Jump to content
Winter
Local
Radar
Snow?

Recommended Posts

Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl
Posted

February 1991 and January 2013 were examples where the block to the ne won out.

image.thumb.png.7ade446312c0238882a96cab2d6a93b8.png  image.thumb.png.9605d72260f1f8e0cf1f4a46762b8cfc.png

1991 was a cleaner easterly with a stronger high that gave about a week of quite severe weather and widespread snow.Uppers as low as -16c reached England.

2013 was more of a battleground but it was a pattern that continually rebuilt from more wedges as the Atlantic continually pushed against the cold from the east.This was quite a protracted battle with the UK on the edge, we could see the -12c uppers just across the north sea.Not as severe, but cold enough with wintry weather.

The 2 images i posted are just snapshots of the evolutions through several days so i posted a Link for the archives for anyone wanting to see how things developed,just change the dates at the top of the frames.

WWW.METEOCIEL.FR

Archives NOAA NCEP de 1836 à maintenant

Worth a look while we wait- and hope- that some more cold interest turns up.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222183
  • Like 1
Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
Posted

 Cold Winter Night my concern is the UK ends up on the cyclonic and mild side of a stalemate between Atlantic trough close to the west and blocking high over Scandinavia. This would mean slow-moving lows and stalling frontal systems over the UK - bringing a lot of rain and risk of flooding. In recent times we've been swinging from periods of dry with little rain quickly into periods with too much rain with flooding developing with such ease. 

It's unsual for energy from a strong TPV to  the NW to undercut from the west a blocking high drifting north from central to to NE Europe. Normally need cold to undecut a high over Scandinavia from the east and northeast to lower heights over central and S Europe, this then opens the door for lows from the Atlantic to undercut.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222164
Posted
  • Location: West Yorkshire
  • Location: West Yorkshire
Posted

Whilst we wait, a quick look at UKV for the next few days in terms of temperatures.

Tomorrow starts the milder trend further north and west, double figures for parts of Scotland but generally mid to high single figures elsewhere. Tuesday is mild a bit more widely, up to around 8-9C widely and locally 10-12C.

image.thumb.png.84dd696e76154ae4767659c706dc21de.pngimage.thumb.png.e9dd481161561586b8211de331c3637d.png

Later on in the week, Wednesday looks closer to average away from the far north, then Thursday somewhat milder for the south, and Friday close to average except in the far north.

image.thumb.png.0e554df4851477309c396d10056e67f7.pngimage.thumb.png.691cd0ca5555c1144bdabe4f48bcd0a6.pngimage.thumb.png.d4c75b95896175f51948971d4848d0c1.png

Overnight lows are generally milder though. Tried to select the coldest frame for each night. Frost may return by Thursday and Friday further south and east.

image.thumb.png.19f1abe71175082c716b0e6f1f6fcf18.pngimage.thumb.png.2b173137e873ecc6108f32bfe620f96f.pngimage.thumb.png.284fdf9d3eaeb3eee2c84ae1c8cca68a.pngimage.thumb.png.33ee37989a69a0a20ee64b76bb967c4b.pngimage.thumb.png.f4e9c030ddc58b8ef7e2f48a67a7e5e0.png

Overall, I'd expect daily means to work out somewhat above average for most areas, perhaps with the exception of some parts of the south and east which have both the highest averages and the lowest temperatures, where daily means will probably be closer to average.

Mild but not exceptionally so overall, at least up to Friday, which is as far as we can look with UKV tonight.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222155
Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)
Posted

The latest NOAA 8 to 14 day 500mb anomaly reasonably demonstrates the battle between the Atlantic trough and European High. Being kinda picky though, would have the pattern shifted a little bit further West as, combined with the upper UK South-Westerly flow that chart shows, it feels like the Atlantic trough would partly (especially across Western areas) be attempting to win the fight. 
 

You_Doodle_2025-01-12T21_46_16Z.thumb.jpeg.b00862aef1ba01e3f98a289f4f2390f2.jpeg
 

And the fact, too, that the 6 to 10 day chart (link below) has the upper heights being in more control over the UK before they lose most of their grip on the 8 to 14 day chart:

https://www.cpc.ncep.noaa.gov/products/predictions/610day/500mb.php

Which suggests, on the whole, a bit of Eastward progression of the Atlantic troughing towards the UK. Not to say it’s definitely won the war. This is still quite far away to know which of the forces, for sure.could claim victory (despite some doubts about how strong the UK/Eastern UK High could prove to be).

You_Doodle_2025-01-12T21_44_58Z.thumb.jpeg.3b27367f7e20f8a1cc4c614a1852be79.jpeg

Having the Eastern UK block/High be at a reasonably high enough latitude would help, encouraging the Atlantic Lows to try slips underneath and decrease the chances of too much of the Jetstream going over the top of the High sinking it like a toy boat in the bathtub. 

As enjoyable that the cold spell has been, will be one of the others looking forward to a dry, quiet and settled High Pressure spell this week, and something at least a bit milder for a time before maybe another outbreak of colder and (hopefully) further wintrier weather at some point. To be honest, it’s just nice having a break from the rain. Been a bit too much of it over the last year especially!


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222257
  • Like 1
Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
Posted
1 hour ago, northwestsnow said:

Collapse of AMOC could lead,likely will lead  to Canadian winters in the UK.

Surely not.  The UK will still be downstream of the Atlantic Ocean, it might just be a bit colder, is all.

Just a couple of things on the extended clusters, T264+:

IMG_0015.thumb.png.9ed072fee5553627519faf2417388333.png

While cluster 3 (12) is +NAO/zonal, the other two clusters raise an eyebrow, after several runs where there was nothing of much interest.

Cluster 1 (23) maintains a Scandi high, which seems to be one possible fate of the initial UK high.  It is worth remembering that what’s pictured is one member, there could be others in the cluster which align to bring in winds more from the east or southeast (I haven’t checked the individual runs).  It is certainly worth seeing if this one develops.

Cluster 2 (16) seems to be what one might call a ‘north based -NAO’ where the heights to our north are too far north to deliver but the Euro trough on the cluster is positive.  A few tweaks from here could also be interesting.

So couple of possibilities to watch in the coming days, both I would say outside bets at the moment.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222258
  • Like 1
Posted
  • Location: Solihull, Midlands. (Formerly DRL)
  • Weather Preferences: Sunshine, thunder, hail & heavy snow
  • Location: Solihull, Midlands. (Formerly DRL)
Posted

Just regarding this week, using examples for mid-day between Tuesday and Friday, it shows fairly well that the further East you are in the UK the more likely it will stay cooler/less mild (although even temperatures around 6 or 7*C, for example, could feel a little steamy compared to what most have had). Ireland, especially tomorrow, have the best prospects of seeing temperatures in the low teens at times. Thursday a bit cooler for Ireland overall though, and Wednesday looking to be the least coolest/mildest day for more areas of the UK. Friday daytime being generally the coolest day away from Ireland for the UK - some places, especially some Central areas of England, may not get any higher than around 5 or 6*C. 

IMG_0465.thumb.png.14c47599d9e85dd353f4655c246dce83.pngIMG_0466.thumb.png.79bab59d758edd436774f6abe7ff8f4e.pngIMG_0467.thumb.png.fb756bd8c186e5854d6558201f7171a6.pngIMG_0468.thumb.png.44edec567fc0362c3c8302b16a49d396.pngIMG_0469.thumb.png.0154edfeb4ea1a66a461e5c288a8dd8a.pngIMG_0470.thumb.png.8ec5966827ab9ec3c930d13ff88bd418.pngIMG_0471.thumb.png.d61029fdeea92539c182b71bbdb2663d.pngIMG_0472.thumb.png.680d547e4f2d7efcc832be94576510ac.png

High Pressure rocking around over the UK and especially over South and Eastern areas bringing some *slack (*except perhaps the fairly far North-West with a bit more of a keen South-Westerly flow) and settled conditions. The High Pressure probably bringing a lot of cloud at times, but some brighter spells are possible, particularly away from the fairly far North-West (today it’s fairly sunny and chilly currently).

Nights overall chilly (mild over Ireland though on Tuesday night), especially over Eastern and Central areas of the UK. Perhaps cold enough for a bit of a frost for some Central and South-Eastern areas on Tuesday night and perhaps over the high ground of Central Scotland, parts of Northern England and South-Eastern UK areas on Friday where temperatures could be fairly close to freezing. Particularly so where skies are clear. This will probably no doubt change a bit throughout the rest of this week. Just a fairly rough guide really using the GFS 00Z charts as examples.

IMG_0473.thumb.png.ac0b0a231d1157a1f2c11639a21719bc.pngIMG_0474.thumb.png.988d9574077387bc0dc413870edb3c3b.pngIMG_0475.thumb.png.333128d06e955dc9bb56e91549c8c087.pngIMG_0476.thumb.png.81f5d7c18dcdcb5089ff2c0e3e66c7de.pngIMG_0477.thumb.png.49c37c0941f884d4d6ac4f408c55483d.png


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222365
Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
Posted

Turning the weather milder over the UK after a spell of deep cold with a high pressure to move has always been brought in too fast. Before computers and now with computers. Once a spell of several days with cold high pressure needing to move to allow warmer (relatively)  low pressure systems to move east timing seems not to have improved to me. Probably in at least 80% of such occasions. This being another one. Double figure maxes by Sunday  was the first forecast I saw. Now double digits may not occur at all this week for large areas of the UK. How this is resolved I have no idea but the physics of this needs some work doing on it perhaps?


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222382
  • Like 3
Posted
  • Location: Central Wales 250m (820ft) ASL
  • Weather Preferences: All
  • Location: Central Wales 250m (820ft) ASL
Posted

Ah, we all love the “something’s brewing” posts on here. Lovely group of people on here too, don’t give each other too much of a hard time when it all goes heavenly abdomen.

There are two aspects to the current outlook that deserve a reckoning, the stubbornness of the European block and the precise positioning of the high pressure locally to the UK and Ireland. The first determines the longer term outlook, the second the feel of the weather in the meantime.

The models trend of recent days continues in the 0z outputs. I often focus on the day 8-10 timeframe, which is the limit of any reasonable traction with what we ultimately see. The breakdown is consistently being pushed back to day 10. 

The 0z EPS and GEFS at day 9 are pleasingly similar. Positive heights building north through the UK and Ireland, 

IMG_1320.thumb.jpeg.e3ef5cf02d4964168d544a219fc3c44b.jpeg IMG_1322.thumb.jpeg.34fc51c9266292ea393dab380f316f2a.jpeg

now far enough north for the GEFS to model a firm ridge westward from the continent into the UK and Ireland, with a pool of colder air at both the T850 and especially the 2 metre level, where tall people’s heads are when they stand up. 

IMG_1323.thumb.jpeg.6e73fa881d830fe8faf7479836365c20.jpeg IMG_1324.thumb.jpeg.1afdfabca8280e09e80585741a6f05bb.jpeg IMG_1325.thumb.jpeg.035dbb7537ae84a66058d406f0025db2.jpeg

This block is increasingly impressive. There was no UK and Ireland ridge on yesterday’s 0z charts for the same day, we were in a southwesterly flow. But what really catches the eye is the development of the low pressure to the west of Portugal and the erosion of heights through the Mediterranean. Compare the above with where we were yesterday…

IMG_1327.thumb.jpeg.0dc4e0bcb556b103b43785b91c127b4d.jpeg IMG_1326.thumb.jpeg.59d6ec50718c3eb8c0a947e1818c8e9e.jpeg

This allied to the trend for cleaner heights further north really is interesting. Does it reach the “something’s brewing” threshold? Each to their own carefully measured evaluation I guess, but one thing’s for sure, the chance of an easterly flow towards the end of the month has steadily increased from zilch to a possibility that should at least begin to be considered. 

Something might be brewing…


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222413
  • Like 2
  • Insightful 2
Posted
  • Location: Ely, Cambridgeshire
  • Location: Ely, Cambridgeshire
Posted

3 potential scenarios as I see it:

1. Block gets pushed away and we get a barrage of LP's with PV lobe remaining over Canada, stormy set-up eventually with zonal cold N/W'lys possible, jet occasionally dipping South.

2. Block remains to an extent, but we are caught in 'no-mans' land ie relatively continental flow keeping temperatures sedate, frosts still likely.

3. Scandi high gains momentum and we switch on a screaming easterly to end Jan/into Feb, subject to positioning, with PV firing up jet to the South enabling major snow events (may be a bit extreme...but hey why not 🤣). 

2 Cooler/cold solutions and 1 relatively milder solution then, maybe forecasting near average temps overall going into rest of Jan isn't a bad bet with a slight chance of something more severe brewing? 


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222480
  • Like 1
Posted
  • Location: Leeuwarden. Friesland, the Netherlands
  • Weather Preferences: Cold with a lot of snow
  • Location: Leeuwarden. Friesland, the Netherlands
Posted

Evolution of GFS operational. Piece by piece a little further west at the same time frame. 

00z

GFSOPEU00_252_1.thumb.png.7449bf1fd70ac1c2110d032617127fa3.png

06z

GFSOPEU06_246_1.thumb.png.8fc5be3080265883a6330dfc76870c74.png

12z

GFSOPEU12_240_1(3).thumb.png.496effa7f12b950b40905088271a89c1.png


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222627
Posted
  • Location: West Yorkshire
  • Location: West Yorkshire
Posted

Seen a few comments asking for some detail on how models work, so just a quick rundown. Oversimplifying here, but to produce the model output, there are essentially three steps.

Observations

Each of the main models takes in an enormous amount of observational data for each run - pressure, cloud amounts, temperature, humidity, rainfall observations, wind speeds, and dozens of other parameters. These are collected in various

Initialisation

The second step is to convert all that data is then converted in some fashion to produce a dataset as of a specific time - this is called data assimilation. For example, to initialise the midnight GFS run, you might have some observations up to 11pm, others from 10pm, others from 6pm, and some last recorded two days ago because the reporting station has been broken since. You need to do a lot of pattern matching and calculating to work out what the actual data should be as of midnight. You also have to account for any known observational biases, and so on. Once you've done that, you have the model initial conditions.

Modelling

The final step, and by far the most computationally intensive, is to run the model. Conventional weather models (ignoring AI models here!) are effectively an enormous set of equations, that have to be solved for each grid square. The equations are of the form: given the following data at T+0 hours, what is the corresponding data for T+1? You then feed that in again, so you take your modelled data for T+1, do the calculations for T+2, then again for T+3, and so on until you have your forecast. For an idea of scale, you need an absolutely massive supercomputer to run one of these models, which is why there aren't that many of them. It's way beyond the reach of anybody except government organisations or very large research bodies.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222731
Posted
  • Location: Central Wales 250m (820ft) ASL
  • Weather Preferences: All
  • Location: Central Wales 250m (820ft) ASL
Posted

GEFS is not just trending too far east with the handling of the block, but also too far south. Not a favourable change in the 12z run.

Looking at the jet stream, comparing with yesterday’s 12z at 228h and today’s 0z at day 9, in one fell swoop, the 12z at 204h has let the northern arm effectively iron out the Iceland ridging, introduced a low pressure to the north of Scandinavia and removed the surface ridge from the continental block to the UK and Ireland, all this despite less energy splitting north from the Atlantic bifurcation. This straightening appears to be further closing the door for meaningful Scandinavian heights, a door that was perhaps only ever ajar now only open a slither!

The big change from the 0z is related to the PV, where the orientation of the centre of the Siberian lobe of the PV has turned a full 90 degrees, sending more energy on the other side of the lobe back across the pole to the Canadian side, the mirroring of this contributing to the flattening of the northern arm on the Scandinavian side.

12z Sun, 0z Mon, 12z Mon

IMG_1331.thumb.jpeg.599b9f821c0bad14769ebc09a74b5b84.jpegIMG_1328.thumb.jpeg.bbf9e7a0f8733e122d14541bd38759f5.jpeg IMG_1329.thumb.jpeg.0783226359e1bb463ad5e7cbc2e4c6df.jpeg

The southern arm has actually strengthened in the modelling, and the disruption through the Azores is if anything progressively more profound, dug further southwest off Iberia, while the low at the tip of Greenland is shallower and the Siberian lobe low deeper.

For better or worse, the balance of the dynamics and transfer of energy along the stretched axis between the two omnipresent lobes of the PV remains the conundrum of this winter’s models. No doubt, more twists and turns to come. 

The continuing strengthening and deflection of the southern arm is an exceedingly interesting development. The subtleties of the fluxing of the two PV lobes and the impacts on, and interactions with, northern ridges and wedges will continue to change from run to run across the models, opening and closing doors, but the southern tracking jet stream gives us consistently open access to the building. 


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222785
Posted
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
  • Weather Preferences: severe storms,snow wind and ice
  • Location: Hoyland,barnsley,south yorkshire(134m asl)
Posted

Been lurking for the last week but just unlurked lol and hello my fellow coldie's

the models have certainly been flirting with this Scandi hp of sort's for a few day's now and it will be interesting to see where the pub run sit's in the gefs ens a bit later,...warm outlier😁

Just looking at the day ten 18z gfs then,this is where we want to see things gaining traction as to how much trough disruption against the block is modelled over the coming day's

gfsnh-0-240.thumb.png.ee79f7b4f21f19e726d27aa90a3d0a07.png

the block is in the perfect place here to stop lows/systems from going over the top because the block has gained enough amplitude to disrupt more energy SE,it's one run though so we see how the 00z runs go

the control look's to be following the op on this occation with the height's to our NW at 180 compared to the 12z 192...

gensnh-0-1-186.thumb.png.84012459a4247f8bdb82b256c9f213c0.pnggensnh-0-1-192.thumb.png.6a1fe993bb96dfe1bb5baa64a58c5c16.png

and the mean shows better height's too compared to the 12z,...so a good upgrade there...

gensnh-31-1-186.thumb.png.b91dd7d89fc1b923bbe7eadf4a771bfd.pnggensnh-31-1-192.thumb.png.38e8a30532c20b070e38f96a145bcbf4.png

that's me for now and let's hope for the 00z to follow suit.

 


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222867
Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire
Posted

The first thing I shall say this morning is to suggest it's only the GFS that is hinting at an E,ly is incorrect. I have seen various other models suggesting the same trend including the 0Z JMA.

image.thumb.png.41318790b8cbf58b493da6f3c445cfe7.png

Looking at the ensembles across Europe and you can see the trend emerging with dropping 850hpa means across locations such as Helsinki, Berlin, Copenhagen but also an increase in the SLP mean across Scandi.

image.thumb.png.1ad211c3a88f682d443c5f951f526898.pngimage.thumb.png.c0a53992896a8c1d6f7c5d0569f796d5.png

I also view the default Atlantic based W,lys vs a Scandi HP E,lys as a game of tug of war. You cannot tell early on who is going to win as the battle keeps going back and forth. What I do know is out of all the various weather patterns, the forecasters nightmare is when you have the mobile Atlantic W,lys coming up against blocking in winter and its associated cold pool.

 

I have no idea what the last week of Jan will bring and the difference between UKMO/ECM only illustrates this. What I do know is apart from the building cold to our NE/E the models are trending away from some of those very deep low  pressure systems hitting the UK that is associated with the very low heights/cold pool spreading into the Atlantic. That is because the models are hinting at these being deflected N towards Iceland or SE towards the Med/France. 


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222974
  • Like 1
Posted
  • Location: Central Wales 250m (820ft) ASL
  • Weather Preferences: All
  • Location: Central Wales 250m (820ft) ASL
Posted

Another morning with enthralling 0z GEFS developments. 

On from yesterday’s day 9 to today’s day 8, and the Atlantic is getting well and truly carved up. The Icelandic heights are diverting the upper flow from 50 degrees north, northwards to the heart of Greenland. 

IMG_1333.thumb.jpeg.f77143b6f2345fc7b4d38377bee6b038.jpeg IMG_1334.thumb.jpeg.b87e66ce944b8d55ccd1afd4f2d8854f.jpeg

The UK and Ireland surface ridge is now extending north to the west of Iceland, and the stalling and disruption of the Labrador Sea low is up a gear, 3 mb shallower on the mean but more notably possessing a much more modest eastward hook around the southern tip of Greenland towards Iceland. The centre of the low is now elongated southeastward.

IMG_1336.thumb.jpeg.fc974b58eeab3dcab67e6e9c65414036.jpeg IMG_1335.thumb.jpeg.3c5c1ead2f7b41890d1e69ced0c99423.jpeg

We can see the disruption as the lower heights are diverted southeast, the low to the west of Portugal benefitting from the energy, deepened 7 mb more to 1007mb, which is enough to invite the upper trough south through Scandinavia. 

This is tempting the pinching off of the UK and Ireland ridge, reinforcing the heights to the north, with a northerly flow from the Norwegian Sea filling in the ridge with cold air. 

IMG_1338.thumb.jpeg.2583ec5d0149e42ae9ec5b51c1fb9566.jpeg IMG_1337.thumb.jpeg.1bbc0d77464b92c580e4bba9cca984a6.jpeg

This in turn is further strengthening the block. We can see the nose of that exceptional pool of North American cold now being pointed at Iberia rather than the UK and Ireland, more evidence of the flow having to take the long way round.

From there, an attack on the block from our west is becoming distinctly less likely, one from the south or southwest now increasingly feasible.

There is little here at this stage to support the development of a true Scandinavian high - I don’t expect one any time soon - unless the Siberian lobe of the PV pulls a good deal further back from the Kara Sea it is a huge ask to get meaningful heights that far north for the core development to be over Scandinavia - however the Icelandic / Norwegian Sea ridge being signalled, linking through Northern Europe to the high over Kazakhstan, and combined with so much energy heading southeast through the Atlantic, may be more than enough. With repeated undercutting, this could I suppose get pushed further north to include Scandinavia.

Much more interest being sustained this morning than I had envisaged from yesterday’s 12z runs - to my eye, today’s day 8 charts are the most promising to date for the chances of the development of a cold setup later in the month. 


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222978
Posted
  • Location: Central Wales 250m (820ft) ASL
  • Weather Preferences: All
  • Location: Central Wales 250m (820ft) ASL
Posted

6z GFS op, absolutely cracking run. As hinted at in the means earlier, here at day 11, the ridge from the Norwegian Sea through Scandinavia to Kazakhstan - showing what is possible with a persistent undercutting of the block to the southwest, and if the core of the Siberian lobe pulls back from the Kara Sea into Siberia proper, letting the high build just that little bit further north. 

IMG_1342.thumb.png.ebf522034371cfcd83709fe531a09b39.png IMG_1341.thumb.png.eaa45d32b846d6dff032683fed88a4e0.png

As others have alluded, this idea that the GEFS / GFS is on its own with this underlying evolution might be overlooking what the other models are showing. 

Looking at the EC46 weekly pressure anomalies for 20th-27th from Sunday, I’d acknowledge the block and move on.

IMG_1339.thumb.webp.052df69bfa43f7ac2444c5d4064445f7.webp

However, looking at yesterday’s, I’d be very interested! The same NW-SE orientated ridge through northern Europe, positive anomalies up into Svalbard with palpable southeastward disruption of the Atlantic trough. We need to further hollow out those heights in the eastern Mediterranean to bring in a truer continental feed.

IMG_1340.thumb.webp.8e04f55308376e133044acd43c51a710.webp

The regimes chart extended the blocking signal from the 23rd to the 27th and delayed the arrival of the +NAO signal from the 24th to early February.

IMG_1344.thumb.png.fc320712d8526749ce69d12803a1bd78.png IMG_1343.thumb.png.41e628ddf1850ade0f5267bca11ce04f.png

Tipping the balance in the ensembles was the increased number of -NAO members that @Mike Poole has picked up on, suggesting easterly flow of some sort. Very early days, but with what we’ve seen so far today, I’d expect today’s anomalies and regimes to continue the trend.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5223069
  • Insightful 1
Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill
Posted

The GFS modelling the Azores low as it did in the GH debacle, where it conjoined with the trough in the west and amplified the pattern, leading to a fake strong GH. It did that for run after run before it backtracked and doing the same again:

image.thumb.png.829a355c2dbd0fa9726b8c442c7ba27a.png

The EC never did that consistently, instead keeping the Azore low detached from the trough as it did on the 0z:

image.thumb.png.77af0502733cfb7f6a65eb1848364d3f.png

Of course, as we saw with the GH, that makes a massive difference in the perspective. Whether this is a trait of the GFS or just a one-off is the question. We will know more in the next few days, and if the GFS is wrong again, then we can maybe put very little faith in these Azores' low modelling.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222996
Posted
  • Location: Manchester Deansgate. Elevation : Garbage
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate. Elevation : Garbage
Posted

 StretfordEnd1996 Its the range of outcomes in the ensemble suite - or between the the 90% and 10%anyway , so the wider the spread, the lower the confidence, that is for 500mb heights, they're available for temps as well, so in other words, a great run would be a mean 1040 high over scandi, and blue colours indicating the high confidence on the spread chart, ditto -10 uppers for the UK on mean plus blue colours indicating low spread - dark colours = high confidence, brighter colours = low confidence, so the nearer timeframes are always going to be darker.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5223131
Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
Posted

Looking at the week 2 possibilities with the ECM clusters this morning, T192-T240:

IMG_0024.thumb.png.d5c817fd7de8f8d88b7ab8fd93278241.png

Cluster 1 (15) forms a decent, strong Scandi high, placed with good potential.  Cluster 2 (14) and 3 (14) both +NAO and zonal.  Cluster 4 (8) is the -NAO evolution that has moved forward to this timeframe, with heights to our north, and low pressure to our south.

T264+:

IMG_0025.thumb.png.86f81c4bdca409e4df4cf644b0bd9646.png

The same 3 broad options in the extended that we have seen consistently on recent runs, +NAO (blue), Scandi block (red), and -NAO (green).  Cluster 1 (27) is the +NAO one, which is just over half the members, so as well to bear that in mind.  Cluster 2 (12) is the Scandi high one - it looks to be better placed than previous runs have had it.  Cluster 3 (12) is the -NAO one, that I have highlighted in recent runs, here it is again, low pressure to the south, but whereas the high to our north was on previous runs flaky, or too far north, this time it is much more defined and well positioned to bring in a proper easterly.  

Clusters 2 and 3 in the extended, almost half the members between them, hold lots of interest…more runs needed.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5222983
Posted
  • Location: Hessen, GERMANY
  • Location: Hessen, GERMANY
Posted

Would advise newer members right now to keep expectations ultra low. In particular, when we see cherry-picked individual ensemble charts showing one of many solutions. Certainly keep eyes peeled to check trends...

- Is the cluster within which it sits part of a growing trend? Are there other trends growing which would hamper the chances of cold here?

- Where does a desired det run sit within its cluster? Does its upstream evolution appear clean rather than messy and chaotic? (If so, more chance perhaps of a longer spell of cold). e.g. clear areas of low and high pressures and in particular N Hemisphere charts of 500 hPa Geopotential heights. Getting a feel for when an evolution looks 'clean' takes some experience and it's wise to always bear in mind it's one of many outcomes shown, all options are on the table. However, the more similar desired 'clean' evolutions showing within a cluster and the more the various clusters converge towards that evolution, then you have a proper growing trend.

- Are the NOAA 6-10 day and 8-14 day 500hPa charts showing the trends you're looking for yet?

- Getting into mid-term (5-8 days before arrival), for an Ely or NEly, is there a trend to build the expanse and depth of cold in 850 hPa temperatures close enough east of you, so you'd actually have something decent to advect to the UK?

- If you're going to start thinking about a snowy Ely or NEly, would the strength of the wind be enough to carry precipitation well inland, assuming there is even enough instability and indeed precipitation?  (related to how clean the shown evolution is and generally shown by enough low pressure being around to allow for convection in the first place... also, if high pressure is just a bit too close, that will impact chances of convection). Then, are the 850s really low enough? (below -7 or -8 to get going at all, below -11 or-12 for the real deal... in other scenarios such as frontal snow, such low 850s aren't that necessary). Also, are dew points low enough? (absolutely must be below 0, but very low dew points are often a sign of dry air, so again check for instability).

These are just some of the signs I look for...


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5223006
  • Thanks 1
Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
Posted

Pressure being put on the strat vortex again on the GFS 6z, T384:

IMG_0026.thumb.png.638b51648c22e27bd80f9560b4aeaed0.png

Leads to a very distorted stretched vortex.  I am not expecting any of this to lead to a SSW, but I don’t think it needs to given the way winter’s gone so far, whatever is going on up there in terms of these stretched vortex events and periods of vortex intensification, is allowing the trop vortex to do its own thing, apart from that brief period in mid-late December when the two threatened to couple (that was discussed extensively in this thread at the time) - you can see that on this plot of the polar cap thickness:

IMG_0027.thumb.png.4dd48d21cefa02dff5ca0025924e8b88.png

This is from the NOAA Polar Vortex Blog, which is always an interesting read:

WWW.CLIMATE.GOV

Is the polar vortex to blame for this recent cold air outbreak? We don’t think so. This seems like a case of the polar vortex getting blamed for being a trouble maker, when it was actually minding its own business.

You can see how the trop and strat vortexes have been out of sync for most of the winter despite a very strong strat vortex.  Let’s hope that continues and gives this new chase the chance to gather some momentum…


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5223051
Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl
Posted

ECM has sharpened the N.American trough and digs it further south compared with it's 0z run and joins the others in amplifying the pattern downstream later on over W.Europe so some agreement there that have the possibility of further height rises to our NE.

image.thumb.png.9f37485ef01e5df7faf32573f5bf4da4.png

It;s worth monitoring the behaviour of the pattern upstream as N.America continues to have cold outbreaks over the east and the cold trough digging so far south means energy spits out into the Atlantic at a much lower latitude. 

GEFS t240

image.thumb.png.f3dc64f0db7987f7959a25c61b9e9fdc.png image.thumb.png.8f0c206c81e1a58befc6357eb70481bc.png

 If the main thrust of the jet does go south then this would help to undercut any heights to our ne,think southerly tracking lows.

This pattern could become quite unsettled and cold towards the last week of the month-if the jet plays ball. 


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5223484
  • Like 1
Posted
  • Location: Fairlight,nr H,East Sussex,Hither Green,SE London.
  • Location: Fairlight,nr H,East Sussex,Hither Green,SE London.
Posted

It must be a pretty strong signal to have all the main model players  singing from a similar hym sheet at such a long lead time.

Normally you have one model that won't play ball at this range unless we are talking a default Euro High or a return to a Zonal Atlantic train.

I still expect today's runs to be a high water mark in terms of potential, while the general theme may remain,we must expect bumps in the road and even the abandonment of this by one of the big three this week.

I am hopeful though that things as we see them tonight will start to really firm up in a weeks time.

Easterly's are notorious for last minute hitches though, so a scenario where you can only really relax 24hrs before a touted arrival.


Original post: https://community.netweather.tv/topic/101097-mid-winter-forecast-and-model-discussion-commentary/?do=findComment&comment=5223488
Guest
This topic is now closed to further replies.
×
×
  • Create New...