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Paul

Mid-winter - models, teleconnections and nowcasting

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According to the GFS further deep lows arrive on the scene over Monday night and through Weds but I'm not buying the detail of this at the moment

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Leaving aside the det run going off on one the mean GEFS is pretty much as expected, albeit the ridge a bit further east

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7664000.thumb.png.14a9ff8acdabed3f2533c144c0620c28.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-7664000.thumb.png.a404f82a1b3a5253ab72145eec263148.png

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Although there are still differences between the ext mean anomalies, as has been previously discussed, the general theme does appear to be consolidating which must be good news

So this morning the EPS has quite an intense vortex just north of Alaska with trough extension into the north west Atlantic

A strong westerly upper flow exiting the eastern seaboard south of this which backs and abates as it swings around the amplifying subtropical over the UK and down to the trough in eastern Europe

ecmwf-ensemble-avg-nhemi-z500_anom_5day-7836800.thumb.png.eb0ec8cd4c0e2dc0210e660ca9fd4bee.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-7836800.thumb.png.8316919b7bbe67f2fea9e0a781aab2ed.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7836800.thumb.png.3d30eb10db2467619c8994ed0cfba61d.png

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Comparing the last two gfs runs for midnight Tuesday shows what a complete waste of time looking very far ahead for any detail at the moment

138.png144.thumb.png.ed8e62dd06209fcfb54984614aace2e4.png

 

Edited by knocker

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The 0600 ecm has the low crossing the south through saturday afternoon/evening

ecmwf-deterministic-eur-t850_mslp_prcp6hr-6962000.thumb.png.1153e964f025118a3a560b94c949f591.png

 

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The overall NH pattern with the ext GEFS this evening is a tad further east than previously indicated which is still okay all long as this isn't the direction of travel. So still portending a quieter and warmer period

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7880000.thumb.png.ec8c408b9c758fc9d1dfad1663dfef98.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-7880000.thumb.png.30c43700e3c0a8dbb46d479c34ebaf10.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-7880000.thumb.png.0f3b79bfdcb00cd848dae3a602452672.png

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Through the first half of next week the ecm finally shifts the upper trough, that as been around for days, south east as the subtropical high amplifies giving quite a settled Xmas day. At least that's how it looks tonight

ecmwf-deterministic-natl_wide-z300_speed-7102400.thumb.png.a6f31b1e2881d00f0f4aec80ab104b83.pngecmwf-deterministic-natl_wide-z300_speed-7188800.thumb.png.4eebba328d8a4b00c5d6917683a74425.pngecmwf-deterministic-natl_wide-z300_speed-7275200.thumb.png.ea76f7e3f721b4c895d3ea7838d0d9cb.png

168.thumb.png.b9c415c2307149c4f1fddb72f3154b14.png

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The continuing differences between the ext GEFS and EPS this evening are very apparent so no further comment really required except this will need to be sorted before one can reasonably be confident of the forthcoming evolution. Albeit the percentage play is still a quieter period of weather with temps a tad above average but a fair diurnal range

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7880000.thumb.png.6f226269600649eecbcee2e2a912a40e.pngecmwf-ensemble-avg-nhemi-z500_anom_5day-7880000.thumb.png.03aadb2641b31f9ab1b7c0b1ce2b3164.png

ecmwf-ensemble-avg-nhemi-t850_anom_5day-7880000.thumb.png.480dd2ff07abd0670e5aa64810efbd0e.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7880000.thumb.png.745ebccc472a6ebdf7848a38280fa959.png

 

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Outlook - One way or tother the upper trough will dominate our weather over the next few days

The North Atlantic 500mb and surface analysis for midnight

gfs-deterministic-natl_wide-z500_anom-6724400.thumb.png.e9eaf9885b31d3007432782044528ce7.pngPPVA89.thumb.gif.c30990b897e4ae05886379516094ffc6.gif

Currently some heavy rain is effecting the north of England which should quickly clear to the north east but further heavy rain from a wave on the trailing cold front will track north from around 1100, effecting most areas, apart from northern Scotland. by 1800. resulting in a very wet and windy day

PPVE89.thumb.gif.6058fbe82337b8ba4657d738e6b8d689.gif2mtemp_d02_20.thumb.png.06e28e7dbcb205e3e9cef97f12316667.pngmeanreflec_d02_18.thumb.png.7fb7eb523f9a4a100dea0645d6cbfa0c.pngmeanreflec_d02_21.thumb.png.2733edaff56976da5af893698ea1c2e9.pngmeanreflec_d02_24.thumb.png.41ce0ac156c8a63a00f434e486ed39a5.png

The rain will continue to swirl around N. Ireland, the north of England and  Scotland through this evening and overnight whilst further south remains dry but a further system tracking north will bring rain to the south east from midnight

PPVG89.thumb.gif.7d96ebb6bd1e4cabdd31dfc883d91e4e.gifprecip_d02_30.thumb.png.2563d799c26a08dff3267d469f27065f.pngprecip_d02_37.thumb.png.e8dd86fd699ec025d7852fbd97799125.png

By Friday the low and associated front are adjacent to the Hebrides so rain will tend to hang around western Scotland whilst the rest of the country should be dry with sunny intervals, maybe the odd shower. But more persistent rain will continue to effect the south east for a while

PPVI89.thumb.gif.6716844ed2484ec0ac927ac4e185b04c.gif2mtemp_d02_44.thumb.png.c38c4a19d05f3ad2407709df00a53d2a.pngprecip_d02_44.thumb.png.07b74e20e4d3bf4236da29c791312325.png

The broken cloud/showery routine will continue over friday night and the beginning of Saturday but a deep low in the southern quadrant of the trough is tracking rapidly east and will bring rain and strong winds to the southern half of the country later on Saturday

gfs-deterministic-natl_wide-z500_anom-6929600.thumb.png.db983894cc49d27183e3cdfebc85dc84.pngPPVJ89.thumb.gif.38ce69a22cb003e70e4f61ad79229686.gifPPVK89.thumb.gif.49c98d8997ebc26934bb0bbe30645ec3.gif

gfs-deterministic-uk-precip_6hr_inch-6962000.thumb.png.4c4ec49da91409561f622232dc598796.pnggfs-deterministic-uk-t2m_c_max6-6951200.thumb.png.9083281597c4f9cc42d5e3408197771c.png

The now filling low will be over northern Germany by midday Sunday so a day of sunny intervals and showers that will mainly be concentrated over western regions

PPVM89.thumb.gif.07f349577e4bf372e22bfeb89c91ee1c.gifgfs-deterministic-uk-precip_6hr_inch-7037600.thumb.png.5686b8cba35d31f7daf6a2175f34cc23.pnggfs-deterministic-uk-t2m_c_max6-7037600.thumb.png.0fcc9ffa8309e21b7f7b06f50541b780.png

Further developments under the umbrella of the upper trough on Monday with a deep surface low to the north of the country resulting in a wet and windy day in many areas with showers and longer periods of rain. But by now the pattern is starting to change as the subtropical zones start to stir.

gfs-deterministic-natl_wide-z500_anom-7113200.thumb.png.e2b78cb873bb0dfce0b576fb38886ff0.pngPPVO89.thumb.gif.eeb414352dd4a6fdbd1703f73e28c828.gifgfs-deterministic-uk-t2m_c_max6-7124000.thumb.png.bf6d4b08af6ac8508a9c057790f7b56a.png

Edited by knocker

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The stirring of the subtropical zones does briefly interrupt the trough dominance but the gfs interpretation is pretty messy si I have no great confidence in the detail for the middle and end of next week

gfs-deterministic-nhemi-z500_anom-7275200.thumb.png.fe664297deceb78fb7e21f47c4d28372.png

132.thumb.png.acc5d7e8e6aa303dc62928f759999d0a.png156.thumb.png.0ded88ef7ab44f1e52c8083b0807a44b.png180.thumb.png.a58dc2982acc8be51f6c6051475eb03e.png

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As noted last evening complete agreement between the ext anomalies is elusive and this morning the GEFS has strong ridging and positive anomalies into Scandinavia so the EPS is probably of more interest than normal later

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7923200.thumb.png.1eea03a6e0f6c5d706daa5570a6a8bb5.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-7923200.thumb.png.90fdc8018dfd1d96480ed4c7300ed465.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-7923200.thumb.png.265cf0ae040a43d5ebf6cbf628581ff2.png

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The ecm is more positive regarding subtropical high influence next week and thus drier and more settled weather

ecmwf-deterministic-nhemi-z500_anom_5day-7534400.thumb.png.6206870fad95ea1947702b18ee591441.png132.thumb.png.9fdca2a72fcd3c2ca0ed2915226b83d4.png

156.thumb.png.5ef517c988a74451f753d7806d4944c0.pngecmwf-deterministic-uk-t2m_c_max6-7296800.thumb.png.a42fc6073626cb2bfa767aaf674827dd.png180.thumb.png.5ad0e31cb977ab1cd3d77f640fd23715.png

 

Edited by knocker

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The ext EPS continues to differ with the GEFS so the downstream Atlantic/European alignment still to be resolved but the outlook remains positive regarding drier and more settled weather

ecmwf-ensemble-avg-nhemi-z500_anom_5day-7923200.thumb.png.e45c4737076395887ac283509234a8f6.pngecmwf-ensemble-avg-nhemi-t850_anom_5day-7923200.thumb.png.7510d78a7dc02c9ee9a6e36c11f14d44.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7923200.thumb.png.32d86b28a6688f9b6ba9685ab113492f.png

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The gfs has been struggling of late sorting next week so how's it doing this evening

By midday Monday it has a wee wave forming at the base of the trough to the south west and runs it north east across the south of the country

gfs-deterministic-natl_wide-vort500_z500-7102400.thumb.png.bdbecb80c97d514210efe5b7297ac0a0.png96.thumb.png.55c750176a71dc31fe451896aa731bca.png108.thumb.png.0a1f356e30b31fd037cff8fcb43a3eb5.png

But the subtropical zones are starting to amplify plunging  the mid Atlantic trough south and so by midday Wednesday a high cell nestles over the UK with just the north of Scotland experiencing any dodgy weather

gfs-deterministic-natl_wide-vort500_z500-7275200.thumb.png.8619e29d00de4e7f24b4c68adccc9a06.png144.thumb.png.f6807574ce74f32eab6cbd40d422aa41.pnggfs-deterministic-uk-t2m_c_max6-7275200.thumb.png.c8746c0069133b6a45b2f289e5314acb.png

But there is still a fair bit of energy exiting the eastern seaboard and it's interesting to see the distribution as it battles against the ridge

gfs-deterministic-natl_wide-z300_speed-7361600.thumb.png.64f89ea4b13e6f2ed7a31b3d2540a500.png168.thumb.png.df7c423c24b6a7652bd4c584a0e5b128.png

gfs-deterministic-natl_wide-z300_speed-7448000.thumb.png.6efb3aec1359b3330e15ca2c42252117.png192.thumb.png.269578fdb3d9b9af92c45ac3bc065843.png

gfs-deterministic-eur-t850_anom_stream-7383200.thumb.png.8b3f03e25bbafc5f1c61a599cbf1d001.png

 

Edited by knocker

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The ext GEFS mean anomaly moving towards the EPS?

Salient points

Strong vortex over the Arctic with trough extension south east to the NW Atlantic

Trough/ridge combination over the southern States

Strong westerly upper flow exiting the eastern seaboard across the Atlantic but backing and abating in the east courtesy of strongly amplifying subtropical high which is now more aligned over the UK

Portending a quiet spell of weather with temps a tad above average which doesn't rule out some nippy mornings

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7966400.thumb.png.a1a8e446ac62f9f37568ab5fbdc78c00.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-7966400.thumb.png.1a999d51282d544436ca0bbca1747b75.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-7966400.thumb.png.cba66ead6d40be82a624eeb948c01cc7.png

 

 

Edited by knocker

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The ecm along the same lines as the gfs next week. Eastbound energy against the ridge

ecmwf-deterministic-natl_wide-z300_speed-7188800.thumb.png.f8dbf5b169e7e93f874bcc5f8a6cf041.pngecmwf-deterministic-natl_wide-z300_speed-7275200.thumb.png.61a9a84eac88c35ed10ebafa8e9e2705.pngecmwf-deterministic-natl_wide-z300_speed-7361600.thumb.png.bc8f38bb5eddb58180d29cf48cdb5e17.png144.thumb.png.87e77b04176b57c1e1c090c55e143f36.png168.thumb.png.195b1c0d228957704beb33e361c99bec.png

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The ext EPS and GEFS pretty much in the same ball park this evening so further comment not required except to add by the end of the run the EPS very quickly loses the subtropical high amplification

gfs-ensemble-all-avg-nhemi-z500_anom_5day-7966400.thumb.png.62cfb117c44ac5da74f86ecdc7cf4563.pngecmwf-ensemble-avg-nhemi-z500_anom_5day-7966400.thumb.png.dad71789fb0c786c20344298121c133e.png

 

ecmwf-ensemble-avg-nhemi-t850_anom_5day-7966400.thumb.png.23cc58c3ca306b12196c43c4186a7a02.pngecmwf-ensemble-avg-eur-t2m_c_anom_5day-7966400.thumb.png.ba3ceec75a60153f057d8207a588e968.png

Edited by knocker

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Outlook - slowly becoming drier

The North Atlantic 500mb and surface analysis for midnight

gfs-deterministic-natl_wide-z500_anom-6800000.thumb.png.168e2312974123493fe76277fab8d139.pngPPVA89.thumb.gif.21cbc9aad8c2926733078371d1033870.gif

The heavy rain currently over central and eastern England will slowly clear to the east though the morning but further pulses will track east from the south west courtesy of a circulating trough. And showers will persist in western Scotland due to the proximity of the low and associated front. Elsewhere generally cloudy but in the clear periods it will feel quite mild

PPVE89.thumb.gif.f5f45e3daa34b24ea990f11a75e9ef12.gif2mtemp_d02_20.thumb.png.e328bfeafc19759fa50066a3b4639e80.pngmeanreflec_d02_13.thumb.png.b3923fb3a7d66f873dd870f7ac0f7d62.pngmeanreflec_d02_18.thumb.png.205098eec1137ce135b8f954192120fa.pngmeanreflec_d02_24.thumb.png.08876e3e29d70856a157ae3def0b1c43.png

The showers will persist tonight over western Scotland and more persistent rain will effect the south west by around 2200 and then track east overnight effecting Wales and much of England, including some heavier pulses, courtesy of a stray occlusion

PPVG89.thumb.gif.5ddd1d2a3c55ade51f83f6552f8a0563.gifprecip_d02_32.thumb.png.ab69486178e89a22da0f5d69a3bca654.pngprecip_d02_37.thumb.png.f0ff5bfac125bf9df6f5619c70d9627a.png

Once this rain clears Saturday will be a day of sunny intervals and a few showers but another low has tracked east around the base of the upper trough and rain from this will encroach the south west by midday and then spread east to effect Wales and the southern half of England during the afternoon and evening and It will be accompanied by strong winds

PPVI89.thumb.gif.3a0a88b9bb79452cfb0037e3f817145f.gifprecip_d02_42.thumb.png.0d7c98fafef3754223436bb7f38dc6e3.pngprecip_d02_48.thumb.png.743b486a15318df6ea4a086a209e835d.png

The rain will clear over Saturday night as the low tracks into northern Germany leaving Sunday to be a day of sunshine and showers

PPVJ89.thumb.gif.9b13838bd4c58fba4869a15ca8af9693.gifPPVK89.thumb.gif.cdf52b619041d09e2744968ca1c1464b.gifgfs-deterministic-uk-t2m_c_max6-7037600.thumb.png.3c204943d31d85c17e95298afeaffe03.png

Monday and Tuesday look like being dry with perhaps the odd showers but another fairly innocuous frontal system will track east across southern regions bringing more persistent rain for a time before a ridge starts to build on Tuesday

PPVM89.thumb.gif.d6500be2d6a48ba639613022be4d1548.gifPPVO89.thumb.gif.0d066315ad5b7d29811c5ac81d42efe2.gif

gfs-deterministic-uk-t2m_c_max6-7124000.thumb.png.58db192c3f4b3f6b0024ee8a1fec0dbf.pnggfs-deterministic-uk-t2m_c_max6-7210400.thumb.png.3f54f794ef632d408efba3b2fc3f62a3.png

Edited by knocker

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I'm not particularly enthused by the next step by the gfs which has a trough breaking  away from the main trough to the south west resulting in an intense surface low low tracking north east to impact the country on Xmas day so best left there

gfs-deterministic-natl_wide-z500_anom-7253600.thumb.png.2d538a597a24dca4a403e436741918ff.pnggfs-deterministic-natl_wide-z300_speed-7253600.thumb.png.167999b3121dd14ac253953e6ae3a662.png

126.thumb.png.c8012372b52122599388ac9bc55cc96f.png138.thumb.png.e00ab261dc5e9fbbd69f485341d9b57e.png

Edited by knocker

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Leaving aside the Xmas day perturbation for the moment this morning's ext GEFS illustrates the uncertainty of the downstream evolution It is indicating less extensive ridging, albeit still quite strong. and perhaps a move towards a flattening of the amplification as indicated by the EPS at the very end last evening. We shalt see

gfs-ensemble-all-avg-nhemi-z500_anom_5day-8009600.thumb.png.6916e0d3cd8395b1374248b1def984d0.pnggfs-ensemble-all-avg-nhemi-t850_anom_5day-8009600.thumb.png.822c4b399f27988e0114ad5d8485038e.pnggfs-ensemble-all-avg-eur-t2m_c_anom_5day-8009600.thumb.png.f1a5caa1f93fd364579abbb61d0bff83.png

 

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Predictable the ecm is having nowt to do with a breakaway trough on Xmas day

ecmwf-deterministic-natl_wide-z500_anom-7275200.thumb.png.f0a5851b2aee1f30582977cee8021cc0.png132.thumb.png.d6df0f97b91a50e9426e695ad103f016.pngecmwf-deterministic-uk-t2m_c_max6-7296800.thumb.png.9df63b5630353980f18d268e05a39f42.png

But the question, how substantial is the ridge?, remains

ecmwf-deterministic-nhemi-z300_speed-7404800.thumb.png.2c6fa48e584c3b8f2648d4cd6eee9e41.pngecmwf-deterministic-eur-t850_mslp_prcp6hr-7404800.thumb.png.ee43e01ae18b83944fbfec25a894bb76.png

 

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A quick glance at the EC weeklies update for the last two weeks of January

14-21

A weak ridge north of the Aleutians adjacent to a weakish vortex over northern Canada with trough extensions south east

A strong westerly upper flow exiting the eastern seaboard but abating a tad in the east as the subtropical high pushes a little north

ecmwf-weeklies-avg-nhemi-z500_anom_7day-9564800.thumb.png.c64d8b626b7eacd97f6c6216af6ef176.pngecmwf-weeklies-avg-eur-t2m_c_anom_7day-0169600.thumb.png.e87bc6c6cbdbb028145bbec47f14cb1b.png

21-28

A much stronger Aleutian/Alaskan ridge and a flatter Atlantic with less subtropical high influence

ecmwf-weeklies-avg-nhemi-z500_anom_7day-9564800.thumb.png.6f64ed2eee6c083c0b70ce25dd1da0ce.pngecmwf-weeklies-avg-eur-t2m_c_anom_7day-9564800.thumb.png.b7ecabde9d429dd0996fb8e4f3b709d4.png

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1 hour ago, knocker said:

I'm not particularly enthused by the next step by the gfs which has a trough breaking  away from the main trough to the south west resulting in an intense surface low low tracking north east to impact the country on Xmas day so best left there

gfs-deterministic-natl_wide-z500_anom-7253600.thumb.png.2d538a597a24dca4a403e436741918ff.pnggfs-deterministic-natl_wide-z300_speed-7253600.thumb.png.167999b3121dd14ac253953e6ae3a662.png

126.thumb.png.c8012372b52122599388ac9bc55cc96f.png138.thumb.png.e00ab261dc5e9fbbd69f485341d9b57e.png

Yes, there was me expecting to wake up to a continuation of yesterday's cross-model agreement(ish) that at least the southern half of the UK would be seeing high pressure by Xmas day, and the GFS has thrown a proper curve ball. That on its own is not a lot in itself, but having expected the GEFS to show that as an outlier, in fact there are quite a few similar scenarios and one or two really stormy ones shown on there. 

ensxmas-hmmm.png

Still, very low confidence for now though, and the mean is a bit more in line with everything else.

xmas-mean.png

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