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Model Output Discussions 12z 08/03/17


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Much as previously intimated, I'm no longer inclined to posting much at all on these threads, winter or summer, but admittedly the perspectives offered sometimes prove too much to resist responding to

Do they?  Oh ok, right you are then. You could of course have quoted said "way of the pear" musings by way of illustration - but I accept that would conflict with the real purpose of the post and

So, the steadily improving picture emerges, from a sea of apparent doubt, and as suggested is timed quite nicely for the approach of summer That background ENSO neutral > weak Nino signal impr

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58 minutes ago, 40*C said:

What a vile gfs 12z. Already one sixth of the summer down the pan

Yep, it's a dogs dinner from Friday onwards and GEM 12z follows suit as well with low pressure locked in over the U.K. and nowhere to go. Charts reminiscent of last years absolute dull-fest in the south, which of course was the dullest on record down here

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Once you see the jet stream head south you always struggle to pull in warmth, Lets think ourselves lucky we have had a hot spell this early,  love looking at the charts everyday to try and find the heat coming its all the excitement, It shows nothing interesting today but wait until tomorrow you never no what might show up, PS never look ahead more than 3/4 days that's my opinion, The weather will smack you write in the face Have a good evening all .

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1 hour ago, Tamara said:

Do they?  Oh ok, right you are then.

You could of course have quoted said "way of the pear" musings by way of illustration - but I accept that would conflict with the real purpose of the post and not match its implication:D. There isn't any further comment needed really....

So, lets look at such a recent pear-shaped extract from almost a week back.

A good illustration of why these summary posts can be so useful - for continuity purposes update and review of progress ....as well of course also any departures from expectations.... They are easily found in anyone's profile...

Notwithstanding the obvious indicated ascendancy of the trough into week 2 as expected  (first full week of June aka next week) the broad-scale pattern is not any departure from that outlined in that previous post extract - and there remains plenty of inertia within an embedding seasonal default Atlantic trough and downstream ridge signature to re-amplify the Euro ridge and adjust the warm air advection profile back towards at least some of us

With geographical re-assignment of the UK an unfortunate human impossibility option to change things, whatever the knowledge and standing of the weather NWP observer, this type of summer pattern always favours southern and eastern UK more than north western most parts of the UK. Still, much better to be starting the season with the default tipped towards a trough/ridge profile than a ridge/trough one. It is, after all, very hard to achieve warm air advection and any plume scenario whatsoever around the top of an Atlantic ridge into an upper cold pool trough...

Whilst the more changeable and mobile outlook arrives from the coming weekend, but only after some further very pleasant and warm weather this coming week, its been notable already in the last couple of weeks, how often operational models have attempted to raise pressure over the pole and towards Greenland and force the jet south beyond the t144 period - but then adjust back to the Atlantic trough/downstream ridge profile. Plenty has already been said about this previously in terms of the default summer pattern

Some will continue to angst over (seemingly) every face value operational suite no doubt as I understand completely that it suits the purpose. ECM 12z unfolds already.  I am equally sure further outputs will suggest more horrid "write offs" of *insert period of choice*

In the days ahead and when time permits I would continue to watch on tropical forcing upstream to start to adjust the pendulum back towards downstream amplification of the Euro ridge and renewed warmth from the continent. Irrespective of what it shows, in that regard it will be interesting to see the updated ECM weeklies from week 3 which suggested support for that on Friday.

For anyone who resolutely sticks to the dark side though, week 3 takes us from about mid June.  If a happy pill doesn't materialise, or the recommendations made here simply doesn't wash, then someone with a crystal ball who can make to measure/manage expectations to any personal wish list will definitely help:). Or maybe the model moods threads is the more suitable place to mutter darkness of the models (or apparent soothsayers) instead.

 

I'm just curious as to what impact the trades strengthening over the Pacific will have and what will happen if the current MJO wave lacks the strength to push those aside. 

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Oh good, last June was nice here. Lots of thunder opportunities and a good bit of sun; and of course I got to laugh as the south got soaked. 

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1 hour ago, SouthernSun said:

Apart from most of last June.......

Not many charts like this from last June at all. Low pressure was often very slack leading to convective weather and the inherent huge rainfall totals, particularly in the week commencing 13th. That chart would more likely bring frontal rain and unseasonably strong winds for such a traditionally quiet time of year. We just have to hope that it either stalls out west or moves northwards nearer the time.

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EDM1-120.GIF?30-12   EDM1-168.GIF?30-12   EDM1-216.GIF?30-12

All a bit hom-hum really, changeable with winds between the west and south west so temperatures at or a little above average in the south, always the chance of fleeting spells of very warm weather if the ridge to our south east can push further north at times, the north west could be quite wet at times. 

Oddly enough there is a blocking related problem but more to do with strong heights over Canada which is developing a deep Atlantic trough and a unusually strong jet stream moving ENE across the south of the UK. Not an awful output but not exactly t-shirt and shorts weather either. Oh well it is only the first week or so of summer.

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The Met Office Fax chart below has the cold front posed to push through the British Isles over the coming weekend to replace a couple of nice fairly warm days to end the working week with rather more unsettled conditions. However, as always it will not be that straight forward. You will notice the height thickness values still strong over nearby France and what looks like a development of a possible heat low formation. Some models develop a cyclostomous development ( flabby low ) to coordinate over the North Sea. If this happens as indicated on the latest UKMO , this would obviously change the forecast for the weekend  for thundery and warm weather to persist in SE Britain. The Longer term N. Atlantic forecast model from the UKMO develops a ridge of high pressure from the Azores across South of Britain with the Atlantic Low centre not as progressive as the other main models. So in a nut shell , still a lot to play for in the outlook , starting with the uncertainty as I have mentioned for this weekend.

C

20170530.0617.PPVL89.png

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Are we finally going to see the cool upper trough make it to nw Europe for more than a brief flirtation ??   looks unlikely we can see a revision to the default trough/ridge that has been prevalent thus far but it's not a given that a  change may not appear 

Edited by bluearmy
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Certainly too early to write off summer (though last weeks experience was not pleasant - too humid), 95, 05 and 07 and 11 all had first halves of June which were quite different to the summer as a whole although i would say that it's a little ominous. 

The models tonight are not 2011 style cool but the upper trough is never far away and this does raise the prospect of at the very least shower activity. Summer 2004 2.0 perhaps.  

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46 minutes ago, summer blizzard said:

Certainly too early to write off summer (though last weeks experience was not pleasant - too humid), 95, 05 and 07 and 11 all had first halves of June which were quite different to the summer as a whole although i would say that it's a little ominous. 

The models tonight are not 2011 style cool but the upper trough is never far away and this does raise the prospect of at the very least shower activity. Summer 2004 2.0 perhaps.  

August 2004 - warm and thundery from what I remember. 

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Longer range, the CFS seems to be pushing the height anomaly further and further N for July, what was once a strip of mid latitude heights which lay across and to the S of UK has now pushed further N to stretch into S Greenland

glbz700MonInd2.gif

As for closer to the present time, the model goes for an unsettled June, though perhaps warm at times too

glbz700MonInd1.gif

 

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The ECM weeklies show week 2 having below average temps with week 3 showing no strong signal

MonthlyAnomalies_T2m_20170529_w2.pngMonthlyAnomalies_T2m_20170529_w3.png

Precipitation wise week 2 looks wetter than average for many especially so in the NW - week 3 sees more of a split developing wetter in Scotland but drier for most of England and Wales

MonthlyAnomalies_Rain_20170529_w2.pngMonthlyAnomalies_Rain_20170529_w3.png

Week 4 (19th to 25) has warmer and drier weather returning

MonthlyAnomalies_T2m_20170529_w4.pngMonthlyAnomalies_Rain_20170529_w4.png

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12 hours ago, CreweCold said:

Longer range, the CFS seems to be pushing the height anomaly further and further N for July, what was once a strip of mid latitude heights which lay across and to the S of UK has now pushed further N to stretch into S Greenland

glbz700MonInd2.gif

 

 

My layman's interpretation of that 1st chart is an indication of a weaker than average jet stream for the N-Alantic/NW-europe sector for that time of year = an increased tendency for an azores high to positively influence weather over the UK?  Would like to think of that as being a classical decent uk summer from the 20th century, i.e no silly extremes of heat, humidty or rain. 

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