Model output discussion - 20th Feb onwards

[offerman]

Ian F  recently said that March will be on the cold side and that this had been  forecast by the Met office models  quite a while back . 

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 09:00 ON WEDNESDAY MAR 2ND 2016

THE CURRENT GENERAL SITUATION A weak ridge will move East across the UK displacing the cold Northerly flow. Following that will be an occluded trough associated with a SE moving depression across England and Wales tonight and tomorrow.

http://www.wetterzentrale.de/pics/Rtavn001.gif

CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the UK will maintain the 1500ft to 2000ft level for the most part but it could rise to 3000ft for a time across the SW later today and tonight. Snowfall will be restrictive to start with but will engage all Northern England high ground tonight along with North Wales as an occluded trough moves in.

http://www.snow-forecast.com/maps/dynamic/uk

http://www.natice.noaa.gov/pub/ims/ims_gif/DATA/cursnow.gif

MODELS-2 WEEK HEADLINE  Rather cold and breezy at first with rain or showers at times with snow on hills. Then becoming less cold but windy with rain at times especially in the North.

THE GFS JET STREAM FORECAST The Jet Stream is shown to continue to blow SE or South across the UK and Western Europe in association with Low pressure over or to the East of the UK for the next 3-4 days. Next week the flow re-orientates to a West to East motion across the UK and maintains this general theme for the rest of the period.

http://www.netweather.tv/index.cgi?action=jetstream

GFS OPERATIONAL The GFS Operational Run today shows a continuation of the cold theme over the next 5-6 days as winds remain focused from a Northerly point and source delivering spells of rain and hill snow at times, mostly but not exclusively in the form of showers with some frost at night. The run then shows a change following a ridge crossing East over the UK midweek next week with Westerly winds between High pressure to the South and deep Low pressure to the North becoming strong and established and bringing milder and changeable conditions with rain at times heaviest across the North and West for most of the remainder of the period with perhaps a brief chilly NW flow again at the very end of the run.

GFS CONTROL RUN The theme of the Control Run stays on track with it's Operational partner until the second week when the change to milder and unsettled Westerly winds is shown to be temporary with High pressure building North across the UK and Scandinavia with cold and frosty conditions but with plenty of warming early Spring sunshine and mostly dry weather likely from then until the end of the run.

http://www.wetterzentrale.de/pics/Rtavn1441.gif

http://www.wetterzentrale.de/pics/Rtavn3841.gif

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=144&mode=0&carte=0

http://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=384&mode=0&carte=0

GFS ENSEMBLE DAY 14 DATA  The GFS Clusters today continue to be undecided in the direction the UK weather takes in two weeks time. This morning's offering shows a range of options perhaps biased more towards High pressure to the West and SW more likely than anything else with winds from a west or NW direction maintaining changeable conditions for most of the UK.

http://www.weatheronline.co.uk/cgi-bin/expertcharts?LANG=en&MENU=0000000000&CONT=euro&MODELL=gefs&MODELLTYP=2&BASE=-&VAR=cpre&HH=372&ZOOM=0&ARCHIV=0&RES=0&WMO=&PERIOD=

UKMO The UKMO model this morning shows rather cold conditions for another 3-4 days under a slack northerly flow with some wintry showers and the odd longer spells of rain and hill snow affects the West for a time Sunday/Monday. A ridge topples across the UK with temperatures edging up to average by midweek with rain at times in places especially in the North thereafter as winds back to a milder Westerly source.

http://www.wetterzentrale.de/pics/Rukm1441.gif

THE FAX CHARTS The Fax Charts mostly follow the raw data well with all action coming down from the NW over the period in the shape of chilly winds, troughs, scattered perhaps wintry showers and a longer period of rain/sleet on Sunday and Monday across the West.

http://www.weathercharts.org/ukmomslp.htm#t120

GEM GEM this morning is more bullish about delaying any quick return to milder weather this morning as it continues to show Low pressure cells drifting SE across the UK and nearby Europe well into the middle of next week and beyond delivering further spells of wintry showers and some longer periods of potentially wintry precipitation over the hills before slowly developing High pressure close to the South of the UK and Europe late next week keeps any mild SW winds restricted towards the NW while the South becomes fine and bright with perhaps night frosts under the influence of the High pressure close by.

http://www.wetterzentrale.de/pics/Rgem2401.gif

NAVGEM NAVGEM shows the end to the current pattern by the middle of next week as the SE moving weather systems become cut off by a ridge of High pressure crossing East over the UK and followed by milder Westerly winds with rain at times for many from midweek.

http://www.wetterzentrale.de/pics/Rnvg1681.gif

ECM ECM too maintains a theme of an end to the rather cold conditions across the UK currently by the middle of next week or soon afterwards as the SE moving weather systems down across the UK become cut off by a Jet Stream realigning it's angle of movement to more of a West to East flow across the UK from the middle of next week. In weather terms there should be another 4-5 days of cold weather with some wintry precipitation from showers or longer spells of precipitation at times before a change to milder Westerly winds moves across Britain from the middle of next week with the potential for some quite mild air reaching Southern Britain at times by the second weekend with most of the rain and showers affecting the North by then.  

http://www.wetterzentrale.de/pics/Recm2401.gif

ECM 10 DAY MEAN The 10 day mean chart continues it's rock steady support for milder and well established SW winds and rain at times for all across the UK at that time.

http://www.wetterzentrale.de/pics/Reem2401.gif

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The pattern between the models appear to be firming up on a change to milder Westerly winds arriving across the UK from the middle of next week.

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKMO & ECM The verification Statistics of GFS, UKMO and ECM show at 24 hours ECM ahead at 99.6 pts with UKMO at 99.5 pts and GFS at 99.4 pts.  At 3 days ECM is leading with 97.6 pts to UKMO's 96.9 pts while GFS lags behind at 96.2 pts. At 5 days ECM leads with 90.7 pts to UKMO at 88.5 pts and GFS at 86.6 pts. Then at 8 Days ECM has the leading spot from GFS with 66.2 pts to 63.1 pts. Finally at Day 10 GFS has the lead from ECM with a score of 50.6 pts to 47.9 pts.

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day1_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day3_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day5_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day8_PMSL_MSL_G2NHX.png

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day10_PMSL_MSL_G2NHX.png

MY THOUGHTS  While there is still rather a lot of rather cold and unstable air around across the UK over the next 4-5 days the models seem to be firming up now on the demise of the current pattern from around the middle of next week. Until then the cold northerly sourced airflow will continue to bring a messy mix of rain and snowfall across the UK with elevation meaning everything to what falls from the sky as the air is not quite cold enough to allow snowfall all the way down to sea level. Most of the precipitation will fall in the form of showers but some longer spells of rain, sleet or snow could fall, notably tonight across Central Britain and Western areas over late Sunday into Monday. Thereafter a ridge of High pressure looks like crossing East or SE across the UK midweek with a fine and frosty day or two before milder and strengthening Atlantic Westerly winds develop as High pressure to the South of the UK and Low pressure to the North becomes the popular theme shown between models this morning. The weather then looks like staying changeable with rain at times until the end of the period and ECM in particular shows the chance of some mild Springlike air moving across the South later backed up by it's 10 Day mean Chart this morning while conversely some Northern areas could see incursions of colder air at times still from the North as troughs pass by. In among all this we have the GFS Control Run which brings High pressure across the UK in Week 2 with fine Springlike days and frosty nights. Whatever happens there is little sign of any marked cold weather shown in the output this morning with any results of the Stratospheric warming event currently not realised in any output this morning that I have seen with very typical varied chart offerings very indicative of what is normal for March on offer this morning.

Next Update Friday March 4th 2016 from 09:00

Edited March 3, 2016 by Gibby

[mushymanrob]

11 hours ago, feb1991blizzard said:

In some ways that 1931 chart is one of the best ive ever seen, The high is further North  so would have given massive North Sea snow convection to a wider area than some of the other stellar Easterlies, even Scotland perhaps.

not necessarily , similar charts from march 69 brought a biting cold easterly under stratus laden skies.

meanwhile the ops seem to be rather progressive bringing back the atlantic systems then the noaa charts suggest - although they do bring the azores ridge closer. either way its looking less cold by midweek next.

[Weather-history]

15 hours ago, chris55 said:

 

After all, statistically we are more likely to see a white Easter than a white Xmas.

Recent stats do not back that up at least from my location.

In 30 years, I have lived around here I have seen 4 Christmas Days with snow on the ground and not one Easter Day. Also more  Bookies'  White Christmases than what would be a Bookies' white Easter.

[fergieweather]

1 hour ago, offerman said:

Ian F  recently said that March will be on the cold side and that this had been  forecast by the Met office models  quite a while back . 

Yes, overall: but much uncertainty as we get later into the month (after a phase of temperature recovery back up towards average). Whilst GloSea5 forecasts of both MJO and SSW response are indicative of a stronger chance (versus average climatology) of blocked/easterly conditions late March-early April, this does not - even if it happens - necessarily translate to *pronounced* or prolonged cold, given steadily increasing insolation by then. Way back in mid-Dec, I recall discussing the GloSea5 strat diagnostics with a senior UKMO forecaster. He noted that whilst all signs were pointing to late Feb-March SSW, it would, quote "....probably be too late to significantly offset an otherwise markedly mild season, which is doubtless how 99% of population will remember it." Now we are at this stage, the point here is to manage expectations of SSW influence: yes, a higher chance of cold weather later this month, but this shouldn't be interpreted as a de facto risk of *very* cold/snowy weather.

[feb1991blizzard]

39 minutes ago, mushymanrob said:

not necessarily , similar charts from march 69 brought a biting cold easterly under stratus laden skies.

meanwhile the ops seem to be rather progressive bringing back the atlantic systems then the noaa charts suggest - although they do bring the azores ridge closer. either way its looking less cold by midweek next.

Those were totally different charts Rob, that chart I quoted earlier was similar to the FI ECM run from the 5th Dec 2012, where I distinctly remember Ian F saying that he couldn't believe people were celebrating a chart that would bring almost certain deaths in the UK, look at the H500 profile not just the 850's, the only slight criticism of the 1901 one was MAYBE not quite big enough kinks in the surface isobars so maybe having to rely on showers and less in the way of longer continuous outbreaks of snow, that's a maybe though, maybe Kevin might be able to tell us more in the historic weather section.

 

 

Edited March 3, 2016 by feb1991blizzard

[Polar Maritime]

GFS 6z Snow risk into tomorrow morning, All subject to change with warnings out by the Meto.. 

Edited March 3, 2016 by Polar Maritime

[Man With Beard]

The idea of a Scandi High on the GEFS has been dropped for the moment. No overwhelming agreement on the ensemble members on how things are going, but generally the westerly idea is favoured today, and temps maybe even above average by D10:

ECM D10 mean even flatter and milder, and very probably wet for NW areas - there's fair spread over the UK, but no significant support for anything remotely cold at this stage:

http://www.meteociel.fr/cartes_obs/ecmwfens_display.php?x=306&y=141&ville=Londres

Both means convincingly remove low heights from Iberia, which could be significant. 

The effects of the SSW will have to be pretty crazy to turn these models on their head for mid-month! 

Edited March 3, 2016 by Man With Beard

[Skiwi1]

Hi all,

I have been following this forum for a long time and have learnt a huge amount so thank you for all your input (this is my first post). I have been looking at the models for overnight tonight/tomorrow morning and am surprised the met isn't making more of the snow potential for Midlands and SE England. 850's look good (-5/-6), precip heavy, dew points are below 0.

Can someone kindly explain what I am missing here. Many thanks

[Polar Maritime]

11 minutes ago, Skiwi1 said:

Hi all,

I have been following this forum for a long time and have learnt a huge amount so thank you for all your input (this is my first post). I have been looking at the models for overnight tonight/tomorrow morning and am surprised the met isn't making more of the snow potential for Midlands and SE England. 850's look good (-5/-6), precip heavy, dew points are below 0.

Can someone kindly explain what I am missing here. Many thanks

Hi and welcome Skiwi, Without taking the thread to off topic.. The Meto do have warnings out; http://www.metoffice.gov.uk/public/weather/warnings/#?tab=warnings&regionName=em&fcTime=1456963200 which are currently being kept under review and emended as and when necessary. As you rightly say certainly 'potential' there for over night tonight re snowfall especially above 200m.

Edited March 3, 2016 by Polar Maritime

[Singularity]

 

 

So is is that the period from tonight through to early Saturday comes into greater focus.

Most models have the overnight precipitation as rain from The Midlands southward, yet the GFS 06z has snow right down to the south coast. I know the model is often rather too keen but the distance from the high-res models is unusually large this morning so it can't be ruled out, especially given the trend from the 00z toward a slightly slower frontal progression with colder air cutting in a little better.

I'm still more inclined to follow the likes of HIRLAM and NMM, though. Some snapshots of the former's 06z effort:

    

We see the occluding front becoming strung out west to east across the middle third of the UK with snow where the precipitation is heaviest or over high ground (around 100 m and above). The likelihood of an absolute pasting for The Pennines is well advertised.

The occlusion then pivots NW-SE and seems to lose some degree of organisation. An area of snow pushes south and stays that way right to the south coast which is intriguing. The 00z didn't pull this feat off, with less of a transfer south of precip. In adding more cloud to the mix, the risk of widespread ice is restricted to the SE - indeed this area would most likely see the most hazardous conditions, assuming snow struggles to settle at low levels across central/CS England.

By dawn Saturday, conditions within the cloudier zone are more toward a low level rain/snow with elevation or perhaps particularly heavy precipitation scenario. Temperatures also rise quite quickly across the SE after the icy start. 
This reflects a change in the low-level air that NMM shows quite prominently:

Dew points of 3-4*C being imported on a NE to E flow in early March, at a time when the North Sea is mostly within 0.5*C of the norm. Not often you see that coming off the back of winter.

Colder, lower dew point air does edge back in from the NW later in the day (but with the flow still NE veering E), but as we often see under such conditions, the precipitation fizzles out. There's another ice risk though, probably more widespread than on Friday night:

So another hazardous start - but as the day gets going, more unstable, but less cold, air moves in from the northeast/east which brings showers of mostly rain, perhaps snow over high ground.

 

This is the broad outcome for the weekend and as usual, local variations may produce a snowy outcome in some places while others only have the risk of icy mornings to worry about. Certainly a wintry feel to the weekend, if nothing else, feeling cold to start both days - particularly Sunday:

  

[Weather of Mass Disruption]

9 minutes ago, Skiwi1 said:

Hi all,

I have been following this forum for a long time and have learnt a huge amount so thank you for all your input (this is my first post). I have been looking at the models for overnight tonight/tomorrow morning and am surprised the met isn't making more of the snow potential for Midlands and SE England. 850's look good (-5/-6), precip heavy, dew points are below 0.

Can someone kindly explain what I am missing here. Many thanks

 

 

[Man With Beard]

35 minutes ago, Skiwi1 said:

Hi all,

I have been following this forum for a long time and have learnt a huge amount so thank you for all your input (this is my first post). I have been looking at the models for overnight tonight/tomorrow morning and am surprised the met isn't making more of the snow potential for Midlands and SE England. 850's look good (-5/-6), precip heavy, dew points are below 0.

Can someone kindly explain what I am missing here. Many thanks

Hi Skiwi1, welcome! 

Don't know what others think, but after several utter car crashes on the Meteociel charts this winter, the only thing I'm believing when it comes to snow is the EURO4. And it isn't pretty for the Midlands/SE tomorrow - parameters wrong when rain comes through, then once parameters are right, no precipitation. Areas around the Pennines / N Wales mountains most favoured for sure

 

http://1.1.1.1/bmi/expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2016/03/03/basis06/ukuk/prty/16030400_0306.gif

 

[fergieweather]

19 minutes ago, Man With Beard said:

Hi Skiwi1, welcome! 

Don't know what others think, but after several utter car crashes on the Meteociel charts this winter, the only thing I'm believing when it comes to snow is the EURO4. And it isn't pretty for the Midlands/SE tomorrow - parameters wrong when rain comes through, then once parameters are right, no precipitation. Areas around the Pennines / N Wales mountains most favoured for sure

 

http://1.1.1.1/bmi/expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2016/03/03/basis06/ukuk/prty/16030400_0306.gif

 

The point to stress here is the distinction between *seeing* a bit of (mostly hill) snow in the south versus what warrants a yellow warning. The latest output from EC/MOGREPS/UKMO-GM (& it's downstream products) have greatly reduced the risk of anything warnable, including ice risk (front decaying readily; ppn intensity needed for snow dropping; WBFL fairly high). Thus, last night UKMO advised warning could be cancelled and sure enough, it duly was as overnight and 06z modelling emerged. 

[knocker]

The ext EPS this morning is no where near as amplified as the GEFS ( no surprise) with the vortex/trough further east with faint ridging in the eastern Atlantic ergo much more zonal with temps a little below average. As previously stated much still to play for with the evolution.

[fergieweather]

16 minutes ago, knocker said:

The ext EPS this morning is no where near as amplified as the GEFS ( no surprise) with the vortex/trough further east with faint ridging in the eastern Atlantic ergo much more zonal with temps a little below average. As previously stated much still to play for with the evolution.

....but Cluster 1 from 00z continues to go blocked, following the story of last EC Monthly (update this eve) and current GloSea5 into later March...UKMO expect models to take a while getting to grips with SSW effect:

[knocker]

Yes given that the blocking scenario does look the form horse, the EC update tonight should be interesting, and frankly I could live happily with that.

[pureasthedriven]

1 hour ago, fergieweather said:

....but Cluster 1 from 00z continues to go blocked, following the story of last EC Monthly (update this eve) and current GloSea5 into later March...UKMO expect models to take a while getting to grips with SSW effect:

Where's an Azores high when you actually want the bugger? . I do so loathe a chilly lead into Easter. No, what I really loathe is a chilly April (which you have suggested MetO products have repeatedly alluded to, FW). Odds on a brisk and fresh NE'ly in May? I wouldn't bet against it. FW, any hint of spring warmth into April from longer-range products (caveats relating to the positioning of any block aside?). Cheers.

[Troubleatmill]

40 minutes ago, pureasthedriven said:

Where's an Azores high when you actually want the bugger? . I do so loathe a chilly lead into Easter. No, what I really loathe is a chilly April (which you have suggested MetO products have repeatedly alluded to, FW). Odds on a brisk and fresh NE'ly in May? I wouldn't bet against it. FW, any hint of spring warmth into April from longer-range products (caveats relating to the positioning of any block aside?). Cheers.

 I don't suppose anyone would stick there neck out that far but....  

Edited March 3, 2016 by Nicholas B

[phil nw.]

Well whatever becomes of the SSW later in the month there's is nothing out of the ordinary showing in the next couple of weeks.

A gradual lessening of the cold seems likely now as after the weekend winds back more westerly with the Azores high ridging nearer.

which the NOAA chart has been showing in recent days so pretty good agreement on this by day 10

The ens graph

In the short term the fax chart for T24hrs indicates that there's a good chance of some quite noticeable snowfall in places like the Peaks/Pennines and N.Wales mountains over the next 24 hrs as that occlusion pivots across N.England in the cold air.

 

perhaps some snow falling lower down early on before surface temperatures start to pick up during the daytime.

 

 

 

Edited March 3, 2016 by phil nw.

[Singularity]

Well well well...

All of the models had the MJO steadily declining between 1st and 2nd and yet it has in fact gained a little amplitude while progressing east.

That should force some amplification across the U.S. and into the Atlantic in the near future and, in my opinion, gives strong cause to believe that the Azores/Euro High will move quite suddenly up to somewhere between NW and NE of the UK around mid-month.

No surprise to see GFS toying with this, albeit with the usual progressive bias upstream:

A case of watch this space.

[Guest]

MJO, AO and Snow Cover updates for 3rd March 2016:

Please refer to my comments on this in my two recent posts (Part 1 on page 48 and Part 2 on page 51). I said that I will provide updates from time to time on some of the key factors that I highlighted. I will add additional comments when there have been any significant changes.

 

MJO Ensemble charts:

As Singularity shows above, there is a slight improvement today in the MJO charts. I show the "ensembles" for the main models + Kyle MacRitchie's modified chart.

UKMO:   http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ukme.shtml

ECM:    http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

NCEP/GEFS:  http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

Kyle MacRitchie:   http://www.kylemacritchie.com/real-time-maps/realtime-mjo/

Kyle remains much more bullish than the big 3. Who will be right? Lots of uncertainty.

 

AO Ensemble Charts: 

CPC/NOAA:   http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

CPC/NOAA:    

Still trending negative but the ensembles are more mixed and also point to an uncertain outlook.

 

Northern Hemisphere and Europe/Asia Current Snow Cover:

Northern Hemisphere - NCDC/NOAA:   http://www.ncdc.noaa.gov/snow-and-ice/snow-cover/nh/20160302

Europe/Asia - NCDC/NOAA:   http://www.ncdc.noaa.gov/snow-and-ice/snow-cover/ea/20160302

Encouraging developments with further spread of snow cover into north-east Europe during last 48 hours.

Edited March 4, 2016 by Guest
The UKMO MJO ensemble chart is now updated to March 3rd like the others.

[fergieweather]

GloSea5 MJO forecast for comparison:

[Singularity]

Just now, fergieweather said:

GloSea5 MJO forecast for comparison:

Thanks for that, I had been wondering if GloSea5 was better at handling the MJO given how well it picked up on the late Feb/early March trends.

A significant period coming up in which we see what affect the increasingly centralised +ve Pacific anomalies have, along with the interference from the warm Indian Ocean.

I have a feeling the suggestions of HP getting into Europe will adjust the longevity downward in the coming days, with a faster transition to the high latitudes. I've seen it before during the spring and summer months in particular, snatching away a pleasant warm/hot spell sooner than was once suggested. We NWP model watchers do put up with a lot in this country!

[mushymanrob]

bring it on!

and yes, the noaa anomaly charts arent a million miles from allowing this