Model Output Discussion 31/03/14 onwards.

[knocker]

No probs. Aren't we all.

[Summer Sun]

After things turn more unsettled during the 2nd half of the BH weekend the GFS ensembles are in good agreement for a steady rise in pressure from the 23rd to around the 28th with a slight fall after wards to around 1015 to 1013mb

 

 

 

[phil nw.]

The change over Easter comes about as the Atlantic jet runs out of steam and moves it's mean position north of the UK come next week.

 

This is evident by the build of heights to our north with a cut off upper trough over nw  Europe.

 

I think there's every sign that the post Easter period will see this rather shallow  upper cold pool gradually warm out as pressure rises across the UK again with the jet remaining further north-a consequence of the main Polar Vortex shrinking with the advancing season.

 

Certainly the ens means from the00z runs for day 10 are full of promise

 

Apart from the expected interruption over the BH, April could well turn out to be quite a dry and relatively sunny month for many of us if those ensembles verify.

 

[Summer Sun]

Big differences with the UKMO 850's this afternoon

 

UKMO at t120

 

 

GFS at t120

 

 

Air pressure at t120 GFS left UKMO right also shows some differences if UKMO is right the far north of Scotland could be fairly dry on Easter Monday

 

Edited April 16, 2014 by Summer Sun

[Captain Shortwave]

12z GFS.... what a surprise

Pretty much with the other models in heights to the north east holding the Atlantic back

So we have good consensus going forward now, some rain or showers at times but drier and brighter spells too. Temperatures close to normal but feeling pleasant in the sun and light winds. The ECM ens seem to think this could persist for some time with lower than normal heights over Europe and higher than normal heights to the north/north east. Though the overall pattern looks very slack. The Atlantic is looking to become very quiet during this period.

Edited April 16, 2014 by Captain shortwave

[Summer Sun]

12z GFS.... what a surprise

Pretty much with the other models in heights to the north east holding the Atlantic back

 

Yep as normal GFS has come in the with the others continued hints of something more settled developing from later next week for a time

 

 

GEM has the block to our east even closer next week as a result pressure rebuilds quite quickly and warm air comes back with it

 

Edited April 16, 2014 by Summer Sun

[I remember Atlantic 252]

That UKMO chart looks an error, no way upper temps will be that cold

[049balt]

Just looking at what the various models are, and, have been telling us, I have come to the conclusion that this Spring /Summer might just be one of the warmest and driest we have seen for a long time.

[049balt]

http://wxmaps.org/pix/prec4.html

 

 

Hose pipe ban anyone!!

Edited April 16, 2014 by 049balt

[Summer Sun]

ECM seems to be picking up on the idea of GEM with the block to our east, GEM has it closer but its something new to throw into the mix of solutions for what will happen next week

 

Edited April 16, 2014 by Summer Sun

[knocker]

If it's of interest

Edited April 16, 2014 by knocker

[johnholmes]

Just looking at what the various models are, and, have been telling us, I have come to the conclusion that this Spring /Summer might just be one of the warmest and driest we have seen for a long time.

 

??

none of the main models goes beyond 15/16 days unless you include the dairly CFS which is close to being as much use as a chocolate teapot. Even the other version is, as with any model at such ranges, more often wrong than right.

That UKMO chart looks an error, no way upper temps will be that cold

 

Can you elaborate on the date and temperature and perhaps why you suggest as you do please?

[Summer Sun]

??

none of the main models goes beyond 15/16 days unless you include the dairly CFS which is close to being as much use as a chocolate teapot. Even the other version is, as with any model at such ranges, more often wrong than right.

 

Can you elaborate on the date and temperature and perhaps why you suggest as you do please?

 

Its t120 John

 

Below is GFS, UKMO, ECM, GEM and NAVGEM at t120 for the 850's

 

 

Out of all the above UKMO is by far the coldest and the only one which has -4 850's down to the south coast and -6's into Scotland which would suggest its an error all the rest range from 0 to around +4 for the 850's

Edited April 16, 2014 by Summer Sun

[I remember Atlantic 252]

yeah, post 16.23 today #459, no way uppers can be that cold off that setup as late as Apr 21st

[knocker]

Sunday – Wednesday. The GFS at 00z

 

The overview is that the colder air in the Atlantic is once again nudging it’s way in and winning the battle with the warmer air to the NE.

 

The 500mb anomaly chart for Sunday the 20th has colder air to the south and south west of the UK with a trough in the western Atlantic and the warmer air to the NE effecting Scotland. Similar story on Monday with the trough consolidating and deepening to mid Atlantic. This progression continues for the next couple of days with the colder air dominating the Atlantic and the much stronger heights moving northwards from the UK.

 

Surface wise Sunday has the low in the English Channel with a strong easterly flow over the UK but mainly dry except in south  with a low and associated fronts in western Atlantic. By Tuesday the low has moved towards the Scillies bringing rain to the west and the Atlantic low has moved ENE. By Tuesday the UK is in a slack area of pressure but the Atlantic trough is moving steadily westward with front lying to the west of the UK and south west winds in Cornwall. By Wednesday the main depression is to the NW of Ireland 990mb bringing SW to S winds to the west of the UK and rain.

 

Outlook after that. Not going there.

Edited April 17, 2014 by knocker

[egret]

Sunday – Wednesday. The GFS at 00z

 

The overview is that the colder air in the Atlantic is once again nudging it’s way in and winning the battle with the warmer air to the NE.

 

The 500mb anomaly chart for Sunday the 20^th has colder air to the south and south west of the UK with a trough in the western Atlantic and the warmer air to the NE effecting Scotland. Similar story on Monday with the trough consolidating and deepening to mid Atlantic. This progression continues for the next couple of days with the colder air dominating the Atlantic and the much stronger heights moving northwards from the UK.

 

Surface wise Sunday has the low in the English Channel with a strong easterly flow over the UK but mainly dry except in south  with a low and associated fronts in western Atlantic. By Tuesday the low has moved towards the Scillies bringing rain to the west and the Atlantic low has moved ENE. By Tuesday the UK is in a slack area of pressure but the Atlantic trough is moving steadily westward with front lying to the west of the UK and south west winds in Cornwall. By Wednesday the main depression is to the NW of Ireland 990mb bringing SW to S winds to the west of the UK and rain.

 

Outlook after that. Not going there.

Yes its an annoying feature for the South Coast tourist businesses! A few miles nudge one way or another would make a big difference. Its a shame this couldn't have held off for a couple of days. Still heartening however that the low is moving westwards rather than NE.

[johnholmes]

yeah, post 16.23 today #459, no way uppers can be that cold off that setup as late as Apr 21st

 

Thanks, does look on the cold side but it has been that cold in late April, I am sure someone can post actual charts to illustrtae this. Whether it is like that this year is another matter, it does seem too cold as you suggest.

[knocker]

Yes its an annoying feature for the South Coast tourist businesses! A few miles nudge one way or another would make a big difference. Its a shame this couldn't have held off for a couple of days. Still heartening however that the low is moving westwards rather than NE.

 

I wouldn't take this as written in stone. The models are struggling for uniformity on this and we are only talking slight changes here. Thanks for correcting the date. A senior moment I'm afraid.

Edited April 17, 2014 by knocker

[Paul]

ACTION REQUIRED - we've changed the forum login system..

 

http://forum.netweather.tv/topic/80037-action-required-login-changes/

[IDO]

I think the models are picking up the demise of the PV and we will be heading for a period of cooler wetter weather for late April to mid May. The GFS 0z mean currently:

 

 Still showing the PV in  its usual winter retreat.

 

 By T120 it is on the move from NE Canada to Siberia.

 

 By T180 we do not have the Atlantic being spurned on by the Canadian vortex anymore.

 

I suspect this is why the models are varying on the smaller scale setups; with the Atlantic coming to a halt and heights building towards the north and the pole, its a messy setup. Upper troughs and surface highs all in the mix.

 

 By D10 the PV is on its last rites and with heights close to the pole I suspect there will be a sustained period of cooler air escaping from the pole. The London ENS highlight the trend for lower uppers:

 

 

ECM & GEM offer a variation of this theme with the driver being the loss of part of the PV from NE Canada and its gradual weakening.  Difficult to know the specifics but cooler looks a good bet.

[knocker]

Why and how is the PV effecting tropospheric weather at the moment and creating new modes of variability as seems to be suggested?

 

Not forgetting there is deep depression over the Arctic at the moment forecast in the low 960s tomorrow.

Edited April 17, 2014 by knocker

[Summer Sun]

UKMO showing the block to our east will start and influence our weather during next week though some do have an unsettled Easter Sunday and Monday to get through first

 

 

That block to our east could play a big part in our weather once we get past Easter

[knocker]

A quick look at the ECM

 

The upper air pattern is similar the GFS and following on from that the surface isn't a million miles away certainly over the holiday and even up to Wednesday but not betting the house on that.

 

[Frank Trough]

A quick look at the ECM

 

The upper air pattern is similar the GFS and following on from that the surface isn't a million miles away certainly over the holiday and even up to Wednesday but not betting the house on that.

 

I think i would re-word that - the GFS is now more similar to the ECM. The Euros have been promoting stronger blocking to our north east/north for a few days now - it's taken a while for the GFS to Catch up. 

 

this is the GFS today for midnight tuesday:

 

 

this was it for the same time (ish) two days ago:

 

 

 

The UKMO/ECM will provide the best guide for next week over the next few days.

Edited April 17, 2014 by New Forest Gump

[knocker]

Actually I was just comparing the two 00Z runs, not looking at who was following who. Just happened to look at the GFS first. Thus they are similar......................................

Edited April 17, 2014 by knocker