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Short range model discussion - into 2018


Paul

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Posted
  • Location: Camborne
  • Location: Camborne

The ecm very similar to the gfs in the short term and has the front just affecting N. Ireland and NW Scotland at T108 before consolidating the block.

850temp_anom_096.jpg?2018021812850temp_anom_120.jpg?2018021812

http://wxcharts.eu/?model=ecmwf&region=europe&chart=850temp_anom&run=12&step=000&plottype=10&lat=51.500&lon=-1.000&skewtstep=0

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Posted
  • Location: Camborne
  • Location: Camborne

Tonight’s anomalies are of interest, not because they shed a great deal of light because they don’t, but because they are part of the very fluid upper pattern changes  that are ongoing at the moment.

Upstream is not too bad as the clockwork cycle begins with the main Canadian vortex lobe in the vicinity of Bank’s Island and the trough south down western North America and subsequently the jet leaving the north east losing some oomph.

The detached lobe is now a trough negatively aligned in mid Atlantic and a key player in the triple amplified complex in the Atlantic and European arena. The other two are the high cell ridging north of the UK into the eastern Arctic and the troughs tracking south west into central Europe along the eastern flank of the high.

It is probably stating the obvious but how these align is critical to the weather over the UK , the temperature in particular, so basically one can only reiterate that this something the det models will have to sort but I think one can say with much confidence that this will not be a static scenario.

ecm_eps_z500a_5d_nh_11.thumb.png.6e4628fc5648ccd965dea75dc62fd77a.pnggefs_z500a_5d_nh_43.thumb.png.1fbfd111a90302b3469f04ccabe89742.png610day_03.thumb.gif.0b4fb792bbc55a81ed90b9ad0f973c19.gif

 

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Posted
  • Location: Camborne
  • Location: Camborne

Today most of the UK will remain in the warm sector as the warm front continues to track east with the little wave on it doing the same across northern France. Thus most areas will also remain cloudy with patch rain/drizzle with some fog with some clearer periods in the west as the weakening cold front approaches  which will bring rain to N.Ireland and western Scotland later.. Very mild with temps in the 12-13C range

overview_014.jpg?2018021900gfs_t2max_c_uk2_4.thumb.png.b846682b4d5edf85384543299b80838c.pngPPVE89.thumb.gif.a154941fd904774e79180048bdde044b.gif

The cloud and patchy rain will continue to to move east overnight leaving clearer and cooler weather behind with some heavy showers for a time in NW Scotland  This clearer weather will eventually reach all areas as the cold  front clears eastern areas during the afternoon albeit the weakening occlusion does linger a while as the high pressure moves in from the south west.

overview_036.jpg?2018021900PPVG89.thumb.gif.1614a6e00ab78869ccad81abbc32ab92.gifPPVI89.thumb.gif.3345a47c69ff5f84f6b0b0d052f6c203.gif

Wednesday heralds the start of a colder and drier period as the high cell continues to track north east to be centred over Scotland at midday whilst to the west in mid Atlantic there is the lobe of the vortex that has detached over southern Greenland and a trough stretching south with a front between the two surface low pressure areas being the interface between the distinct airmasses.

gfs_t2min_c_uk2_11.thumb.png.ccd81f134b2a6db6cdea41010334f113.pnggfs_ptype_slp_eur3_11.thumb.png.1005e51d893fd2fadd151d3b8bca4641.pnggfs_t850a_natl_11.thumb.png.718be8949bf66e45ce778e5b5ac12308.png

gfs_t2max_c_uk2_12.thumb.png.64a6c356ff41fd310ff6e1db6bd8ee94.png

Despite pressure from energy running south of the aforementioned detached lobe the high pressure remains steadfast and reorientates to the north east and by so doing initiates  the easterly regime in southern England

gfs_ptype_slp_eur3_15.thumb.png.6c6ad4e2dc24d36778b6cee5522c7393.pnggfs_uv500_natl_15.thumb.png.0f8ae77252e741385def7771441dcc96.pnggfs_t850a_natl_15.thumb.png.09d35117642e738584c05a52692e5776.png

By Friday this regime is firmly established with light snow flurries possible in the south east as attention now turns to the east where the colder air  resides.

gfs_ptype_slp_eur2_19.thumb.png.031a1236ad08d01e6f2b93a178c14edf.pnggfs_thickness_natl_19.thumb.png.03697c853a13b5266adab32370ab5682.pnggfs_t850a_natl_21.thumb.png.78ea0f6e8152fc0a97eda07535309d13.png

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

The ecm does not follow that closely to the gfs around t96-120 . The easterly is initially established but pressure from the west ensures a slightly different position of the high which serves to isolate the colder air to the east and tends to veer the quite light wind south east.

ecm_mslp_uv850_natl_5.thumb.png.f4330340fee8ab42a6b550685c35c416.png850temp_anom_096.jpg?2018021900

ecm_mslp_uv850_natl_6.thumb.png.103b8dd1e271f79fef28a41a1efd1cc2.png850temp_anom_120.jpg?2018021900

http://wxcharts.eu/?model=ecmwf&region=europe&chart=850temp_anom&run=00&step=000&plottype=

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Posted
  • Location: Camborne
  • Location: Camborne

The cold front will slip east overnight bringing patchy rain to England and Wales but a spell of heavier stuff in Scotland. Clearing behind the front with initially some showers in the north west but tomorrow will be  dry and mostly sunny as the high pressure moves in, albeit a bit cooler than of late, apart from in the east where the rain will linger.

PPVE89.thumb.gif.16c05dc5586e708a72cf4bdf3a794592.gifoverview_014.jpg?2018021912overview_024.jpg?2018021912

There is no great difference from this morning as we pop forward 48 hours which is to be expected of course. By 12 Wednesday the high cell is over Scotland en route to Scandinavia when by Thursday 1200 it has initiated the easterly regime in southern England.

gfs_ptype_slp_eur3_9.thumb.png.37aabd247f4d8bd01bf03d3585ead30a.pnggfs_ptype_slp_eur3_13.thumb.png.ec36d3703d4178b092aff74788e981d6.png

It's not bad idea to have an overview of the upper air for these times as the phasing of of the Atlantic and European troughs has an important role to play in the gfs evolution.

gfs_z500a_natl_9.thumb.png.92313a4d80d5c5aae2651ee1376369a7.pnggfs_z500a_natl_13.thumb.png.91f17ddf141517d790446b659c5838b9.png

No significant change by 1200 Friday but by the same time Saturday the wind has strengthened and veered a tad making it feel very cold whilst the very cold air is poised in eastern Europe.

gfs_ptype_slp_eur3_17.thumb.png.7ed7bca67aeb5fde27bfd810f93bbac7.pnggfs_ptype_slp_eur3_21.thumb.png.36bd3ae774fe0eb3f5af543fd4ce738f.pnggfs_t850a_natl_21.thumb.png.f3b4ba18ce5a3854928ac1b7f37c4ba2.png

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

Not surprisingly there are some differences between the GEFS and EPS anomalies this evening although they do agree on temps over the UK being significantly below average.

Upstream more or less okay with the vortex over Banks Island and the trough down western North America  but I suspect here lies part of the problem and best kept in mind when considering the differences downstream, This period overlaps the transition of the high pressure in the eastern Atlantic retrogressing to Greenland and the vortex shattering into two fragments, one popping north across the Arctic and the other to NE Canada.

But back to downstream in this period. The crux here appears to be the interplay between the high pressure centred near Iceland and the complex Eurasian/Europe and North Atlantic trough conduit and how precisely this is aligned. Irrespective of the slightly different alignments here, as mentioned earlier temps, would be significantly below average but the differences could well impact the likelihood of significant snow and the whereabouts of such. This of course the det runs will need to sort over the next couple of days.

NOAA seems to generally fit the above with the upper flow of them all tending towards the north east but this could be modified by the actual surface analysis.

A tricky business all round.

ecm_eps_z500a_5d_nh_11.thumb.png.7d5d799e3c798da0f10e9f7566658c9e.pnggefs_z500a_5d_nh_41.thumb.png.1447ee5f9d9475f1be7aab3d08d3be33.png610day_03.thumb.gif.1fea5476dbcc0a3e2b4c708854ec3087.gif

gefs_t850a_5d_nh_41.thumb.png.ca328b60b95eda0b4b9422cb4df22952.png

 

 

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Posted
  • Location: Camborne
  • Location: Camborne

Essentially today marks the beginning of the transition into a pattern change and a different regime, albeit not overnight. Today frontal systems are still affecting the east so pretty much an west/east split with the east remaining cloudy with patchy rain and drizzle whilst the west will be bright with sunny periods with perhaps the odd shower in the north west. Much the same picture this evening and overnight, the patchy rain in the east may move a little west on the dieing occlusion  qQite likely a frost in the north west after a clear night

PPVA89.thumb.gif.d0e8d68f3600c0bc099d42b58e1cb01f.gifoverview_014.jpg?2018022000PPVE89.thumb.gif.ce7ad8308877cbd26d2a34892518ff38.gif

gfs_t2min_c_uk2_6.thumb.png.7d6d2243391fd4680407103d4f6e58af.png

By 1200 tomorrow the high cell is established across the country thus light winds and plenty of sunshine in the north and west but cloud and patchy drizzle may linger in central, southern and eastern England on the remnants of the front and temps in the 7-8C range  Away to the west another front marks the interface between the airmass over the UK and the major upper low over southern Greenland and the cut off low to the south west which have linked and at this stage there is still  a lot of energy leaving NE North America eastbound.

gfs_ptype_slp_eur3_7.thumb.png.83126d33908727c406b67842d548304d.pnggfs_t850a_natl_7.thumb.png.0346fe59ee8fd96f670259ec89294cb7.pnggfs_uv500_natl_7.thumb.png.a7d53aca2f726f88e328c6c2ad72aa46.png

By 1200 Thursday the energy has pushed the northern section of the front east whilst the high cell tilts and migrates north east thus initiating the aforementioned new regime as an easterly component to the wind is introduced in the south but at this stage not adversely affecting the temp noticeable.

gfs_ptype_slp_eur3_11.thumb.png.83bf565fe7d02f485d56fb14c8b9d65a.pnggfs_t850a_natl_11.thumb.png.2ac7643116738c571c3e3967ac0d03c4.png

Over the next 24 hours, by 1200 Friday, the front does actually get quite close to NW Scotland, and further south the wind is picking up and veering a tad.

gfs_ptype_slp_eur3_15.thumb.png.eabe773ca0b248593798c46f8f5fa759.pnggfs_t850a_natl_15.thumb.png.70c331558a55c29b993f7ea450113411.png

Which brings us to the weekend. The wind continues to freshen in the south and with the colder air gradually encroaching from the east it will feel very cold in the wind chill although it will remain dry apart from maybe some snow flurries it the S/SE

gfs_ptype_slp_eur2_17.thumb.png.66543a349cfcf6f29c5a323346271497.pnggfs_ptype_slp_eur2_21.thumb.png.e0c39dd1b18cd5879ed7f34bc9a167bf.pnggfs_t850a_natl_21.thumb.png.274724b719634406125fc7f2db1f75d6.png

gfs_t2max_c_uk2_20.thumb.png.5d9f8e03b0a9e4540783144c787cd2da.png

Edited by knocker
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Posted
  • Location: Milford Haven, Pembrokeshire
  • Weather Preferences: Extremes
  • Location: Milford Haven, Pembrokeshire

Thanks Knocker (or is it really Sidney that works all this out?..?)

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Posted
  • Location: South Norfolk, 44 m ASL.
  • Weather Preferences: Varied and not extreme.
  • Location: South Norfolk, 44 m ASL.
2 hours ago, knocker said:

Current surface analysis and satellite

PPVA89.thumb.gif.7a198f4c694ba1d4bb541ed8753e7793.gif

Occluding cold fronts over the UK?

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Posted
  • Location: South Norfolk, 44 m ASL.
  • Weather Preferences: Varied and not extreme.
  • Location: South Norfolk, 44 m ASL.
Just now, knocker said:

As JH oft says, Exeter do like their fronts whichever which way up. :)

Not only that, they've moving towards each other!:cc_confused:

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Posted
  • Location: Camborne
  • Location: Camborne
4 minutes ago, chrisbell-nottheweatherman said:

Not only that, they've moving towards each other!:cc_confused:

The excellent Modis image for 1115 shows the cloud over the east associated with the fronts (Courtesy Dundee Satellite Receiving Station)

ch38.thumb.jpg.3748643caa08beeded2f9a9a29e6c8ae.jpg

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Posted
  • Location: South Norfolk, 44 m ASL.
  • Weather Preferences: Varied and not extreme.
  • Location: South Norfolk, 44 m ASL.
3 minutes ago, knocker said:

The excellent Modis image for 1115 shows the cloud over the east associated with the fronts (Courtesy Dundee Satellite Receiving Station)

ch38.thumb.jpg.3748643caa08beeded2f9a9a29e6c8ae.jpg

Thanks, Malcolm, my confusion stems from the fact that I thought what had been the warm front was stalling over my area, with the cold front occluding thereby increasing ppn. here as compared to yesterday.  It appears instead from the Met Office that the former warm front now lies in the North Sea as an occlusion, while a cold front has appeared, and the latter is heading west towards the original cold front that is arriving from the west.

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Posted
  • Location: Camborne
  • Location: Camborne

It looks like the fronts mentioned above will continue to influence the weather in eastern and central areas overnight and into tomorrow with patchy rain/drizzle the showers whilst elsewhere it will be dry and sunny. The detail for the rest of the period is much the same as this morning so suffice it to post a couple of charts for Sunday as by now, in the very fresh wind, it will be feeling bitterly cold with snow showers quite likely in eastern and southern areas and with the colder air knocking on the door.

gfs_ptype_slp_eur2_21.thumb.png.5d749c4facbaabf5229f4790dd6d0f23.pnggfs_t2max_c_uk2_21.thumb.png.2a87e6ca0af38f1301a811e342bea215.pnggfs_t850a_eur_21.thumb.png.0d423e6eb78de8dd041bb34867d2d080.png

gfs_thickness_eur_21.thumb.png.48e7879b703ecd1a174ab0f66dc70849.pnggfs_windchill_eur2_21.thumb.png.ae8bb0673be520d06209d56cbeb3262a.png

Edited by knocker
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