stodge

The 06Z changes little - even the Parallel joins in with some serious retrogression. Had that LP to the west of Norway come SSE rather than SE it would have been perfect for some late April snow. The OP conversely ends pleasant as we get an increasingly SE flow off a warming continent while Control in low-res shifts the block far enough north to allow the trough to take over the British Isles so a changeable end after a settled spell.

Morning all An interesting start to the week - having looked as though the E'ly might not last too long the main outputs are much more bullish this morning about a continuation into next week and perhaps beyond. It seems as though an intensifying Scandinavian HP will hold off the Atlantic LP which will then fragment ESE maintaining the E'ly flow. GFS 00Z OP is a thing of beauty in low-res with a Greenland HP setting up and a good old fashioned late winter cold blast incoming from the NNE - almost perfect, Parallel beings back a westerly flow while I note GEM also teases retrogression at T+240. ECM and UKM are fairly close at T+144 but UKM maintains a stronger Atlantic profile so it all looks very precarious for E'ly fans. ECM keeps a strong Scandinavian HP with a ridge through to Greenland but it's a warmer SE'ly over the UK by T+240 so much more pleasant. Taking the ECM and UKM evolutions, I'd have a look at the 00Z GFS Control and see if that's where ECM might be heading after T+240.

Afternoon all I thought after the ECM 00Z we would like a general lifting of the threat of colder air for next week but the GFS 06Z OP and especially Control are superb output for cold weather fans not just in terms of severity but longevity with sub zero 850s lasting several days so cool, if not cold conditions and plenty of prospect for wintry convective activity. Looking through the 06Z ENS, some agreement for maintaining an E'ly sourced air flow right out to T+240 with only a couple of members trying to being back the Atlantic. Not all the runs are cold with some bringing in warmer 850s but that's a detail to be resolved. After T+240 much more scatter as you'd expect so we'll see but certainly a strong possibility after a slightly milder weekend of an increasingly chilly regime during next week.

Yes this isn't January and we can all go on about we wish it was but it's not. However, for model watchers the synoptics are unusual though not unprecedented and temperatures well below normal (while not to everyone's taste) are as noteworthy as temperatures well above (which a lot of people enjoy a lot more). Oddly enough, it may be the strength of the chill next week which undermines the E'ly in terms of longevity. As the HP squeezes down from the north and forces the airflow to a colder NE'ly it causes the mid Atlantic LP to stall and that in turn raises heights further east turning the flow to a much warmer SE'ly direction. Watch the GEM evolution for an example of that. To keep the E'ly going you need to keep the Atlantic LP flowing ESE into Europe.

Apologies, Matt. For some reason I assumed the UKM 12Z updated at 4.30pm and it had updated. Here's the 500HPA chart for T+144: ENE'ly flow from Scandinavia so probably pretty chilly. Confirmed by the 850s:

UKMO bringing in the colder blast for next midweek: Like many Easterlies at this time of year there's an initial warming phase as air from further south is picked up in the flow having moved round the trough. After that, the colder air from points further east comes into the flow so you get a much colder segment. Those who recall the B from the E last year - the really colder air came in two or three days after the initial set-up and that's how easterly patterns behave. In the same way, easterlies are often initially cloudy as warmer, humid air is the start of the flow before colder, drier, clearer air spreads in.

As others have said, some very cold (for the time of year) options in the 06Z GEFS and Control, in particular, would have -8 850s widely over the British Isles. It's interesting to watch the cold pool develop over southern Norway and head WSW in the flow. Obviously a source of instability so we could see some heavy showers with hail and thunder and obviously snow to higher (and perhaps at times) lower ground. Once again, the trend (as on the 00Z) is to cut the easterly off at the end of next week as pressure rises from the SW and sends the jet back north but interesting to see both Control and Parallel suggesting any warmth could be short-lived. IF the Azores HP remains to the west it would allow the trough to sink SE into Europe and we might be returned to a cold NNE'ly (parallel). The other route (less likely) is if the Azores HP stays too far west and ridges north toward Greenland. OP brings the Azores HP in much closer and keeps the Icelandic LP well to the north and east so while we might see a WNW'ly it wouldn't be anything of note.

Morning all The key to breaking the E'ly won't be an Atlantic LP but the Azores HP returning to the scene and ridging north pulling the jet back north with it. Very confused modelling this morning from the 0Z suite in my view with a lot of uncertainty as we approach mid month and beyond. I note Mr Beard's comments with regard to the EC ENS clusters and he may be right. The problem though isn't from the north, it's from the south.

Afternoon all As others have said, the Easterly looks set for next week after an unsettled, chilly and showery spell to end the current week. ECM teases an ENE'ly with a strong east-based NAO and as ideal a Greenland HP set up as you could ever want. Other models aren't wholly convinced in FI - GFS 06Z OP maintains the E'ly flow for most of FI and we have the unusual synoptic of an area of LP moving east to west across Scotland and indeed the medium term synoptics are reminiscent of the synoptics of the B from the E last March. 06Z Parallel shifts the E'ly to a NNE'ly at the very end of FI and it's how the models profile the LP in mid-Atlantic that provides the clues. IF we get a deep cut off LP over or near the Azores, we might well see a warm SE'ly set up but if the LP is shallower and extends into western Europe as a trough, it's more of an E'ly flow as the heights remain to the north. Control goes its own way and brings back the Atlantic and it's fair to say the GEFS diverge widely as you'd expect in the medium term though the northern blocking scenario remains the majority call on this output at this time. GEM keeps the Atlantic LP further north so the E'ly soon collapses. As for the strat and the PV, not too many surprises for April. The OP develops a weak warming from the Eurasian side in far FI which would suggest perhaps a return to a more Atlantic-based regime later in the month. It's also worth that both OP and Parallel, having chased the coldest air out of Greenland by T+240 show a return of -24 uppers at the very end of FI which again would suggest a weakening of the Greenland HP and a return to a more traditional pattern but this is a very long way off.

Afternoon all The output continues to point to an Easterly wind-flow becoming established next week. Nothing too cold - indeed, could be quite warm for western and north western areas with the greatest risk of showers for southern and south-western areas. 06Z Parallel keeps the core of heights to the north of the British isles throughout FI so an E'ly flow is maintained but as the HP centre migrates first West and South West into the Mid Atlentic, we then see a hint of retrogression as the air flow turns to a NW'ly and a large LP moves toward Scandinavia. 06Z OP keeps heights to the NE of the British Isles throughout FI so an ESE'ly flow tending more E'ly with time but fairly benign stuff in all honesty. 06Z Control eventually weakens the E'ly as LP becomes established in mid-Atlantic bringing in a much warmer SE'ly air flow so some pleasant conditions on offer. The GEFS are strong about northern blocking but less so about its location though there's clearly a signal for blocking over Greenland as we near mid month. That then offers some cold perturbations at the very end of FI but that's a very long way off. Just worth noting GEM 00Z at T+240 very much in line with GFS. The 10 HPA number show the slow but predictable waning of the PV as we move into April and the polar night jet fades away. The new core of coldest air shifts to Siberia as warmer air finally moves into Greenland.

Evening all For those who like unusual or interesting synoptics, tonight's 12Z output delivers in spades with GFS OP, Control and Parallel all suggesting a spell of E'ly winds as we move into April. The OP is surprisingly the chilliest with the core of heights shifting to Greenland in far FI and introducing a cold NE'ly airflow for mid month. The trough looks like dropping south through the British Isles at the end of next week and after a wet spell, especially for the south, the rising heights to the NE draw in the E'ly flow. 12Z GEM joins the E'ly party as well. UKMO is a little more reluctant as it holds the heights further back with a chance for the Azores ridge to move back in and keep things more Atlantic-biased. These are classic "early spring" charts as the PV relaxes and the cold air to the north is able to filter south and we see the battle between colder and warmer air masses which is characteristic of many Aprils and Mays. We know the warmer air will prevail but the struggle often produces some of the year's most interesting weather and synoptics.

If you want to get yourself really upset, run the Parallel from 192 to 384 and imagine it was January rather than April and try to work out how much snow southern England would collect in that week,

More like the GEM 00Z but the heights build first from the NE, transfer SW and then start to retrogress so we get to our mid month cold spell (-8c 850s over northern Scotland in deep FI)

Morning all Yes, a very much more interesting look to the model output this morning with GFS 00Z OP, Control and Parallel all featuring Easterly wind flows in Fi. ECM gets there a bit quicker but so much depends on the behaviour of next week's trough. GEM 00Z gas the trough just to the east allowing the very strong and displaced Azores HP to throw a ridge back across southern Britain. On other models, there's time for the Scandinavian HP to build from Eurasia and for the trough to evolve into a European feature maintaining an E'ly or ESE'ly flow. Nothing too cold to be honest and indeed OP is on the warm side and this is the difference at this time of year between an ENE and an ESE - the former draws the air from Scandinavia and can still be quite chilly but the other is drawing air from much further south and this has already warmed. Cold fans need to see the core of heights shift west to sit to the NW of the UK but I suspect that won't happen. These are T+192 on GFS 00Z Control, OP and Parallel to illustrate the differing evolutions - all lead to an E'ly but with variations as you'd expect. ECM and GEM 00Z at the same time for comparison: Perhaps worth noting GEM holds the trough a little further north and has the Azores HP a little closer. Also worth noting the Parallel evolution doesn't so much build heights west from Scandinavia but east from Greenland.

Afternoon all Once again, some interesting twists and turns as we move into April. The 06Z OP goes into classic retrogression with what would be a very chilly NE airflow as we approach mid month. The Parallel sets up a pattern where lobes of the trough are dropped through the British Isles to the south between heights to the NE and SW. Control also retrogresses the HP to the NW setting up a fairly benign ESE'ly flow. ECM threw the proverbial cat among the metaphorical pigeons this morning with the trough not dropping fully to the east but moving back NW across the British Isles (plenty of rain you'd think) and ending up with a pattern slightly reminiscent of a west-based negative NAO but I simply don't see why the LP should pivot back NW. There's plenty of spread in the 06Z GEFS but if I had to call a form horse at this time I'd suggest ridging of dome form to the west or north west but that's as far as I go. The Parallel continues to weaken and warm the strat in advance of the OP but both now show the coldest of the air lifting north through Greenland and indeed Parallel sets up a new cold air to the north of Siberia indicative perhaps of the vortex destabilising as the final warming takes hold.

Afternoon all :) The morning's ECM 00Z was a kick in the teeth for cold fans and there's no point sugar coating it. A glancing blow looks the best on offer for those looking for a serious Northerly or Arctic outbreak next week. What we do have though is a rare degree of agreement across the major models going into the new month and beyond. As the current HP weakens and retreats east, two more cells take its place and while centred a tad further north and allowing a light E'ly to affect southern areas, it's the next HP cell coming out of CONUS this time next week which is catching my eye. It takes up residence in mid Atlantic but at T+240 with the ridge across the south of the British Isles but OP, Parallel and Control are all similar in weakening its influence and holding it out west. The OP develops a trough over the British Isles while both the Parallel and Control hint at retrogression with the trough dropping down either into NW Europe or Scandinavia. Either way, the airflow shifts to North or North East approaching mid month which is far from unusual in April. Just to add GEM 00Z OP isn't far from it either so there may be a signal developing for some form of mid Atlantic ridging as we move further into April. The PV continues to weaken as you'd expect and the 06Z Parallel posits a shift to the Siberian side in far FI which would obviously support the retrogression indicated in the 500HPA forecast. Control goes even further with a significant displacement allowing for significant height rises over Greenland. It's all a long way off but it's not an atypical pattern for April/May so a colder period with northerly or easterly domination remains a strong possibility as we move into April.

Afternoon all Plenty of teases on the models in low-res but the first question is will the Arctic push early next week? Some form of N'ly is clearly the majority call on the 06Z GEFS at T+168 but it's far from a done deal. From there the synoptics in FI get very interesting with heights to the NE and low heights yo the south developing as either the trough drops down into NW Europe or the LP over Iberia expands and creates a new European trough. Both relate to the winding down of the PV - the Parallel is more bullish then the OP as usual. OP and Parallel in far FI a negatively tilted trough with the core through the British Isles but over on the Strat thread Gray Wolf has argued this is all wrong and we will be in a warm S'ly flow. I'm not convinced - the form horse looks to be a N'ly or cold E'ly incursion before a sudden shift to a much warmer airmass (a SE'ly perhaps?)

Afternoon all Indications of a relaxing, warming and weakening PV on the 06Z Parallel and mirrored on the Control see mid-Atlantic ridging and the trough dropping SE across NW Europe and the British Isles. Those which hold the PV in place keep flattening the Azores LP east into Iberia or France and hold a relatively mild pattern. The 10HPA temperatures rise to -56 in early April as the final warming (or at least a return to more normal conditions) develop and the zonal wind eases too allowing amplification in the Atlantic. It may need repeating but if you want unusual synoptics and a N'ly or E'ly your best chances are April and May as the warmer and colder airmasses mix and meet and the winter set up relents. Cold 850s in April usually mean convection and that can mean heavy thundery and wintry showers with hail and snow to higher ground and large temperature variations during the day as showers pass over (and with calm surface conditions quite intense downpours can result). Needless to say as the warmth of the day relents frost and fog take over and quite sharp frosts are still possible well into April even in southern lowland areas. The other player is the falling heights to the far south over Iberia and North Africa. These are not unusual and indeed a precursor to summer but if we see a significant LP develop that will force the Azores HP to ridge further north and north east offering an E'ly which would being cool gllom to eastern and southern coasts but warm sunshine to northern and western areas and a risk of thundery showers to the far south over time. This is another aspect of mid-Atlantic ridging and the declining PV which sees heights rise in the ocean but fall over southern and south western Europe.

One or two interesting bits and bobs around on the 12Z output. The very well-forecast anticyclonic spell is upon us but may not prove as durable as earlier forecasts had hoped with another push of Atlantic air into next week. The successive HP cells seek to re-enforce the settled weather especially but not exclusively the south but in the early part of next month we are starting to see some signs of a pattern change. It does finally look as though the PV is weakening and the cold air is being washed out of NE Canada which in turn slows the Atlantic and allows for heights to build elsewhere. One option is to see the trough spread down from the NW: The parallel goes somewhat further: The Parallel in particular is weakening the PV very sharply into April with the vortex warming and starting to split. Slower, it has to be said, on the OP. As we know, if you want an Easterly, April or May is the most likely month so nothing desperately unusual as yet. but it's also the time of year with the most interesting synoptics.

Morning all :) The signal for rising pressure from the SW continues unabated this morning with a strong MLB forming close to the British Isles in the last week of the month. At this time of year HP can still mean fog and frost early and late and as we saw late last month some noteworthy diurnal values. The PV continues to slowly weaken as you'd expect, reducing in size with the 10 HPA temperature rising slowly as well. By month end the coldest air is lifting out of North America with the Atlantic slowing as well.

Afternoon all :) I'm struck by the unremitting strength of the Canadian PV in the output this morning. Signs of the PV lobe draining away or moving to Siberia seem to have been erased in the form of a strengthening in the Canada/Greenland area (perhaps due to some faint Wave 1 warming from the Eurasian side which would trigger such a consolidation). The problem for the trough diving down into Europe is a small cut-off LP in mid-Atlantic which forces the Azores HP to ridge further east back across Iberia and France so the LP can't dig too far SE. There's also (as per Exeter) a signal for rising pressure later in the month (the GFS 00Z OP rises pressure from the NW which would be interesting) with the more likely option rising that pressure from the SW so warmer, drier and more settled as we head toward month end (again, as you'd expect). With the 10HPA temperature of the PV declining only slowly, it looks currently as though the PV will slowly dissipate by end April so nothing too dramatic.

Just to observe GFS 12Z OP, Parallel and especially Control all putting some form of northern blocking on the table later in the month. See if this is a trend in the days to come.

Afternoon all The 06Z GFS output raises the Stodge eyebrow another notch as we head toward mid month as the Azores HP withdraws further and the jet oscillates to the south of the British Isles. The OP introduces some seriously cold air (-8 850s) and the Parallel isn't much warmer. We know snow can settle in mid March so still a chance for some spring snow for many and especially anywhere to higher ground with the Scottish mountains looking set for a succession of blizzards. This is a pretty cold air mass profile for mid March. The Mean for T+240 indicates some solid agreement at this time for a more NW'ly element to the airflow: Worth noting the Parallel looks to be setting up a Wave 1 warming in the second half of March which would be interesting if it were sustained but with the zonal winds at near record levels for the time of year it's going to need something pretty dramatic to disrupt the PV. Plenty to keep the cold fan interested over the next couple of weeks.

Two observations - first, I agree there's little prospect for lying snow in lowland southern Britain but I think the current set-up and especially next week does offer prospects for snow to high ground in many areas. Second, the PV, as you say, continues almost as if it were mid-winter rather than early spring. However, just the very first signs on the 12Z output of a new burst of Wave 1 from the Eurasian side after mid month. As was discussed last night, the question is whether the final warming will be slow and unremarkable or whether we could see an SSW-like burst of heat in late March or early April which could enable HLB in mid April and beyond.

Evening all Perhaps the first hints of a change emerging on the models tonight: Not 100% what's happening here with the closed LP north of the Azores but on other models that gets picked up in the flow and crosses southern England. Has ECM picked up on another signal with the Atlantic slowing and amplifying? GFS OP and Parallel at the same time are very different: