Model Output Discussion 31/03/14 onwards.

[Dancerwithwings]

Well , it was only a few days ago that this chart was being shown.....the weather can make fools of us all.Whats being shown today isn't necessarily correct either.

image.jpg

"Wasn't expecting a chart showing up like this!!!" That was my remark and in saying it, i wasn't expecting it to happen either... I don't remember -4 -5s in May at anytime, but i'm sure some will prove me wrong .

[Summer Sun]

Well , it was only a few days ago that this chart was being shown.....the weather can make fools of us all.Whats being shown today isn't necessarily correct either.

http:////forum.netweather.tv/public/style_images/master/attachicon.gifimage.jpg

 

Yep only needs todays 12z's to flip back to something like they had yesterday and we'll be none the wiser for after BH Monday given its only Tuesday we have a lot of runs yet before we'll get a better idea

[Summer Sun]

12z UKMO shows the high declining by BH Monday after a settled Saturday and Sunday

 

[IDO]

GEM and UKMO both now showing the GFS route for early next week.

 

UK:   GEM: 

 

GFS maintains that line: 

 

The SE holding onto three nice days over the Bank Holiday.

 

After that the GFS tries to ridge the AH N/NE but it becomes a bit messy with a mish mash of lower and higher heights close to the UK:

 

 

To be resolved with further runs I think.

[phil nw.]

GEM and UKMO both now showing the GFS route for early next week.

 

UK: http:////forum.netweather.tv/public/style_images/tctc91_simplify/attachicon.gifUW144-21 (1).gif  GEM: http:////forum.netweather.tv/public/style_images/tctc91_simplify/attachicon.gifgem-0-156.png

 

GFS maintains that line: http:////forum.netweather.tv/public/style_images/tctc91_simplify/attachicon.gifgfs-0-144 (1).png

 

The SE holding onto three nice days over the Bank Holiday.

 

After that the GFS tries to ridge the AH N/NE but it becomes a bit messy with a mish mash of lower and higher heights close to the UK:

 

http:////forum.netweather.tv/public/style_images/tctc91_simplify/attachicon.gifgfs-0-300 (1).png

 

To be resolved with further runs I think.

Yes some uncertainty after the BH on the 12z runs so far but at least for once the weather looks like being kind for the main 3 days of the holiday weekend.

First of all though still some unsettled conditions until then as the Atlantic low moves in by Thursday

 

giving quite a wet day for many,especially England and Wales before it moves away and fills by the end of the week as pressure build in quickly across the UK with some fresher drier air moving down from the north.

A decent looking high across the UK  then just in time for the weekend

 

Dry and bright with sunny spells quite widely, although not especially warm, pleasant enough with temps.further south mid to high teens but some cold nights with a frost risk under clear skies.

[Winter Cold]

Its amazing how quickly things can change isnt it.

 

After last nights ECM, and all its supporting output, plus the other models also, we now have cross model agreement on a breakdown for next Tuesday from ECM, GFS and GEM. UKMO doesnt go out that far yet though.

 

[draztik]

All 4 models from the CFS ens now showing an unsettled first half of May, with low pressure in control!

Days 5-10, MSL anomaly

Edited April 29, 2014 by draztik

[IDO]

All 4 models from the CFS ens now showing an unsettled first half of May, with low pressure in control!

Days 5-10, MSL anomaly

 

 

Not surprised as the model I usually use for LR, the JMA, has been strongly hinting at this scenario. Last Friday's weekly update shows for D17-30 (10th May to 24th):

 

[draztik]

Not surprised as the model I usually use for LR, the JMA, has been strongly hinting at this scenario. Last Friday's weekly update shows for D17-30 (10th May to 24th):

Y201404.D2312.png

Absolutely true. And while the ecm had been showing high pressure and widespread warmth, at the back of my mind was the jma. I was thinking 'wow jma lost the plot'. But no, the ecmwf was leading us up the garden path? (as usual?!)

Tho I am cautious, when there is this much flipping day to day, it doesn't fill me with confidence post day 5!!

Edited April 29, 2014 by draztik

[Cloud 10]

Looks like the AO is going positive again within the next week,with our weather coming

from the west after a very decent looking bank holiday weekend for many.

 

 

 

 

Must say i wasn't impressed with recent negative phase of the AO.

 

At least the failed northerly for the end of the week should be the final kick in 

the teeth for coldies until next winter.  

[knocker]

I think everyone has covered the angles no point in repetition. Just the position of the jet stream Tues and Weds. Significant?

 

[Frosty.]

Tonights ECM 12z op run shows a very pleasant spell coinciding with the BH weekend with the cool, rather cloudy and breezy weather on friday being replaced by progressively warmer and sunnier conditions as time goes on. The fine spell lasts into early next week the further southeast you are, but further north and west becomes more unsettled and relatively cooler, eventually the unsettled weather reaches all of the uk by later next week with a showery cyclonic pattern.

[knocker]

Not much change for the holiday but not great in Scotland.

 

Very briefly from the 00z GFS. Sunday has high pressure over the UK but a frontal system curling down from Iceland effecting Scotland bringing wet weather. Temps quite cool there but elsewhere in the low 60s.

 

By Monday a new frontal system is approaching Ireland bringing wet weather there and patchy rain in Scotland.  Temps again cool here but clear and warm elsewhere.

 

Tuesaday the rain is now into most of the UK apart from an area south east of a line from Cornwall to Cleethorpes. Here the temps still in the low 60s but lower the other side.

 

Outlook

 

Unsettled during week and by Friday a battle between low pressure to the north and high to the south  with a frontal system lying over Ireland and Scotland. I think we can safely discount this scenario at this range.

[Captain Shortwave]

Whilst the UKMO/GEM/GFS agree on a breakdown on Tuesday, the ECM decides to flip again

Interesting development, and allows the UK to continue to hold onto dry and fine weather.

[Summer Sun]

Whilst the UKMO/GEM/GFS agree on a breakdown on Tuesday, the ECM decides to flip again

Interesting development, and allows the UK to continue to hold onto dry and fine weather.

 

Yes another different run from ECM this morning t168 shows the highest pressure still clinging on to the east

 

 

By t192 it looks like pressure will still be rising again

 

Edited April 30, 2014 by Summer Sun

[knocker]

The MSL ECM progression.

 

[Frosty.]

The Gfs 00z op run shows high pressure building in for the BH weekend with increasingly sunny and warmer weather, especially by sunday, but then by monday the weather will be turning more unsettled across the northwest of the BI and then the atlantic systems briefly break through across all areas towards and during the middle of next week with spells of rain and showers BUT the azores anticyclone then builds in strongly and brings a more sustained settled spell to all areas with temperatures approaching 70F widely...so, a settled weekend followed by an unsettled blip before high pressure takes control..sounds good to me.

[Gibby]

HERE IS THE LATEST ANALYSIS FROM THE OUTPUTS OF THE WEATHER COMPUTER PREDICTION MODELS FOR TWO WEEKS FROM TODAY WEDNESDAY 30TH APRIL 2014.

 

THE CURRENT GENERAL SITUATION. A trough of Low pressure will move slowly NE across SW England later today and tonight with shallow Low pressure developing over Central Britain tomorrow along it's axis.

 

GFS This model shows High pressure slipping down across the UK over the weekend and next week with fine weather for many clinging on for most areas as the High slips slowly away East midweek to allow Atlantic fronts in for a time with occasional rain in places. The longer term outlook suggested by it's morning ensembles suggest that towards the end of the period High pressure may well build back North across the UK setting up an Easterly flow and largely fine weather again with some warmth in the West should it verify as shown.

 

UKMO After the weekend sees High pressure dominant across the UK pressure will relax away SE early next week beginning to open the door to the Atlantic with the risk of rain increasing as we move towards the middle of next week.

 

GEM The GEM operational continues to show a deterioration in conditions as we move through next week with the weekend High pressure being replaced by Lower pressure moving across the North with Atlantic fronts affecting all areas at times. Winds would settle Westerly and be fresh at times with temperatures close to average outside of the rainier periods.

 

NAVGEM too shows High pressure easing away SE next week with fine weather being replaced by windier and more unsettled conditions as Low pressure passes East to the North. Troughs associated with this feature will cross East over all areas with some rain or showers for all at times.

 

ECM this morning is rather slower than recent runs to deteriorate conditions next week as a High pressure ridge is shown to hang on across the UK for a while longer from a centre to the NE and SW.However, it does give way later in the run covering the end of next week as Low pressure to the NW brings cloud and rain across all areas by then in Westerly winds.

 

MY THOUGHTS  The general trend this morning remains unchanged although timings differ between the outputs. All models continue to highlight a fine weekend with some good sunny spells and the early weekend risk of frosts should dissolve away quite quickly as we move into next week. Then it's a case of how quickly High pressure dissolves away SE that determines the surface weather as we move through next week and beyond. As it stands the NW will show changes to cloudier and wetter weather quite soon after the Bank Holiday while Southern and Eastern parts are last to see this change, probably soon after midweek. In the far reaches of the longer range models the pattern remains unclear with GFS showing signs of rising pressure again with attendant fine and possibly warmer weather through Week 2.

[johnholmes]

the summary by Gibby above is about right it seems to me. There is uncertainty and this is also obvious in the anomaly charts. They are more often than not a good guidance for the 6-15 day time period as to the general upper air pattern. Over the last 2-3 days this is less apparent and I made this comment in my notes having looked at the NOAA output last evening and the ECMWF-GFS this morning:-

 

I tend to feel we are entering the period when all 3 main anomaly charts shift too much from day to day to give reliable guidance=the seasonal change period, so called!

 

This spell sometimes only lasts about a week or a bit less, sometimes getting on for 2 weeks. It is caused, or seems to be, by the massive changes that take place as the pole moves from winter to summer mode and then back again in the autumn. None of the models seem able to deal with this very well. They are similar but less variable during the hurricane season or more especially the time when any hurricane gets into the Atlantic. Again I assume it is the huge changes in energy, temperature and moisture that the models, at all levels and all centres, find difficulty habdling.

[knocker]

A couple of mean anomalies next week

Edited April 30, 2014 by knocker

[Frosty.]

Encouraging Ecm 00z ensemble mean this morning with generally settled weather having the upper hand, moderately high pressure values of 1020 mb or slightly higher, some leaking of pressure as we go further into next week which would indicate to me an increasing shower risk, heavy and thundery but with the PFJ to the northwest of the uk in the outlook period, the charts have a more summerlike look about them with temperatures around average and sometimes rather higher, the mean suggests that the azores anticyclone has a good chance of building in towards the end of next week onwards and filling the gap.

Edited April 30, 2014 by Frosty.

[draztik]

CFS ens days 5-10 all showed low pressure in control yesterday. Today? Not so much. Hopefully the models will make their mind up soon, and we can have some consistency. May just give this watching a miss for a day or 2, and see where we are on Friday.

Msl anomaly days 5-10

[knocker]

Just to add to the uncertainty the GFS ops at 06 has a low 995mb at 12z  centred north Scotland giving a completely grotty day for the whole of the UK on May 7th.

Edited April 30, 2014 by knocker

[Summer Sun]

Latest GFS seems to be following the met offices thoughts rain moving into NW Scotland on BH Monday with this spreading further south over time probably reaching eastern parts during the early hours of Tuesday warmest and driest weather looks likely to be in the SE though most places would feel warm when the sun is out given its strength now

 

[draztik]

GEM out, and things are going downhill (depending on your pref.) Canadian forecasting unsettled conditions into early next week and beyond, with cooler conditions nationwide.

 

 

t144/168/192 GEM 12z

 

UKMO similar ideas

t144

Edited April 30, 2014 by draztik