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Model Output Discussion 01/09/17


phil nw.

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Posted
  • Location: Evesham/ Tewkesbury
  • Weather Preferences: Enjoy the weather, you can't take it with you 😎
  • Location: Evesham/ Tewkesbury

Evening All , models that's gfs and ecm show a big rise in pressure to the northeast of the uk  just enough at the start of the ten day period to influence our weather , but the jet stream is too strong and brings us to some volatile weather as we end the ten day period as we leave September and Greet October....The devil will be in the detail,

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Posted
  • Location: Camborne
  • Location: Camborne

Although the anomalies this evening are in the same ball park vis the neg. trough/ pos. ridge axis there are some significant differences regarding the alignment, The GEFS for example has the trough far less negatively aligned and thus the block further west and the weather over the UK potentially not so unsettled

So the det. runs will need to sort out whether systems will wing their way east on a strong upper flow and impact the UK or whether there will be enough inertia and split in the flow just to the west of the UK to alleviate the worse case scenario. Close call

ecm_eps_z500a_5d_nh_11.thumb.png.d4372a0be3a3e4000c1341d531842920.pnggefs_z500a_5d_nh_41.thumb.png.8853da56ea6b22ffe6a86e2d48113cd5.png610day_03.thumb.gif.f10f1853c23a959cc12c6a60d7202741.gif

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Posted
  • Location: Camborne
  • Location: Camborne

Today there is a  front across the country moving slowly north so many parts of the south will start with cloud and drizzle which will move north during the day. Thus clearing later in the morning and then quite warm in the southerly drift The east will be drier and probably sunnier. .In the north the reverse of this will be a reasonable assessment. Tomorrow an occlusion is stuck down the west side of the UK so cloudy with outbreaks of patchy rain as a few wriggles develop on it whilst to the east sunny intervals and quite warm.

PPVA89.thumb.gif.2a819e316d061c635eb0eaf07b08b21e.gifPPVE89.thumb.gif.cdc4cffd8ef27fbbd3fac6c7f0d089bb.gifPPVJ89.thumb.gif.8384a7809dfce7c321198946e4b18ba1.gif

Monday will be cloudy in many areas as the remnants of the occlusion stagger across the country and then Tuesday and Wednesday should be quite pleasant with little wind with temps possible pushing a little above average. But by 12z Wednesday a large trough dominates the Atlantic giving quite a messy surface analysis but the main point to note is surface fronts with accompanying rain band lying across Ireland.The configuration of the upper trough and the blocking/ridging high pressure is quite evident here with the UK at the pit face and over the next 24 hours the trough does push east bringing rain Wednesday evening through Thursday before clearing into the North Sea by 00 Friday.

gfs_ptype_slp_eur3_19.thumb.png.ee5ca09a7cbbceb37536b3876f6c2f8f.pnggfs_uv250_natl_19.thumb.png.172f096877e26bd2db83184e54ba966f.pnggfs_z500a_natl_23.thumb.png.8af7aa3f3e057a4467a05c6b6b898759.png

So after some transient ridging on Friday the next low arrives NW of Ireland by the early hours of saturday with the associated fronts down the Irish Sea which get stuck over the UK as the block once more becomes effective  Further complicated by the Azores getting in on the act and ridging north east which splits the trough creating once more a cut off upper low to the south. In essence inertia sets in and the whole caboodle comes to halt in the vicinity of the UK. Any slight adjustment to this evolution, as with the Azores for example and it's a different ball game so the end of next week still in the pending file

gfs_ptype_slp_eur3_30.thumb.png.005a72a5d33a84b1e7cbcefeadacb861.pnggfs_ptype_slp_eur3_37.thumb.png.f404412290e688feb76ea3b4db6f3c9a.pnggfs_z500a_natl_37.thumb.png.d910300ba1212060979af08fe48bd084.png

so what to say in summation? Changeable should just about cover it with two or three good days and some not so good but nothing drastic. But I wouldn't bet the farm on any detail past Wed.

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

No big surprise, given last night's EPS, that the ecm has a much different take on the end of next week.

More or less okay up to Thursday but by 12z Friday it has swung a new low into central England tracking north east bringing a fair amount of rain with it and possibly gales in the south and west.

Thus by 12 Saturday we have the  dumbbell scenario with one vigorous low just to the north of Thurso with the other west of Ireland ready to swing east into the UK which it duly does bringing some very wet weather and possibly severe gales in the process overnight saturday into Sunday.

Unnecessary for me to say at this stage that next weekend is a long way from a done deal

Note not a glimmer from the Azores The gfs and ecm are chalk and cheese but if the gfs lost the Azores ridging NE I doubt they would much different. (of course the gfs may be right :shok:)

ecm_mslp_uv850_natl_8.thumb.png.fa1d3ed54d404bd0e989e96a9a5b576b.pngecm_mslp_uv850_natl_9.thumb.png.055d023560b33e4168df4aac3beef683.png

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

You have got to hand it to the gfs, all change every six hours.

This evening it merges Maria with the main trough to the NW and at T192 there is a large complex low pressure area in mid Atlantic. Twenty four hours later having engaged with a very strong jet some explosive cyclogenesis has occurred and there is low 955mb about 250k WNW of the Hebrides. Completely at odds with the previous run

gfs_ptype_slp_eur3_33.thumb.png.ad6798c59da38b2c44877a21d1b83e8b.pnggfs_uv250_natl_37.thumb.png.9691d54c67d493845547d36c3a8ea426.pnggfs_ptype_slp_eur3_37.thumb.png.3f270abee4e178ab10e57adc01bb58e6.png

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

To be fair to the gfs the ecm also has some major changes from the previous run in a pretty close time frame,

On the latest run it now has quite a deep low 978mb NW of Ireland at 00 Friday with fronts and rain down the Irish Sea. In the next 24 hours these cross the UK into the North Sea as the low itself swings NNW towards Iceland. But there is no respite as by 00 Sunday the next depression has arrived 980mb NW of Ireland, courtesy of 160kt jet, bringing heavy rain and gales for the UK on Sunday.

Obviously the detail for next week is a long way from nailed down but with all of these depressions flying about we will lucky to avoid at least one.

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

Just briefly as last night's anomalies are not significantly different to previous. The high pressure/trough axis continues to dominate proceedings in the Atlantic, particularly the east. albeit there are still some orientation differences noticeable between the GEFS and EPS.

So essentially we are still looking at a very strong westerly upper flow in mid Atlantic abating somewhat in the east and tending to back somewhat in the vicinity of the UK. Thus the question is perhaps still open on the track of some of the troughs that are likely to impact the UK and how much they will tend to track NE.The percentage play is still for this to be a quite an unsettled period with potential to continue longer and temps no great shakes at average or a little below.

ecm_eps_z500a_5d_nh_11.thumb.png.47064e7c716565bbe5be59240672d51a.pnggefs_z500a_5d_nh_41.thumb.png.a1f71421e06a708c00f094fbb077c1eb.png610day_03.thumb.gif.2a92f47069e7b05cb1e1c46998f6e4f7.gif

Closer to home and keeping it very general. Over the next couple of days the occlusion that is currently residing along the western coasts of the mainland will move very slowly east so very much a west/east split with bouts of intermittent rain in the west and dry and warmer in the east. THe area in the east will tend to dwindle as time moves on and brighter and clearer weather will reach western parts.

PPVE89.thumb.gif.9e4a52b5614f0fd73cbbd7306bc1f698.gifPPVI89.thumb.gif.62d1f3fb36655f50ee463978766f5d56.gifaccumprecip_d02_49.thumb.png.f3fe15659b54caff0eda373d88e4c8b2.png

Once the front has cleared away Tuesday and Wednesday will be quite pleasant and will quite warm in the light winds but the next front arrives from the west late weds bringing some more rain  This soon tracks into the North Sea by Thursday but by 00 Friday a deepening low has swung NE to be  around 400km WNW of Ireland with associated front over Ireland. This in turn traverses the country to be in the North Sea by Saturday lunchtime as the low drifts north and fills.

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From this point the gfs once again goes off script and develops the low to the west but it tracks it south east as the upper trough undercucts  the high pressure and connects to the trough in south east Europe (it is quite keen on this scenario). Thus we end with a large area of low pressure to the S/SE and the Azores once again ridging strongly NE. Either the gfs keeps picking up something vis the Azores or it keeps going off on one.

gfs_z500a_natl_31.thumb.png.c6a2f04c71fa89e4ee23937a025ba167.pnggfs_ptype_slp_eur3_31.thumb.png.f00c4a3ed8227b8ba9b670c58091798c.pnggfs_ptype_slp_eur3_35.thumb.png.918e0b5f072310f9589abd31ec5a39ac.png

You can just about see where it's coming from by glancing at this morning's GEFS anomaly Weakening trough to the NW, etc And of course it could also be to do with the fact that it has Maria ending as a deep low in the Denmark Strait.

gefs_z500a_5d_nh_43.thumb.png.bdf2a729c89e79ed272150a9deeaf4de.png

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

No great surprise that the ecm interpretation for next weekend is different. By 00z Sunday it has the next low swinging north south of Iceland with associated fronts and heavy rain over Ireland. These track east, complicated by a small depression forming on them, giving a very wet and windy day on Sunday through to Monday  By Tuesday an area of low pressure is situated over N. Ireland.

Meanwhile Maria has merged with other troughs in the NW and the whole caboodle is tracking east to be negatively tilted just to the west of the UK by the end of the run portending gales and more wet weather. It's a long way off but this is where we came in.

ecm_z500a_5d_natl_11.thumb.png.01945574c30aa7fef9dc4036bbb8dfcd.png

Edited by knocker
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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Quiet in here today.. a bit of a stand off at the moment between a significant blocking feature to our NE and the atlantic, consequence a mild few days, with rain slowly moving through the country by the middle of the week. Models suggesting the atlantic will gain the upper hand as we enter next weekend, with low pressure becoming dominant and strong winds blasting through, with heavy rain for some, and becoming cooler for all. 

This can be a rather trying time of year, chances of warmth diminish rapidly, but more often than not we end up just mild and at the mercy of the atlantic, it is not a time ripe for unusual synoptics..  

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Posted
  • Location: st albans
  • Location: st albans

A promising ec op run late on for snow cover developing over Siberia and the retrogressive nature of the run to our north would be a nice  pattern for coldies to see repeating over the next 6 months 

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Posted
  • Location: Evesham/ Tewkesbury
  • Weather Preferences: Enjoy the weather, you can't take it with you 😎
  • Location: Evesham/ Tewkesbury

Good Evening All.....! Make the most of the rather benign conditions Jet stream is screaming to the uk from mid week onwards , so feeling like Autumn Gales wet and windy ...Yes , but lots of sparkling Autumn sunshine in between the systems ,,,,,Can I put any Spin on this ...Perhaps not:rofl:

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Posted
  • Location: Camborne
  • Location: Camborne

I will keep this brief as there are no indications of any significant changes in the medium term outlook from last night's anomalies. The key still remains the orientation and intensity of the high pressure/trough axis. Thus a strong westerly flow mid Atlantic abating to the west of the UK with a split flow not out of the question which could well effect the direction of travel of systems generally tracking east when they get withing the vicinity of the UK. As ever the det will need to sort the details but the percentage play remains quite unsettled with temps varying around the average.

ecm_eps_z500a_5d_nh_11.thumb.png.b59e4de286d77adec40d6c26e9c81910.pnggefs_z500a_5d_nh_43.thumb.png.23214d9b2653a0c0491bbcb55ae2e46c.png610day_03.thumb.gif.5e33691f6a4c528270c5ae3c991642ef.gif

Today we have the occlusion which more or less has ground to a halt down the spine of the country so many areas will be quite wet, the exceptions being the east and far west. this generally remains the picture tomorrow but the front is in the process of fizzling out so less rain, cloud breaking, and quite warm where this happens.

PPVI89.thumb.gif.f2281ab3fa7d643763e4f7624809d429.gifPPVK89.thumb.gif.6cd18691194b89dd1eacf1a583ea0149.gifaccumprecip_d02_49.thumb.png.3d2646c95e77e4a6b2b22a13b283f379.png

Wednesday will be quite pleasant and relatively warm but by 12 the next front and rain has arrived over Ireland which proceeds to track irregularly east late Weds and Thursday petering out as it goes with outbreaks of sporadic rain in most areas In the meantime the next quite deep low has tracked up from the  south west and is south of Iceland 975mb by 12 Friday with the associated fronts lying down the west of the country bringing another bout of general rain.

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From this point things get a little more complicated and by 18 Saturday the main depression is over Iceland the nest low just west of Ireland but the split flow mentioned earlier comes into play here as it ducks south east and fills, At the same time ex tropical storms Maria and Lee have merged with another trough and are busy getting organized to the west.

gfs_ptype_slp_eur3_24.thumb.png.356180c696db2bdafb4711f2fb3a3a7e.pnggfs_uv500_natl_24.thumb.png.bf60244ef021500e056b448ca67e26d6.png

And organised they get and over the next 48 hours as the newly formed low low deepens considerable as it tracks north east on the very strong jet with the associated fronts crossing the country on Monday bringing heavy rain and possibly severe gales in Scotland.

.gfs_ptype_slp_eur3_28.thumb.png.cd2fd0caf1cf7ede5e758771760c7064.pnggfs_uv250_natl_29.thumb.png.332f3b6293c339120a299d86d5db93cb.pnggfs_ptype_slp_eur3_32.thumb.png.1c532b12c66b67e847af51e1f2320852.png

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

The ecm also has Maria and Lee merging at the end of next week but thereafter they differ on the track and depth, (very importantly) as the question of the split flow arises once more.

By 12 Monday it has the new intense low just west of Ireland but over the next 24 hours it moves ESE to be over Kent by 12 Tuesday. From here it continues down into central Europe and fills.

This is obviously a long way from a done deal but will need close attention over the next couple of days as there is the potential for significant rainfall and high winds.

ecm_mslp_uv850_natl_9.thumb.png.294846c6b0c4a41fbdef4ca7c9a0161c.png

Edited by knocker
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Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

Some deep lows back on this mornings ECM the first is shown to move up towards Iceland

ECMOPEU00_96_1.thumb.png.79963a501c05f0797e99201abbbda9ad.png

Another low moves in on Sunday

ECMOPEU00_144_1.thumb.png.6e1700b68f6b060c8b3e703a37350f56.png

That clears to leave a calmer slot before another sweeps in on Tuesday

ECMOPEU00_192_1.thumb.png.99707108471f981c3114f97bc936c9fa.png

Tuesday's low has some pretty warm air trapped in it until it gets to us

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)

Morning all, don't think I've posted in here for a while, but will do when things look interesting weather-wise.

Following on from Knocker's post above, running MSLP loops of the N Atlantic for the 00z GFS and ECM from later this week until early next week you can see Hurricane Maria (west) and Hurricane Lee (east)  joining forces over mid-N Atlantic, by which time ex-tropical over much cooler waters to the north, before running NE as a deep depression towards the British Isles and arriving early next week.

00z GFS 

gfs_mslp_wind_atl_fh96-168.thumb.gif.8d82c5a8c17a8113b452a423bf2f423d.gif

00z ECMWF

ecmwf_mslp_uv850_atl_fh96-192.thumb.gif.6e0e7aba385346fd219759cc3a84b1e5.gif

Ensemble mean MSLP seems to be pointing to disturbed Atlantic affecting the UK from later this week.

ecmwf-ens_mslpa_atl_fh96-168.thumb.gif.64a828b86e169eaf7f460ace053a9964.gif

Edited by Nick F
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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth
1 hour ago, Nick F said:

Morning all, don't think I've posted in here for a while, but will do when things look interesting weather-wise.

Following on from Knocker's post above, running MSLP loops of the N Atlantic for the 00z GFS and ECM from later this week until early next week you can see Hurricane Maria (west) and Hurricane Lee (east)  joining forces over mid-N Atlantic, by which time ex-tropical over much cooler waters to the north, before running NE as a deep depression towards the British Isles and arriving early next week.

00z GFS 

gfs_mslp_wind_atl_fh96-168.thumb.gif.8d82c5a8c17a8113b452a423bf2f423d.gif

00z ECMWF

ecmwf_mslp_uv850_atl_fh96-192.thumb.gif.6e0e7aba385346fd219759cc3a84b1e5.gif

Ensemble mean MSLP seems to be pointing to disturbed Atlantic affecting the UK from later this week.

ecmwf-ens_mslpa_atl_fh96-168.thumb.gif.64a828b86e169eaf7f460ace053a9964.gif

I'm reading 60+ knots on the ECM. How long before the press start speaking of a "direct hit from Hurricane Maria"?

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Posted
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
  • Location: Caterham-on-the-hill, Surrey, 190m asl (home), Heathrow (work)
43 minutes ago, Man With Beard said:

I'm reading 60+ knots on the ECM. How long before the press start speaking of a "direct hit from Hurricane Maria"?

Maybe Storm Brian, though calling an Atlantic depression Hurricane Maria, though obviously incorrect and liable to confuse joe public if the storm is named by the Met Office, will be greater 'click-fodder' for the media.

Edited by Nick F
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Posted
  • Location: Camborne
  • Location: Camborne

Just to note as this is a along way from being settled the gfs take this evening. It's massively different to the previous run but it's joined the track SE brigade.

gfs_ptype_slp_eur3_29.thumb.png.49908533056083de669fda47a5f54a04.png

Edited by knocker
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Posted
  • Location: st albans
  • Location: st albans
7 hours ago, Nick F said:

Maybe Storm Brian, though calling an Atlantic depression Hurricane Maria, though obviously incorrect and liable to confuse joe public if the storm is named by the Met Office, will be greater 'click-fodder' for the media.

It needs to be be Lee maria or Maria Lee. Otherwise it will be Brian nee Maria .........

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