Model Output Discussion - Spring 5th March Onwards 6z--->

[knocker]

No great sign of Azores domination in the EC32 output. Very much LP to NW with a NW/W flow with perhaps the HP influencing the south occasionally and temps around average or slightly below towards the end. Still the Canadian vortex playing it's role.

[Frosty.]

Morning Gang,

The GFS 00z shows milder weather this week, 10-13c instead of the chilly 7-9c recently. Sunshine amounts also increasing, mainly dry but rain for Scotland after midweek and most of the UK is at risk of a few showers on Friday but then the Azores high ridges in again next weekend and it becomes fine. Unsettled early next week with a band of rain spreading south and east followed by colder, brighter and showery weather with NWly winds, the showers turning wintry on hills and there would be a lot of showers breaking out inland, some heavy with hail and thunder and cold nights with frost and icy patches.

Edited March 17, 2015 by Frosty.

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON TUESDAY MARCH 17TH 2015.

 

THE CURRENT GENERAL SITUATION Winds will be very slack across the UK as an anticyclone forms over Northern Britain tomorrow.

 

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

 

MODELS-2 WEEK HEADLINE A lot of dry weather with some sunshine and just occasional rain mostly in the North later. Temperatures will be close to average or a little below especially at first.

 

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow blocked to the West of the UK with the thrust pushed north and South to our West. The flow spills further east later returning South across the UK while a stronger flow remains over the Atlantic. With little direct indication to the flow guaranteed later it is currently shown that an undulating pattern is most likely during week 2.

 

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

 

GFS OPERATIONAL The GFS operational run shows High pressure mostly in control down to the SW through this morning's run. It will be most influential to the UK at the start of the period when a lot of dry weather is likely but with just a little rain here and there as a trough slips South late this week. Then after a chilly NE flow at the weekend next week looks more generally changeable and sometimes cold with winds predominating from a NW quadrant and rain or showers a frequent commodity by then wintry on hills. The SW maintains the best chance of seeing the least rain as High pressure edges closer in from the Azores at times.

 

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

 

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

 

THE GFS CONTROL The GFS control run shows a very similar scenario through the period with the same drift towards more unsettled and windy weather after this week in Westerly winds and rain at times next week following a brief and cold northerly for a time early in the week.

 

THE GFS CLUSTERS The clusters have switched somewhat again this morning in that there is a better agreement on the positioning of High pressure to the SW in two weeks time. The majority of members support High pressure close enough to the South and SW to at least hold off the worst effects of Atlantic winds and rain to more Northern areas than was shown at this time yesterday.

 

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 UKMO this morning shows High pressure across the North at the weekend with a cold NE flow over the South for a time following a band of cloud and patchy rain South on Friday. The High pressure slips away South by the start of next week with winds switching Westerly with some rain bearing fronts approaching and moving over northern areas at least at the end of the period. 

 

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

 

THE FAX CHARTS The Fax Charts mirror the raw data rather well this morning with the High over the UK at the weekend following a chilly NE flow over the South for a time at the start of the weekend.

 

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

 

GEM GEM today shows High pressure migrating further towards the South and SW after being across the UK at the start of the weekend. Being on the periphery of it and with troughs moving SE over Europe periodically the weather could stay cool with a little rain over the North and East at times before winds back West at the end of the run with less cold air filtering East across the UK with some rain for the North. High pressure is shown to hold close to the South though.

 

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

 

NAVGEM NAVGEM holds High pressure in control as it shifts further towards the SW by next week maintaining a ridge over or at least close to the South later in the period. Any rainfall is restricted to the far North and East as weak troughs cross SE late this week and drift East over Northern Britain to start next week. 

 

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

 

ECM ECM this morning shows the positioning of High pressure in relation to the UK dominant in determining the weather type we all see over the next 10 days. With a centre building over the North late this week and start to the weekend a cold NE flow will be re-introduced to the South for a day or two before a trend towards less cold air coming across the UK on Westerly winds from off the Atlantic is shown as High pressure drifts SW to lie close to Southern Britain in 10 days time with any rain mostly restricted to the North. 

 

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

 

ECM 10 DAY MEAN There is strong support now from the ECM model members that in 10 days times we will lie under a westerly feed of air between Low pressure South of Iceland and High pressure near the Azores with a typical early Spring changeable weather pattern for all. There is a shift towards High pressure being held closer to the South though by 10 days with most of the unsettled weather held over the North of Britain.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend has firmed up further on High pressure migrating to the SW in 10-14 days with a Westerly flow of some sort across the UK.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.8 pts followed by UKM at 97.3 pts and GFS at 96.6. At 5 days ECM  continues to lead the field at 91.3 pts over UKMO at 88.9 pts and GFS at 87.6. At 8 days ECM remains the leader with 66.1 pts over GFS's 60.4 pts. Then at Day 10 ECM retains superiority at 48.6 pts over GFS at 44.7. 

 

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.prig

 

 

MY THOUGHTS The weather pattern across the UK over the next 10-14 days across the UK looks like being largely benign and controlled by the positioning and proximity to the UK of High pressure centred across the North of Britain at the weekend and then drifting down to the SW and South of the UK with a Westerly flow developing for all. While this will inevitably bring some frontal activity across the North at times with occasional rain and showers it looks increasingly likely that there won't be too much ingress over Southernmost areas with High pressure never looking far away and no more than the odd burst of patchy rain or drizzle in among a lot of periods of dry if rather cloudy weather. On the subject of temperatures the current warming theme looks to be interrupted again by the weekend especially in the South as a day or two of cold NE winds look likely for a time. Next week though shows the greater hint that temperatures might recover nearer to normal as winds take on a more Atlantic based source. Sunshine amounts could be rather suppressed for many throughout the period though as weak troughs and naturally moist laden maritime crosses the UK from the West next week and because of this it is unlikely that any particularly warm and springlike sunny days occur. Nevertheless, given that March is quite capable of bringing  some very inclement weather across the UK the current synoptics indicate that nothing severe or particularly unpleasant is likely across the UK over the next few weeks with some very useable weather for those conducting out of door activities through the period.

 

Issued at 08:00 Tuesday March 17th 2015

[Summer Sun]

Like GFS and GEM last night ECM is now showing the high lasting longer than previously shown and with air coming in off the Atlantic temperatures are likely to recover though given the direction of the winds a lot of cloud is likely with it

 

[Frosty.]

Beautiful end to the Gfs 06z with high pressure to the south / southeast and temperatures widely into the low 60's F.

[NO LONGER POSTING]

Beautiful end to the Gfs 06z with high pressure to the south / southeast and temperatures widely into the low 60's F.

 

PENG WEATHER!!!!!!!

[Frosty.]

PENG WEATHER!!!!!!!

Absolutely agree, it would be nice to see high pressure centred to the south instead of the northeast or west...hopefully something Similar to the 6z will occur as we reach the start of April. :-)

[Frosty.]

Looking at the 6z in more detail, very similar to the 0z through high res with increasing amounts of sunshine during the next few days and pleasant temperatures compared to recently, rain spreading across Scotland on Thursday and our high briefly pulling further west with the risk of a few showery outbreaks of rain on Friday but many areas still dry with sunny spells, the Azores/ Atlantic high topples southeast through the weekend and the north of the UK turning unsettled by Sunday. Early next week, a band of rain pushes SE on Monday but fine ahead of it in the south and behind it before showers start to spread into the NW. Next Tuesday shows the UK in a colder NWly airflow and although the morning would be sunny, the afternoon would turn very showery, some heavy with hail and thunderstorms and cold enough on hills for sleet and snow, especially late on but then turning cold and frosty. Low res looks unsettled, more so further north, the best of the weather in the south and then that beautiful end to the 6z I mentioned earlier.

Edited March 17, 2015 by Frosty.

[winterof79]

GFS 12z looking at building Scandi again.GEFS sniffing it also.

[Polar Maritime]

Yes the GFS is showing some pretty cool/cold charts this evening, Before the Atlantic storms back in..

 

 

[Frosty.]

Gfs 12z creates a battleground later next week as Atlantic low pressure clashes with a scandi high and the result is some hilly parts of the UK, especially further north, have snow at times as cold air from northern Europe gets sucked into the UK.

[Frosty.]

The Ecm 12z shows the Azores high building in across the south through the second half of next week so it would become fine and milder in the south but continue more unsettled further north.

Edited March 17, 2015 by Frosty.

[IDO]

GFS 12z looking at building Scandi again.GEFS sniffing it also.

 

Thats the GFS op up to it's tricks of over amplification again I suspect. The D10 ECM and GEM are not even close to any HLB'ing;

 

 

 

The GEFS D10 mean is rather coy on that as well: 

 

Next 7 days temps look OK for the SE/S. I suspect they will be a degree or two higher than that. ECM had London max of 10c today on its 0z run but the high was 12.3c in the end:

 

 

So average as a whole in the reliable time scale but as today, with a light wind, feeling quite mild when the sun comes out. Good signal after D8 for another cooler period for a few days but still some variation between the models in week 2.

[ANYWEATHER]

Gfs looks tasty with some great potential convection early next week with an unstable cold airmass  in place . The strong spring sunshine will give plenty of  convective activity, the gfs chart caught my eye this evening with the most interesting chart for a while ,Rain ,hail sleet, snow etc    

[Frosty.]

Tonight's Ecm 12z ensemble mean shows an unsettled spell next week, especially further north, much more unsettled than the op which showed the PFJ further north and the Azores high building in across southern Britain. I think the mean is more in line with the generally unsettled met office update issued earlier today with bouts of wet and windy weather interspersed with colder and showery conditions with the showers turning wintry on hills and night frosts during quieter interludes. The south would at least have more in the way of fine weather compared to the rest of the UK whereas the northwestern corner of Britain would be the most unsettled.

Edited March 17, 2015 by Frosty.

[IDO]

Following on from yesterday there still remains divergence amongst the GEFS after D6: 

 

it is a repeating problem with the GFS when there is phasing of heights. It still maintains that a wedge of HP breaks off into Scandi around D7 and although mobile with no WAA this HP does allow some undercutting. The D8 charts:

 

  

 

The GFS op is the most bullish with the northern extent of this wedge. It has a cluster within its GEFS but TBH the ensembles are struggling for clarity after D7 so that is probably not significant. Based on recent fails something like the ECM may be the call.

 

With the proviso that the GEFS are showing spread after D7 it is still pleasant to see the recent trend for the mean to show the Azores continue to move towards the UK by the end of the month:

 

D13 D16

 

The clusters for Maundy Thursday are promising for a decent Easter though early days: 

 

The CFS for April is consistently showing that the pressure anomaly to remain higher than average:

 

 

 

 

 

 

[Frosty.]

The GFS 0z next week shows a mild Monday but then turns cold with snow on hills and easterly winds returning, there are charts which would bring melt down in winter, by late March standards, most of next week would be wintry in my opinion.

Edited March 18, 2015 by Frosty.

[Polar Maritime]

Yes Frosty, As you say GFS again showing winds turning a cool/cold North/N/E flow from around the 23rd. With the risk of Wintry showers for some.

 

Edited March 18, 2015 by Polar Maritime

[Frosty.]

Yes Frost, As you say.. Winds turning a cool/cold North/N/E flow from around the 23rd. With the risk of Wintry showers for some.

 

Yes Pm it's what I would call wintry by late March standards, temps struggling at 4 / 5c and colder on hills with snow, totally different to ecm but the ecm has been very poor,only a few days ago it was showing an Arctic blast for this Friday and Saturday.

[johnholmes]

The anomaly charts continue to show a flow from somewhere north of west not from the east, although GFS this morning does show a hint of an upper ridge in that area. NOAA last evening supported the north of west upper flow with heights shown to be about 552-555DM from the Gt Lakes area. So no major warmth but the odd day with any surface ridging in the right place could make for a pleasant day. Overall temperatures would be at or a bit below average. So hill snow for Scotland and the northern hills of England at times rather than beach weather! That is for the 6-15 day time scale, so the rest of March really.

Edited March 18, 2015 by johnholmes

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS ISSUED AT 08:00 ON WEDNESDAY MARCH 17TH 2015.

 

THE CURRENT GENERAL SITUATION High pressure across the UK will recede South-west somewhat tomorrow as a cold front moves South towards Scotland tomorrow.

 

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

 

MODELS-2 WEEK HEADLINE A lot of dry weather with some sunshine and just occasional rain mostly in the North later. Temperatures will be close to average or a little below.

 

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow blocked and as a result flowing North and South to the West of the UK currently. This blocking slowly collapses with the flow moving South over the UK by the wekend and later rather stronger over the Atlantic and steered more west to east across the UK later in the period.

 

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

 

GFS OPERATIONAL The GFS operational run shows a very mixed and changeable sequence of events ths morning. The current fine weather looks like being interrupted by weakening cold fronts across the UK with a little rain and a resurgence of cold NE winds following them over the South between tomorrow and the start to next week. Then a more definitive surge of cold air behind a more active front sets up a Scandinavian High and a cold and unsettled phase across the UK when there could well be some wintry weather around as Low pressure to the SE is joined by Atlantic disturbances bumping into the cold air over the UK at that time. Later still sees the Scandinavian High collapse away East and the Atlantic take control with milder at times Westerly winds with rain at times to end the period.

 

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

 

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

 

THE GFS CONTROL The GFS control run shows less influence from the formed Scandinavian High next week as the Atlantic steadily overpowers any influence this has in preference to a strong Westerly flow later with milder temperatures and rain at times especially in the North.

 

THE GFS CLUSTERS The clusters this morning show universal support at the end of the period for the UK to lie in a West or NW flow with High pressure anchored to the South, SW or West of the UK with the most changeable conditions within this flow felt more in the North where rain at times will be more common.

 

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 UKMO this morning shows High pressure slipping away SW out into the Atlantic early next week as a deep Low over Scandinavia drives a cold front SE with some rain followed by a chilly NW flow with some showers, wintry over the North. 

 

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

 

THE FAX CHARTS The Fax Charts mirror the raw data rather well this morning with the High over the UK at the weekend following a chilly NE flow over the South for a time at the start of the weekend.

 

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

 

GEM GEM today follows the UKMO model with the cold air behind the cold front next week with a High pressure ridge following SE with fine and chilly conditions for a time before Westerly winds develop as the ridge clears South with occasional rain over the North.

 

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

 

NAVGEM NAVGEM shows things becoming much more unsettled as that cold front moves South early next week and with cold air in place at that time there will be rain and showers with snow on hills complicated still further by Low pressure taking more influence across the UK from the Atlantic by the middle of next week. 

 

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

 

ECM ECM this morning shows the same cold front early next week clearing South leaving a chilly flow of air over the UK in rising pressure as a ridge moves SE. then following this ridge the weather is shown to turn more unsettled from the NW as westerly winds and rain at times in falling pressure arrives later next week with more average temperatures and rain at times. 

 

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

 

ECM 10 DAY MEAN The ECM 10 Day Mean positions Low pressure well to the NW of the UK with a Westerly flow across the UK with High pressure near the Azores. The most likely weather across the UK at the 10 Day mark will be one of changeable conditions with some rain at times especially in the North and West with temperatures fairly close to average for all.

 

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

 

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The trend has firmed up further on High pressure migrating to the SW in 10-14 days with more changeable conditions looking likely especially for the North.

 

31 DAY HISTORICAL VERIFICATION STATS FOR GFS, UKM & ECM The current verification statistics for the past 31 days shows ECM leading the way at 3 days with 97.8 pts followed by UKM at 97.3 pts and GFS at 96.6. At 5 days ECM  continues to lead the field at 91.3 pts over UKMO at 88.9 pts and GFS at 87.6. At 8 days ECM remains the leader with 66.2 pts over GFS's 60.6 pts. Then at Day 10 ECM retains superiority at 48.5 pts over GFS at 44.6. 

 

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.prig

 

 

MY THOUGHTS The most striking thing about this morning's output is the trough of Low pressure which is expected to move SE across the UK in the early days of next week. Up to that point the weather remains fairly benign with a weaker front bringing a little rain SE late Thursday and Friday spoiling the partial solar eclipse for some before setting up a chilly and rather cloudy weekend with a return of a chill NE wind over the South for a time. As this ridge then moves away South a more active front in association with a deep Scandinavian Low crosses SE down over the UK with some rain for all. It's from that point that models diverge on conditions thereafter with many suggesting a short cold interlude with wintry showers steadily replaced by a more Westerly airstream across the UK and more changeable conditions in average temperatures later in the period. However, some also show a more wintry scenario as the exiting depression over Scandinavia early next week is replaced by a Scandinavian High pressure dragging cold air across the UK on a flow across the UK powered by falling pressure to the West of the UK linking to lower pressure to the SE. The GFS operational shows this scenario best while others also hint at it to a lesser degree and for a shorter time. That aside all output seems to suggest that High pressure could well become much less influential across Britain by the end of next week with rain at times and average temperatures as the High pressure of late recedes to it's traditional ground to the SW, near the Azores. So providing the minority of model output showing the colder scenario is misplaced then the main message is for more unsettled March conditions being possible but not before early next week with the usual story in Westerly winds of the main focus of the wettest conditions likely across the North and West and temperatures close to average.

 

Issued at 08:00 Wednesday March 18th 2015

[johnholmes]

Looking at the 3 main models for their 144h output and they each go for a similar idea, that is a cold flow from the north as surface ridging to the west and surface troughing to the east pull Arctic air south over the country. This is something that the anomaly charts don't show but their idea of a 500mb flow generally from n of west does allow for this to occur. Whether the 144h is a one of or will be repeated is uncertain but colder rather than milder is the theme after the weekend.

[Frosty.]

The GFS 06z continues with the wintry weather from the 0z between next Tuesday and the end of next week with snow on hills and sometimes to lower levels and with frosts and icy patches overnight. Next Tuesday shows the UK in a polar airmass and after a sunny start, clouds would bubble up and then the afternoon and evening would turn very showery with hail, thunder and snow on high ground. Further wintry ppn occurs, especially with elevation on Wed, thurs and friday, some hilly areas would have a good covering next week.

Edited March 18, 2015 by Frosty.

[stodge]

Afternoon all

 

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

 

The AO continues to tell an uncertain story toward the end of the month. The current negativity (lower than anything seen in the 2014-15 winter period) won't last with a rebound to something nearer normal with modest positivity but into the second week and there's a huge scatter. One member goes back negative but all others are positive and some very strongly so.

 

That suggests that the option of a cut-off Scandinavian HP by which I mean without cross-polar ridging is still very much on the cards with strong LP over the Pole itself. The majority would however seem to fit a more classic W'ly profile with nothing too dramatic either at the Pole or at lower latitudes.

 

The problem over the winter just gone is to get the AO significantly negative we need not only heights to the Pole but lower heights to the south. We've managed (rarely) one or the other but never both at the same time. 

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

 

NAO staying strongly positive - it should be remembered from April the anomaly pattern used to calculate the NAO shifts slightly and it might be that closer HP to the British Isles would lead to a more positive value for this index. The current mean is 0.8 but some approach 2 so quite a divergence. It should be noted not all members are following this - some are more neutral so the possibility of the HP being further west and south is still very much in evidence.

[Frosty.]

The latest expert view from the middle of next week onwards is for high pressure to decline southwards allowing periods of unsettled weather, this is shown on the Gefs 06z mean but looking further ahead to the Easter holiday period, the Azores high starts to build NE and push the polar front jet further north by early April so although a period of more unsettled weather is likely, it may not last. :-)

Edited March 18, 2015 by Frosty.