Don't forget the NAO is only an index reflecting the synoptics you see on the charts. If the charts change so does the NAO. It's not an external input anymore than strat warming is. I think some people (not saying you) get very confused about this sort of thing. An external input would be something like solar activity which isn't factored into the medium range numerical models and arguably is linked with the weather patterns we experience.

Here's what Euro4 predicts will fall prior to the arrival of the second frontal system tomorrow. This includes what has already fallen today in the SW since noon. Quite a sharp drop off in amounts heading inland from the coasts in the affected regions, except of course where high ground gets involved.

The model develops countless areas of heavier precipitation which stream across the affected area. Their exact locations will vary around what is shown on this individual run, which is why forecasts such as those from the Met Office choose give a range of possible precipitation totals (latest values in the warnings here: http://www.metoffice.gov.uk/public/weather/warnings/#?tab=map)

Based on the Euro4 chart above, coastal counties look to be in for 10-25 mm while high ground may see as much as 40 mm.

Then the second frontal system comes along, and Euro4 makes more of this one, which appears to be due to the presence of more convective elements, particularly showers Wednesday daytime, which are still ongoing at the point the run ends.

Totals for 12 noon today through to 12 noon Wednesday:

It looks like a large part of Northern Ireland is in for a real soaker, with up to 50 mm possible from the two fronts combined.

Across England and Wales, the distribution of totals remains similar to the previous chart shown, but the accumulations now extend a lot further inland, as the fronts make more progress NE Tuesday night, after which convection initiates across much of the UK on Wednesday.

By noon Wednesday it appears that southern coastal counties will have seen 25-40 mm, while the mountains of Wales could receive as much as 60 mm. That ties in closely with the Met Office warnings, as you might expect.

Now for another take on things - the 12z WRF-NMM run:

The distribution of the areas seeing 5-20 mm is actually very similar to what Euro4 shows, but the regions with over 30 mm are larger, particularly across the southernmost counties over which the leading front is expected to stall tonight (W and NW of the Isle of Wight).

Within those regions, the model suggests that totals of 40-50 mm will be widespread. This is getting beyond what the Met Office have warned for, suggesting that WRF-NMM might be overdoing things a bit... either that or it has trended towards higher values since this morning - I did not see the 00z or 06z so can't give an opinion there.

Regions with over 50 mm projected are largely those with higher ground, with a few exceptions. One of those extends up towards my house. 50 mm in the next 48 hours would leave me with over 110 mm at less than half way through the month 

At least the model does go on to show a respite Wednesday evening through to Thursday noon, during which little is added to the above totals for England and Wales.

What about GFS then? Well, despite the lower resolution, it tells a similar story, and it throws down 62 mm onto the coastline between Weymouth and Bournemouth with 45-50 mm across Dorset and 25-40 mm across neighbouring counties. Steer clear of Bournemouth beach unless you like being drenched to the bones  

Oh and here's the accumulation for the next 6 days, which adds the Thursday-Saturday stalling front events to the above:

At this rate, the UK will start to tip over sideways  

thank you stormcasher . Very much appreciated

Ah... let's not get carried away here  but thanks, it's good to know that my weather insomnia is being put to good use 

I've just looked at the GFS 18z and it increases the draw of warm, moist air into the mix on Friday, further increasing the rainfall amounts. It's becoming of great concern for the western half of England and pretty much the whole of Wales. Scotland doesn't seem to do too badly out of all this.

I'm surprised an event-specific thread hasn't appeared by now. Might as well kick one off... 

This Mornings GFS and the UKMO have reduced the depth and intensity of next Weekend's Low Pressure and Convective Intensity, but cool and rather cloudy with scattered heavy showers and a few rainy spells added in, winds Cyclonic in General.

Then after the following Monday things do appear uncertain and quite dry and certainly quiet and brighter with some partly cloudy to cloudy weather possible, Temps will be near average not in the mild Category in Week after this weekend.

And this week plenty of wet and windy stuff as has been talked about already, Friday sees much awaited rain in London, but of course London could see showers later this Tuesday and early on Wednesday.

Prediction of Colder weather with wintry stuff not likely until we get to 22nd of November as most usual trends are at all probable given the last two decades trends.

Spot the trendsetter! I think that's the first -10c ensemble from GFS this winter for London. First of many hopefully.

http://www.wetterzentrale.de/pics/MT8_London_ens.png

A mean cooling trend here would you agree?

http://www.wetterzentrale.de/pics/MT8_London_ens.png

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY TUESDAY NOVEMBER 11TH 2014.

NEXT UPDATE WEDNESDAY NOVEMBER 12TH 08:00

THE CURRENT GENERAL SITUATION Slow moving troughs of Low pressure over Western Britain will edge slowly East across all areas tonight and tomorrow with a showery SW flow following.

MODELS-2 WEEK HEADLINE  Unsettled with rain at times across the British Isles especially over the South and West. Drier and slightly colder weather over the North and East for a time from this weekend.

THE JET STREAM ENSEMBLE FORECAST The GFS Jet Stream Ensemble forecast shows little sign of any significant shift in the flow from it's 50-55 deg North location with just varying strengths and orientation this side of the Atlantic the only changes through the period.

GFS OPERATIONAL Today's GFS operational run shows the UK under bombardment from Low pressure areas crossing the Atlantic and becoming slow moving close to the West and SW of the UK with repeated spells of rain and showers affecting the UK especially the South and West with mild Southerly winds for all through Week 1. Through week 2 the pattern is shown to relax as pressure builds, first from the North and then over the UK with fine weather developing for all with frost and fog night and morning, slow to clear in the day and as a result it could feel very chilly.

THE GFS PARALLEL RUN The GFS Parallel run carries the same sequence of events through Week 1 with the Northern High pressure to the NE collapsing later with a more direct hit of Atlantic wind, rain and gales for all as a result with Low pressure allowed to cross the UK directly at times rather than being held up just to our West in potential storminess later in week 2.

THE GFS ENSEMBLES  The GFS Ensembles are similar in stance to the Parallel run in as much that Northern blocking collapses by early next week with rain and gales sweeping the UK on a strong and occasionally stormy SW wind in association with deep Low pressure areas crossing East close to NW Scotland. Mild weather is shown to persist for all.

UKMO UKMO today shows Low pressure close to SW Britain filling slowly with time but sufficiently strong enough to continue rain and showers across the UK in a cyclonic flow with pressure quite High to the North and NE keeping the wettest weather away from these parts.

THE FAX CHARTS  The Fax Charts maintain the theme of Low pressure just to the West of the UK throwing troughs North and East across the UK. The Eastward shift is much slower with repeated waves running quickly North across the UK with copious rainfall events in Central and Western areas while there will be more showery interludes and  drier weather more generally towards the NE.

GEM  GEM shows Low pressure in total control of the UK weather over the next week as deep Low pressure drifts slowly ESE towards Southern England by a weeks time filling steadily. Rain and showers for all as a result will slowly become confined to Southern parts before a build of pressure develops High pressure over the UK by Day 10 with fine and dry weather for all then with some sunshine but fog and frost at night too.

NAVGEM NAVGEM keeps Low pressure domination across the South of the UK with a deep centre over the Atlantic drifting down over Southern England by early next week filling steadily. As with GEM rain for all at first will become more restricted towards the SW for a time before a renewed Atlantic attack returns NE across the UK later as High pressure to the North and NE collapses.

ECM  ECM this morning shows a very similar pattern of deep Low pressure making it's way down into Southern England by next weekend with rain at times for all becoming more restricted to the far South later as the Low fills in situ and High pressure to the North and NE becomes more influential. It doesn't look like holding though as the Atlantic pattern at Day 10 seems poised to make a renewed attack soon after term of the run.

THE ECM ENSEMBLES   The Ensembles point to a SW flow of some sort the most likely outcome covering the UK in 10 Days time in association with Low pressure over the NW Atlantic and higher pressure over Europe. No doubt that troughs of Low pressure will lie somewhere close to the UK delivering rain at times in continuing mild conditions.

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend today shows something of a rise in pressure from the North and NE by next week though particularly cold weather as a result of this seems unlikely.

MY THOUGHTS  There is something of an agreeance in the sequence of events through much of the output this morning. This week and next weekend is agreed by all output as the well worn Low pressure belt from Western Britain and the Atlantic persists with slow moving troughs crossing slowly East and more quickly North over the UK continuing with heavy rain at times especially in the West and South in mild conditions generally. With Low pressure then shown to fill steadily as it reaches Southern Britain early next week the North and East looks like becoming dry and perhaps bright as higher pressure to the North begins to ridge down. With no cold air to tap into we have to rely on our own home made chill from frost and fog at night to bring temperatures down to average levels for many next week more likely in the North and East. The main differences between output this morning then hinges on how successful this build of pressure from the North is in first displacing any Low pressure close to Southern Britain at that time and secondly how successfully it holds any push of the Atlantic back over Britain as the block to the North becomes displaced. It does look generally accepted between the output today that the belt of High pressure to the North will not give the UK any particularly cold weather this time as it is favoured to collapse away SE next week as deep Atlantic Low's to our NW take over and possibly deliver SW gales and heavy rain at times for all in average temperatures then. The lone cold weather flag is flown by the GFS operational in it's last few frames offering the only chance of cold from the NE possible. My own thoughts are that the Atlantic will win out after a short hiatus for some Northern and Eastern parts over the weekend and early next week with rain most likely in the South and West extending back to all areas later next week with temperatures still holding at respectable levels well out towards the end of November.

In the words of Bruce Forsythe, "GFS P2, you're my favourite".

http://modeles.meteociel.fr/modeles/gens/run/gens-2-1-384.png?0

If only it was summer!

Hot, humid and very thundery.

I really enjoy your daily analysis,Gibby, and yours and Stormchasers interpretations are always pretty accurate.

Imo model watching and accurate forecasting beyond a 10 day range is pure speculation and one can read what you want to see in them.

Given the trend that 2014 is heading to be the warmest cet on record I for one hope November comes in as another 1c+ above average month, which is looking highly likely, followed by a December like 1974 to smash the cet record this year.

As for the rainfall totals and accumulations as per Stormchasers excellent post, in my location,Wareham, we are up to 89mm before todays deluge,by the end of the week we could be up to 150mm, 6 inches in English by mid month!

Nearly a repeat of last year maybe?

We have to wait till the meto installs the super computer Deep Thought.

And wait for the answer to the ultimate forecast, will it snow next month?

I hope we wont have to wait seven and a half million years for the answer.

If that was a forcast I'd say that's pretty accurate! (as forecasts go!)

Meanwhile. Not much change if you believe GFS!

http://www.wetterzentrale.de/pics/Rtavn37217.gif

Certainly some chillier temps if verified

GFS - GSM v12.0.0 6z ran this morning for the first time on TWO. I'll make available on the chart viewer soon. 

Here's are the 384 charts from the existing GFS op and the GFS - GSM v12.0.0

Typical dull damp dark November day

I like it mild but even I want to kick the models up the backside to shift in some colder frosty but sunny weather

Couldn't agree more although it's not really that mild today in Herts. Around 11c and with the with the wind, coupled with lack of sun, it feels a fair bit less than that. It's just the permanent 9-11c 24 hours a day and greyness which is a bit depressing.

..... 41 and a half*

* well obviously it isn't 42 as that's the answer to a completely different question

This looks like trouble - the main jet stream on the GFS 12z op run is a bit stronger and a lot flatter days 7 and 8 than on previous runs. This brings more Atlantic storms to the UK and they continue to grind to a halt either over us or close to the west. Not good news for areas at risk of flooding.

For those looking for a shot of cold late this month or early next, there is a silver lining - a more energetic undercut of the Scandi High is achieved, which allows a ridge to build NW to Greenland more effectively, and that in turn supports high pressure over the Arctic better.

That then leads to a splitting of the PV, and on this run it's aligned in the right way for building a high latitude block over Scandinavia that starts off in the Arctic. This floods said region with very cold air which by day 16 is very close to the UK:

It's an interesting run in that respect, and to be honest not one I was expecting after the idea of a split PV was dropped by most of the model output yesterday. It requires a lot of luck as usual - the parallel run is similar to day 10, yet only produces a huge mid-latitude block to our east days 12-16 due to the Atlantic storms winding up big-time.

It seems like the parallel GFS has a strong tendency to power up the Atlantic jet and storms beyond day 10, which makes the current GFS look tame... if the parallel turns out to be barking up the wrong tree this time around, it will be something to really bear in mind in future.

GEM has a good go at the split PV idea but it's undone by a very strong trough over Canada - well beyond what GFS models.

In conclusion, best to sit back and let the models try and sort it out because it seems to be impossible to anticipate which scenario will eventually win out. At this time I am considering any resulting cold spell prior to mid-December to be a bonus event.

GFS12z and the Met keep things unsettled, wet and on the odd occasions windy.

General November crappy weather.

What is going on with the GFS and UKMO 12z run?.

We sit under SW Based Cyclonic Low's, with Large Greenland and N E Central Europe Blocking High.

Low's over NE USA, with High's also popping to ESE USA west N Atlantic, as Low P go over them.

Cold Low's track Across Svalbard and NE Canada - Cold Plunges in NE Central Mid USA at occasion's, and Norwegian Sea ESE Arctic Sea PV Low's tracking ESE to Affect a north NW Russia as well.

Southerly Winds to this Friday with following Saturday to Tuesday UK Low Pressure vs, High over Greenland and N Central and East Europe domination.

Mid West N Central Atlantic to across NW Europe particularly the UK heavy showers and Cool chilly weather average seasonal daily nightly temps. And The Jetstream Energy location on a Southern position Wes to East over UK West Cent. N Atlantic, this is good, so is Cold PV to our West and SW, push mild air away in Low a pressure belt.

very good sequential GFS and UKMO 96-144 and GFS further extend by 4 days ahem.

CFS end of the month into Dec (long way off) looks nippy