Model Output Discussion - 30th November onwards

[Frosty.]

teits was spot on about not being interested by this northerly, look what it delivers for southern britain, it's a joke. the other day I said at this rate it will be over before it begins...½ right then.

Edited December 4, 2013 by Frosty.

[swfc]

Nothing in this mornings outputs to interest any coldies imo.dry and settled after the next couple of days and staying that way.Any future interest ie blocking towards scan is as usuall a trend and nothing more.very underwelming for me atm but at least it should be dry and bright.

[TEITS]

Little change for me in the output. A dry, settled outlook although temps still look uncertain except the extreme W/SW where it could be very mild. Still the risk of Central/E/SE being cold during both night and day.

 

Ensembles show this clearly with a mean SLP between 1020 - 1030mb.

 

http://cdn.nwstatic.co.uk/ensimages/ens.20131204/00/prmslCambridgeshire.png

 

A bitter E,ly is still a long shot. If we look at the Berlin ensembles only one member suggesting a very cold airmass.

 

http://cdn.nwstatic.co.uk/ensimages/ens.20131204/00/t850Berlin.png

 

A rather boring period of weather coming up to be honest.

[BLAST FROM THE PAST]

the only trend at the moment is which model will produce the warmest scenario! Glad i ain't put my bbq away yet, somehow i think i may get to use it again and cut the grass. My roses are flowering again...There does seem to be a trend to put Hp in the wrong place for uk cold.

 

If I can't get bitter cold then a good period of gales, lashing rain, deep lows and sub lows is what I look for in winter.......but we look like getting this....urghhhh 

 

 

The 'mildies' dream

 

BFTP

Edited December 4, 2013 by BLAST FROM THE PAST

[nick sussex]

Nothing that exciting this morning from a cold perspective although I'm mightily relieved to see the ECM drop last nights horror show!

The surface flow into the UK generally looks more se so it could stay on the cold side even though the upper air might suggest milder conditions.

The models now seem intent on moving a chunk of the PV back east again and try to develop a split, its perhaps this trend that might cause a bit more model variability.

[cyclonic happiness]

IDK, I always believe that early cold in the winter, write the rest of the winter off and we really shouldn't be looking for too much before Christmas anyway, it's just we've been spoilt the last few years.

 

Next week I'm gonna use the warm weather to clean up the garden and get everything ready for the 'real winter' weather, which will start in a couple of week's time.

 

Warm weather in winter is very disappointing, but this is warm weather born from a block and not raging zonality, we have that to be thankful for too :-)

[winterof79]

Agreed , a few days ago this wkend was looking very cold and snowy for some , now it's a brief cold snap for the north over 24hrs thurs afternoon and fri morning , with westerly air under high pressure for the wkend dominating .

The models are doing what they do all the time , over reacting to a signal , of milder air early next wk , and we have folks talking as if it's a "done deal" which is bizarre , wasn't this very cold wkend a "done deal" ?

The scandi ridge is showing signs of showing its hand , but not yet , and IMO it is a good 12-15 days away . Which is what Ian f talked about . I'm going for 3 days of mild 850hpa's next week , before a decline from a southeasterly air , but no 'Deep cold' until 15th . But it will come IMHO.

 

To be fair for the models to prog a direct hit from the north to a country 140 miles wide in the middle is a big ask from mid range.

Agree with your feelings about the timing of the scandi block.

Friday the 13th may be the lucky day for a pressure build

http://modeles.meteociel.fr/modeles/gem/runs/2013120400/gemnh-0-222.png?00 

[garbagebags]

If you ask me, the models (all of them) have been underestimating the eastward track of HP systems (hence our constant downgrade to northerlies). Because of this, I don't forsee this Euro high lasting as long as it's currently modeled to. Now that might be straw clutching but I would put a £10 on it.  

[winterof79]

IDK, I always believe that early cold in the winter, write the rest of the winter off and we really shouldn't be looking for too much before Christmas anyway, it's just we've been spoilt the last few years.

 

Next week I'm gonna use the warm weather to clean up the garden and get everything ready for the 'real winter' weather, which will start in a couple of week's time.

 

Warm weather in winter is very disappointing, but this is warm weather born from a block and not raging zonality, we have that to be thankful for too :-)

Even the GFS only has mediocre temps.

http://www.wetterzentrale.de/pics/Rtavn18017.png

 

I would not call that warm really.

[Gibby]

Good morning folks. Here's my take on the midnight outputs from GFS, UKMO, GEM, NAVGEM and ECM for today Wednesday December 4th 2013.

 

All models show a change to colder, windier and brighter conditions beginning today as the first of two weak cold fronts cross SE bringing fresher and somewhat colder conditions with some sunshine later today and some frost tonight. At this time all models also show a rapidly deepening depression crossing East to the north of Scotland and then on over Europe with a fast moving cold front moving South tomorrow bringing a narrow and short-lived burst of rain followed by very much colder weather with severe gales in the North for a time along with snow showers, appreciable on Scottish mountains for a time. High pressure then builds quickly back across Southern areas and cuts off the cold feed to bring a less cold weekend and probably rather cloudy again with a little rain possible in the North for a time.

 

GFS then shows the High settling to the South, most likely over France with a mild SW flow over the North and West with cloud and a little drizzle possible. The South and East will share in this benign weather pattern but here there remains a risk of patchy night frost and fog should cloud breaks occur. Things then turn more changeable for all briefly with some rain possible for just about all as troughs move through before thing again return anticyclonic and benign at the end of the run and still relatively mild for December.

 

UKMO today closes it's run for next Tuesday High pressure well established to the SE of Britain with relatively mild Southerly winds moving North over the UK. The North and West will likely feel the full benefit of these with largely dry and cloudy conditions while the South too sees a lot of cloud too but less mild with some mist, fog and frost patches possible at times should cloud breaks drift across in association with drier continental air to the SE.

 

GEM shows a similar pattern to begin the week but it pulls High pressure to more northern latitudes over Europe maintaining a ridge towards Britain. This then allows colder and brighter conditions to gradually infiltrate the South of the UK from Europe with frost and fog patches night and morning while the North clings on to milder weather.

 

NAVGEM is virtually the same with High pressure to the East drawing up Southerly winds with the mildest air to the North and West with the same patchy fog and frost risk likely towards more South-eastern parts of Britain.

 

ECM keeps High pressure towards the East and SE with a slack SE flow over the South for much of the time. There looks likely to be a lot of cloud trapped in the flow but as with the other models a SE feed from Europe could carry clearer and colder air in at times with frost and patchy fog night and morning. Further North and West this looks less likely with the mildest weather likely in the NW.

 

The GFS Ensemble data suggests a very dry period for Southern and Eastern areas with high uppers aloft once the cold phase clears out of the way early this weekend. There is little rain shown throughout for the South with any shown transitory to a route with more High pressure.

 

The Jet Stream is expected to maintain a position well Northwest of the UK next week and beyond probably near Iceland offering the UK no real chance of tapping into cold conditions anytime soon with High pressure maintained over Southern and Central Europe.

 

In Summary today there is no chance of any real cold shown in any of the output this morning under the time span covered. This gives us two weeks in which to relax from wondering whether the atmosphere will throw anything at us that will affect any outdoor plans as after the next few days with High pressure close to the SE days of useable benign weather conditions look likely when we will be chasing areas of cloud around to allow some pleasant and relatively mild sunshine or conversely as to how much frost and fog such clearances at night will allow. Such breaks are more likely over the South and East where conditions shouldn't be overly mild but further North and West mild weather is likely and here there is more risk of occasional rain from Atlantic fronts.

[fergieweather]

UKMO caution (as have some on here) that with light gradients & little mixing, the higher Theta-W regime in SE/S shouldn't be taken as signal for 'mild': boundary layer still chilled and temps typically to average at best. Based on 12z suites yesterday, lower prob now of deeper cold from E into 15d trend period but beyond that remains an imponderable. Dry signal remains striking in all but MOGREPS-15 ensembles (latter a bit noisier for heavier PPN later in period). 00Z analysis due later this morning.

[legritter]

If an easterly is going to develope which was hinted at yesterday on the postage stamps and other data available i think it would be wise to wait for a few more days looking to see if its still showing .but must admit the vortex is all over the place with chunks heading out of the arctic at different points in the northern Hemisphere .todays ecm a little better but  Gfs is giving us NO comfort at the moment .Lets see what Met office update hints at as they have info we dont always see at their disposal ,but probably they will side with caution . so a day of scraping around but dont be tempted to reach for Prozack or blades as tonight at 7PM it all could flip the other way .

[sunnijim]

A taste of winter tomorrow for much of Scotland, but in truth the much vaunted Arctic blast looks even weaker and more wobbly this morning, with the main feature going to be the potentially damaging winds. When we think back to where we were with this N'erly some 5 or 6 days ago, what now looks likely to transpire can quite rightly be described as bitterly disappointing for most.  Looking forward, lovers of mild weather will be screaming BANK at almost every run the models churn out atm, with the early part of next week in particular still expected to see some unseasonally high temps...the only real difference this morning being over a wide area rather than localised.  No doubt someone will manage to find some 'cold straws' to clutch this morning, but I must admit I'm struggling, with the only positive for me being plenty of dry weather and no raging zonality...yet!

Your first paragraph shows just how unreliable the models can be 'at distance' quite how you then assume in your second paragraph that the mild is somehow anymore lilely to transpire is beyond any logic.Apart from some western extremities,there are no useasonably high temps in the offing,looking at the 850,s i would assume? Very likely temps will be way below average toward the East and South next week,and possibly very cold under any fog or low cloud.

[shedhead]

I think the main +ive to take from the current outputs is at least there will be a good deal of dry, usable weather around, especially across England and Wales. So often in the UK mild and wet go hand in hand, in fact mild and very wet at times, so given the choice I'd plump for the former.

[492]

But it might be cold at the surface?

 

At the moment 850 temperatures are around +8C over Europe yet surface temps are widely sub zero with dewpoints as low as -10 C in places. So if this senario is repeated next week and with a SE feed it could indeed be cold perhaps very cold in the SE.  

[shedhead]

Your first paragraph shows just how unreliable the models can be 'at distance' quite how you then assume in your second paragraph that the mild is somehow anymore lilely to transpire is beyond any logic.Apart from some western extremities,there are no useasonably high temps in the offing,looking at the 850,s i would assume? Very likely temps will be way below average toward the East and South next week,and possibly very cold under any fog or low cloud.

Hi sunnijim....it's simply about the model reliability in certain synoptic senarios. All struggle with modelling N'erlies or E'erlies in the mid range...say post T+120hrs.  They don't struggle to model weather from between S and W in quite the same way, so when every model is saying pretty much exactly the same thing right now there's a much better chance of it verifying.  We don't have to like it, but I'm afraid we do have to accept in...at least for now. 

[carinthian]

At the moment 850 temperatures are around +8C over Europe yet surface temps are widely sub zero with dewpoints as low as -10 C in places. So if this senario is repeated next week and with a SE feed it could indeed be cold perhaps very cold in the SE.  

 

 Spot on. Here this morning at 1580m the temp is +6c and down in the valley at St Michael ( 15 min drive down the mountain )

the temp is -12c. A south east surface flow would be cold in the SE of UK.

C

[georgiedre]

UKMO caution (as have some on here) that with light gradients & little mixing, the higher Theta-W regime in SE/S shouldn't be taken as signal for 'mild': boundary layer still chilled and temps typically to average at best. Based on 12z suites yesterday, lower prob now of deeper cold from E into 15d trend period but beyond that remains an imponderable. Dry signal remains striking in all but MOGREPS-15 ensembles (latter a bit noisier for heavier PPN later in period). 00Z analysis due later this morning.

Morning Ian. Just a quick question re the last part, is this precipitation the Atlantic trying to push south of the high pressure? I think it was said yesterday that the sw might get glancing blows from low pressure could these systems bring an easterly with chances of snow for southern Areas??

[rory o gorman]

At the moment 850 temperatures are around +8C over Europe yet surface temps are widely sub zero with dewpoints as low as -10 C in places. So if this senario is repeated next week and with a SE feed it could indeed be cold perhaps very cold in the SE.  

Basic thermodynamics ,  in winter a lack of solar heating and a stagnant air mass cause's a stronger inversion that can intensify to more 10 c or more as seen yesterday over parts of france. As mid level flow increases the BL normally mixes out and the sounding becomes much more adiabatic. Therefor don't expect cold surface temps with the forecast synoptics next week. 

[sunnijim]

Hi sunnijim....it's simply about the model reliability in certain synoptic senarios. All struggle with modelling N'erlies or E'erlies in the mid range...say post T+120hrs.  They don't struggle to model weather from between S and W in quite the same way, so when every model is saying pretty much exactly the same thing right now there's a much better chance of it verifying.  We don't have to like it, but I'm afraid we do have to accept in...at least for now.

For sure,we are an island where the prevailing wind is from the SW on the whole,so easier for the models to model.I don't accept that we have to feel certain of Fi mild though,models have been swinging between an easterly via a Scandi high,Bartlett doom gloom and despondentsy,and this morning more of a SE feed via the HP ( meaning cold values for the East if not further West) all of this in the space of a few days.

[fergieweather]

Morning Ian. Just a quick question re the last part, is this precipitation the Atlantic trying to push south of the high pressure? I think it was said yesterday that the sw might get glancing blows from low pressure could these systems bring an easterly with chances of snow for southern Areas??

They mention 'low chance of snow later in trend period'. So major theme, as expected from current output, is a dry one.

[chionomaniac]

Hi sunnijim....it's simply about the model reliability in certain synoptic senarios. All struggle with modelling N'erlies or E'erlies in the mid range...say post T+120hrs.  They don't struggle to model weather from between S and W in quite the same way, so when every model is saying pretty much exactly the same thing right now there's a much better chance of it verifying.  We don't have to like it, but I'm afraid we do have to accept in...at least for now. 

Ahh, so you have found proof of this now Shed! Yet again this is your assumption - please can you provide statistical proof that this is the case.

[phil nw.]

It does look like the 00z models have followed yesterday's 12z runs in backing away from developing a Scandinavian high later next week.

Instead a period of mid-latitude blocking around W.Europe is now modeled which will give mainly dry and quiet weather for the next couple weeks by the looks of it.

Some surface variation of temperatures depending on the exact  placement of the main high cell but further se could see some rather colder daytime max's with possible night frosts where any drift comes off the cooling continent.

[forecaster]

Looking at the UKMO FAX for Sunday:

 

 

I think there may be enough gradient there to mix in mild air for most of the country. The very far SE might escape, but given the trend we've seen over the last few days, I couldn't rule out further changes. If this westerly flow does manage to replace the boundary layer air with Atlantic sourced air, then that would be the prevailing story into next week. If the S/SE becomes anticyclone dominated into next week, then instead of cold, continental surface air we might be left with milder, muggier maritime air at the surface. That could lead to average daytime temperatures, persistent fog, but a lack of cold nights.

 

What I'm saying is that a light continental drift, if it sets up next week, is going to have a hard time displacing surface mild maritime air if that has managed to mix in during the weekend.

[shedhead]

For sure,we are an island where the prevailing wind is from the SW on the whole,so easier for the models to model.

I don't accept that we have to feel certain of Fi mild though,models have been swinging between an easterly via a Scandi high,Bartlett doom gloom and despondentsy,and this morning more of a SE feed via the HP ( meaning cold values for the East if not further West) all of this in the space of a few days.

Not sure anyone has spoken seriously about FI mild to be honest. Yes an SE feed would be cold, especially in the SE, but the models I've looked at this morning are not suggesting that at 144hrs for the vast majority of the UK

 

 

GFS

 

 

UKMO

Beyond this timeframe the flow may start to back a bit, but then again it's equally likely to veer a bit. So looking 48-144hrs the

big 3 suggest any surface cold will occupy a similar size area to any significant warmth...i.e c.10-20% of the country.

 

Most of us will be on the mild side rather than the cold side.