When you think we are around about 4 days from the half way mark of Winter , much to play for still. No need to write anything off yet.

I didnt understand your question I have Autism and find it hard to understand normal gender of the question so sorry,

What does TM mean?

This is an illustration of why to take any forecast with a pinch of salt.

The ECMWF doesn't develop it enough for me to draw a track. Its a complete mess. 

Hmmm, I quite like that track diagram Quantum . Shows the diversity in the model's projected paths very clearly 

PS, 'TM' = Trade Marked 

Ah thanks! 

Anyway from what I can gather the low is indeed caused by upper level divergence. Since I haven't written a script for the jet stream jet, grudgingly here is the meteociel version.

The jetstream is stronger downwind, so air is being removed at the 200hpa level, this lowers the pressure at the surface, although apparently not enough to give a closed circulation at the surface. Note the upper level ridge at the 200hpa level also.

http://modeles.meteociel.fr/modeles/gens/runs/2015011118/gensnh-0-1-228.png

The control gets close to a brief Easterly

Continuing to look well ahead for now, but don't worry, I'll finally turn my attention to potential snow etc. come tomorrow evening :

This is among the most interesting chart's I've seen in years as far as potential is concerned (not the best of outcomes in this specific case). It's at two weeks range but it is in keeping with what could happen given an increasingly weak polar vortex coupled with a new slide of low pressure SE through the UK.

All that really changed from the previous GFSP run was a reduction in the Atlantic jet intensity beyond day 10. In fact the signs of potential within the 10 day range were lower than seen on the ECM 12z op run.

The 18z of the old GFS is closer to ECM out to day 10 (a big shift from the GFS 12z) but takes longer to reduce the jet intensity afterward, meaning that, for the sliding feature needed, we're left waiting for the next low in sequence beyond the one that's near or over us in 10 days time.

All this evolves from hints of higher heights toward Svalbard in the 8-10 day range that have been fluctuating in that region for a couple of days worth of runs now.

That is in turn thanks to the polar vortex breaking apart and allowing height rises across the Arctic - the AO trending well negative. A weak Atlantic jet with a tendency to dive SE through the UK is one of those situations in which a -ve AO can really make a difference to our weather in a fairly direct manner.

So I believe this is something to keep an eye on in the background while all the wild weather is happening. Part of my mind is insisting that GFS has long had a habit of showing the Atlantic pushing straight on east, with an Azores ridge in play, at times when a signal for height rises to our NE are starting to emerge. Does anyone else have the same feeling?

I suspect that the extended ECM ensembles feature some easterly options, given that Fergie mentioned an anticyclonic signal with a wind direction that was 'hard to place'. A wind from the southwest was then put forward as perhaps the more common outcome on offer, but it's early days on this and we are talking about two weeks from now - room for large adjustments one way or the other.

I'll admit that I've made this post largely as something to reflect on if Scandi Height rises gain a strong footing in the output by the latter stages of this week - for the time being, most aren't going to be too bothered about what's coming beyond the weekend.

Look at how low the latitude height gradient is on that chart, it would be quite difficult to get back to raging zonality from that. 

Interesting UKMO with diving shortwave on Sunday

Only 1 post concerning this morning's output - can't be a good sign. 

From my cursory glance at my local GFS ensemble, it's as you are really -lot's of 10% snow chances, but nothing coherent.

Hi Kieran,

Not seen the latest fax chart, looks 'seasonal to me'

Indeed. 

528 DAM line well to the south 

low pressure to the south the of the Isle of Wight

Occluded Front over south East

Troughs moving along south coast

I'll take it

Indeed, that together with an inch or two of snow tomorrow night for some lucky ones in SW - not ruling out seeing a few flakes myself - a 'wintry' week ahead.

Odd that the GFS isn't showing anything particularly wintry for down here though.  I'd sooner trust the fax charts though!

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY MONDAY JANUARY 12TH 2015.

NEXT UPDATE TUESDAY JANUARY 13TH 2015 08:00

THE CURRENT GENERAL SITUATION An active cold front will decelerate as it crosses SE over Southern England followed by a cold and showery Westerly flow across the UK tomorrow.

MODELS-2 WEEK HEADLINE Continuing mostly unsettled with rain or showers at times. Near average temperatures will fall rather cold at times with some snowfall at times on all higher ground.

THE JET STREAM ENSEMBLE FORECAST The Jet Stream Forecast shows a very strong Jet Stream this week weakening slowly thereafter. There will be plenty of cold zonality type weather as the Jet lies South of the UK through Week 1. Through the second week the Jet flow weakens steadily though it's projection and orientation still close to or to the South of the UK may probably lead to little difference in the overall Atlantic driven pattern with a bias towards colder zonality conditions.

GFS OPERATIONAL The GFS operational continues to show a very disturbed pattern with spells of cold and showery weather with a marked period of wet and stormy period soon after midweek. Through week 2 pressure does show signs of building closer to SW Britain with time diluting the worst of the cold zonality and other wet and milder conditions away towards the North under a much weaker jet flow.

THE GFS PARALLEL RUN The Parallel run is broadly similar in the sequence of events throughout the period with cold zonality the order of the day through the next week. Through Week 2 improvements are slower that with the operational although by the end of the run a pattern change has taken place with cold High pressure over Europe extending a ridge back west over the Uk with frost and fog more likely than for some time especially across the South.

THE GFS CONTROL The GFS control run too shows that Westerly winds under polar maritime air rules the roost throughout it's run this morning through Week 1 before it too shows slow improvements and moderation of the zonal pattern later in Week 2 as pressure builds from the South under a weaker Jet flow.

THE GFS CLUSTERS The GFS Clusters today show a split between a selection of Low pressure to the North with West or NW winds and continuing unsettled and changeable conditions but also with a 30% collection showing a chance of High pressure close to the West of the UK with a ridge towards Scandinavia.

UKMO UKMO shows a cold and unstable Westerly flow following the midweek storm with spells of wintry showers and sunny spells. At the weekend a small but potent depression crossing East over the English Channel could bring a spell of rain or snow across Southern areas for a time.

THE FAX CHARTS The Fax Charts shows Low pressure dominating the synoptics across the British Isles over the coming 5 days with cold fronts crossing East across the UK bringing spells of heavy rain and followed by cold westerly winds and embedded troughs and wintry showers, heavy and thundery in places. Little change is expected or shown this side of the end of the weekend.

GEM GEM today follows a GFS type route over the next 10 days with another week or so of cold and unsettled weather with rain or indeed snow showers at times before High pressure slowly builds up from the South towards the end of the period bringing drier and brighter conditions later next week.

NAVGEM NAVGEM reflects the storm system midweek too with rain and strong winds interrupting a spell of cold westerly winds before and afterward before a ridge of High pressure crossing East next weekend brings a breather from the strength of the Westerly flow for a day or two with some bright and sunny spells in places.

ECM ECM this morning also shows a lot of strong Westerly winds with spells of rain and wintry showers to come for all this week. Unlike UKMO it makes nothing of the weekend Low pressure sending a weak ridge instead across the Uk with drier and cold conditions with some frost by the end of the weekend. then next week Low pressure retakes command from the North with a further mix of wet and windy weather alternating with colder and brighter periods with showers, wintry on hills.

ECM 10 DAY MEAN The ECM 10 Day Mean Chart overwhelmingly maintains the likelihood that cold polar maritime winds from the West or NW around deep Low pressure to the North and a trough over Europe is the most likely scenario with the Jet stream well South of the UK. Sunshine and wintry showers and some longer spells of rain and sleet would be the common weather forecast surrounding this pattern..

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend this morning is showing a gradual favouring of a moderation in conditions as High pressure gradually feeds up from the SW next week. This trend has not got full support though yet with plenty of Atlantic driven options also shown.

MY THOUGHTS The coming days show many parts of the UK it's best chance yet of seeing some snowflakes coming down from the sky and ironically in this topsy turvy climate of ours they are likely to fall under a Westerly wind off the Atlantic. There is some very chilly air over the Atlantic at the moment and behind the current cold front and another one tied in with an ative midweek depression will see this air flood over the UK with plenty of maritime convecton giving rise to plenty of active showers especially in the west and near the coasts with snow hail and thunder all a possibility even at lower levels at times. This weather will be interrupted by a very short milder period midweek with SW gales and heavy rain before the cold re-establishes thereafter. The weekend hilds several possibilities between fine and dry cnditions under a ridge and wet and wintry weather if the UKMO is to be believed this morning. then next week there looks good evidence that the cold zonal pattern may modify somewhat as High pressure creeps up close to the SW steering the worst of the rain and wintry showers back towards the North and NW of the UK.. However with a lot of dynamics in the atmosphere at the moment there s every chance that the status quo could persist with further rain and wintry showers featuring prominently at times in a similar Westerly driven scenario. There still looks little chance of any real sustained Winter cold from an Easterly or Northerly source with Low pressure refusing to give ground in a major way to the north of the UK and the persistence of an Azores High. Nevertheless, the weather currently could hardly be described as boring with all areas seeing some interesting weather of one sort or another over the next few weeks, especially this coming week.

A risk of some significant snow from that if it were to verify.

Almost an absolute classic from GFSP late in the run - height rises to our NE gaining ground with increasing signs that an Arctic High might lend a hand. Just a bit too progressive with the Atlantic lows day 8 onward.

ECM really starting to produce the right sort of setup by day 10 with shortwaves starting to edge underneath the high. Would have been more dramatic earlier on had the main Atlantic trough not developed a SW-NE orientation. Day 11 potentially a snow event though. NOtable is LP in far-western N. Atlantic much slower than on GFSP which helps keep the Azores High well west of the UK as an amplified ridge.

It's always a bit of a lottery with those Scandi Highs, but this is not a bad time to have it lurking in the background - we can focus on near-term events rather than fretting over whether the beast is likely to pay a visit in some 12-14 days time.

Ref my post earlier, looks good for Mendips/Exmoor areas as per Ian's tweet:

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2015/01/12/basis00/ukuk/weas/15011400_1200.gif

Of course, northern snow on the cards for sure.

a rare snowfall from a southwest wind for some parts this week according to the EURO4

Frustrating! How many times I've cursed the winds coming in from just north of a straight westerly, as it funnels PPN along the N Wales coast into NW England. Frontal snow is now forecast, and there's just enough of a WSW'ly component to the wind for the N Wales mountains to create a bit of a rain shadow for here.

Still time for things to change, though.

Interesting to see that the latter part of the GFS parallel run and ECM are suggesting a pressure rise around Svalbard/Finland. Something to keep an eye out for in subsequent runs.

In the meantime an interesting week of weather to come. Quite notable that if it hadnt been for the very mild days just before christmas and last week, this winter would have below average temperatures. Not by much but we have done well for a winter which has had such a high +NAO value so far.

A snowy week to come up here, it has already started 

Upgrade on latest Euro 4 for Wales and SW Midlands:

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2015/01/12/basis06/ukuk/prty/15011400_1206.gif

A mot definite upgrade, these are the latest snow acc charts:

http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2015/01/12/basis06/ukuk/weas/15011406_1206.gif