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Model Output Discussions 12z 08/03/17


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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
7 minutes ago, West Sussex Kate said:

Its been way to warm and dry for the last month and now winters back

Yes it certainly looks like a late taste of winter is on the way according to the Gfs 12z..The S word is going to be used several times next week:cold:

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Edited by Frosty.
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Posted
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
  • Weather Preferences: Sunshine and 15-25c
  • Location: Edmonton Alberta(via Chelmsford, Exeter & Calgary)
4 hours ago, knocker said:

Looking at this morning's anomalies and last nights NOAA the only thing one can say with any conviction is that we looking at a pattern change next week with the demise of the amplified meridional pattern and the unwanted colder spell.

Upstream not too bad with the twin lobes Franz Joseph and N. Canada with associated trough Scandinavia and the negatively tilted one orientated into the Atlantic. It could well be the handling of these troughs that is causing the disagreement downstream Although no strong anomalies NOAA and the GEFs are attempting to build a ridge in close proximity to the UK whilst the EPS is making much more of the Atlantic trough. The latter evolution would tend towards more unsettled zonal weather than indicated by the other two. Hopefully this wil quickly get sorted and the det runs start to agree. indications are that temps would still be little below average but rising.

ecm_eps_z500a_5d_nh_11.thumb.png.8f37376df9bc6269933bbe8a3fadbb3c.pnggefs_z500a_5d_nh_41.thumb.png.c97e21c23180f5311afd34d9891d36d8.png610day_03.thumb.gif.fa6bae45ff6868ed64f05c7cc37c45c7.gif

Looking further ahea, again no agreement with NOAA tending to be the odd one out although that is possibly down to the longer time period but they are all on the same page, The Atlantic trough takes centre stage but with significant postive anomalies to the north and east of the UK the upper flow backs south west and temps edge above normal. NOAA has gentle westerly upper flow. Actually on reflection GEFS isn't hugely different to NOAA, it's the EPS that pushes the trough further east.

gefs_z500a_5d_nh_59.thumb.png.360700a3a796c1a7630c56638b967170.png814day_03.thumb.gif.79f08914263380b878446b7a1a14536d.gif

 

These really are some poor outlook charts for my neck of the woods...this cold unsettled spring continues well into May

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

After this colder snap temperatures head in the right direction as we move into May the odd less warm day now and then can't still be ruled out as per chart 6 but on the whole it should warm up from later next week

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Fans of unseasonably cold action packed weather will be in nirvana next week with the potent Arctic air, strong sunshine and heavy showers with thunderstorms, hail, sleet and snow with local accumulations and significant snow on hills and mountains in the north and not forgetting sharp night frosts and ice..winter bites back.;):cold-emoji:enjoy it coldies, we haven't had much to cheer about in the last 5 months!

Edited by Frosty.
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Posted
  • Location: Kensington
  • Location: Kensington
56 minutes ago, Chris.R said:

If I see a flake of snow this week i'll eat my Macbook.  27 months and counting. 

Wow you've had no snow this year?  Altitude I expect 

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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

I wonder why the west has a better chance than the east of seeing a very light dusting

90-780UK.GIF?21-12120-780UK.GIF?21-12138-780UK.GIF?21-12144-780UK.GIF?21-12

Nothing too exciting tbh it's mainly over by Thursday as winds slowly veer round to the west

Edited by Summer Sun
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Posted
  • Location: Camborne
  • Location: Camborne

Yes it's all looking very exciting for a time next week and I'm all of a quiver.

Monday sees most of the action in Scotland before we really get into the swing of things on Tuesday with a cold northerly with some wintry showers on high ground and exposed areas, Wednesday sees the ridge nudging in but still cold with possible snow showers concentrated to the north and west and the east coast. Thursday sees fronts winging in from the Atlantic to bring an end to this two day wonder. Such a shame.

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Edited by knocker
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The Ecm 12z is showing a late Arctic blast during the first half of next week with 520 dam thicknesses! widespread sharp frosts / ice is likely and Snow will feature and not just on hills either..maybe even thundersnow!..looking very interesting for coldies next week with a potent cocktail of wintry weather by late April standards!;):cold:Enjoy

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Edited by Frosty.
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Posted
  • Location: Haute Vienne, Limousin, France (404m ASL)
  • Weather Preferences: Warm and sunny with night time t-storms
  • Location: Haute Vienne, Limousin, France (404m ASL)
1 hour ago, knocker said:

Looking at both the gfs and ecm possibilities of a Pembroke Dangler early Wednesday.

What is a Pembroke Dangler? My mind is boggling...

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North
5 minutes ago, Spikecollie said:

What is a Pembroke Dangler? My mind is boggling...

It's a convergence zone which forms a line of continuous showers aligned north-south across the Irish sea.:)

Edited by Frosty.
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Posted
  • Location: Newbury, Berkshire. 107m ASL.
  • Weather Preferences: Summer:sunny, some Thunder,Winter:cold & snowy spells,Other:transitional
  • Location: Newbury, Berkshire. 107m ASL.

One word sums up next week. CONVECTION. After all, it is April. Get your cameras out.

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Posted
  • Location: Camborne
  • Location: Camborne
1 hour ago, Spikecollie said:

What is a Pembroke Dangler? My mind is boggling...

The term was coined by Jon O’Rourke, a regular contributor to USW. It is used to describe a line of showery precipitation which forms in a NNW to NNE airflow, typically from Pembroke to Cornwall. This often results in frequent showers, or even more persistent rain, in quite a narrow band. When this occurs a narrow strip can receive quite a high rainfall total, whilst the rest of the south west is virtually dry.

It is by no means an unusual phenomenon, occurring several times a year, particularly in autumn and winter. The long fetch across ‘warm’ water from the Irish Sea to Cornwall, provides the right conditions for showers to form. The shape of the Pembrokeshire Peninsula has the effect of concentrating this unstable northerly flow, in the same way as an obstruction in a stream would concentrate the flow around it. The resultant line of often heavy showers is a convergence zone.

The long and narrow Cornish peninsula protrudes into this line of precipitation, and often has the affect of intensifying it further. Below are just 2 examples from 2008.

http://weatherfaqs.org.uk/node/216

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

Great looking Ecm 12z ensemble mean for the first half of next week if you like unseasonably cold wintry weather direct from the Arctic in late April..which I do!:D

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

Its all rather exciting really, I am no fan of frost and snow in late April, but if its going to happen anyway then bring it on, and to think it was like summer here a couple of weeks ago when we hit 24/25c. Its quite remarkable to think that you look for these sorts of charts all winter and they turn up when its almost May, and its actually looking cold enough for even a few flakes of snow in the South of the country.:cold-emoji:

 

Night temps looking particularly cold on the 18z, some damaging frost on the cards.:help:

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Edited by snowray
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Posted
  • Location: Llangwm, Dyfed
  • Weather Preferences: Anything but wind & rain
  • Location: Llangwm, Dyfed
1 hour ago, knocker said:

The term was coined by Jon O’Rourke, a regular contributor to USW. It is used to describe a line of showery precipitation which forms in a NNW to NNE airflow, typically from Pembroke to Cornwall. This often results in frequent showers, or even more persistent rain, in quite a narrow band. When this occurs a narrow strip can receive quite a high rainfall total, whilst the rest of the south west is virtually dry.

It is by no means an unusual phenomenon, occurring several times a year, particularly in autumn and winter. The long fetch across ‘warm’ water from the Irish Sea to Cornwall, provides the right conditions for showers to form. The shape of the Pembrokeshire Peninsula has the effect of concentrating this unstable northerly flow, in the same way as an obstruction in a stream would concentrate the flow around it. The resultant line of often heavy showers is a convergence zone.

The long and narrow Cornish peninsula protrudes into this line of precipitation, and often has the affect of intensifying it further. Below are just 2 examples from 2008.

http://weatherfaqs.org.uk/node/216

Absolute snow machines in the right conditions. Ive seen them pull the temperature down 5 degrees and over 8 inches of snow in a very short space of time in pembs.

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Posted
  • Location: Camborne
  • Location: Camborne

The GFS this morning has the cold air reaching Scotland late Monday (keep still my beating heart) as a section of the upper trough associated with the low to the east swings south.

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By Tuesday the colder air covers all of the country under a fresh N/NNE wind so feeling quite parky with probably frequent showers, wintry in nature in places, particularly on exposed coasts. Unfortunately this is short lived as the high pressure sticks it's nose i from the south west and the ridge becomes more influential on Wednesday veering and slackening the streamlines The previously mentioned shower scenario still applies (still a possible Dangler) and maybe the coldest night of the week Weds/Thurswith a possible severe frost further south.

gfs_ptype_slp_eur3_19.thumb.png.bda1db4eb5223b587eccf12647625947.png

The  aforementioned ridge does not last long as the next upper low is ejected from the complex lobe/vortex area over N. Canada and tracks east to Iceland and the surface fronts associated with this encroach on Friday and traverse the country on Saturday.

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In a nutshell a dry, not unpleasant weekend, before a couple of colder more unpleasant days next week before continuation of a scenario not unusual of late of the phasing and interaction between the energy/troughs exiting upstream and the Azores high pressure. Hopefully this will find a favorable solution as we move on.

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Edited by knocker
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Posted
  • Location: Camborne
  • Location: Camborne

No significant differences between the ecm and the gfs up to mid week and by Saturday the ecm has the major low south of Iceland with associated fronts aligned Scotland/Ireland. The end of the run sees a deep upper low spawned from the vortex lobe quite a way south in mid Atlantic forcing WAA over the UK but obviously this is just a watching brief at the moment.

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Edited by knocker
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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The Ecm 00z is looking good for a potent cold snap for the time of year for most of next week with cold uppers lasting until / including next thursday. There are some impressive thicknesses at 518 / 520 dam and most of the uk is at risk of wintry ppn and even some snow, especially further north and on hills with frosts becoming widespread, sharp and damaging for a time..Bring it on!:D

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Edited by Frosty.
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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
15 hours ago, Summer Sun said:

I wonder why the west has a better chance than the east of seeing a very light dusting

 

Fairly common outcome, generally more precipitation in the west than east. Any troughs or disturbances will further enhance any showers.

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Posted
  • Location: Bexhill-on-Sea, East Sussex
  • Weather Preferences: Winter Snow, extreme weather, mainly sunny mild summers though.
  • Location: Bexhill-on-Sea, East Sussex

Both the 00z and now the 06z have this area of snow moving SE through the country Monday night, could be a covering of snow for areas all the way down from from the NW, Midlands and southern areas by Tuesday morning if this was to verify.

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Posted
  • Location: Pemberton, Wigan, 54 M ASL. 53.53,-2.67
  • Weather Preferences: Winter - snow, Irish sea convection. Summer - thunderstorms, hot sunny days
  • Location: Pemberton, Wigan, 54 M ASL. 53.53,-2.67

 Wind is north-westerly on Monday night so anyone with in 20 miles from the coast in Northwest England is likely to be disappointed. Just the way it is. 

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Posted
  • Location: Castle Black, the Wall, the North
  • Weather Preferences: Spanish Plumes, Blizzards, Severe Frosts :-)
  • Location: Castle Black, the Wall, the North

The Ecm 00z ensemble mean is a thing of beauty (IMO :D)early next week, especially tuesday with arctic air flooding south..a late taste of winter next week, some of us will see a covering of snow at times.:cold-emoji:

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Edited by Frosty.
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