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Short range model discussion - into 2018


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

Indeed, John - there's a pronounced veer behind the front but no obvious backing ahead of it; is this unusual, and do you have any idea what might cause it?

Chris if you run through the icon charts using the facility at the bottom of the page you will see it does actually back quite a lot. And it illustrates the sharp veer behind the front as well. Hope this helps

http://wxcharts.eu/?model=icon_eu&region=europe&chart=overview&run=06&step=018&plottype=10&lat=51.564&lon=-0.609&skewtstep=0

Edited by knocker
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Posted
  • Location: South Norfolk, 44 m ASL.
  • Weather Preferences: Varied and not extreme.
  • Location: South Norfolk, 44 m ASL.
1 minute ago, knocker said:

Chris if you run through the icon charts using the facility at the bottom of the page you will it does actually back quite a lot. Hope this heps

http://wxcharts.eu/?model=icon_eu&region=europe&chart=overview&run=06&step=018&plottype=10&lat=51.564&lon=-0.609&skewtstep=0

Cheers Malcolm - it appears that the area of backing wasn't shown on the image in the Tweet.

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
1 hour ago, chrisbell-nottheweatherman said:

Indeed, John - there's a pronounced veer behind the front but no obvious backing ahead of it; is this unusual, and do you have any idea what might cause it?

Not that unusual, there are a variety of reasons why it may not have backed.

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Posted
  • Location: Camborne
  • Location: Camborne

A quick look at Wednesday 1200 where we have deep depression south of Iceland and the fronts already through Ireland with the triple point in the south Irish Sea.so we again have the conundrum of if and where snow.  Probably just along the leading edge in the north at thw moment with some heavy rain and strong winds further south. Firm this up tomorrow

PPVI89.thumb.gif.1a3eb195af7c5678163575d3e8dfe749.gifoverview_048.jpg?2018021212gfs_t850a_natl_9.thumb.png.95ec380663f9be21e21bf56f36fdcfc1.png

 

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Posted
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
  • Weather Preferences: Winter: Snow>Freezing Fog; Summer: Sun>Daytime Storms
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
2 hours ago, chrisbell-nottheweatherman said:

Cheers Malcolm - it appears that the area of backing wasn't shown on the image in the Tweet.

I thought there might be an error on those charts somewhere. It would be nice to see a little snow from this front, if only for a short while, to make up for the successive all rain affairs since December 10th (snow not forecast here then either).

Edited by The Enforcer
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Posted
  • Location: Camborne
  • Location: Camborne

For one reason and another I couldn't do the usual medium term anomalies up date last evening so for the sake of conformity and because of the interesting times and recent major pattern changes just a quick run through this morning.

Everything is now more amplified and upstream still a Siberian vortex lobe, strong Aleutian ridge into the Arctic and still an active Canadian vortex with a trough running SW through central canada to the SW United States and still with a strong westerly flow leaving NE North America. So far so good but not so downstream where there is disagreement as to the the orientation of the Atlantic trough/ridge duo and consequently the trough to the east/south east as well. This will obviously impact on the det runs and the subsequent surface analysis so I'll just leave it here for the time as it will be updated today.

ecm_eps_z500a_5d_nh_11.thumb.png.4b17d28a2216c21167862d18be01491e.pnggefs_z500a_5d_nh_41.thumb.png.78c9ac59dc1d62a7f808b7f6b7348e86.png610day_03.thumb.gif.5066c32fd1a545275247f1c88ddf2564.gif

Back to the here and now.

The occlusion is currently over western parts (moderate rain here) and it and the developing wave will move east during the morning bringing with it strong winds, snow sleet and rain. Fairly significant snowfall in central and southern Scotland even at low levels and perhaps down to the north of England and higher ground further south but here it will essentially be rain. A case of radar watching. behind the front still windy in the north and wintry showers, particularly in the north west but everything will die down later with a quiet night ensuing with a widespread frost by morning.

PPVA89.thumb.gif.3485171b93999a8c12745244db7b100d.gifoverview_013.jpg?2018021300PPVE89.thumb.gif.ae3d93aac90f75e1e5f9424391b17f74.gif

gfs_t2min_c_uk2_6.thumb.png.f323429aae79c0a40d1d32e59431036b.png

so a quiet start to Wednesday but by 1200 the next frontal system has arrived over Ireland, SW Wales and Cornwall heralding very much a replay of today with strong winds and rain, sleet and snow tracking east  The snow is again likely to be in the north and favouring the higher ground but as always this doesn't rule out some further south and again probably down to radar watching

PPVG89.thumb.gif.30b3f7c6e4d794a1749eeb49e2e4cef1.gifoverview_040.jpg?2018021300gfs_thickness_natl_7.thumb.png.b19ae8bcc1cc51ae079f66d74ba9d569.png

The occlusion will have cleared the east coast by 00 Thursday leaving most of the UK in a fresh, west/south west airstream with frequent wintry showers, particularly in the north but the triple point is still over east Anglia so the rain will persist in the south east for a while

PPVI89.thumb.gif.67692d434c923699c41778d88da23f54.gifoverview_048.jpg?2018021300

The westerly showery routine continues through Thursday and Friday but ridging in the Atlantic is becoming more influential

gfs_ptype_slp_eur2_12.thumb.png.c837c59e1f5ccedef676366d141e75d3.pnggfs_ptype_slp_eur2_15.thumb.png.257a8a8e282cc1fec15f1fecc2c5b99a.png

And by the weekend a more settled and drier regime is on the cards with temps around average albeit quite a diurnal variation.

gfs_ptype_slp_eur2_19.thumb.png.238ca48350b7487ff208ac4795813093.pnggfs_z500a_natl_19.thumb.png.b94003963b36f4a2fe69a9d7d245213f.png

 

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

Current surface analysis. The front is through here SW 320 gusting 30mph, temp 6C and a rain and hail shower.

2018021307_eur_full.gif?1518505763

And the 1-5 850mb temp anomaly and contours

ecm_t850a_5d_natl_6.thumb.png.1b05d9be08bbe89aefd2a51959cdc07f.png

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

Current surface analysis. The front is through here SW 320 gusting 30mph, temp 6C and a rain and hail shower.

2018021307_eur_full.gif?1518505763

You can see the shortwave (a genuine example as the circulation is still opn) to the west that is likely to affect the UK later tomorrow, I presume?

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Posted
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
  • Weather Preferences: Winter: Snow>Freezing Fog; Summer: Sun>Daytime Storms
  • Location: Abingdon - 55m ASL - Capital of The Central Southern England Corridor of Winter Convectionlessness
2 hours ago, knocker said:

overview_007.jpg?2018021306

I noticed earlier that the 850 temperatures on the GFS 06z, having been consistent for around a week have suddenly jumped starting at T+0 both ahead and behind the front, making the mild sector bigger (compare with GFS 00z) to be in line with the limited UK snow on that chart. At least the channel snow anomaly has been removed.

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

You can see the shortwave (a genuine example as the circulation is still opn) to the west that is likely to affect the UK later tomorrow, I presume?

Well one of them but they tend to get subsumed lol

PPVA89.thumb.gif.4dbdfdfb4601a33c6d0ffdbbf98ff5bf.gifPPVE89.thumb.gif.1b44a3e0514b71fd37cf1d6bf9513de3.gif

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Posted
  • Location: Camborne
  • Location: Camborne

Well get tomorrow out of the way and we might see a few days of drier, quieter and warmer weather (relatively speaking), excluding the north at first but then maybe everyone.

But first tomorrow. A fairly clear night tonight tonight for most places with frost in many areas but by 0600 cloud and rain associated with the next frontal system will already have reached N. Ireland, western Scotland, west Wales and Cornwall. The band of rain, heavy at times will track east during the day, perhaps some snow preceding it in the north leaving showers in it's wake predominately in the north west.

gfs_t2min_c_uk2_4.thumb.png.e69f55dbf19fc7ca3cd1f4a8adf02bbf.pngoverview_018.jpg?2018021312overview_030.jpg?2018021312

So by Thursday 1200 after the fronts are out of the way the UK is in a very breezy westerly and quite sunny but frequent wintry showers in the north west. But away to the south west the high pressure is shaking a tail and beginning to stretch north east and by 1200 Friday has become much more influential with drier and quieter weather in most places apart from remnants of a front affecting the NW of Scotland

gfs_ptype_slp_eur3_9.thumb.png.b47ef9715566f4910b56fd55a40db108.pnggfs_ptype_slp_eur3_13.thumb.png.182d7d5b05b8a21473e72ec51c3583f8.png

Much the same on Saturday with max temps around 8C in many places (according to the gfs so pinch and salt applies) and Sunday in the southern half of the UK but windier with showers in the north courtesy of a weak front.

gfs_ptype_slp_eur3_17.thumb.png.7e3fe540bd7d9b98823f6e79b5404a9c.pnggfs_t2max_c_uk2_18.thumb.png.8783d8c8da6889c75fae1896ed55fdf5.pnggfs_ptype_slp_eur3_21.thumb.png.2630d4c0bc0a531713b7388c736638e7.png

 

 

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

A quick catch up with this evening's medium term anomalies, which given the circumstances show pretty good agreement

Upstream still the vortex lobe over Siberia and strong Aleutian ridge into the Arctic and the quite intense vortex N. Canada with influence east over Greenland. There are two troughs associated with this vortex, one aligned SW through central Canada to the SW United States and the other SE into mid Atlantic with some positive anomalies in between over the SE of the States All in all a highly amplified scenario which continues in the Atlantic arena with high pressure ridging north to the east of the trough with the surface high cell likely very adjacent to the UK. To complete this pattern another trough dips south over central Europe. Ergo all of this portends a period of dry and settled weather with temps a little below average for the UK

ecm_eps_z500a_5d_nh_11.thumb.png.70e4485b9f59ce7af93bf7d39f7a709a.pnggefs_z500a_5d_nh_41.thumb.png.892a4de2c4c71cde3235186a6197895d.png610day_03.thumb.gif.88ec4d6de1b2e4670afc415ae6e1fc74.gif

gefs_t850a_5d_nh_41.thumb.png.4c139c64566a2ad6e65eef9ea4e372a8.png

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

This morning's update is not significantly different to yesterday afternoons. Essentially becoming dryer and calmer for most by the weekend but before arriving there some wet and very windy weather to negotiate.

At midnight there was a deep depression in mid Atlantic with the associated fronts lined up to the west of the UK. After a frosty start in many areas the rain from these fronts, which is already impacting the south west, will move steadily east during the day preceded by snow on the high ground in Scotland, where there could be blizzard conditions for a while, and northern England. Perhaps even some snow north Wales and the Pennines. Some very strong winds also in some areas with 50-60mph gusts not out of the question. The rain will clear to the east late on and through the early hours and the gales will abate except possible the far north west where wintry showers will be frequent. Milder in the south west with temps reaching 11C

PPVA89.thumb.gif.77c5699807f5419844a2492ea32ed190.gifoverview_013.jpg?2018021400overview_020.jpg?2018021400

PPVE89.thumb.gif.6fe152b6838293fc91b0872e389af1ef.gif

So by 1200 tomorrow the UK is in a very breezy westerly with frequent wintry showers in the north and west and feeling quite cold in the strong winds, less so in the south

PPVG89.thumb.gif.0749bf910e965a0e38056a7bc0699ea3.gifoverview_038.jpg?2018021400gfs_t2max_c_uk2_8.thumb.png.992a1cf39cdab58defd2f3182f082765.png

Friday sees the start of a drier period as the high pressure to the south west pushes north east. This will initially exclude Scotland and N Ireland as showers and perhaps some drizzle will run around the tip of the ridge/high cell on the south westerly wind.

gfs_ptype_slp_eur3_11.thumb.png.28fa4bf9f743e0c2508b4f99d53a52fc.pnggfs_ptype_slp_eur3_15.thumb.png.277a36fb7a55e92faae34f46ea4d86ca.pnggfs_ptype_slp_eur3_19.thumb.png.924497ce9337fe7865d85dfb72af82b8.png

Thus the warmer. drier airmass is established by Sunday but with it comes a fairly large diurnal range with frosts in the morning. The temp charts not to be taken as definitive.

gfs_t850a_natl_19.thumb.png.079bd8650f0d8e40b6a74d2b52471af1.pnggfs_t2max_c_uk2_20.thumb.png.8a88faf86c84e74a04942a10aa16858d.pnggfs_t2min_c_uk2_18.thumb.png.77940f8289df75c6fd2bdf6a5919caec.png

 

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

The ecm appears not quite so blasé about a dry weekend and has a weak front tracking SE Friday night (to be fair the gfs does indicate this as well) but by Sunday 00 it has a wave that has developed to the west over Ireland. which brings an area of patchy rain to Wales and England Sunday morning.

ecm_mslp_uv850_natl_5.thumb.png.aa16dd86967231997d49de97202fd472.pngecm_t850a_5d_natl_6.thumb.png.ccadb29812f0c24e6cd7837ed541391c.png

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

The 0600 fax where they now have the first occlusion as an upper feature, I should have mentioned earlier the rain in the south west might be slightly more complex with proximity of the triple point but it will be clarified by the radar. Or not,

PPVA89.thumb.gif.5a33decfded0baea2522ebf10a158501.gifeur_full.gif?1518595765

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

The 0600 fax where they now have the first occlusion as an upper feature, I should have mentioned earlier the rain in the south west might be slightly more complex with proximity of the triple point but it will be clarified by the radar. Or not,

PPVA89.thumb.gif.5a33decfded0baea2522ebf10a158501.gifeur_full.gif?1518595765

Very messy FAX chart, Malcolm - fronts all over the shop!  I'd imagine, as a layman, that trying to generate a forecast from that given that there are numerous front, most at the surface but some at upper levels. must be a thankless task.

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

Very messy FAX chart, Malcolm - fronts all over the shop!  I'd imagine, as a layman, that trying to generate a forecast from that given that there are numerous front, most at the surface but some at upper levels. must be a thankless task.

Yup and further confused down here by how close will the warm sector be. Probably just to the south

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Posted
  • Location: Camborne
  • Location: Camborne

Looking at the high res. Modis at 1145 one front appears to be across central Ireland and the 1200 geostationary shows the deep depression very well also. Images courtesy Dundee Satellite Receiving Station.

ch38.thumb.jpg.f8ccdc84f6d57d6e3b555018e31c4869.jpggeo.thumb.JPG.b6ea059e364c4b160607bde834e08bb3.JPG

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Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks
1 hour ago, chrisbell-nottheweatherman said:

Very messy FAX chart, Malcolm - fronts all over the shop!  I'd imagine, as a layman, that trying to generate a forecast from that given that there are numerous front, most at the surface but some at upper levels. must be a thankless task.

Messy is not the word for it-unlikely!

Fronts are supposed to occur where there is a marked change in 'thickness' lines. I would be hard pushed to justify that number on there if at a forecasting course at Exeter. They seem to scatter them around these days.

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