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Paul

Mid-winter - models, teleconnections and nowcasting

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Between t120-168 the gfs amplifies the subtropical zones thus 'trapping' the upper trough over the UK. All resulting in a continuation of unsettled weather over the latter and Europe swamped by WAA

gfs-deterministic-nhemi-z500_anom-6324800.thumb.png.2d343e4aa7dbe853b93b6f7ac5691eb6.pnggfs-deterministic-nhemi-z500_anom-6411200.thumb.png.9f099663e67be3f95531fd7a742987b7.pnggfs-deterministic-nhemi-z500_anom-6497600.thumb.png.24418b5e0101f10291acd82e16e3f162.pnggfs-deterministic-nhemi-t850_anom_stream-6497600.thumb.png.cbc6e02a1abaecd6828ee5d123d0a92a.png

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What happens next can only be viewed after the watershed

Edited by knocker

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The salient points of the ext mean GEFS this evening

Aleutian ridge into the Arctic adjacent to the east Pacific trough

Tpv northern Canada with trough extension south east into the NW Atlantic under the high cell over southern Greenland

Still a strong westerly upper flow exiting the eastern seaboard across the Atlantic but backing in the east courtesy of the subtropical high amplifying in central Europe

This would indicate less unsettled but tending towards a NW/SE split with temps rising nicely. The usual caveat that this is just a broad scale assessment and the det runs need to sort the detail

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7102400.thumb.png.976c414877091dd5e5c6905455194da4.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-7102400.thumb.png.b860420aee41dd448bb41f764d8f58d1.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-7102400.thumb.png.908628f654f84ab9bf1064aae658a070.png

Edited by knocker

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The ecm goes through a similar Subtropical zone amplification in the 120-168 period so the charts unnecessary  but the Bermuda ridge is soon removed by the rampant energy exiting the eastern seaboard which now hits the block of the intensifying European high resulting in, oh my, south westerly zephyrs

ecmwf-deterministic-nhemi-z300_speed-6605600.thumb.png.39b094ead2cf29596740f4abfa10a84b.png198.thumb.png.fb6efd89f720a3dff4b38b05fa0bc97f.png

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And the salient points of the ext mean EPS (those of a nervous disposition look away now)

Upstream a high cell over the Arctic; east Pacific ridge and tpv northern Canada

Downstream a trough extension from the latter into the NW Atlantic south of the east Greenland ridge

A strong westerly upper flow running south of this combination across the Atlantic but backing in the east courtesy of the burgeoning European high.

Thus indications of it becoming less unsettled but tending to a NW/SE split with temps rising. The usual caveats apply

ecmwf-ensemble-avg-nhemi-z500_anom_5day-7102400.thumb.png.60129c2c80cd885eccd2f6638a4b9a3c.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-7102400.thumb.png.20669c214e40d4d8419ca0073ca793d3.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7102400.thumb.png.361a792e71376996645961375936501d.png

 

Edited by knocker

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Polling day continues to look wet and windy as yet another low develops just west of Ireland stretching it's frontal boundary across the UK.

fax72s.thumb.gif.f9d181f96e2f4b932d715ef22d4de71e.gif926498077_viewimage(1).thumb.png.6d3bff8ad87c15dee2d88f22602ce201.png

Colder air to the north turning rain to snow across the higher ground of Scotland.


viewimage.thumb.png.cf16c8538d6834208b7e3af72dce548f.pngpr.thumb.png.3dc022c893e560f2c1c5ab2208cf8a50.png

 

The wind chill making it feel bitter up there.

wc.thumb.png.c39007db613c59e70d9a1903f5c00cce.png

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Spare a thought for Iceland and the rapid cyclogenisis with lots of snow with blizzard conditions

ecmwf-deterministic-natl_wide-t850_mslp_prcp6hr-6000800.thumb.png.6b5347f4dfb387130cead08b43816f61.pngecmwf-deterministic-natl_wide-t850_mslp_prcp6hr-6022400.thumb.png.6318ab73161c7bdfe25a7cc2f4c36cb6.png

Edited by knocker

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A quick look at the EC weeklies update for the first two weeks of January

01-o8

Upstream an Alaskan ridge with the tpv northern Canada with trough extension to the NW Atlantic

Strong westerly upper flow exiting the eastern seaboard which abates somewhat, and diverges a tad, in the east courtesy of the Azores high nudging north and low pressure in the eastern Mediterranean.

Thus portends changeable weather but inclining towards a NW/SE split

ecmwf-weeklies-avg-nhemi-z500_anom_7day-8441600.thumb.png.7517db44305205587e0aa1d330578495.pngecmwf-weeklies-avg-eur-t2m_c_anom_7day-8441600.thumb.png.f0eeb8ec9a191ec67a3955c0ad3780f5.pngecmwf-weeklies-avg-eur-precip_168hr_inch-8441600.thumb.png.be50081dd8ce7492017017d649f895db.png

08 - 15

More emphasis on the Alaskan ridge/vortex combination which drags the Atlantic trough west a tad allowing more general height rises over western Europe, including the UK  Thus more settled weather over most of the country, with the temps teetering around average, the exception being the north west

ecmwf-weeklies-avg-nhemi-z500_anom_7day-9046400.thumb.png.59bb4fc20eb2ac2d3285d3241e9773c0.pngecmwf-weeklies-avg-eur-t2m_c_anom_7day-9046400.thumb.png.cfebc8ddff5993ac53362528a1b02a87.pngecmwf-weeklies-avg-eur-precip_168hr_inch-9046400.thumb.png.0038cd407649e84b0904c5e4f47fd438.png

Edited by knocker

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Meanwhile back on the farm. Over the weekend and the beginning of next week there is a brief hiatus, discussed yesterday, When the subtropical zones amplify resulting in the orientation, and eventual deconstruction, of the trough over the UK, I say brief because the Bermuda ridge is quickly over powered by the energy exiting the eastern seaboard

ecmwf-deterministic-natl_wide-vort500_z500-6368000.thumb.png.e06f2ddfd3c83698b06c029a0a272e2b.pngecmwf-deterministic-natl_wide-vort500_z500-6454400.thumb.png.f7c01d47834dcf25e04a949f79f290d4.pngecmwf-deterministic-natl_wide-vort500_z500-6540800.thumb.png.01e33cbc8d34030480d546bd8928af54.png

So after Saturday when an occlusion brings some rain and some hill snow, particularly in Scotland

PPVO89.thumb.gif.f9c56e10063db4f1fe61d682bb4de2cd.gifecmwf-deterministic-uk-t2m_c-6324800.thumb.png.579c1991fafe6a7301f0ee33f7de0208.png

This is the surface picture as seen by the ecm Unsettled and easing briefly before the next Atlantic system arrives. This is of course subject to change

144.thumb.png.e183d247f92c83201735d980bc335e39.png168.thumb.png.b226620a98966d418767b4a43836ee78.png192.thumb.png.39551737de6e83b172744ca08021cf2d.png

But really the key feature of the run is the increasing strength of the European high

ecmwf-deterministic-nhemi-z500_anom_5day-6800000.thumb.png.5165c13d615933a5b25d512878ad0105.png

 

Edited by knocker

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A quick look at today. Rain from the first frontal system will cross the country this morning but by midday the heavier belt of rain associated with the cold front will effect N. Ireland and western Scotland and track south east through the afternoon with frequent squally showers following

PPVA89.thumb.gif.439b94a7a29a4ae06b2f6ef1e731d62e.gifmeanreflec_d02_9.thumb.png.cbec4ea9b91b00e81efe71b0182d7b82.pngmeanreflec_d02_15.thumb.png.413eacc00b892724173b1cfa1b2bed3f.pngmeanreflec_d02_15.thumb.png.385abf2c114e367ef824a0391b45cc2f.pngmeanreflec_d02_18.thumb.png.4ec63f4ec2dfb04a720e19acff316cd4.png

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The salient points of the ext mean EPS anomaly

A col over the Arctic with a trough in the eastern Pacific adjacent to the Canadian vortex. The latter has a trough extenson into the NW Atlantic south of the east Greenland ridge

So still a strong westerly upper flow south of this which backs in the east, courtesy of strong height rises over Europe

This would portend a NW/SE split over the UK with temps nudging above average

Looking good for Sidney's Xmas barby 8)

ecmwf-ensemble-avg-nhemi-z500_anom_5day-7167200.thumb.png.6d6fb3ae6848e592f63c83ea46864e30.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-7167200.thumb.png.6bcfea8ada5a0650d786c3171bbc7e33.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7145600.thumb.png.d023f8c1764a8d7dad9d1e55c46064f4.png

 

 

Edited by knocker

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PPVA89.thumb.gif.a337beba165d45793baa8611fae7b7d0.gifPPVE89.thumb.gif.6e569a87981bf95f9ea186d95ddc5b29.gifPPVG89.thumb.gif.a8ff95c3ccdd68aaecb5dafc50f38378.gif

Through the rest of this afternoon and through this evening the cold front and the belt of heavy rain will continue to track south east clearing the coast by midnight. The very strong winds currently effecting W and NW regions will abate during this time but it will be quite gusty along the front. Once it has cleared  During the evening frequent squally showers will effect Scotland which could be of snow down to quite low levels

sfcgust_d02_12.thumb.png.2d6ec2a2c3cf86eaf272ffe9dd073b0e.pngmeanreflec_d02_10.thumb.png.ff01fd73017f14ab637adf01d80fef46.pngmeanreflec_d02_13.thumb.png.ac1244b8138f36677671290bcaecc076.pngmeanreflec_d02_18.thumb.png.dbfbbdd08f5cc2269880d33e617fa25b.png

Through the rest of tonight and tomorrow the country, is under the influence of the deep low north of Scotland so windy, particularly over the north of Scotland. And in this area the frequent squally showers will be of snow and they may well coalesce courtesy of fronts/troughs within the circulation. And this may well apply to Wales and England as well during tomorrow as a trough tracks east

sfcgust_d02_33.thumb.png.6438fdd867b2c3cfbf2573e217f0081d.pngpreciptype_d02_21.thumb.png.749271c8847b8e3eec5d698760095b62.pngpreciptype_d02_24.thumb.png.c91aa71afb86ad8f1efa392984d78b0c.pngpreciptype_d02_27.thumb.png.79994759cab6ef6b491043e064dc9203.pngpreciptype_d02_30.thumb.png.42b10c10b7cdf7239ad4f05cd5d06f2c.pngpreciptype_d02_33.thumb.png.e7f2f4b00377ced0996db06879cb02cf.png

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The west > east train is briefly interrupted at the beginning of next week by some transient amplification  of the subtropical high zones so a couple of days of quieter weather

gfs-deterministic-natl_wide-z300_speed-6497600.thumb.png.b37d6e4d0d56ce2db117173986d3aacc.pnggfs-deterministic-natl_wide-z300_speed-6584000.thumb.png.ed3c15239a22653774b8eed60fc4cc41.png

Well transient in the Atlantic as the eastbound energy soon batters down the ridge but certainly not so over Europe

gfs-deterministic-nhemi-z500_anom_5day-6843200.thumb.png.254ee0ebfb66d7ca1d20b3a21ba4a0ba.pnggfs-deterministic-nhemi-t850_anom_5day-6843200.thumb.png.0af65d1fb64af76dc9e3ca831872dbd7.png

Edited by knocker

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On 06/12/2019 at 11:23, Paul said:

An impressive, sharp gradient cold front being shown by the UKV on Tuesday. Could be some wintriness on its trailing edge, and squalliness along the convergence line. If it plays out as forecast of course.

cf2.png cf1.png

cf4.png cf3.png

 

Sorry for quoting my own post, but just wanted to highlight what a good job the UKV did for today's forecast of a squall line along the front, some 100 or so hours out..

screenshot-www.netweather.tv-2019.12.10-17_53_41.png

Edited by Paul

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42 minutes ago, Paul said:

Sorry for quoting my own post, but just wanted to highlight what a good job the UKV did for today's forecast of a squall line along the front, some 100 or so hours out..

screenshot-www.netweather.tv-2019.12.10-17_53_41.png

That's quite impressive

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53 minutes ago, Paul said:

Sorry for quoting my own post, but just wanted to highlight what a good job the UKV did for today's forecast of a squall line along the front, some 100 or so hours out..

screenshot-www.netweather.tv-2019.12.10-17_53_41.png

Wow.

It passed through here in Bingley ,west yorks at 4:45pm.

Very impressive for 15 mins with torrential rain and sleet here in sheets.

Edited by joggs

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The cold front just passing through here in Warks.Fax for 1800hrs note the continuing storm around Iceland with severe winds with the driving snow.Must be horrendous up there.

1859319433_fax0s(1).thumb.gif.0963f8c8f67d761f18652ba86a8e9eef.gif

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Gefs 500 Pa pattern/anomalies and 850 hPa temp.anomalies days 6-10 and 11-15.


gfs-ens_z500aMean_nhem_6.thumb.png.869d2ff7740ba500d0dc9e1d6f19bf9b.pnggfs-ens_T850aMean_eu_6.thumb.png.5648e6ae6f437b132277a81f3c107b00.png

gfs-ens_z500aMean_nhem_11.thumb.png.2cb7ac5a676fef1ec478492cc1ecd2bf.pnggfs-ens_T850aMean_eu_11.thumb.png.26103a0b96a6674735a31cad8426fc00.png
The westerly pattern continues but turning milder around day 10 as the flow backs more south west with the Euro ridge building to the east.  

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The salient points of the ext EPS mean anomaly

Slack gradient over the Arctic with an east Pacific rtrough adjacent to the Canadian vortex which is not exactly singing and dancing,

The trough extension from the latter into the Atlantic south of the east Greenland ridge is a tad further east than previously

Thus the westerly upper flow is not backing very much prior to hitting the UK  courtesy of a weakening European high

Small margins

ecmwf-ensemble-avg-nhemi-z500_anom_5day-7275200.thumb.png.13f6f43c171cf4514db92777620572d1.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-7275200.thumb.png.379f69a9231bcbb400c6aa1a570703c1.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7275200.thumb.png.5220674fe0c8c1899e2c2e31df2e7da3.png

Edited by knocker

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The latest NOAA 500mb anomaly charts (the 6 to 10 day and 8 to 14 day ones) continue to show signs of the main area of troughing holding out West in the Atlantic. This results in ridging and higher than average heights occurring to the East of the UK into mainland Europe. A mean upper flow still from the South-West over the UK, so certainly could be chances to see some milder outbreaks at times. Likely for the Greenland and Arctic area to loose some of its deep cyclonic conditions with modest higher than average heights in those parts. This especially evident on the 6 to 10 day chart.

4BEE5A7F-B8CE-49D0-B511-DC03007C33F0.thumb.gif.f63c9d0778f51189dc6ca434c41b0b26.gif

0245AB6F-E325-4AA1-ADC9-48029FD28BC8.thumb.gif.29496ea55d970f25dcfb714b3a46a2b5.gif

In general, the operational models have been playing about with High Pressure developing to the East and South-East of the UK, with Low a Pressure rocking about to our West.

The 00Z GFS this morning, for example, showing this sort of theme at 192 hours:

4DF494AE-6DEB-4CD7-B47F-1FEBAA8732A4.thumb.png.d9d6ae6ac50ed352a9f7a4044770d778.png

And this at 216 hours:

501387E1-760A-4635-BF27-C01977917AD4.thumb.png.3b692f18b00c295aeedb5f172e63f3db.png

So I feel, for now, it’s a possible solution. (It’s also possible that Low Pressure could quite easily break through further East within time). 

In the closer range, it looks as though the models are painting a rather chilly picture for the next few days. A deep area of low heights over Northern and Western UK keeping the weather cool and cyclonic with the flow mainly from a Westerly Polar Maritime direction. The Lows will bring mixture of sunny spells, lively winds (especially towards Western UK), rain and showers. The airmass likely to be cold enough for some of the rain and showers to be wintry on high ground at times. Particularly so over Scotland. But perhaps further South as well.

5FB21982-480F-4810-AA66-2882169D02D0.thumb.png.7836be82e809bb8d541dadfc97cdbc52.pngF0BDD284-5F5D-45B1-80E8-79A88EE6DB91.thumb.png.5fab9b9fbbe690b1807ebb5b8e3315c8.png06CDF228-44C6-4548-A229-FA487FD86A00.thumb.png.72c6e6d606d90adcc5c5f0852719f087.png0BC7FF00-A3AD-47C7-9C1C-00F862AB8400.thumb.png.65e924da6c776984308b169b83bd0a6e.png91DAF2BC-0A7D-47EE-B587-F6E277948E4E.thumb.png.7777eda83a92c2c0069af5b133bee053.pngAF0A5724-0360-4A64-93BF-ACC964F7B5C1.thumb.png.812d36c7e49bf01952411136825d0d59.png
 

Possibility of showers being wintry to lower levels by Saturday as models, such as the GFS, shows areas of -5/-6/-7*C 850 hPa temperatures running in from the West. (Though this could be overdone a bit). 

8FB719A7-90B8-41A1-B568-695A8C23C33F.thumb.png.a5fdbd6133315647c97c6f2a4549bc00.pngEF50A0AB-9466-4CCA-9EC0-CDF8CD2C37BE.thumb.png.4a4273cb7cc4acafa4691089951fe49d.png

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