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Short range model discussion - into 2018

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5 minutes ago, chrisbell-nottheweatherman said:

Heading south-east, perchance?

Indeed and not far from where the 00 ecm has it

overview_072.jpg?2018010806

 

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At Weds 1200 the ecm has the little intense low pressure 993mb WSW of Brest, a slightly different evolution than the gfs and the Arpege, as the upper trough starts to deconstruct under pressure from the Azores HP starting to ridge north, and a cut off upper low slides south east.

Over the next 12 hours the ridge intensifies and edges east and the low also moves east becoming negatively orientated and centred close to Brest bringing the south west briefly within the south easterly flow of it's NE quadrant.

I say briefly because over the next 12 hours by T72, the ridge has progressed north east over the UK forcing the further south into the Bay of Biscay.with the cut off upper low now in the Mediterranean

ecm_mslp_uv850_eur_3.thumb.png.391691988607857572df873c9336e527.pngecm_z500_anom_natl_3.thumb.png.6c2e2e1ca9b200e1530680ec898a9526.png

ecm_mslp_uv850_eur_4.thumb.png.94d02a06b95dbbf0397e01f55e40ff2e.pngecm_z500_anom_natl_4.thumb.png.6cbfebc5e88f6fa0470921582a9dd563.png

PPVI89.thumb.gif.0946ec3543bfc6379eadf2d1308c0404.gifPPVK89.thumb.gif.411665bb531a195f4961bde5ff6ac854.gif

Edited by knocker
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1 hour ago, knocker said:

At Weds 1200 the ecm has the little intense low pressure 993mb WSW of Brest, a slightly different evolution than the gfs and the Arpege, as the upper trough starts to deconstruct under pressure from the Azores HP starting to ridge north, and a cut off upper low slides south east.

Over the next 12 hours the ridge intensifies and edges east and the low also moves east becoming negatively orientated and centred close to Brest bringing the south west briefly within the south easterly flow of it's NE quadrant.

I say briefly because over the next 12 hours by T72, the ridge has progressed north east over the UK forcing the further south into the Bay of Biscay.with the cut off upper low now in the Mediterranean

ecm_mslp_uv850_eur_3.thumb.png.391691988607857572df873c9336e527.pngecm_z500_anom_natl_3.thumb.png.6c2e2e1ca9b200e1530680ec898a9526.png

ecm_mslp_uv850_eur_4.thumb.png.94d02a06b95dbbf0397e01f55e40ff2e.pngecm_z500_anom_natl_4.thumb.png.6cbfebc5e88f6fa0470921582a9dd563.png

PPVI89.thumb.gif.0946ec3543bfc6379eadf2d1308c0404.gifPPVK89.thumb.gif.411665bb531a195f4961bde5ff6ac854.gif

Quite a big change really short term, but is it right, and might it change more.

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The Fax charts are certainly not infallible but a much better guide to what is likely to happen out to 96h than GFS in my opinion and the 120h also is usually a better bet than following the ups and downs of GFS every 4 hours. Might not be as much fun if that is your want but it will usually end up more accurate.

Just seen the latest 6-10 (partly in the range of this thread) and the 8-14 500 mb anomaly and it looks to me as if the actual trough is less marked and perhaps the -ve heights over the UK suggest that part of the trough may end up over the UK? No sign at all again of any trend for +ve heights in an area of direct use to the UK for ridge building. The ridge on the 6-10 day still shown out of north Norway towards Svalbard is predicted to pretty much disappear on the 8-14. These charts have been consistent re this evolution for several days, and fairly consistent with one another thus, in my view, should be expected to verify.

So a flow from the west at high level looks pretty much assured for the foreseable to me, Pm type air mostly, possibly very briefly Tm ahead of any fast moving surface lows and turning into Am perhaps behind one of them for 24 hours or more. This will give temperatures over the UK as a whole around or a bit below average most of the time (6-10 days) and rather cold in the NW'ern 1/3 of the UK more than in the south.

http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

Edited by johnholmes
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38 minutes ago, johnholmes said:

So a flow from the west at high level looks pretty much assured for the foreseable to me, Pm type air mostly, possibly very briefly Tm ahead of any fast moving surface lows and turning into Am perhaps behind one of them for 24 hours or more.

Given that you've stated that you're going beyond the T+72 hour span of this thread, what are you classing as the "foreseeable"?

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First time in here and I can’t believe this thread is so quiet given that interest lies in tweaking the next few days let alone 7 days plus which seems to be far too far ahead to have anything set in stone! 

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10 hours ago, chrisbell-nottheweatherman said:

Given that you've stated that you're going beyond the T+72 hour span of this thread, what are you classing as the "foreseeable"?

The foreseeable is probably best summed as not much change and the Met O Fax charts out to 72H are perhaps as good a guide as any? Weakish frontal systems trying to make progress east but the high looks to keep fending them off. No really active fronts so not much rain, with temperatures just a bit too high, and upper air cross sections not conducive in the this time frame for sleet or snow away from mountains.

Once a surface high and upper ridge develop somewhere east or NE of the UK we always try to move the Atlantic in too quickly. The overall upper air pattern beyond 3-4 days away

Beyond 4-5 days and the upper air models consistently show a marked upper trough from NE Canada across southern Greenland over the UK and down across Europe into the mediterranean, later charts show this trough weakening slightly and slowly edging further into the continent. A mobile flow, mostly just south of the UK occurring with this pattern.

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Midnight Thursday with the upper ridge to the west disrupting the trough

250wind_anom_64.thumb.gif.e4e97db57563b47b4beb7e942d8629fe.gifPPVI89.thumb.gif.4bbb44d02252f124505e741994b3ca71.gif

Which 24 hours later pretty much leaves the UK and the area to the east becalmed as the next roughs and the energy and more troughs pile up in the Atlantic

250wind_anom_68.thumb.gif.9f16ce89d43cd3577f1a17a8c96def59.gifPPVK89.thumb.gif.4b269a5f063e2155bc98a50567818d87.gif

By T102 a broad area of high pressure to the east with the upper trough over Ireland and a good illustration of the two energy flows

250wind_anom_74.thumb.gif.b7f418a9f3a410a052a6436dd993bd43.gif

Edited by knocker
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A little bit of license vis the parameters of this thread as we are coming up to weekend of interest.

At T72 the ecm shows the upper trough deconstructing around 20W with the surface front west of Ireland and the UK in a col.

By T96 it has deconstructed with the southern segment south west of Cornwall with the surface front fragmenting against the high pressure in the Irish Sea with intermittent rain down the western half of the country which is now in a southerly airstream

Must leave it there but just to comment the deconstruction of the trough has opened a door for east bound energy to rush through.

.ecm_mslp_uv850_natl_4.thumb.png.283d1695f0b1ff97c02ae02c08a9ebe1.pngecm_z500_anom_natl_4.thumb.png.f786ee1fd65c48005f652fe2063e82b2.png

ecm_mslp_uv850_natl_5.thumb.png.2a07bc6c1d9cc9970093f8b033d286ab.pngecm_z500_anom_natl_5.thumb.png.07745c2851cd245823b3ca67b8526b88.png

Edited by knocker
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The GFS 250mb wind field at T96 shows the vortex lobe Hudson Bay/Greenland and the very strong jet leaving NE N. American with wind barbs in excess of 150kts. This splits around 25W but still a huge amount of energy running around both arms. The divergence area is about to move east

250wind_anom_73.thumb.gif.612d46ddb8a5705884b71e3da02d5564.gif

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22 hours ago, khodds said:

First time in here and I can’t believe this thread is so quiet given that interest lies in tweaking the next few days let alone 7 days plus which seems to be far too far ahead to have anything set in stone! 

To be fair, most are standing by and watching how this one plays out,somets up,but what remains to be seen...forecast of PV distruption could stick it's two penneth in an all.

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Last for this evening the 500mb field from the 1800 showing the upper trough Canadian vortex to the UK.

gfs_z500_natl_20.thumb.png.8ce72bfc7524374795c4ea5a9847f982.png

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Today there is a slow moving front traversing the country as a small wave forms to the south west which tracks north east to be near Cornwall by 1800 before ducking south east into Biscay as the HP to the west ridges north east.

PPVA89.thumb.gif.d40f18dc51d3ec81063fcfd0f1485fa7.gifgfs_ptype_slp_eur3_4.thumb.png.c6b2ed2c1d85bfad4c773ee01c2fc961.pngPPVE89.thumb.gif.daa99c25c8a3274492536af62caa06d1.gif

Over the next 24 hours or so (Friday 00) the ridge continues to move east over the UK as the cut off upper low is relegated to the Mediterranean and the next trough promulgated by the Canadian vortex arrives in mid Atlantic. The result of this is the UK is in a very slack pressure gradient over Thursday/Friday.

gfs_z500a_natl_9.thumb.png.b139b5ebb0ba1e65fbd03ba2b0a65a3d.pnggfs_ptype_slp_eur3_9.thumb.png.4c38422534e4bb75544905ed45ce71b7.pngPPVJ89.thumb.gif.f4561e950df1e87b5a81bce23367f4c1.gif

But there are some very powerful forces at play here with high pressure block to the east and the energy flowing east around the southern tip of Greenland so the Trough follows a familiar route and deconstructs with one segment tracking SSE just to the west of the UK. Thus the surface front stalls over Ireland and begins to lose it's identity by 00 Saturday and the UK slips into a light southerly flow. The light rain associated with the front will thus peter out.

gfs_z500a_natl_13.thumb.png.d989b795f46936655e2e48971bfadaad.pnggfs_jet_300_natl_13.thumb.png.ae9f025843e1aeb4258e2822d8db3871.pnggfs_ptype_slp_eur3_13.thumb.png.1d0e5fa9e6fd4433e2c33f1ca615afdc.png

The result of all of this is the UK is once again plunged into a col scenario between the two fores but there is only one winner here, Note where the colder air is.

gfs_jet_300_natl_18.thumb.png.8f5c7e50d3f35466b56c09bc453f0c74.pnggfs_ptype_slp_eur3_18.thumb.png.93df3129e9d1c5acd78ac44dd4e3f465.pnggfs_t850a_natl_18.thumb.png.1e0b4ce9f90f64ef7a9767f2395f0ab6.png

 

Edited by knocker
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5 hours ago, knocker said:

 

The result of all of this is the UK is once again plunged into a col scenario between the two fores but there is only one winner here, Note where the colder air is.

 

Would you care to elaborate on which airmass will win for those of us who are less confident in interprting outout, please Malcolm?  Thanks.

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Not Malcolm but I still reckon the Pm air on the deep cold trough will be what we get, see my post in the main thread, this morning and one last night.

Beyond, way beyond this thread, say post 15 days=no idea, but certainly 6 days onwards I would suggest as above and possibly a day or so before.

hope that helps?

 

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Just out of interest this is the fax for 12 today showing the two centers to the west and the HR Modis for 1300 courtesy Dundee Satellite Station

PPVA89.thumb.gif.00c4cefde37e64c703e772a0eb889379.gifch38.thumb.jpg.566f973d5a6cfd433714a9eb464c6138.jpg

 

Edited by knocker
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One area to keep an eye on the near future is Saturday when the front stalls as it slowly approaches western Britain which could lead to some substantial rainfall amounts

overview_070.jpg?2018011012PPVM89.thumb.gif.318c6010ccb1efacd7a36093e2117ef9.gif

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40 minutes ago, knocker said:

One area to keep an eye on the near future is Saturday when the front stalls as it slowly approaches western Britain which could lead to some substantial rainfall amounts

overview_070.jpg?2018011012PPVM89.thumb.gif.318c6010ccb1efacd7a36093e2117ef9.gif

The type of front that would normally lead to a snowy battleground in mid-January, but an astonishing absence of cold this time round!! 

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7 hours ago, knocker said:

Just out of interest this is the fax for 12 today showing the two centers to the west and the HR Modis for 1300 courtesy Dundee Satellite Station

PPVA89.thumb.gif.00c4cefde37e64c703e772a0eb889379.gifch38.thumb.jpg.566f973d5a6cfd433714a9eb464c6138.jpg

 

That satellite view shows the heavy cloud that affected my area all day, and the FAX explains why.  Although the main part of the country was (AFAIK) affected by a Col, there are several low pressure centres on the FAX chart which tend to make analysis complex for those of us with limited knowledge.:oops:

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There is quite a lot of interest over the coming weekend meteorologically speaking so I hope its okay to extend the remit of the thread a tad to save ending in the middle of the transition. Apologies if it's not.

It's difficult to integrate the narrative so for simplicities sake I'll deal with a couple of the important issues separately.

By 12 Saturday there is a huge amount of moist air and WAA taking place around the north east coast of North America and the tip of Greenland as the air is transported around the Bermuda high pressure. With the cold Arctic air to the north west we have a baroclinic zone and a breeding ground for cyclogenesis which is precisely what takes place with the resulting very powerful jet.

gfs_z500a_natl_11.thumb.png.c635fbb9ea37ba346b129c8a61249280.pnggfs_uv500_natl_11.thumb.png.7904fc47bf5028a89ebc52b706defb3c.pnggfs_t850a_natl_11.thumb.png.57803d83a24538f9a9dd1477c37a135b.png

The result of all this on the surface can readily be seen with the rapid formation of a very deep depressions one of which moves east to Iceland over the weekend as the jet realigns  and the colder air/trough also heads east which heralds the breakdown of the block over the UK with the jet in the region of 200kts.

gfs_ptype_slp_eur3_11.thumb.png.b3f9faf295d88836411d40a3f53927f7.pnggfs_ptype_slp_eur3_13.thumb.png.417eb7eafb795b0989dc7230d175ff35.pnggfs_ptype_slp_eur3_16.thumb.png.b86e48d38f5086fe0f150b4aeb3a1eb3.png

gfs_uv250_natl_15.thumb.png.ec7fac1717d482f9c85d3fd10e6f9a50.png

Whilst all this is going on it's a relatively quiet weekend over the UK as the block is still holding initially. Thus we have the front edging east on saturday stalling with the rain becoming intermittent in western parts whilst the rest of the country remains dry,

overview_063.jpg?2018011100

But by Sunday fronts and rain are beginning to affect the north west and they proceed to track south east under the massive pressure already discussed above and by Monday the block is no more.

PPVI89.thumb.gif.6ddda4c310c6db689334a1eb1774106c.gifPPVM89.thumb.gif.2fa40d55891f2cf357f05f45df289b50.gifPPVO89.thumb.gif.d01697c6417d80543b9809b6aa3cf6c5.gif

 

Edited by knocker
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As I pointed out in my medium term anomaly update posted yesterday evening in the ramp thread it would appear that our upcoming weather will be greatly affected by the Canadian vortex lobe taking a hike east, facilitated by the Pacific jet and ridging in north west North America, Best and quickly illustrated here by a couple of NH charts this morning.

gfs_z500a_nh_4.thumb.png.ccf6aae18266c7062490aba63fd8a7bf.pnggfs_z500a_nh_17.thumb.png.f7311414f5b3bfb02065162210a7aa57.png

That's the overall picture so following on from yesterday morning's post a bit more detail. By midnight tonight the Atlantic upper trough is deconstructing as it hits the still effective block to the east with the shallow surface low and fronts virtually stalling over Ireland whilst the main trough over north east Canada is on the move east with a very strong thermal gradient in place as the Bermuda high pushes north.

gfs_z500a_natl_5.thumb.png.dac26e534a239f55c8ad4da5f261a78d.pnggfs_uv500_natl_5.thumb.png.cd51ee8e411056a31ec5382698097191.pngPPVE89.thumb.gif.56c0aea0d45b978b266c9a99aff8ae0e.gif

Wind forward 24 hours and most of the UK is in a col as the front is still faffing about in the west but stronger winds are starting to impact the north west as the evolution the the west and north west gets into gear. In a nutshell the trough has continued it's movement east initiating some very rapid cyclogenesis in the Iceland are and realigned the very strong jet which is in the region of 200kts.

gfs_z500a_natl_9.thumb.png.bc6696b5f118d50d17f2108125e25721.pnggfs_uv250_natl_9.thumb.png.f30a4535ca29d55d110e7f69bafb9394.pngPPVI89.thumb.gif.eb69a8df4348d36a0f0ed745d3b0b12e.gif

So now the transition to the next phase is well under way with the energy and colder air associated with the lobe tracking east rapidly impacting the UK from the north west with fronts and rain moving south east through Sunday/Monday before clearing. All of this accompanied by strong winds veering north westerly on Monday with frequent wintry showers

gfs_t850a_natl_15.thumb.png.023055e78aaa8d099c75c41d8c56bce3.pngPPVK89.thumb.gif.aeea7c4284d0407c3e214469ac2d0056.gifPPVM89.thumb.gif.207e29fb9b1fa5df1c38cca2f79d2dbb.gif

gfs_ptype_slp_eur3_19.thumb.png.7c57aaa9f8e5580f83bd3aedd3ef5eca.png

As previously mentioned my thoughts on the medium term are  in the ramp thread One thing worth noting but outside the remit of this thread is that the major upper trough to the north west does drag in some Am air.

Edited by knocker
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Interesting to follow the low forming at T84 off the eastern seaboard through to T132

gfs_mslp_wind_atl_15.thumb.png.e21d95cc26f8d5f32bfa265a5822da63.pnggfs_t850a_natl_15.thumb.png.538c01464d03921844f8027d8483640d.png

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10 minutes ago, chrisbell-nottheweatherman said:

Might that force the jet north again, Malcolm?

Not really Chris as the upper trough is becoming very negatively tilted and the very strong 500mb flow inclines from running North of east to south and this dictates the track of the developing low as it swings around the high pressure to the east.

Edited by knocker

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