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Model output discussion-mid Autumn and beyond


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By T120 the strong easterly has been established for 24 hours but according to this evening's ecm the high cell is under pressure from the trough to the west and low pressure over Europe and has been displaced west of Norway so still frequent showers over the UK which do spread inland. By T144 the low pressure to the south is still putting pressure on the high and this becomes a double whammy as energy swinging around the north of the cell compounds this resulting in the high becoming compressed and thus the easterly over the UK increases a tad and still frequent showers. Feeling quite chilly in the wind, particularly in the south which is on the fringes of the colder air over France

By t180 low pressure is centred over the UK and Iberia thus the easterly is cut off very very cold with frequent wintry showers.

T120.thumb.png.47ded15294f1126db067aff05289586e.pngT144.thumb.png.58fec32bfcdb90beb9624bb0098bd2b1.pngT180.thumb.png.a7c1f71205d35ccfcfd82903f337465e.png

And by the end of the run another major trough in the Atlantic

index.thumb.png.708816c0153f55116629186dc7fb17c8.png

 

Edited by knocker
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Thanks knocker. Useful to come over to this thread for a dose of reality rather than seeing P14 of the 18z GFS run which shows cold weather at 300 hours, when we all know that it's standard wet, windy

Hi Malcolm, I just saw your post after doing mine above. Yes this thread seems under used which is a shame.The idea of this one as you probably know is for any members to post what hopefully

Finally getting time to check how the 500 mb anomaly charts have been over the past week. They have not consistently but generally gone from suggesting trough domination to one that now has ridging as

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A good image from the 12z GFS of the blocking to our ne and the cut off northern arm.The jet recurving around the block in the form of an easterly for the UK.

viewimage.pbx?type=gfs;date=20181115;tim

and all the energy going into the southern arm heading across North Africa.Not a common setup for late Autumn.

 

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Evening all ?

Thought I would post this here rather than in the bearpit.

My take on far FI is signs of the PV re-establishing so we aren't going to have three months of northern blocking and its' going to be a 7-10 day spell of below average temperatures before a reversion to something more "normal" but we'll see.

 

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So where does the gfs go from the end of the short range, Well it continues the promote the aforesaid low pressure areas in the SW/SE putting the high cell under pressure which is compounded by the energy sweeping around it to the north. Thus the easterly tends to blow a little stronger whilst backing a tad more with a continuation of the showers in eastern regions a and possibly along the south coast  with temps now below average.

gfs_z500_vort_natl_25.thumb.png.1d11273d8579792e658a6080a71ac62a.pnggfs_z500_vort_natl_29.thumb.png.cae539879c7c6a1f0b782b77cc9a6a05.png

By Saturday the low has tracked a tad further over the UK so possible the showers becoming more widespread and certainly not feeling very warm in the quite strong wind

gfs_z500_vort_natl_33.thumb.png.f14732cad4225f8737c6dfa3ecf5a548.pnggfs_thickness_eur_33.thumb.png.a933285e941dd51251f338be8490af5e.png

Edited by knocker
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A couple of soundings for next week and as yet the gfs is not indicating a particularly cold airmass and certainly not ragingly unstable with rain showers

2113965194_soundingth.thumb.png.b63daf1562a487e72f9b8b5191aee44a.png1292022482_soundingfr.thumb.png.ceb96e69edecbe73c72893d63318af16.png

Edited by knocker
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At T144 the ecm has low pressure to the south spreading north east with the high cell to the north under pressure from this and the other energy flow to the north. Both flows initiated by the polar and sub tropical jets exiting north America. All resulting in a strong easterly with frequent rain showers spreading inland with perhaps sleet/snow on high ground.

By T168 the orientation of the low pressure area has realigned more N/S to the the west of the UK which has veered the surface wind south east thus showers more inclined to the north east and western areas but chilly with a widespread frost but less so in the south

By T192 low pressure still influencing the UK but with high pressure ridging to the west it's rather caught between the two high pressure systems resulting in strong south easterly surface wind with less showers generally  and temps around average.

1248895951_index1.thumb.png.1c28885070177f8d1691cf72b5ad762d.png724199652_index2.thumb.png.ab39e94b04c215f60eb9e33f027e982d.png

Edited by knocker
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The EPS continues to have surface temps over Europe a fair bit below average out through the ext period but still with a west  > east bias and the the UK less so. And with little precipitation

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The 00z ens outputs continue with a colder theme,certainly out to day 10.

The expected gefs/eps NH pattern for T240hrs

viewimage.pbx?type=ens;date=20181116;timnpsh500.240.png

and the latest London ens.Temp/rainfall

ensemble-tt6-london.gif    ensemble-rrrcum-london.gif

underlining the colder outlook with little precipitation.The change is for winds to come from an easterly quarter with the  gradual  advection west of the cold through the coming days.

Interestingly the main themes of a southerly tracking jet and +ve ht.anomalies to our north remain until day 15 on the gefs

viewimage.pbx?type=ens;date=20181116;tim

with a more dominant Siberian vortex.

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Would perhaps be one of the reasons why the recent GFS and ECMWF charts haven’t been as good for cold and snowy weather in FI. Can understand some of the frustrations from some in the other thread because of those two runs (though wouldn’t say they are that bad). But at the same time, feel like some people (I can be guilty too), take some of the model runs a little bit too seriously at times and believe they’ll happen. Probably just the fear of having something great snatched from you lol ?

The general pattern does still seem to be there with the weather looking quite blocked. While a cold and snowy spell isn’t certain within the next two weeks, in the shorter range, next week may possibly throw up a few wintry outbreaks with the possible Easterly. Albeit it may be mostly for the hills, but some lower level wintry weather could be possible. Looks like it could be fairly potent Easterly. Just not of the late-February 2018 or November 2010 league that some may hope for.

There looks to be further mild weather to come before chillier conditions break through from the East next week. Apart from today with the cloud and patchy, light, drizzle, been liking the last few days with the sunny spells and mild conditions.

Edited by DiagonalRedLine
Changing size of text - came out kinda big earlier
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The models hold firm with the signal for heights to remain high to our north generally throughout the rest of the month, with the atlantic in quiet mode, subtle changes in the orientation of the high will make the difference, a weak trough feature possibly becoming cut off languishing to the SW, could allow more of a SE feed as we move through latter part of next week, preventing any northerly influence. However, the block looks very strong and trough disruption thereafter looks likely with the jet still to our south.

After this weekend a generally colder than average period - nothing significant but very seasonal, with frost and fog at times, possible wintry showers. 

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There is not much to be gleaned from looking at the GEFS, EPS and mean anomalies this evening although the GEFS and NOAA are pretty much in the same ball park.

So in general terms suffice it to say the main features are the vortex over northern Russia with the associated trough eastern Europe;  and the high pressure/ridge tending to migrate west towards the negatively aligned trough in the north west.

Ergo still a strong upper flow exiting the eastern seaboard until mid Atlantic where the energy flow diverges but precisely how is anybody's guess and it is further complicated by colder air flooding into Europe from the vortex trough. Whilst all of this is being sorted to the west and east, and south for that matter, the UK is stuck in the middle so the detail here will have to await a few days but the one reasonable percentage play is that the temp will be below average.

8-13.thumb.png.f58c695115769f928bcef3a237e623e2.pnggefs_z500a_5d_nh_53.thumb.png.bca3a488b04d61d68f52692453e09fa1.png814day_03.thumb.gif.755bcbaa7aafff82aef21e47162f901d.gif

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I've no idea how much credence one can give to the continuing evolution of the gfs next week but the energy flows completely disrupt the high cell to the north east of the UK and establish low pressure in the eastern Atlantic and the UK before some semblance of order returns. Not too much point in going into much detail at this stage but generally a tad unsettle with temps below average.

gfs_z500_vort_natl_25.thumb.png.baf1e31151bf3d5fcbadb70bd434b575.pnggfs_z500_vort_natl_29.thumb.png.c5f472e844764a27d784e61e5f4ea67b.pnggfs_z500_vort_natl_34.thumb.png.6d9db9ab140edd2796616c546994c2a8.png

 

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As a general overview the ecm is not dissimilar to the above and by t198 the subtropical jet has aides lows to track east and effect the UK with temps a tad above average. Keep still my beating heart

t168.thumb.png.c25d94edcb2bfe04c39f0b1f6f9e22e2.pngindex.thumb.png.7f520e458ed84ac5fb62477a5997d138.png

 

Edited by knocker
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I'm not one to jump towards the end of a run but the quite marked difference between the last two runs with the ecm is in the east with an intense Aleutian low and marked ridging into the Pole from Siberia in this morning's. This in turn adjusts the N. Russian vortex and east European through west and thus the colder European air with it. Whether of course this is supported by the EPS is another matter

ecmwf_z500a_nhem_10.thumb.png.64a48249e30ebceef27e78e785d861b1.png

Edited by knocker
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Are people in the other thread actually surprised that charts near/after t+240 have changed? Happens more often than not.

At this time of year I'm happy for last weekend's weather.. pretty stormy on the seafront on Friday evening, and then sunshine and showers with thunder heard from multiple cells, and hail, until Monday. Yet it was also pleasant in the sun with a few beautiful sunny mornings. 

I prefer either that or sunny clear weather with frosts (like we had at the end of October), over any chilly cloudy 'not worth it' weather that cold synoptics can often bring this time of year (although not always, such as late November 2010).
 

Edited by Evening thunder
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46 minutes ago, I remember Atlantic 252 said:

Vile run, the rain concerning on Wednesday, could be flooding, timed for the day too, wish we could have this weeks dry weather back

Snow on high ground this coming week inbetween sleet.

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On 12/11/2018 at 15:15, DiagonalRedLine said:

Yeah, the North-Western Europe area would say seems the favourite place for now for the High Pressure. The models do appear to hint at that. It’s possible that Beast may not be too far away! Guess it will depend for sure how that block behaves. 

And I guess you could say that, lol. Not just an exit from Brexit, but the models would have us believe we’ll be leaving the Atlantic! (At least for the time being ?).

And so it proved to be, talk of some sleet and snow showers on the mainstream media next week and not specifically at height or up in prone Northern areas either. A fascinating week ahead for coldies, if nothing overly dramatic, at least it's a start.

Edited by gottolovethisweather
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On Tuesday there is a couple of convergence zones within the fresh easterly portending frequent squally showers in northern regions and the Channel which may well include south coast regions according to the ecm

PPVK89.thumb.gif.e71d012134ca5a78b2d7a283b9f6be11.gifT72.thumb.png.2304f2714acdad6b4c3e9e4a2d4fe14f.png

Over the next three days amplification of the subtropical high pressure in mid Atlantic, in association with it's European counterpart, tend to trap the developing low pressure area (trough) to the south west of the UK which also encompasses the latter, Thus generally very unsettled and cold initially and gradually becoming warmer and drier.

t96c.thumb.png.2f68a0aaf71b21f17f9714e9559ca677.pngt120v.thumb.png.9ee33ddabbcf2f96690cd7efc9e46881.pngt144v.thumb.png.5e33e6d1f03663247b927a79f3d9754a.png

 

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Moving on into the weekend and the beginning of next week with the gfs finds a very strong Pacific jet initiating amplification over North America with the subtropical jet exiting the southern States across the Atlantic south of the now elongated high pressure which broadly speaking results in a westerly flow across the UK

gfs_uv250_natl_29.thumb.png.dbd06c871e5a3a2d525fa30eeec5fcbe.pnggfs_ptype_slp_eur3_29.thumb.png.8f866ce35dbd1bbebb0d1fa1bd713ed5.png

But by Tuesday the increasing energy to the south has become the dominant factor with a major trough in the Atlantic relegating the high pressure further to the west and thus introducing cooler Pm into the UK

gfs_z500_vort_natl_38.thumb.png.b8335b1245b52f9e3bf4384c12df1209.png

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Rereading the above  and the conclusion of the opening paragraph is utter nonsense.

Quote

Moving on into the weekend and the beginning of next week with the gfs finds a very strong Pacific jet initiating amplification over North America with the subtropical jet exiting the southern States across the Atlantic south of the now elongated high pressure which broadly speaking results in a westerly flow across the UK

It should read which results in an area of low pressure to the south west of the UK resulting in a strong easterly flow across the UK

My senior moments are increasing.

Edited by knocker
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The ecm is generally along these lines but has a different alignment of the high pressure and thus a northerly component to the wind over the UK by the end of the run

T144.thumb.png.33b58540a69edd2e6d9ee2c35c37ae58.pngT168.thumb.png.7596b78dfb84d1835a51cf78b36efa09.pngT216.thumb.png.bfb134d4685205ab55c80557aa44f8db.png

Edited by knocker
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