I just thought I'd start this thread for any posts relating to the Low pressure system which incorporates the remains of ex-hurricane Gonzalo leading to an active storm as it passes through the UK.

The Met Office has a warning out for tomorrow with mentions of gusts up to 80mph in exposed northern parts.

http://www.metoffice.gov.uk/public/weather/warnings/#?tab=map&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1413846000

It is nothing unusual for autumn but worth a mention as it is the first such active system of the season. Given that many trees are still in leaf and the combination of wind and rain I wouldn't be too surprised to see a few trees down in places. There will also be some rather rough seas especially later on in the North Sea.

Definitely worthy of a watch Michael, especially as you say it's the first decent gale of the season and trees are still in leaf.
I am pleased to say the majority of the people who enquire about the weather have not fallen for the killer storm headlines typically printed by The Express today - perhaps the message that Rao et al are basically scaremongering sensationalists is finally getting through.

It will however be noteworthy for the North and later Northeast but rain may well be the more important risk with this one given some ex-tropical air is in the mix of the open trough as it passes.

I see the GFS has suddenly decided to bring back the idea of this low pressure/ex Gazebo combo taking on a second wind (as so to speak) by running south east wards over the North Sea heading towards the Low Countries in doing so with severe north west gales in it's wake. With that to mind, it looks North Sea ferry crossings may be postponed on Wednesday morning due to stormy conditions out at sea.
  Here at Kent, it also looks like people living over the Thanet area may want to batten down the hatches and every weather-related clichés I can think of. 

I See the Met Office Yellow warning is getting lower to this area. Changed this morning.....Going to be somewhat blowy...

Okay here we go, this is another analysis on cyclone Gonzalo. Labels are 1 to 6, left to right, top to bottom. Approximate location of fronts are shown. Semi circles represent warm fronts, triangles are cold fronts, triangles+semi circles are occluded, lines are troughs, and the feather is a convergence line. Only features associated with Gonzalo are shown. 

1) Gonzalo surprisingly still has tropical characteristics by 6am tomorrow with tropical warm air riding over a frontal system which is displaced from the center of the low. While the fronts are underdeveloped  rain associated with the low itself is heavy. 

2) This is the point when any tropical characteristics still remaining have pretty much dissapeared. The frontal system is now becoming more active with a well defined rain belt spiraling into the centre associated with an occluded front. Baroclinic deepening also begins at this point 

3) Note my cold front on this diagram is too far west. The warm moist air associated with a small warm sector is riding over the cold front making the precipitation heavy and possibly even giving a few thunderstorms. The warm front is an altogether weaker feature that is giving persistent rain to Ireland and N ireland. 

4) I find the evolution of the fronts between these two pictures quite hard to imagine so this should not be taken too literally. The cold front overtakes the warm front to produce a cold occlusion. Precipatation will be particularly heavy around the triple point just south of the centre of the low which is now secondary to a system further north. Further south however both the cold and warm front have weakened, the warm front is likely to produce lighter rain for southern England and the cold front will produce a much narrower band of showery rain. In the north though the picture will be miserable, winds will be picking up to about 50mph sustained around the triple point.

5) The warm sector is completely displaced to the south indicating the low is going past its prime and the outflow is ceasing allowing the low to start a filling process. The triple point will still be active, however precipatation is likely to be weakened by the pennines; while Cumbria gets a poor show, the rain will clear through quickly for more southern areas. To the north the occluded front bends back towards the low taking a heavy shower band with it. Along with the rain the winds will continue to pick up. 70mph sustained from the NW is possible in E scotland briefly at this point, just to the south of that low. In the south, behind the weakning cold front, several troughs mark some very unstable air. The troughs give a good estimation about where the heaviest showers will be. Soft hail and the odd rumble of thunder here is not out of the question.

6) As is rather typical with a weakning low, things get more complicated here. The occluded front is starting to break up, and any persistent rain will fragment into heavy showers. Conditions will be very nasty in E scotland with showers, squalls and gales. There is also a risk of swelling as the low passes over the N sea, this could be a problem for E anglia later. In the west the showers continue, the precense of a convergence line indicates the possibility for some very slow moving heavy showers in SW scotland - however some areas will miss these completely and enjoy sunshine. In general the showers will become more isolated, though there will still be some heavy ones. 

To sum up.

Wind risk: Scotland, particularly the East where 70mph sustained could briefly be recorded. Gusts possibly 90mph. Generally sustained 50-60mph with gusts 70mph. Squalls possible also on the cold front (particularly at first) and the occluded front (throughout) as it passes through, biggest risk here is N ireland, NW England and possibly NE england. Squalls possible in heavy showers in the west and south west later.

Rain risk: Ireland will see a very active cold front to start off with, and the triple point will produce heavy and persistent rain for most of scotland and NW england later. Wrapping occluded front will make the rain the most persistent over NE scotland where there will be a transition to showers rather than dryness. Heaviest rain expected in N ireland, S scotland and the Higlands. Risk of heavy showers later in the W and SW but these will be localized.

Snow risk: Showers will readily turn to snow over the highlands as the frontal system goes by. Snow level 800m at first on the back edge of the occlusion, falling to 200m generally by the afternoon in central and northern parts of Scotland. In the heaviest showers in central scotland (best chance 6pm) the odd sleety flake may be visible. But snow mostly restricted to above 400m where blizzards will be likely as the winds will be strong particularly in the hills. 

If anyone has any good webcam links for later tonight/tomorrow please post them as they could be an interesting watch :)

Thanks doc.

Anyway, just to illustrate that this system is still partially tropical. Here is a cloudtop image where you can just about see the eye! The brighter the colours the colder the clouds, hurricanes have cold eyewalls because the clouds extend very high into the atmosphere.

The eye is quite clearly visible here! The eye wall is also shown. The frontal system at this stage is well displaced from the centre of the low, again illustrating its partial tropical nature, as it moves towards the UK this will change rapidally as the storm completely looses what tropical nature it has left. 

900ft asl here north of Aviemore good chance of something sleety falling tomorrow afternoon/evening 

In the last couple of hours the eye was completely blown outside the storm, presumably by high wind sheer, its sad in a way to see it loose the last of its tropical characteristics. I advise people to look on cloud top and IR satellites earlier today, the eye and eye wall were remarkably visible!

I should like to add too, thanks for the analysis Q - very detailed. Very Bren J like, and very informative 

Looking forward to it myself. Heading West tomorrow morning too, so hopefully see some action 

Surprised there are no rainfall warnings out, as we are forecast upto 40mm, but i guess this is due to all of it falling overnight when most folk are in bed

 LLTNP 105m asl 

Yes indeed. I love reading pre-event analyses on here. Very interesting and educational. Watching the Shulista weather page with interest!

Expected rain amounts seem trivial in NE England but not sure about the wind.
It was gusting around 40mph yesterday so I suspect were it not for the ex-hurricane hoohaa this won't seem much different - a typical Octoberish spell.
More serious further north and west though.
The change to colder conditions in the afternoon will be notable with quite severe windchill.

Thanks everyone I appreciate the compliments.

Anyway the eye is back! If it was tropical I would call it an eyewall replacement cycle. 

I think my warm front there is too far east, its not easy to get it right on these cloud level maps. The stuff in front of that is just high cloud garbage from a weak occluded front I think. Anyway the storm is weakening and the occluded front does seem to be getting closer, but you can still see a distinct eye and eyewall. Usually on a midlatitude depression, particularly a young one like this, that area is the domain of the cold conveyer belt (just behind the cold front), so its usually actually a really dry area with no showers, and the bands of showers are adjacent to it. However we still have some convection managing to maintain the remains of an eye wall and an eye! There must still be some tropical energy here, I said earlier that it would be 6am until it looses the last of the tropical characturistics, that seems about right.

Note: this is not a tropical system of any sort, it isn't even sub-tropical at this point; but it does have some tropical characteristics, so its not 100% mild-latitude either. It will be interesting to see if we can see the eye and the eye wall on the radar. 

The precipitation on the current radar is nothing like the MetO computer protection for this hour that was used on the evening broadcasts. 

Okay I think I can see it, I've quadruple checked that this is correct, its all to easy to label any hole in the precipatation an 'eye'. But I'm pretty sure this is it.

It doesn't look like much (and one might be forgiven for naming the empty area to the south of it), but hopefully it will look more impressive as the radar picks it up when it moves further east. I'm amazed such a feature is just about visible, but I tracked the storm from Newfoundland and I'm pretty sure that's the centre. 

It also agrees with the models:

Unfortunately as the system hits land, whatever convection is still left will be destroyed. Perhaps there will be one kwl radar image of the 'eye' before it hits the land. 

Wow this one is more impressive:

Its starting to look much more like an 'eye' now with the precipitation looking more like shower bands (look at that little shower right inside the eye). I think its too much to hope we will get a full circle, but I've got my fingers crossed. Eye heading for outer Hebrides. 

Time lapse of approach of storm

http://www.youtube.com/watch?v=wlPf4Z-q33s

Nice one Kev