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Paul

Short range model discussion - into 2018

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The weak front across the south

gfs_midRH_eu_4.thumb.png.7522d528d71b978f99b9d8e61f9a92d6.pnggfs_t2min_c_uk2_4.thumb.png.224c49c4ec71ff0d7887d2804a21e975.png

Edited by knocker

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The fluidity of the pattern means the cold air behind the front on Sunday is very short lived

PPVK89.thumb.gif.5308ab25c1495de5a98116a3694e2e7e.gif941139280_sun12.thumb.png.b623039ab5eb5842fa0525a698aa1b54.png

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Not much to add to previous comments. With the center of the high pressure remaining in the west the resultant ridge influencing the UK will always be under pressure from the energy exiting N. America driving systems around it and thus, as always in this situation, a tendency for a N/S split. Having said that there is nothing particularly alarming in the woodshed in the short range with positive anomalies in the Atlantic apart that is from some rather cool temps. .Last evening's EPS anomaly illustrates it pretty well.

ecm_eps_z500a_5d_nh_6.thumb.png.60e0ce892cfa62e0a08c9dc84906f332.png

This morning sees the high pressure in charge as the very weak cold front continues to drift south, eventually into France. Thus still some cloud around in some central southern and eastern regions but this should clear fairly quickly giving a sunny day with light winds in all areas with perhaps the odd shower in the north of Scotland.where it will also be a tad breezier. But noticeable cooler than of late.

gfs_midRH_eu_2.thumb.png.be0b963bd946ec83cb2068617d1df666.pngPPVE89.thumb.gif.d7cadeff37e85c4ebe5c144a32c4f97f.gifgfs_t2max_c_uk2_4.thumb.png.74105fd331f916af20d73cc8b37d23ae.png

The clear skies and light winds will continue this evening and overnight leading to quite a chilly start to Saturday with some widespread ground frost. It will continue to be sunny in England and Wales through Saturday bur a cold front associated with the low tracking NE to be west of Norway is approaching the north west and will bring rain and strengthening winds into western Scotland and N. Ireland by evening.

gfs_uv500_natl_7.thumb.png.cea7060c1f5962266983570a5c4617ed.pngPPVI89.thumb.gif.bd11445cb6c8354b0fbb3fe05852f443.gif

gfs_ptype_slp_uk2_8.thumb.png.4e6aa8dced2c96ba7c8d9a09b70e9ad7.pnggfs_t2max_c_uk2_8.thumb.png.9e27d5e2e69d1d855993a4947ba3dfeb.png

The cold front will continue to track south east and weaken as it goes through Sunday but it will briefly introduce a cooler, showery, regime in it's wake as the surface wind veers to the NW/N South of the front it will be mainly sunny.

PPVK89.thumb.gif.b2240ca2d9ef99156c265d06a24460e7.gifgfs_ptype_slp_uk2_12.thumb.png.bd41c46585af1e93b55d9d7c0874b3a7.pnggfs_t2max_c_uk2_12.thumb.png.4e1a46b8a6215e72049df37d85ec3f39.png

Once the front is out of the way the ridge again reasserts itself leading a pretty sunny day on Monday, albeit not overly warm, but another low is tracking into the Iceland area and the associated fronts will bring rain and strengthening winds to N. Ireland and Scotland by evening. This shunts the colder air east but only of course to start the whole process over again.

PPVM89.thumb.gif.9a111b57ef32a48dadfc0d790979e4a5.gifgfs_t850a_eur_16.thumb.png.20234d909ba4a3a9a639c91b5a41c883.png

gfs_ptype_slp_uk2_16.thumb.png.86b979012b49f17f37a50ab9de0d98b3.pnggfs_t2max_c_uk2_16.thumb.png.29acc39f404adaa2a65195f75b0258da.png

Actually this is not quite true as this low is driven on a more easterly track as the high cell is nudged a tad further south and thus pretty windy over the north on Tuesday and showers generally as the frontal system is driven south east during the day.

gfs_uv500_natl_19.thumb.png.1807a6071550db874d49b680bb810623.pngPPVO89.thumb.gif.a4a4e58befd211b447197a49e1bd8dfc.gifgfs_t2max_c_uk2_20.thumb.png.818ea7f37594ad1698d9ac3b1ecdf256.png

And the NH profile at T120

gfs_z500a_nh_21.thumb.png.bfae62e92252d8b771c2214b7d16796f.pnggfs_uv250_nh_21.thumb.png.66a3673ad21d1b7111668759a0e6efcf.png

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Hmmm, some quite large cu here in the last two or three hours, base around 3,000ft and tending to spread as broken Sc.(Culdrose reporting this also) I assume drifting in from the Channel. The sat image is for 1330 UTC

modis.thumb.JPG.b31cef7bd0f663e47b7e751fc80c3671.JPG2018092812.03808.skewt_parc.thumb.gif.96dfb98cd45925d97afbcf852c94af17.gifPPVA89.thumb.gif.894cbba0b3f61bee768cad60ae3faf35.gif

Edited by knocker

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This offshoot from Leslie running along the front is not without interest

gfs_midRH_atl_17.thumb.png.a45a4173d46081b52cf27941a85984dd.pnggfs_ptype_slp_eur3_17.thumb.png.7747bf60bd20dd73f83099334699ceae.png

As it deepens rapidly with some quite cold air behind

gfs_ptype_slp_eur3_21.thumb.png.fad1921cbd4c88bbd522e8c1ef53ec48.pnggfs_t850a_natl_21.thumb.png.e52b040bb1fcdf8fac67d7d797d75b5c.png

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The outlook i the short range is continuing to favour a N/S divide with incursions in the north struggling against the ridge further south but certainly cooler the of late.

The 500mb chart and surface analysis at midnight.

eur_full_500.thumb.gif.3e759fc3eebc47140a4b6037b14f2456.gifPPVA89.thumb.gif.5783b46812ff1e2b85fc63f47966c6bc.gif

With the ridge in charge it's been a mainly clear night with temps dropping (radiation and subsidence inversions at Camborne at midnight)

2018092900.03808.skewt_parc.thumb.gif.dc2e4cd00177121d41805651fbb515d4.gif

and after the cool start it will be a dry and sunny day in most places, albeit not overly warm. The exception being Scotland where showers have persisted overnight and more continuous rain will encroach during the morning as cold front(s) track south east. The rain will reach N. Ireland and central Scotland by evening.

PPVE89.thumb.gif.4bb26808f3a8a9e2cd6536e767083c45.gifgfs_t2max_c_uk2_4.thumb.png.1d1366349cc3d82935a190c9987036b3.png

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The cold front will continue south east overnight and through Sunday but becoming just a cloudy feature as it fizzles out against the ridge but it does introduce cooler air in it's wake. An added complication is an occlusion tracking south in the circulation of the main low west of Norway which will bring frequent wintry showers to Scotland and later northern and north east England and getting distinctly chilly as the wind veers northerly for a time.

PPVG89.thumb.gif.1afb871b2e7041f4f70736da81e465de.gifPPVI89.thumb.gif.a1f609e745b1caae9b42b86e3804e978.gifgfs_t2max_c_uk2_8.thumb.png.a58e0b3410d8a7997d033ba5652b9781.png

overview_033.thumb.jpg.332836f80c1730fbbeef92f1c877e1f1.jpgoverview_036.thumb.jpg.3cbdcb9687db0a605244abeb5245e40e.jpgoverview_039.thumb.jpg.0d0f97fee03799b4f3948ebb0ba3fa15.jpg

Overnight and through Monday the ridge builds once more leading to a very chilly start to Monday with a widespread frost, but the next low is arriving in the Iceland area on the strong jet and the associated warm front will bring rain and strengthening wind to N. Ireland and Scotland by the afternoon.whilst England and Wales remain dry with sunny intervals.

gfs_uv500_natl_11.thumb.png.1ae4436924aea2e4c9514ddba974ccb3.pngPPVK89.thumb.gif.b2464d1f4a0ba508aca97139fecd15d1.gifgfs_t2min_c_uk2_10.thumb.png.ffcd1b3643c5f2d684200384d3cf7930.png

gfs_ptype_slp_uk2_12.thumb.png.422e765d01713deea8bdc2ced0c40f56.pnggfs_t2max_c_uk2_12.thumb.png.c37cfc35d5dacfd42f565ac0e9a83512.png

By midday Tuesday the cold front is straddled across the Midlands with the south in the warm sector and the cooler air to the north as it brings with it some showery rain on it's travels. But note that to the west a wave is forming on the front which winds all the way back to TS Leslie which is amazingly still around.

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Over the next 24 hours the wave will deepen rapidly as it tracks between Iceland and Scotland whilst the warm front traverses the UK. But as ever the front weakens in the south against the ridge so fairly dry here concentrating the wet and windy to the north. Temps around average but naturally feeling warmer in the south

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And the NH profile at T120. Worth noting here the astonishing WAA in the Arctic and the contrasting temps across N. America,

gfs_z500a_nh_21.thumb.png.52c21e36176e0d5e334d9c66ecd2e683.pnggfs_t850a_nh_21.thumb.png.d7946c8f84868602c89646fa1fc301f3.png

 

Edited by knocker

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Looking at the 0500 surface chart certainly some frost around in some places this morning

05.thumb.gif.6aa2080b94302cf4d449be096c81a3f2.gif

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Cold start to Monday before rain arrives in the NW

25475007_minmon.thumb.png.79dd8b2c876930bc61fdf36cbecb3f12.png1417259143_pmon18.thumb.png.ed8528db40522cf56145f6578a9b40f9.png

Edited by knocker

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MODIS at 1230 UTC showing some nice waves in the north and much the same as yesterday with some cu drifting in off the Chanel to spread as Sc here on the SSE breeze And the Medicane getting organized#

modis.thumb.JPG.c22062285ce7623648836b4632170894.JPGeur_full.thumb.gif.d9af0f48fefa115b5015e129a81e787f.gifgeo.thumb.JPG.266a3ca11148e852fb9793af636b24be.JPG

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Still a continuation of the pattern which lends itself to a NW/SE divide over the UK

987995856_120rain.thumb.png.7bf821539c094c9f6aaab7b4360f837a.png

The 500mb and surface analysis at midnight essentially showing low pressure to the NE and high pressure to the SW with a weakening cold front edging south over the UK

eur_full_500.thumb.gif.416a7c5fb00837587516e15806bc0deb.gifPPVA89.thumb.gif.351d43e76c34510b33dbc2562d9f3f18.gif

This movement will continue during today but by now virtually just a cloud feature whilst blustery showers over N. Ireland and Scotland will encroach further south and east as another cold front within the circulation of the main low also tracks south east. Generally a pretty cool day in the north westerly wind.

PPVE89.thumb.gif.cf73e31f31ecbf6da4ded668811e7137.gifmax.thumb.png.49984918cdb69e2702b4c4055ee286c7.png

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The showers will fizzle out this evening and overnight as high pressure builds from the west except down the east coast where they will persist in a stiff northerly breeze as the front slips into the North Sea.

PPVG89.thumb.gif.3e20ed82b78f48f1d48e4388d83bafd4.gifr00.thumb.png.1c7f67e95dc4ebb1eae372445928e437.pngg00.thumb.png.9bc0aab4993fd3aaa8ebaf3dcd5ebd92.png

So a cold start to Monday with a widespread frost portending a clear and cool day but a frontal system associated with a low over Iceland will bring cloud, rain and strengthening winds into N. Ireland and western Scotland by midday.

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Overnight and through Tuesday the low moves east to be west of southern Norway whilst the fronts track south east across the country bringing patchy rain, followed by showers, in the fresh north westerly wind although the winds are lighter and it's getting a tad warmer in the south.

PPVJ89.thumb.gif.1786acc15937044891785b4d510ec1da.gifPPVK89.thumb.gif.44ef24607fbe4c32bc83c3685513e9af.gif

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But as can be seen on the midday chart above a wave is forming on the front away to the west and over the next 48 hours this deepens and tracks north east to be 973mb east of Iceland by midday Thursday.

gfs_uv500_natl_17.thumb.png.52527f4d6bd6675ccc350195e0c8cac3.pngPPVM89.thumb.gif.bec425a3ecc48271effc7af9daf9879e.gifPPVO89.thumb.gif.39a80af54b7e9de90a6f6f48db075cd3.gif

Simultaneously the associated warm front crosses the country but the patchy rain and stronger winds are concentrated in the north with the temps now generally rising to be a tad above normal That is until Thursday afternoon in the north as the cold front arrives on the scene.

gfs_ptype_slp_uk2_17.thumb.png.35f95c6157b316dc64a91c0bc0a76548.pnggfs_t2max_c_uk2_16.thumb.png.150aad0958aba1411c5792736f9eff57.pnggfs_t2max_c_uk2_20.thumb.png.79a8cd8cbe0cc7ae1a5f15f76661d43b.png

And the NH profile at T120

gfs_z500a_nh_21.thumb.png.72f46bee319667927117d7e09256dece.pnggfs_uv250_nh_21.thumb.png.e9fd92a18184a71de95f0f4c8f7b30b2.png

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The development of the trough to the west and the front orientated N. Ireland to Leslie is not without interest in the ecm output this morning

801229000_120v.thumb.png.801e5a95d9df113e1ac001d16608428a.png1966832799_120850.thumb.png.8b5e953fc218c5731451fce56c60abc1.png

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Geostationary image at 0900 UTC showing a broad swathe of frontal cloud and frequent showers over the north of Scotland behind the trough, Cloud here mainly Sc but Ac and Ci above.

geo.thumb.JPG.d1f42997e899be9d28c3f71a1608b3a6.JPG09.thumb.gif.a271fec9a3a6432a08d618cc14e41c4a.gifPPVA89.thumb.gif.7dedc7e0fdd9dd2972e3b35ecc4dc9d5.gif

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And on the other side of the world at 1200 UTC from Himawari 8 typhoon Trami and Kong-Rey expected to be a suoer typhoon shortly

trami.thumb.JPG.60923b248dadd560f5cb87b116dc75e7.JPG

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The cloud from the front in the south and the frequent showers elsewhere will clear this evening and overnight except down eastern coastal regions where they will persist in the northerly wind as the trough clears into the North Sea. Elsewhere with lighter winds a fairly extensive ground frost my morning.

PPVE89.thumb.gif.6a3388d3e948ca69b4fc861f32278884.gifg00.thumb.png.6d8219aa0df725cd8e91542b4be6273d.pngg04.thumb.png.1027571c13d7fdf3f3f25a3fdd0ff251.png

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min.thumb.png.08117d6d026f92b56d16d05d7a4ecd16.png

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Still looking at development on the mid Atlantic trough with tenuous connections to Leslie and low pressure in the Azores area.

gfs_z500_vort_natl_20.thumb.png.44f9bad78eb8dc6082fd4c823eb00a07.png

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The pattern is still favouring a NW/SE divide but of course this does not rule out frontal incursions further south and one such is indicated on the 500mb and surface analysis at midnight.

eur_full_500.thumb.gif.a2f16ca5f31fdf8c31064edaf72df32d.gifPPVA89.thumb.gif.9958388d239812734bab7c50120b1919.gif

A fairly clear and cool start to the day, the odd shower still around the Norfolk area, and it will stay sunny in many areas with perhaps some cloud popping up in the west. But the low east of Greenland is tracking east and the associated fronts will bring cloud and rain into the western Isles by mid morning. The upper cloud already showing on the midnight sounding at Valentia.

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The fronts and rain will sweep south east during the day and evening, the rain tending to be less intense as it goes, reaching the south coast by late evening Behind the fronts showers and sunny intervals

PPVE89.thumb.gif.68eadb14bd1ac71305cbdb4e54f11d39.gifPPVG89.thumb.gif.75ae1cd4e4d198dd7477e888ede7f0e8.gif393853022_maxm.thumb.png.af484b352868c26cfa20cc639bbeeccf.png

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The low continues east to be north of Scotland on Tuesday thus the northern half of the UK in a strong showery north westerly whilst the south languishes in the warm sector with cloud and patchy drizzle and thus also a quite marked temp difference.

PPVI89.thumb.gif.96756ac6f81ac0b509fbc5697e0ff66b.gifr14.thumb.png.1409d4b164dd5bdcf73539100c053c81.png2075755123_maxt.thumb.png.8d42cab007067b97200b19e3589050f5.png

Meanwhile a wave is forming on the cold front which trails way back into the Atlantic and this tracks north east through Wednesday to be south of Iceland by midday. This forces the front across Britain and Ireland, albeit it is very weak in the south where the ridge is influential, thus any patchy rain confined to the north. Warming up a tad with the temps a little above average.

PPVJ89.thumb.gif.8328be5c9efc6ab0057392ce3f1b3019.gifPPVK89.thumb.gif.945ca53ddbef9a932b5d3a2c6d17e25e.gif

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By Thursday the low has deepened to 981mn west of southern Norway with the cold front across central Scotland which means windy and showery in the north and much cooler than the south where there are light winds with temps above average. A very marked temp differential.

PPVM89.thumb.gif.717e1b272bebe107d5a8742c03a7192f.gifgfs_ptype_slp_uk2_16.thumb.png.c2256986b5eef2cac17bd758d99bf1ce.pnggfs_t2max_c_uk2_16.thumb.png.ca34415e6acb285910a0e3b919f30be7.png

By Friday the front has slipped further south so a generally cool day apart from the far south but complications are arising to the west. An upper trough is tracking east and another wave is forming on the front which still trails all the way back to TS Leslie. How this develops is interesting but outside the remit of this thread.

gfs_z500_vort_natl_19.thumb.png.fed4869d79c09e6618151a72484d88b8.pngPPVO89.thumb.gif.81826fbb2acfa2c069dee06d012d8014.gif

gfs_ptype_slp_uk2_20.thumb.png.cbf1d6fc573e68dd5e332af4eea51f73.pnggfs_t2max_c_uk2_20.thumb.png.7e948c646c6f565f958eaa8a6ff6c4bb.png

And the NH profile at T120

gfs_z500a_nh_21.thumb.png.4e63a065f8d729bd95fa8c1375c4fef6.pnggfs_uv250_nh_21.thumb.png.63f386cf8668ce27deef26b7ca62883e.png

Edited by knocker

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The 0500 surface chart and the ecm take on the developing trough next weekend. All in all an interesting morning output

05.thumb.gif.8aa63993df411649848a55a1531faa77.gifv.thumb.png.e67df3d3f6a419ca57fec6b5c13b7c5a.png

Edited by knocker

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The 0900 geostationary illustrating the frontal cloud approaching the north west and showers streaming down the North sea.

geo.thumb.JPG.732962c2d248853eba9907fb512b3fb7.JPGPPVA89.thumb.gif.19090ac0eb99f43e98c9255e4cef1930.gif

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The EPS 500mb anomaly this morning. The Aleutian low pushing anomalous moisture into the Arctic.

ecm_eps_z500a_5d_nh_7.thumb.png.74c25d7510e35d023c5dc97fb7caa911.png

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This evening's gfs has the cyclogenesis a tad further south on saturday with srong ridging behind but the next major trough is about to be driven east with the ubiquitous Leslie waiting in the wings

gfs_z500_vort_natl_21.thumb.png.246e81004429ddf66bd3969b584aa1f2.pnggfs_uv250_natl_21.thumb.png.31f61c6a792428d69e3bdaad9ef49459.png

 

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