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Model Output Discussions 12z 01/06/2017


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I had to double-check that I wasn't looking at cached charts with the ECM 12z! That's really put the cat among the pigeons :shok:

Perhaps it works with a slower propagation of the signal from the C. Pacific, such that the jet stream does not ease off quite soon enough for the trough to escape and become cut-off. Imagine how edgy we'd be if this was a winter's evening with a sinking low interacting with an easterly incursion having suddenly been put back up for questioning!

Has to be a 'hmm, really?' for now, but perhaps the way GFS shifted the initial low NW with a bit more interaction with the mid-N. Atlantic jet stream segment was a more restrained version of ECM's response to some tweaking of the propagation rate of the tropical signal?

Making a call for next weekend has become a whole lot trickier again. Amazing to think it could still end up fine and warm in the south... oh how we'd look back and laugh. Or maybe cry, I don't know... :cray::laugh::D     :unknw:

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An unseasonally wet, cool and windy day amidst an underwhelming week of weather does not a summer make. Much as anticipated through the second half of Spring, the hand-over to Summer sees the atm

There have been some strange observations made today, as too often occurs in this thread whatever the time of year, and largely based on the usual knee-jerk response to longer term suggested NWP.

You always seem to jump in on my posts, along with a few others. Why don't you try giving your assessment of the models instead of picking holes in others efforts!

Posted Images

It will be interesting to see the T96/120 UK fax charts issued later this evening.

Looking specifically at next Thursday the one issued from yesterday's 12z run and compared to today's 12z raw chart

fax120s.gif?1UW96-21.GIF?16-19

and it can be seen the UKMO view remains the same wrt that Icelandic cut off low heading towards W.Scotland.

It doesn't happen too often but the fax could get adjusted but it would be a bit of a surprise in this case when comparing the ECM with GFS/UKMO at T96hrs.

ECM1-96.GIF?16-0UW96-21.GIF?16-19gfs-0-96.png?12

 

Notable that the difference is so close in time with the way ECM throws up a weak ridge ahead of the low which keeps it further north.

Edited by phil nw.
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2 minutes ago, johnholmes said:

Anyone of a nervous disposition had best not look at the NOAA 6-10 recently issued!

Back in the moaning / ramping thread for me then..more reverse psychology needed!:rolleyes:

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610day.03.gif
We must have the strength to face up to this sort of thing.

Fact is, with so many recent and indeed current runs painting this sort of general picture, the guidance was bound to look something like this. A run like the ECM 12z would need to be repeated on the next 00z, and by more than just one model, before adjustments toward it can make much sense.

Not sure why they've gone quite so far toward GFS over UKMO but... they have their reasons and they should be well-founded.

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2 minutes ago, Singularity said:

610day.03.gif
We must have the strength to face up to this sort of thing.

Fact is, with so many recent and indeed current runs painting this sort of general picture, the guidance was bound to look something like this. A run like the ECM 12z would need to be repeated on the next 00z, and by more than just one model, before adjustments toward it can make much sense.

Not sure why they've gone quite so far toward GFS over UKMO but... they have their reasons and they should be well-founded.

Not to forget this is the weekend so no forecaster intervention

Edited by knocker
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I really hope us here in Skellingthorpe, Lincoln gets something. I'd be happy if we even just got a lightning display from the edges of a storm. We had a few good rumbles and flashes earlier this month but we havent had a proper one on top of us for a fair while. But I feel we'll get the edge of whatever may come again. The only positive signs is that the latest GFS run edges the storm risk slightly further towards NE including precipitation. 

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Just now, knocker said:

Not to forget this is the weekend so no forecaster intervention

Ah thanks for reminding me. Looking at the 'guidance used' it does appear to be all-American so that must be their default.

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5 minutes ago, TJS1998Tom said:

I really hope us here in Skellingthorpe, Lincoln gets something. I'd be happy if we even just got a lightning display from the edges of a storm. We had a few good rumbles and flashes earlier this month but we havent had a proper one on top of us for a fair while. But I feel we'll get the edge of whatever may come again. The only positive signs is that the latest GFS run edges the storm risk slightly further towards NE including precipitation. 

Woops, posted this in the wrong topic discussion; thought I was on the storm discussion. My bad : P

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6 minutes ago, Frosty. said:

I think I'm right in saying the NOAA was never on-board with the prolonged settled and warm spell the models were showing recently..

I seem to recall some fairly promising looking charts being around a few days ago - just not full-on 'entirely settled'. Being at 8-14 the signals are usually more muted anyway but I can see that they were being more cautious than they could have been - wisely so it would appear!

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1 hour ago, Singularity said:

Ah thanks for reminding me. Looking at the 'guidance used' it does appear to be all-American so that must be their default.

Here we go again with the usual 'red herring' about no forecaster. In about 8 years of using these charts every single day I have, at most, felt that the weekend was somewhat different from either side of it, on perhaps 4 or 5 occasions. So forget lack of a forecaster. All it shows is a development, as a forecaster, I would expect, based on the previous 2 outputs.

of course it may be wrong but I doubt it being far out when we compare the actual 500 mb charts over the period it is forecasting for.

Edited by johnholmes
vital bit of a sentence missed - sorry
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29 minutes ago, johnholmes said:

Anyone of a nervous disposition had best not look at the NOAA 6-10 recently issued!

The writers of the NOAA clearly didn't look at the ECM op OR ensemble mean tonight (which 60% follows the op)!

What on earth happened this afternoon to change things, did a flock of geese cross Iceland??

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18 minutes ago, Man With Beard said:

The writers of the NOAA clearly didn't look at the ECM op OR ensemble mean tonight (which 60% follows the op)!

What on earth happened this afternoon to change things, did a flock of geese cross Iceland??

Actually the EPS 6-10 anomaly is not a million miles from NOAA. The trough is a little further east and no closed low. And on the mean 850mb wind stream chart at 00 Sunday the low if over Faeroe Islands with the UK in a brisk north westerly

Edited by knocker
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I think a north / south split is increasingly likely by the end of the week onwards with high pressure / ridging close to the southwest and low pressure to the northwest with the uk in a broadly westerly atlantic airflow with temperatures close to average across the south, in other words, pleasantly warm with some reasonable fine spells and just occasional rain / showers whereas northern / northwest uk would be somewhat cooler and more changeable / unsettled.

Edited by Frosty.
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1 hour ago, knocker said:

Actually the EPS 6-10 anomaly is not a million miles from NOAA. The trough is a little further east and no closed low. And on the mean 850mb wind stream chart at 00 Sunday the low if over Faeroe Islands with the UK in a brisk north westerly

Further

ecm_eps_z500a_5d_nh_11.thumb.png.f82da0dc8e3bd1ae52176dd1062cb313.pngecm_eps_z500a_nh_8.thumb.png.b9634b90d0ccb7fa1d1535d72711d9e9.png

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4 minutes ago, knocker said:

Further

ecm_eps_z500a_5d_nh_11.thumb.png.f82da0dc8e3bd1ae52176dd1062cb313.pngecm_eps_z500a_nh_8.thumb.png.b9634b90d0ccb7fa1d1535d72711d9e9.png

No not a million miles away at  all. 500 miles maybe - not a lot in the D6-D10 range, but the unique thing about the "dartboard" low scenario is that just 300 miles either side and it's a complete miss for much of the country.

Somehow all roads seem to lead to a North Sea trough by D10, interestingly, many GEFS members have been on to that for a while, too.

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2 hours ago, johnholmes said:

Anyone of a nervous disposition had best not look at the NOAA 6-10 recently issued!

they were wrong about the ridging off the azores to the scandi highs though john... as were all model runs. reliability cannot be great in this very volotile situation.

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GFS 18Z is a partial move to the ECM. The centre of the trough is a few hundred miles north west of Scotland by next Friday, tracks through the northern isles before moving down the north sea early next week. England/Wales far less influenced until D8

Edited by Man With Beard
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Quite a mixed bag from the gfs this morning and I'm not sure it's worthwhile looking too far ahead. This probably applies every morning.

By Wednesday 00 the upper trough is centred between Greenland/Iceland and negatively tilted stretching down to Iberia.with the surface fronts lying to the west of Ireland and the thundery  low to the south moving north and already affecting the south west heralding quite an interesting day for many with thundery outbreaks and a varied temp distribution.

gfs_ptype_slp_eur3_9.thumb.png.39ced8f9f956e2984283a2112e3fc3ed.pngPPVJ89.thumb.gif.addd480fd242afaeed06054183f346b4.gif

From this point the fronts and the low amalgamate and the whole caboodle tracks north east to be clear of the UK by midday Thursday allowing the Azores HP to briefly ridge in from the south west. But the trough to the NW has got it's act together and has become an enclosed upper low and tracked south east to west of the Hebrides by 00z Friday as has the associated surface low. The fronts from the latter affecting western Scotland and N.I.

gfs_ptype_slp_eur3_17.thumb.png.e0581b7d10a36c00c804f9b6221ee881.png

Here the complications begin. There is renewed amplification over the weekend with the Azores surging north in the Atlantic which introduces a very meridional flow That brings virtually to a halt any west-east general pattern movement, Ergo the upper low, and of course by association the surface low, swan around to the north of Scotland over the weekend and into Monday with showery conditions affecting much of the UK, albeit the west and north being mostly in the firing line. Temps no great shakes around average possibly a little below.

gfs_uv250_natl_27.thumb.png.c04f5c93b839777c54b515cd94441150.pnggfs_ptype_slp_eur3_31.thumb.png.3cc273fec67a67a221dd568e21890def.png

By the middle of week pretty much an Omega block but this to far ahead so time to stop.

gfs_z500a_natl_37.thumb.png.e0857d697d46b8a9a207899eeb9ad697.png

 

Edited by knocker
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The ecm is pretty much along the lines of the gfs up until Sunday with the low northern Scotland at 00z Saturday which will be wet and quite drafty. After that it is better news as the renewed amplification doesn't trap the low and it escapes north east allowing the Azores to ridge NE at the beginning of the week. This is not a permanent transition though as the ridge is quickly broken down by the next Atlantic system by midweek.

ecm_t850a_5d_natl_11.thumb.png.5734e732731a0da68eb042f845be4305.png

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