stodge

By any sense, an extraordinarily powerful storm for this stage of the "season". 917 MB in November is matched only by the 1932 Cuba Hurricane and I fear the damage and loss of life from this will be considerable. This has developed from almost nothing in six days. Let's just hope it's not as destructive as Mitch was back in 1998 - the damage then was caused by days of uninterrupted rainfall from a slow-moving storm.

Evening all Well, it's all been said, it would seem. The GFS 12Z OP and Control are certainly heading in a very different direction and if GEM went beyond T+240 it could be very interesting. ECM at this stage doesn't want to know and the build of heights into Scandinavia at T+192 just isn't sustained as the Russian HP is too far to the north and east. This looks to be the critical point - T+216 tonight - so really still very much FI and reliant it seems on the continuing disconnect between the stratospheric and tropospheric vortices.

Evening all The step away from a colder blocked outlook last evening was considerable but we move on and as someone has said elsewhere, cold weather in mid November isn't that important - we want to see it in mid-December onward. So, to tonight's NH profiles at T+240: ECM, GEM, GFS OP and GFS Control respectively: Fairly broad agreement to this observer but while some may feel the charts don't show much, I beg to differ. ECM, GEM and GFS Control all have a large storm moving over the Pole and to the north of Siberia. This seems to take a significant chunk of PV energy and what's left is weakened by this - the response further into FI is to allow the HP over SE Europe to move back north toward Scandinavia. GFS OP is perhaps least favourable to this scenario keeping plenty of energy over Greenland but the other models keep reasonable heights to the NE of the British Isles. The outlook toward mid-November seems quite benign - dry for many with chilly nights and reasonable days. As a thought, we've often had the Azores HP setting up close to the UK in November but at the moment it's not a player which may offer some hope down the line for amplification but it's a waiting game as usual.

Evening all The tenor of above posts doesn't really need me to put up the T+240 NH profiles but I will anyway: That's ECM, GEM, GFS OP and GFS Control from 12Z Hopes of the PV decamping to Siberia have now been put on the back burner and it's very much the same old story. The strong storm moving across the Pole causes the HP to sink south and kills off any prospect of advection of colder air from the east and the Atlantic takes over. GEM offers a hint of ridging to the north of the British Isles and ECM's block might be more resilient beyond T+240 than seems the case but it's not a great prospect of fans of cold conditions moving into mid month and beyond.

Evening all I wasn't sure of the evolution looking at last night's 12Z models but as a wise man once said, "tomorrow's just another day" so let's see where we are tonight: Similarities but also subtle differences between the ECM, GEM and GFS OP at T+240. Both ECM and GEM build the HP over Southern Scandinavia but the GEM HP orientation draws a warmer SSE'ly feed with the ECM threatening more of an advection of frigid air. GFS OP has the core of the HP further to the NE - it's a proper HLB and the potential for advection is obvious but it looks too far to the east for coldies. Looking at the PV profile - ECM has an elongated lobe suggesting a transfer of energy to Siberia which would help hold the Scandinavian HP in situ. GEM has plenty of colder air over Siberia with the vortex core edging further into Canada. GFS OP keeps a strong PV in its usual place but a lobe has detached into the Atlantic. GFS keeps the Atlantic most active and the profile doesn't look the best for cold to this observer with too much energy. ECM looks the most promising with the Atlantic quiet and a possible energy transfer across the Pole.

Evening all As the stratosphere thread becomes more animated, are we looking at a more "interesting" spell of mid-autumn weather? Looking at the T+240 NH profiles for mid-month tonight: 12Z ECM, GFS OP and GEM: I'm not seeing the optimism for a change others are. For a second successive evening, the PV seems to remain entrenched in its usual place. Perhaps a hint of the vortex moving back over Canada and that may be enough to encourage height rises over Scandinavia (and GFS OP takes that much further in FI bringing the Russian HP west as a significant blocking feature). The question of whether we'll get s genuine HLB or a variation on the MLB remains to be resolved. There seems too much energy in the northern arm on ECM to sustain true HLB. We really need to see some energy swinging south to help support the HP otherwise it will inevitable sink south over eastern and central Europe.

Evening all After yesterday's GFS 12Z offering which got everyone very excited, let's see what this evening's output provides in terms of similar: The NH profiles at T+240 from GEM, GFS OP and ECM The "clean" break for the PV from its usual home seems to have bene put on hold with substantial residual vortex energy around Greenland though ECM is the most interesting in that the PV is angled more toward Canada allowing heights to the north of the UK while both GFS and GEM take the height rises to Scandinavia. GEM digs the trough well to the west of the British Isles but all the output has a quieter Atlantic and certainly the zonal train is in the sidings for the moment. The ECM and GEM profiles have a shift of PV energy to Siberia and the ECM in particular has the two vortex lobes positioned ideally to allow height rises from the Pole south to the north of the British Isles. There's a hint of this on GEM but GFS OP has the more traditional Scandinavian-NW Russian HP which can be intense and often frigid in midwinter making it very hard to shift. Further into FI, the GFS OP development is fascinating with the PV diminished and heights over both Greenland and Scandinavia and the trough digging to the south-west (the GEM hints at this at T+240).

Evening all We may be heading toward lockdown but this site is heading toward meltdown. I imagine the GFS 12Z OP FI has got many salivating - it's classic retrogression and were it mid-December rather than mid-November and at T+24 rather than T+348, apart from those claiming it was a "downgrade" and could still go "mammatus verticus", I imagine the snow-chasers would be heading to the lamposts. Anyway, this is as irrelevant as a hat-stand in a Transformers movie so instead I'll focus on the medium term and the NH profiles: 12Z ECM, GEM and GFS OP at T+240: The key seems to be whether we can get a "clean" displacement of the PV toward Siberia. GFS OP and ECM just about manage it though GEM doesn't going instead for a more defined polar ridging profile which suggests Scandinavian heights rather than Greenland heights. It's perfectly possible as 1962-63 showed to have a strong PV but for it to be oriented to enable heights over Scandinavia. It really needs the core of the PV to be pushed further back into Canada rather than to Siberia and the latter is the key to Greenland height rises and all the fun of retrogression which then brings the trough into Scandinavia. At T+240 of course one can only note words like "potential". The form horse looks like heights to the north or east of the British isles at least initially. I'd also argue those arguing for retrogression should be careful what they wish for - it's a fine line between a successful transition to a cold N'ly or NNE'ly and a west-based negative NAO which will get you the Greenland heights but a return of milder air.

Evening all Well, I'm sure the GFS 12Z OP FI has attracted plenty of attention. The NH profiles at T+240 this evening: - GFS, GEM and ECM respectively. One lobe of the vortex is where you'd expect it to be while the other is over Siberia (again as you might expect). Not quite sure what to make of it at this time but I'm not really seeing a raging Atlantic and a zonal train. Hints of heights over Scandinavia but nothing substantial.

Evening all Interesting contrasts between the 12Z models on the Northern Hemisphere profile. GFS OP keeps the PV in its usual place while GEM moves the PV over to Siberia and ECM significantly weakens it in situ. GEM and ECM look similar while GFS OP is very different - take your pick or if you play ice hockey, take your puck.

Evening all Strong build of HP from the south-west more or less certain next week so, as others have said, perhaps a "traditional" early November spell of fog and frost by night and sparkling chilly sunny days - we'll see. From there, plenty of possible evolutions - I note both ECM and GFS in FI are looking to break the PV from its usual home in NE Canada and perhaps send it over to Siberia which is always welcome by those who want to see colder conditions. The Northern Hemisphere profiles from the 12Z GEM OP, GFS OP and ECM at T+240: ECM holds the HP over south west Britain while GFS OP has transferred the HP east and GEM has a ridge with the PV perhaps moving over the Pole. Plenty of interest as we move through the first half of November.

Fairly predictable early autumn fare as others have said but broad signals for a rise in pressure into November with the HP ridging through the British Isles so a period of settled conditions lasting 7-10 days looks likely in the early part of next month.

The key player seems to be Hurricane Epsilon which is an intense beast which may cause Bermuda some problems but mercifully is nowhere near any other land. It keeps a fair strength as it transitions to an extra-tropical feature and is absorbed into and causes severe deepening in a run-of-the-mill North Atlantic LP. This tropically-enhanced storm becomes a significant feature introducing plenty of energy and throwing the HP forward into Europe. The central pressure seems to be around 950MB (ECM, GEM) or 945 MB (GFS OP) but that strength of storm generates secondary features which can themselves deepen strongly as the sub-tropical and polar airmasses meet giving the UK rain and strong winds. It's called autumn. One of the consequences of the infusion of energy is to pull the jet north and that allows HP to build across southern Britain and NW Europe and we see this hinted at on GFS as it has been from Exeter. I wonder if further into November we'll see the Azores HP cell and the Eurasian HP bloc dominate with the UK left in a ridge between the two with light winds (fog, frost under clear skies) and sparkling mid-autumn days. Often the HP transits to the east with time as the Atlantic eventually breaks through from the west.

Not quite sure what to make of the evening output. A lot seems to depend on an ex-hurricane finally allowing the Azores HP to ridge into Europe and re-aligning the trough positively toward month end and off goes the Atlantic express powered, as is often the case at this time of year, by energy from ex-tropical features.

The temperature profiles "suggest" a strong block over western Russia feeding S'ly winds through eastern Europe into Scandinavia leaving north-west Europe on the cold side of the trough so more N'ly or NE'ly winds and that explains the increased probability of colder and wetter (snowier on the highest ground) outbreaks. I have to say I've seen more unsettled GFS 12Z runs but not that many - a dismal rest of the month with a lot more rain and only the briefest of drier interludes. GEM plays a different set of cards as it did last night with the HP bloc moving further north into the far NW of Russia allowing some early cold air to come further west than you'd expect. As others have said, we have the wildcard of renewed hurricane activity - GFS brings a powerful hurricane across Cuba and Florida and up the east coast becoming a strong ex-tropical LP - this is often how the Atlantic jet gets fired up at this time of year. GEM keeps the hurricane out at sea as a weaker feature but brings it NE further south so we'll see. ECM rolling out now and again the themes are northern blocking and negative alignment.

Have to say the ECM evolution from T+216 to T+240 stretches credibility for me a wee bit. 12Z GFS OP and Control restore a much more traditional autumn pattern in far FI - the first cold plunge down the east coast of North America fires up a very deep LP and the jet and off we jolly well go...

Evening all It seems certainty has gone out for the evening and left confusion in charge. Relative unanimity among the models yesterday evening has been replaced by disagreement. GEM has completely abandoned the LP to the SW and the warm S'ly scenario: What happens is the main LP moves too far SW - past the Azores - and the link to the northern LP breaks and the latter slips down across the British Isles. ECM at the same time still on-board with the warm S'ly albeit, as we saw yesterday, the infusion of sub-tropical air from the south invigorates and deepens the LP which quickly pushes away any warmth. 12Z GFS OP at the same time. The thing that catches my eye is the LP sneaking between the two HP cells in the far west of the North Atlantic. That moves across and adds extra energy pushing the trough over the UK as part of a complex feature. Plenty still to resolve.

And the price for that infusion of sub-tropical air:

Early indications of a more settled spell by the middle of the month but with the trough over Europe, HP doesn't set up in a place to bring warmth. Whether it's to the North or North-West, it looks as though the SE will be plagued by a chilly breeze and it could be a traditional autumn HP of fine sunny days and foggy, frosty nights.

Evening all Perhaps just a hint of the pattern easing in FI this evening but no clarity on the possible way forward. GFS 12Z OP builds HP to the north whereas ECM builds the HP through the British Isles. GEM also settles things down from the west.

Afternoon all The quieter period in the hurricane season isn't going to do us any favours in the near term. We rely on the infusion of energy from these ex-tropical features to shake the pattern and to (ideally) build the Azores HP over the British Isles. GFS FI charts (and outliers) notwithstanding, the pattern of strong heights over Eurasia wouldn't be a problem in and of itself but the orientation of the block toward Scandinavia and the Arctic forces the LP trough SE over NW Europe and the British Isles and keeps the Azores HP as an irrelevance to the far SW. The 06Z GFS OP offers a possible way out as the LP withdraws NW and re=aligns positively allowing the Azores HP to build back again toward Europe. That's the logical evolution - the other option is to have the trough move cleanly through NW Europe and allow the pattern to re-set behind though I note again the tendency for heights to build NW across Scandinavia and to our north which would re-align the pattern but keep us far from settled with the jet moving across or just to the south of the British Isles.

Yes, no real change in the overall pattern with the heights actually moving NW into the Arctic so we see the trough being squeezed fractionally to the SW - not a great help for the British Isles to be honest.

Yes, the block is too far east to offer the possibility of the trough sitting out to the west of the British isles and allowing for a S'ly flow though GEM OP this evening keeps the HP a little closer to Scandinavia and is certainly the direction of travel you'd want to see if you fancy some autumnal warmth. Otherwise, it looks distinctly unsettled and often quite wet. GFS OP and Control in far FI try to re-set the pattern by having the LP dive south east through the British Isles allowing the Azores HP to build in between but that's too far off to be anything more than wishful thinking for now.

12Z ECM at T+240 following the trend: The block over NW Russia forces the trough SE through NW Europe and down toward the Med. LP developing over Greenland and Iceland slide SE - unfortunately, the block is too far east for us to get a warmer S'ly flow which is what often happens in the European autumn as the LP digs south to the west of the British Isles. This year, the synoptics at least for late September/early October aren't so promising. If the block can build slightly more to the west and we advect a S'ly flow it's perfectly possible to see 25C in October but not from this chart.

Evening all 12Z ECM still rolling out - 12Z GFS OP not much to look at if you are after more settled weather. The strength and persistence of heights over NW Russia leaves NW Europe in a difficult position as it becomes the home of the trough and negative alignment becomes the name of the game as successive LP come down SE from Iceland/Greenland. 12Z GFS Control is a little better as the LP are able to pull away NE and the alignment is positive so heights rise to the south keeping the air flow mainly TM. 12Z GEM isn't too far from GFS OP but the HP is over Scandinavia rather than NW Russia but the net effect is similar. The problem in microcosm: The LP cannot ease east as there is a strong ridge in the way, nor can it go north for the same reason so it becomes static over eastern Europe with the British Isles on the cold flank so we get a chill NNE flow. The trough stops the Azores HP coming in so it aligns negatively opening the door for the next Atlantic LP.