its correspondingly slower with the 2nd) with an increasing Risk of more general sleet / Snow developing.

NEWS: Monthly retrospective for January 2010

January was again a cold month- but one of two halves. Though mean temperatures were 3C below average the first half saw them around 6C below whilst the second half was near average. N Scotland was only a degree below average though. This made it the coldest month since January 1987. Rainfall was around 75% across England and Wales but as high as 100% across SE England and the Midlands and only 55% across N Scotland. Sunshine was well above average overall at 124% and especially in the first half of the month and in western UK where 130-150% was recorded. However it was quite dull in places in the second half, especially the east, meaning Eastern Scotland saw just 88%.

The year started rather cold for most; a little less so in the south as snow fell by the 3rd, mainly across E Scotland, NE England and W Wales. Braemar (Aberdeenshire) recorded a minimum temperature of -17C on the 3^rd. However the cold continued through the first week and by January 8th the coldest temperature since 1995 was recorded at Altnaharra (Sutherland) of -22.3C (and the coldest this month) with a rare snow cover across almost all of the UK. Many minor roads remained snow covered or icy. Some areas in the south (especially around Reading, Berks) had seen 30cm of level snow fall. Salt & grit supplies were "stretched" with thousands of schools remaining closed whilst rail and air travel were hit by cancellations and delays with emergency services running. Motorway hard shoulders were no longer being gritted as priority for the salt was given to the worst-affected regions. Milk deliveries were disrupted too as the tankers struggled to reach dairy farms with farmers. The 12th saw more snow overnight for many in the south, along with the upland SW too, with 5-10cm quite widely. Temperatures across England and Wales were just -1.9°C, a full -6.1 degrees below average, possibly one of the coldest starts to January ever recorded . By the 15th though the very cold spell was over as much milder weather started to return to many areas and a slow thaw began. Given the amount of snow in many upland areas it took a considerable time to thaw though. On the 16th a balmy 12.3C was recorded at Chivenor (Devon), the warmest temperature this month. 

By the 26th after a milder, somewhat uneventful spell for a week or so, somewhat colder weather returned as an arctic northerly blast developed giving further snow in places mainly exposed east and west coasts. The month ended on a cold note as well. Minimum temperatures fell to -8C in the south at Hurn (Dorset) (and Benson, Oxon) on the 30th/31st and -13.3C on the grass at Hurn. The period around the 26th-28th saw unusually coloured sunsets in places also. Atmospheric expert Les Cowley believed the bright pink and dusty orange colours seen could be a type of Polar Stratospheric Cloud (PSC) lit by dust in the upper atmosphere. 

Soil temperatures were below average generally esp around East Anglia & the SE & fell markedly by the middle of the month, esp in central, northern England & much of northern, eastern and central Scotland- to well below average with frozen ground common here but rose generally after then to generally somewhat  below average. Sea temperatures remained near or rather above average around most parts though but were below average around the western & SW approaches, east Anglia and Irish Sea by the month's end. 

MODEL WEATHER LINKS

Model Discussion Discussion of how the models are tracking the potential weather patterning across UK and further afield (ie: not for just any potential cold weather discussion) Model Watch - Into Mid-Winter

Cold weather chat thread For anything you care to talk about in relation to the potential cold spell and its effects.. serious/less serious Possible Snow Event - Thursday/Friday 28th/29th Jan - Chat Thread

Synoptic discussion and analysis forum We usually invite various met savvy people to add a more detailed commentary in this area, if the meteorological set up warrants it..  Synoptic Discussion & Analysis