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Model Output Discussions 12z 08/03/17

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The influence of the high pressure begins to break down on Friday with the passage of a small perturbation crossing Scotland followed quickly by fairly weak fronts associated with the main depression away to the north west. There is still a touch of N/S about the analysis with the HP still exerting influence to the south thus quite a windy flow from the westerly quadrant.So sporadic rain and temps still above average.

gfs_ptype_slp_eur3_19.thumb.png.b83e679f4579ea096d3f8967b9f4e40f.png

At the beginning of next week the next upper trough approaches from the west and deconstructs, courtesy of the east European ridge, which results in a shallow surface low pressure area to the west, and then the south west of the UK, but more importantly  facilitates the next surge north east of the Azores HP.

gfs_z500a_natl_28.thumb.png.d674894f23c5d4df1cc96b8f9b0e7fe6.pnggfs_ptype_slp_eur3_30.thumb.png.08fe06592fcd4745c3137c9b7c789115.png

This duly happens and for the rest of the week there is a high cell over the UK with cut off low to the south west. Ergo a period of dry weather with temps around average but likely some sharp diurnal and possibly longitudinal variations.

gfs_ptype_slp_eur3_34.thumb.png.38e620914c5cb4de387749744299ea65.png

Now last night's anomalies did indicate pressure rises to the west, moving slowly east, after a very brief unsettled period, and the GEFS this morning continues the theme so perhaps a quiet confidence keeping in mind it's a fair way down the line.

gefs_z500a_5d_nh_49.thumb.png.790def6d6b75d330ed64771c6cdfa802.png

Edited by knocker
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The ecm has the trough disruption early next week but rather than facilitate the HP ridging it just encourages ingress of energy from the north west with the HP pushed SW and thus an unsettled picture with temps trending below average Signs right at the end of the belated appearance of the Azores. So still a long way from done and dusted,

ecm_mslp_uv850_natl_9.thumb.png.c98bd2787bcaa6234184fd5c64ccd0ee.png

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GFS following on from yesterday

Rain spreading to most areas during Friday

ukprec.pngukprec.pngukprec.png

Saturday sees the rain becoming lighter and more patchy during the morning with most parts dry by the afternoon

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Saturday night sees another band of rain spreading across the country this clears fairly early on Sunday with any remaining rain confined to the west

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My goodness it's so quiet in here, very sad. The Gfs 6z is a changeable run with temps around average and plenty of early spring variety, even some snow for a time up north and during low res high pressure builds in across the south of the uk with a spell of pleasant late march weather, a recurring theme of the gfs in the mid / longer range, hope its on to something like the glorious 18z last night which was as good as it gets for late march with wall to wall sunshine and low 60's F.

Edited by Frosty.
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7 minutes ago, Frosty. said:

My goodness it's so quiet in here, very sad. T

Indeed it is but no great surprise when the nearest cold air is Franz Joseph Land and snowflake is downtown Boston. Time to role the boulder across the entrance

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11 minutes ago, knocker said:

Indeed it is but no great surprise when the nearest cold air is Franz Joseph Land and snowflake is downtown Boston. Time to role the boulder across the entrance

True but there's plenty of interest for weather enthusiasts with a changeable few weeks coming up and hints of a warm anticyclonic late March as per the Gfs 18z last night..that would be great.

Edited by Frosty.
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The GEFS 6z mean shows plenty of Azores high influence from around day 9 / 10 onwards, especially further south so a pleasantly warm anticyclonic late march is possible..fingers crossed:)

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Edited by Frosty.
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Well is it the polar vortex or the Greenland vortex? Approaching the end of March and still it goes on and on!

gfsnh-0-198.png?6

Guessing that that black hole will be the centre point that everything rotates around, the UK over the course of the next 10 days will be just above average in temperatures with the storms passing to the NW picking up sub-tropical origins (the old colder day behind passing fronts) and the eastern US will see another couple of winter storms as air filters down from N Canada.

The UK bit isn't what the chart shows but is the natural progression a couple of days later.

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Whilst the weekend won't be completely dry I don't foresee a total washout with plenty of usable weather to be had for many if you don't mind the wind

ca2c7060-361d-4570-a1a9-471414e457e1.thumb.png.17f5a0845298e68ce4dedac3c34259c2.png575675.thumb.png.fc4922b34976d619c4b86a2f32c683a4.png

Edited by Summer Sun
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Just flicking through the GEFS 6z shows plenty of support for a pleasant anticyclonic late March period.

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Edited by Frosty.
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The GEFS 6z isn't alone indicating  an anticyclonic late march / early april because Exeter is also mentioning an increasing chance of high pressure becoming more influential towards the end of March with largely settled conditions bringing a risk of night frosts with some sunshine too and into next month continues to show a blocking signal with the emphasis on fine weather with average / above average temps but still with a risk of night frosts, it's still only a relatively low chance but hopefully continues to develop and bring the uk a prolonged spell of pleasant spring weather later this month and well into April. 

Edited by Frosty.
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ARPEGE (00z) shows the rain on Friday slowly moving in from the west during the day the further south and east you are the longer you should stay dry - some snow is possible for high ground in Scotland and the pennines

arpegeuk-1-83-0.png?14-05arpegeuk-1-86-0.png?14-05arpegeuk-1-89-0.png?14-05

By Saturday morning most parts are just left with some isolated showers

arpegeuk-1-102-0.png?14-05arpegeuk-1-94-0.png?14-05

Very much an east-west split in rainfall totals by Saturday dawn

arpegeuk-25-101-0.png?14-05

Edited by Summer Sun

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Pressure is slightly higher through Saturday according to UKMO (time difference I know)

12z                                                               00z

UKMOPEU12_96_1.thumb.png.dc21749c446e2d2bb1cffe0ad6833320.pngUKMOPEU00_96_1.thumb.png.36393c59f96c7fe4a32dce8d85c1d3bd.png

 

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Still no clear agreement at t120

gfs-0-120.thumb.png.3486bbc8d726cfa63a093d70511bc363.pngUW120-21.thumb.GIF.e125ffc994477c8950f931d7ee615f17.GIF

A case of wait and see which (if any) ECM follows later

GEM is sort of in the middle

gem-0-120.png?12

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Hello 18th Dec 2010 in mid March 2017.

gfsnh-0-348_aii3.png

 

And the uppers ARE comparable - even heading south across the whole country, which is proof you can get a good cold spell for over half the year rather than just the winter.

Edited by feb1991blizzard
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ARPEGE (12z) pretty much following on from it's 00z

Driest for longest in the east and south on Friday

arpegeuk-1-71-0.png?14-17arpegeuk-1-74-0.png?14-17arpegeuk-1-80-0.png?14-17

By Saturday we're left with a few showers away from NW Scotland where we could see some snow on high ground

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The early hours of Sunday sees another band of rain and hill snow moving west to east and dying out by early morning further east

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The Gfs 12z again shows a more settled spell with high pressure taking control for a while through late march with some rather warm air making inroads across the s / se..it's a recurring theme from the gfs, hope it continues.

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Edited by Frosty.
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Highs of 9C on that last chart for here Frosty - brr. What a waste of high pressure that would be.

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3 minutes ago, cheese said:

Highs of 9C on that last chart for here Frosty - brr. What a waste of high pressure that would be.

The trend is what I like most, high pressure building in which would hopefully become centred over the uk and then drift a little further east so we could import warm continental air across most of the uk..

Edited by Frosty.
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1 minute ago, Frosty. said:

The trend is what I like most, high pressure building in which would hopefully become centred over the uk and then drift a little further east so we could import warm continental air.

Ends with a beautiful Arctic plunge bringing snow bearing uppers

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Would be interesting to get something like this...just think of the convective landscapes.

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37 minutes ago, feb1991blizzard said:

Hello 18th Dec 2010 in mid March 2017.

gfsnh-0-348_aii3.png

 

And the uppers ARE comparable - even heading south across the whole country, which is proof you can get a good cold spell for over half the year rather than just the winter.

Except it's deepest FI, and has zero chance of coming off!

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2 minutes ago, CreweCold said:

Ends with a beautiful Arctic plunge bringing snow bearing uppers

gfsnh-0-372.png?12

gfsnh-1-372.png?12

Would be interesting to get something like this...just think of the convective landscapes.

I've given up on arctic plunges in deepest  fantasy island..would rather see a warm plume or a big fat high sat on top of the uk.

Edited by Frosty.
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2 minutes ago, Frosty. said:

I've given up on arctic plunges..would rather see a warm plume or a big fat high sat on top of the uk.

Remember late April last year? That day of the Arctic plunge produced one of the best days of weather in my weather memory. It had everything- hail, sleet, snow, thunder and some beautiful cloudscapes. 

We've had months and months now of a mainly HP dominated weather pattern. Time for a change now.

Edited by CreweCold
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4 minutes ago, I remember Atlantic 252 said:

Except it's deepest FI, and has zero chance of coming off!

Agreed, one wild goose chase too many! Hope we see high pressure building in later this month..I think it will.:D

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hahahaha feb1991,  you could have posted that chart as a copy of 95% of the last 4 frames for every run this winter.  I'm Only a novice on here but one thing I have learnt is that GFS is a joke beyond about 180hrs and much of the time that is generous!  It does provide entertainment mind... even if very frustrating

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