Model Output Discussion 1200 hrs 30/09/14

[knocker]

To be fair Captain I agree the ridge is out of the picture but the GEfs still seems dominated by the upper low to the south west.

 

[phil nw.]

It does look like the changeable theme continues into next week.

No sooner are we rid of the current low than another Atlantic low approaches us around mid week.

http://www.wetterzentrale.de/pics/Recm1201.gif

Warmer uppers as the flow turns more south or south west but accompanied by further rain or showers through the rest of the week.

With the southerly mean position of the jet heading near the Uk any settled weather looks unlikely for the time being.

[ANYWEATHER]

A quiet weekend coming up with some showers but given light winds these will be well scattered , but slow moving. Clearing skies overnight especially on Saturday night into Sunday morning may well lead to localised frost and perhaps widespread fog conditions especially  for southern uk. A mild airmass for next week for all , so positive temperatures, but bands of rain moving up from the southwest and very windy at times to the southwest of the the uk due to a large area of low pressure in the Atlantic just west of the Uk.. All in all a genuine October pattern......Oh and I forgot to mention that some wet and windy weather will spread north during sunday into Monday......

Edited October 10, 2014 by ANYWEATHER

[Frosty.]

Tonight's Ecm 12z op run is generally unsettled throughout with tomorrows sunshine & showers replaced by heavy rain spreading across the south and east of england during sunday as a feature pushes north from france, however, it looks largely fine and bright across the north and west for a change and then more rain for southern uk early next week before a window of calmer weather midweek and a risk of overnight frost and fog but it's only a lull before the next batch of wet and windy weather arrives from the SW as a deepening area of low pressure pushes NE to the west of the uk, at the same time, high pressure builds across the near continent and we get a squeezing up of the isobars so although it temporarily turns much warmer late next week / weekend, with the strong winds it probably won't feel it...hints of a cooler / colder blast beyond T+240 hours as low pressure tracks east to the north of the BI.

Edited October 10, 2014 by Frosty.

[Nick L]

ECM monthly ensembles (going out to +768) were updated last night, just had a chance to look at them. Continuing to show a westerly dominated couple of weeks with a Euro high seeming quite persistent. Again showing a cool down towards the end of the month, but this is mostly due to it becoming more unsettled with low pressure passing to the north dragging in returning polar maritime air rather than anything genuinely wintry.

[knocker]

The ten day anomalies are all roughly sticking to the same pattern. Dominate feature trough to the SW of UK, ridge western Atlantic and east/SE of the UK. The ecm with a meridional fairly weak jet. Translates to a low pressure dominating the Atlantic with various short wave changes in the east effecting the UK with unsettled weather. Not of course written in stone.

 

[summer blizzard]

Worth a note that we now have Sub-Tropical Fay which will recurve over the coming days and then a cherry underneath which could also recurve. Both of these could start to throw the models.

 

Looks a wet setup to me..

 

[knocker]

Yes I was looking at this last night. The 00z run

 

Listening to the METO forecast for the low moving north there would appear to be disagreement with the GFS. The METO had it moving NE across E. Anglia Sunday evening through Monday bringing windy and wet conditions mainly in the east. The 00z GFS has the low south west England 1002mb 00z Tuesday.

Edited October 11, 2014 by knocker

[Frosty.]

The GFS 00z op run shows winds sourced from north africa by next weekend with temperatures soaring into the low 20's celsius across the south / se and with a large blocking high to the east it also brings a window of dry and sunny weather with the unsettled weather diverted to the west and north.. For the SE this would be exceptional warmth for the second ½ of october.

[knocker]

The ECM take on next weekend and the brief window although the low is further north.

 

[Gibby]

HERE IS MY LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM 8AM TODAY SATURDAY OCTOBER 11TH 2014.

 

NEXT UPDATE SUNDAY OCTOBER 12TH 08:00

 

THE CURRENT GENERAL SITUATION. An unstable and slackening SW flow covers the UK over the next 24-36 hours.

 

MODELS-2 WEEK HEADLINE  Changeable weather with rain at times and strong winds too later but with some dry and bright weather for some next week especially in the East.

 

THE JET STREAM ENSEMBLE FORECAST The general thrust of the Jet stream looks like remaining over or to the South of the UK in varying strengths and trajectories over the coming two weeks.

 

GFS The GFS operational today shows the current slack pressure gradient tighten by the middle to end of next week as a deep mid Atlantic Low slowly edges towards the UK from the West. The slack pressure early on will contain upper Low pressure near to the SE which will throw some wet conditions across the SE for a time and the increase in Southerly winds later in the week will bring warmer weather before the rain slowly edges in by the weekend. It then shows a steadily cooling and unsettled  period developing through week 2 as the Jet flow strengthens over the UK and deliver some rain and showers for all.

 

THE GFS ENSEMBLES. The GFS Ensembles are similar to the operational in many respects especially as one would expect early in the run but differs in Week 2 with a marked deepening of Low pressure areas steaming in from the West and delivering potential severe gales and heavy rain to all areas later in Week 2.

 

UKMO UKMO this morning shows  a deep Atlantic Low midweek with a strengthening mild South or SE flow with rain edging slowly in from the SW. By the end of the week the Low becomes more complex and a SW flow will continue to bring breezy, mild and unsettled conditions with rain at times to end the week.

 

THE FAX CHARTS  The Fax Charts are supportive of the raw data gradually bringing the influence of deep Atlantic low pressure towards the SW of Britain soon after midweek.

 

GEM The GEM operational today shows the deep Low in the Atlantic remaining in situ until deep into the run. This supports a slow rise of pressure from the South and NW towards next weekend with a spell of fine and bright weather with mist and fog by night before High pressure quickly collapses SE and the Atlantic finally breaks through with stronger winds and rain to end the run in 10 days time.

 

NAVGEM NAVGEM shows the Low moving gently NE later next week and bringing all of the UK into mild SW winds with rain at times towards the North and West while the South and East could more likely stay largely dry and bright at times. 

 

ECM The ECM operational today shows mild SW winds as well later next week following a trough across the UK soon after midweek with some rain. After a few drier days across the South a change in the orientation of the Jet Stream brings a change to cooler Westerly winds and spells of rain and showers to end the run as Low pressure crosses East just to the North of the UK.

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend is still showing a conflict of interest in whether Low pressure to the West and North overcomes the power of High pressure to the SE in the longer term outlook this morning.

 

MY THOUGHTS  There remains confusion between the models on which way to take the weather later in the forecast period this morning. It all hinges on how the deep mid Atlantic low developing next week behaves. Most output has it slowly moving East or NE towards or to the NW of the UK. Those that show it moving East would bring a greater threat of UK wide unsettled but mild weather with rain at times while a NE movement would restrict most of the rain eventually towards the North and West allowing pressure to rise to the SE and setting England and Wales up in very mild air for a time. In those models that go further out there is a general agreement that the Jet stream will strengthen through Week 2 and as the GFS Ensembles suggest this morning this could power up some major depressions later delivering gales and heavy rain on a more widespread basis by then. On the counterpart side GEM holds the Low out in the Atlantic to allow the higher pressure to the NW and SE later next week to combine and give a period of quiet and settled conditions next weekend before it too breaks this down to Atlantic low pressure to end it's run. My own general thoughts this morning is that ECM may not be far from the mark with the North and West seeing the greatest threat from wind and rain after we all see a band of it move East soon after midweek. The South and East may well see a dry and mild period next weekend before the unsettled weather returns on a cooler West to East airflow later. While some fog and frost patches could occur towards the North and West over oncoming nights the rest of the period looks like being very mild at times particularly at night with balmy SW winds for a large portion of time from midweek next week.

[Bobby]

Looking at the GFS ensembles there a lot of tropical systems popping up later on, some of them getting sucked into the jetstream and bombing towards the UK. Something to keep an eye on  perhaps. I have a feeling we will see a nasty storm sometime in the latter part of October.

 

Also there is the possibility of a warm conveyor setting up as that low in the Atlantic trudges towards us, sucking up a long fetch of warm moist air from the SW. Could be very mild/warm with large rainfall totals on Western hills. Still uncertainty on the behaviour of the low with some modelling having it stalling and fading and others bringing it in quite quickly and strongly. It looks likely it will make it here eventually one way or another though.

 

Very warm airmass moving over the UK

 

 

Increased support for the low on Sunday night now although still uncertainty, somewhere looks to get a fair bit of rain, probably most places in the south/central parts ATM.

 

GFS 06z

[Frosty.]

A mini cold snap on the Gfs 06z op run following the very warm end to next week, a few frosty nights and some ice with even a risk of sleet and snow at elevation in the north with a burst of polar maritimes..nice to see and hopefully much more to come as we go deeper into autumn, I think next weekends warm blip will be the last real warmth until next spring. :-)

[Polar Maritime]

Yes nice to see in the output Frosty.. The PV continuing to look disrupted towards Months end.

 

Edited October 11, 2014 by Polar Maritime

[Iceaxecrampon]

Yes all in FI  - first Jock plunge of late 2014 to look forward to on the 22nd.

 

 

The wait maybe over? - let the Winter commence

 

Ian

[shaky]

Is it me or are the 12z gfs and 12z ukmo showing stronger northern blocking and lows sliding under it compared to the 00zs this morning!!!this is really starting to get interesting now from a cold perspective!!

[knocker]

I think we need to get a TS to nip this, eh, cold spell in the bud.

 

[carinthian]

Is it me or are the 12z gfs and 12z ukmo showing stronger northern blocking and lows sliding under it compared to the 00zs this morning!!!this is really starting to get interesting now from a cold perspective!!

First signs of the ridge holding on longer to the north. A strange looking flow pattern on the latest 144hr UKMO. A northerly flow over Grimsby and a southerly over Hull at 1015mb.

[Cloud 10]

Is it me or are the 12z gfs and 12z ukmo showing stronger northern blocking and lows sliding under it compared to the 00zs this morning!!!this is really starting to get interesting now from a cold perspective!!

 

Check out the GEM!

 

http://www.meteociel.fr/modeles/geme_cartes.php

[Barry12]

Snow for scandi

 

 

[LomondSnowstorm]

Looks like a helpful shortwave (from a cold perspective) has developed around D6 over Scandi, helping bring colder air westwards:

Good for Snow Advance Index prospects too...

edit: the Euro ridge doesn't do us much favours but at least the milder air doesn't get too far east:

Edited October 11, 2014 by LomondSnowstorm

[Captain Shortwave]

Perfectly fine ECM to be honest

limpet high over the north pole with mid Autumn warmth for the UK under a Euro ridge. In any decent sunny spells the temperature could still reach 20C in the south.

ECM is the most positive on this, but all models want to retain higher heights over the Arctic and a rather sluggish Atlantic pattern with low pressure being slow moving to our west.

[ANYWEATHER]

Unsettled sums the weather pattern up, indeed it looks potentially stormy the second half of this month but before then,one or two chilly nights and next week mild and breezy with rain quickly moving north east . later it looks colder from mid month but pmr air looks likely

[Frosty.]

The models are continuing to firm up on an unseasonably warm spell late next week with a long draw sw'ly / s'ly airflow and although most of next week looks unsettled, tonight's Ecm 12z op run then shows high pressure building to the SE which extends it's influence across the south & east of england in particular where it should fine up and become very warm for the time of year for a few days, this has been the trend for a few days now with the north and west probably staying unsettled but turning milder after a cool start to next week. Later in the run it turns cooler for all areas from the west / northwest and changeable.

 

I hope we see colder and unsettled weather developing during the second ½ of october or at least the last ¼, coldies deserve something to smile about for a change!    

Edited October 11, 2014 by Frosty.

[knocker]

Last nights anomalies at day 10. The GEFS has a ridge western Atlantic and Europe with swathe of colder air Greenland- N. Europe/Asia with a brnch over the UK. The ECM is similar but does push the warmer air further north thus restricting the extent of the colder air. The ECM still sticking to a weakish meridional jet.

 

On the surface the GEFs has low pressure northern Atlantic (relative to the UK0 spreading into eastern Europe with the HP pushed south. The ECM on the other hand pushes the HP further north and develops the Greenland high thus pushing the low pressure further east. Both scenarios tend to bring a easterly component into play over the UK with temps around average or even slightly above in the south.

 

Having said that there must be little confidence in this because of influence from ex TS. Although this won't happen there is brilliant example of cyclogenesis on the GFS 18z