Model Output Discussion - 1st February Onwards 12z--->

[knocker]

To sum up this mornings GFS out o T384.

 

An alternating pattern of Pm and Tm representing the interplay between the LP systems running west-east and the dance of the HP to the south. So periods of settled/very unsettled weather with temps bouncing above and below average.

[IDO]

No improvements up to D10 on this morning's runs. ECM and GEM are sinking the UK high around D9 so at D10 both have full scale UK zonality, with GEM importing that as early as D7:

 

 

 

The GEFS mean and the op have a north/south split: 

 

  

 

Lots of variety again on the GFS FI and that shows its head around D9, so uncertainty on this GEFS suite. Probably not worth much analysis because of that, apart from the mean late in FI suggesting low heights settling in the Med area, so again the repeating pattern may start to evolve for later in Feb?

 

 

In the short term we have the low/front today bringing rain to many and the cold front crossing east on Monday, bringing an organised spell of rain. Then rain for the west midweek. As for cold and snow, look west, the US are in for further reloads:

 

  RyanMaue
Second Arctic blast sweeps into Texas. Tropopause temps show #polarvortex rippling / whipping across eastern US http://t.co/TjU4SAOThU
13/02/2015 06:42

 

Whilst that remains the case past experience has told me that the UK will struggle for a cold spell.

Edited February 13, 2015 by IDO

[Frosty.]

Ecm 0z has followed through with the promise shown on last night's op / mean with a cold plunge sweeping SE bringing wintry showers and snow for some of us, very good to see 522 dam thicknesses digging south. I hope the models can build on this for the period beyond T+240 hours.

[knocker]

Seriously? High anomalies to the north and a broad euro low anomoly week post day 21 drifting into a sceuro low anomoly by the end of the run. Maybe difficult to get great surface wintry ness early march but an easterly would help. That follows the high that topples across - re my post last evening.

 

Yes but that sceuro anomaly could just translate into a general area of LP to the N/NE which would just put the UK into a Pm flow. And looking at the 850mb temps there isn't much cold air around in NW Europe. To me it just looks like a possible period of unsettled weather with no obvious cold routes. Then I freely admit I'm no expert at reading the latter part of the EC32 output regarding significance.

Edited February 13, 2015 by knocker

[fergieweather]

Seriously? High anomalies to the north and a broad euro low anomoly week post day 21 drifting into a sceuro low anomoly by the end of the run. Maybe difficult to get great surface wintry ness early march but an easterly would help. That follows the high that topples across - re my post last evening.

...although postage stamps offer an increasingly indistinct and muddied signal post week 3 albeit the drier-than-average PPN/higher-than-average MSLP anomaly into first half of March is fairly striking before becoming weak thereafter. Equally, an emerging divergence and complexity in prevailing temperature regime by mid-March between (chillier) EC Monthly and latest GloSea5. Conclusion: No worthwhile assessment currently possible. Latest EC has MJO weak phase 6-7 in near term but signal likely contaminated (see earlier post).

[Paul]

Can we keep it to the models in here please - moans and ramps can go over into the banter thread:

 

https://forum.netweather.tv/topic/81281-model-banter-moans-and-ramps-autumnwinter-201415/

 

Winter discussion can go into the winter thread:

 

https://forum.netweather.tv/topic/81936-winter-2014-15-thread/

[Frosty.]

The Ecm 0z also has short bursts of polar maritime earlier in the run, all in all, not bad at all and has a strong finish.

[Severe Siberian icy blast]

Ecm 0z has followed through with the promise shown on last night's op / mean with a cold plunge sweeping SE bringing wintry showers and snow for some of us, very good to see 522 dam thicknesses digging south. I hope the models can build on this for the period beyond T+240 hours.

Frosty the cold you talk about is about as glancing as you can get . We will see no snow away from the Scottish mountains . And with low pressure to the north of us the high that amplifies the flow is just a displacemeant of the azores .but unable to ridge North its blown over us before returning South . Not saying won't change but your clutching at straws . I understand s positive mind set but there really is nothing to be positive about . The only way March provides snowy weather is by a very cold sustained northerly or an easterly via a Scandi high, I don't pretend to no what's gonna happen in March but if there were definate signs then we would all see it now . March 2013 was a result of the second SSW in mid February. We have nothing like that in the outlook. I'm thinking a warm March with the azores having a big influence by keeping the General pattern of the last 8-10months going .

[carinthian]

Guten Morgan to all. The South of Britain has maintained the fairly cold spell into much of this week. Interesting, the latest Deutschen Model has a upper easterly drift across the SE of Britian by Wednesday with a swath of sub zero 850hPa temps. Also, noted is a advection of a very cold airmass into SE Europe, perhaps knocking on the door step of Austria later next week. I know this is unlikey to affect the UK and snowfall remains out of sight for many, but looks like the current theme of below average temps likely to last in the south, especially.

C

Edited February 13, 2015 by carinthian

[carinthian]

Guten Morgan to all. The South of Britain has maintained the fairly cold spell into much of this week. Interesting, the latest Deutschen Model has a upper easterly drift across the SE of Britian by Wednesday with a swath of sub zero 850hPa temps. Also, noted is a advection of a very cold airmass into SE Europe, perhaps knocking on the door step of Austria later next week. I know this is unlikey to affect the UK and snowfall remains out of sight for many, but looks like the current theme of below average temps likely to last in the south, especially.

C

Have attached the chart for Wednesday.

[Gibby]

HERE IS MY LATEST ANALYSIS USING DATA SUPPLIED BY THE NWP OUTPUT COVERING 5 OF THE WORLDS MOST POWERFUL WEATHER COMPUTERS.

THE CURRENT GENERAL SITUATION A depression to the West of Ireland will move SE across Southern Britain tonight and on into Northern France tomorrow. Troughs will cross East today decaying later tomorrow near the East coast.

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

MODELS-2 WEEK HEADLINE Changeable at first and then becoming largely dry and quiet if rather cloudy. Temperatures generally near average.

THE GFS JET STREAM ENSEMBLE FORECAST The Jet Stream Ensemble Forecast shows the flow continuing to be one of West to East across the Atlantic strongly later, towards the North of the UK. There are frequent occasions through the period when the flow becomes undulating in response to troughs near to the UK and western Europe in general.

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

GFS OPERATIONAL The GFS operational today shows a change to more unsettled weather today as Low pressure moves SE across Ireland and Southern England tonight with rain followed by showers spreading East. Then a further trough and strong winds crosses East on Monday followed by a rebuild of pressure to the South and mild SW winds for many through the middle stages of next week. Then alternating periods of winds between SW and NW occur as High pressure remains to the South and SW and Low pressure moves ESE to the NE of Scotland with some rain followed by showers up here while the South stays largely dry and sometimes bright but never overly cold.

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

http://www.wetterzentrale.de/pics/Rtavn3841.gif
 
THE GFS CONTROL The GFS control run is more High pressure based later in the run than the operational meaning less of a West or NW flow as High pressure steadily becomes established centred over the UK in Week 2 with fog and frost becoming widespread but with bright and sunny weather by day.

THE GFS CLUSTERS The GFS Clusters today show a complete outlook of Westerly or NW winds in two weeks time with High pressure looking further away to the SW of the UK than has been shown of late. A variety of options are shown between milder Westerlies and colder NW or even Northerlies with rain possible in all areas and some wintry showers at times especially across the North.

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 a mild and strong SW flow towards the middle of next week before another cold front begins to approach the west next Thursday with a likely spell of rain followed by clearer and fresher conditions later in the week.

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

THE FAX CHARTS The Fax Charts this morning show a complex structure of troughs crossing East over the UK over the coming 2-5 days blocked just to the East of the UK by Eastern European High pressure before this slips SE later next week as an Azores High becomes more prevalent to the SW.

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

GEM GEM shows a steady return to more unsettled and windy weather from the middle of next week as Westerly winds increase and Low pressure to the North of the UK comes closer in spreading the influence of troughs, rain and showers down across the UK later with colder conditions then at times over the North wintry in places as High pressure resides back to its home base of the Azores.

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

NAVGEM NAVGEM shows a period of mild SW winds next week, strong in the North with some rain. Weak cold fronts then move SE down over the UK later next week with a temporary cooling off before the same mild SW flow returns across the NW one week from now.

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

ECM ECM is not too dissimilar to last night's run with winds always blowing from a Westerly quadrant. Through a period of next week the winds will be mild and strong across the North with some rain while the South sees more moderate breezes and a lot of dry weather. Later in the week a cold front moves down with some rain for all with a slow trend towards more unsettled and windy weather extending to all areas by the end of next weekend.

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

ECM 10 DAY MEAN The 10 Day Mean this morning shows a Scandinavian Low pressure being popular between it's members and with pressure still relatively Low over the Eastern Med and High near the Azores a popular consensus must be for a West or NW flow across the UK with bands of rain alternating with rather colder and more showery weather being the likely weather type over the UK in 10 days time.

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

NOTABLE TREND CHANGES FROM PREVIOUS RUNS The long term trend continues to show High pressure to the SW still dictating the UK weather over the period although positioning of this differs between the output and therefore maintaining the differential between members of each pack on how much it influences weather over 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 97.4 pts followed by UKM at 97.0 pts and GFS at 96.1. At 5 days ECM just about leads the field at 89.9 pts over UKMO at 89.1 pts and GFS at 87.1. At 8 days ECM remains the leader with 63.3 pts over GFS's 62.1 pts. Then at Day 10 ECM retains superiority at 47.8 pts over GFS at 43.7.

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 We are now entering our unsettled phase of weather lasting through until the beginning of next week with the first Low drifting SE today and tomorrow to lie across Northern France in a weakened form tomorrow. then after a brief quiet spell a new trough crosses East on Sunday night and Monday with showers following a band of rain. Pressure then rises from the SW and a mild SW flow looks likely for a time later next week. Then after that it's all about how much High pressure lying to the South and SW of Britain declines or not and how such changes affect the weather over the UK. From the output today it looks like that there could be a slow decline in conditions especially through Week 2 as High pressure retreats back over the Azores and Low pressure to the North takes a broader swipe at the UK with all areas seeing rain at times and possible interventions of colder NW winds and wintry showers especially over the hills in the North. What no output shows is a long term or major injection of cold from the North through this period though as I hinted at yesterday I still believe there is a lot of mileage left in the possibility of a cold surge from the North across the UK looking likely later this month or into March as the pattern that has been semi-permanent throughout the Winter of High pressure to the SW and Low to the North and sometimes East of the UK shows little sign of changing soon and feeding the risk of a repeat of the type of cold and showery periods we have seen as our only type of UK cold this Winter so far.  

Issued at 08:30 Friday February 13th 2015

[bluearmy]

Going back to the eps, the 00z suite continues to place the UK between the sceuro trouging and the Atlantic ridge dropping into w Iberia

However, the spread on the day 10 shows the lower heights Iikely to extend further southwest which may well mean this theme is relevant thereafter.

I would still be wondering about the sustainability of any blocking atop the UK

[Frank Trough]

with the more interesting (?) weather that is around today i thought i would just take a look back at the models to when today first came into the t+144 range (i.e. the UKMO). 

 

So current chart today:

 

 

..and how the GFS saw it:

 

 

the ECM:

 

 

 

and the UKMO:

 

 

 

So the UKMO did pretty well. I remember that run being treated with a bit of skepticism at the time, especially given the GFS high pressure-fest theat preceded it. ECM seemed to offer a bit of a messy mid-ground version.  

[Polar Maritime]

There is 'potential' for some very stormy conditions towards the last 1/4 of the Month, As deep Lows swing S/E over the UK from the N/W on a cold Pm flow. With cold uppers and strong winds it would feel bitter.. Some places could see blizzard conditions. Who said Winter was over!

 

 

Edited February 13, 2015 by Polar Maritime

[Midlands Ice Age]

with the more interesting (?) weather that is around today i thought i would just take a look back at the models to when today first came into the t+144 range (i.e. the UKMO). 

 

So current chart today:

 

 

..and how the GFS saw it:

 

 

the ECM:

 

 

 

and the UKMO:

 

 

 

So the UKMO did pretty well. I remember that run being treated with a bit of skepticism at the time, especially given the GFS high pressure-fest theat preceded it. ECM seemed to offer a bit of a messy mid-ground version.  

 

New Forest,

 

A good post. GFS has not performed at all well over the last week for our corner of the world.

 

This is the 'new' improved GFS op and will need to be viewed more suspiciosly in future, particularly by those looking 10 days ahead.

 

It was absolutely miles out in picking up this change in pattern and only picked it up correctly within 48hrs .. ECM was aware that something was about to happen (including a Scandi high at one stage) but never really picked the middle ground position of its various runs until 3-4 days ago.  

 

MO, As you show, picked it up at +144. Well done and it has gone up in my estimation. 

 

MIA

[karyo]

Regarding the above discussion, the ECM was the first to pick up today's low. It dropped it in the next run and the UKMO picked it up so the ECM was the first although it was not consstent with it.

[Midlands Ice Age]

Regarding the above discussion, the ECM was the first to pick up today's low. It dropped it in the next run and the UKMO picked it up so the ECM was the first although it was not consstent with it.

 

Karyo

 

Yep I agree, as I said above it was aware something was changing but gave several solutions (including the correct one) and no-one was ever convinced that any individual run  was correct. MO on the other hand never really wavered apart from a slight waver when it moved the main low center to Scotland and held the low pressure belt further north. But it has been very good.

 

MIA . 

Edited February 13, 2015 by Midlands Ice Age

[mushymanrob]

My biggest hope is we reach page 48,been stuck on p47 all day..come on chaps!

As for models, I'm still looking for that pot of gold at the end of the rainbow. At least there are some polar maritime incursions showing on the models in the next few weeks, better than nothing I would say.

 

thing is karl... theres nowt to say. those of you who have posted have covered the topic very well , its looking very 'normal' to me, abit of cold, abit of mild, unsettled-ish but not extremely so.

[karyo]

Karyo

 

Yep I agree, as I said above it was aware something was changing but gave several solutions (including the correct one) and no-one was ever convinced that any individual run  was correct. MO on the other hand never really wavered apart from a slight waver when it moved the main low center to Scotland and held the low pressure belt further north. But it has been very good.

 

MIA . 

Yes, fair enough. 

[phil nw.]

Just scanning through the ens. outputs this morning and the Atlantic pattern does look well set out to week 2 of the runs.

The naefs and ecm ht anomalies at day 10 

 

however just a hint that the jet turns more nw-se in towards month end so a chance perhaps of something colder if this develops.

 

the overall pattern looks similar but if the Azores high retreats a little then a colder Northerly shot rather than the brief north westerlies we will see in the next few days could be quite possible.

 

In the meantime over the next 10 days or so it all looks very average some cooler and some milder days between the frontal systems with the drier conditions further south and east.

[492]

Latest UKMO T+84 fax resembles a chart from an earlier decade with a big high to the NE, trough disruption over the UK and with an occlusion trying to move westwards across the southern half of the UK. A bit of a westward correction when compared to the previous run e.g yesterday evenings T+96.
 
http://www.wetterzentrale.de/pics/brack2a.gif

http://www.wetterzentrale.de/pics/brack3.gif

[Frosty.]

Looking further ahead, there appears to be an increasing bias towards northwesterly winds and below average temperatures during late February, next week on the other hand, looks like becoming milder with south westerly winds although the SE will probably take longer to see the change, however, winds then veer more westerly and eventually northwesterly with an increasing risk of showers becoming wintry. In the meantime, a marked nw / se split takes shape next week, unsettled and breezy / windy at times the further NW you are, the driest and brightest conditions further SE. My hope is once we get into the colder northwesterly regime, something even colder and more wintry could pop up...something like P12 for example.

Edited February 13, 2015 by Frosty.

[carinthian]

Latest UKMO T+84 fax resembles a chart from an earlier decade with a big high to the NE, trough disruption over the UK and with an occlusion trying to move westwards across the southern half of the UK. A bit of a westward correction when compared to the previous run e.g yesterday evenings T+96.

 

http://www.wetterzentrale.de/pics/brack2a.gif

http://www.wetterzentrale.de/pics/brack3.gif

Still causing concern that front for the Met Office. Mainly, a timing problem.

C

[Tamara]

However, the eventual destination is the same one as posted last week - with troughing on a NW/SE axis ahead of further amplification in the extended period. The question, as posed towards the end of last week, is when this occurs and not if it will occur

This process will serve to send vorticity energy across the pole and the weather become increasingly more mobile into the medium term. Timing is hard to be precise, but towards the 15 day period we are looking towards a next incoming amplification phase feeding downstream from the Pacific - and whilst it is difficult to know the extent of any possible colder conditions this might provide, it fits precisely with the cyclical pattern seen this winter.

GWO set to increase amplitude into Phase 1/2 in the extended period. This is only forecasted at this stage, but it is logically underpinned as  torques re-initiate low AAM tendency - which subsequently drives the GWO orbit on to these phases.

Much as it has done at least three or four times since December

Phase 1/2 signals that next Pacific retrogression - which will serve to draw the Azores High further west much as it has done periodically during this winter to give the colder spells we have seen. These low AAM phases in (probably) late February teleconnect well to a NW European trough and NE Atlantic ridge. 

 

 

There is no general change in expectations. Ensembles/ NAEFS as phil says indicate the beginnings of change of jet axis in the extended period which is an early signal that the pattern is attempting to amplify upstream.

 

This is not a post to attempt to precisely predict any degree of cold that may (or may not) come from downstream feeding retrogression as we head to the final days of the month, or soon thereafter - it is simply an update to show that the extended signals are staying constant with yet further negative tendency occurring in the atmosphere as it has through this winter. In this respect, to try to keep on illustrating how useful these tools are for picking up longer term relative micro changes in pattern, within a larger scale NH dominant pattern.

 

Such a longer term change in the pattern may simply be an intra cycle pattern change such as we have constantly seen in the last couple of months, and not a definitive change to a completely different hemispheric upper wave pattern which can occur as large scale changes occur to atmospheric tendency with consequential high impacts on global weather

 

The shorter/medium term has been muddied by some incoherent tropical and extra tropical signals, but the eventual evolution continues to be anticipated well enough. By understanding a little at least about the framework of the atmospheric signals that have dominated the best part of the last 2 to 3 months, it becomes possible to appreciate how repetitive and locked in our winter pattern has become (and why they have been locked in), and also possible to try to anticipate future developments. 

 

As repeated so often, in respect of the repetitive pattern, it additionally very graphically tells us why the Azores High has dominated proceedings, closer to home, for the UK and NW Europe.

 

Amplification along the polar front jet in the Atlantic has been restrictive for quite a bit of the time due to phases when the Azores High has been especially strong, and mostly aided into the start of the second half of the winter up to the first few days of this month, as we know, by a displaced polar vortex.

 

Stratospheric support continues, as mentioned in previous posts, in the later month period for something of a return to the vortex being displaced towards our side of the pole, which fits with the suggested effects of GWO induced vertical wave activity - and should assist a possible return to colder conditions, not a large freeze by any means, but somewhat colder NW'erly conditions this side of the Atlantic.

 

The Global Wind Oscillation orbit can be viewed as a measure of the total amount of Atmospheric Angular Momentum in the atmosphere. As it enters Phase 1, as it is set to do over the coming week or so, it is a representation of the Jetstream colliding with the Rockies (a US Mountain torque). This torque mechanism removes AAM from the atmosphere  ( i.e it represents further -ve atmospheric tendency).

 

The MT sends Rossby waves into the stratosphere in that part of the Northern Hemisphere. The net effect of this is to create a disturbance to the polar vortex and a jet stream amplification which feeds downstream. This amplification is manifested as a retraction of the Azores high further west which has the effect of angling the jet stream and allowing colder air to advect south

 

Apparent techno-babble it might seem - but by looking at model forecasts of expected GWO progression, having also already gauged previous torque intensities (i.e. corresponding +ve torques over the Himalayas which have become an increasing feature as this winter has progressed in the AAM/GWO cycle - with AAM tendency briefly rising during Phase 4/5 orbit) it becomes possible to make some estimations as to the likely strength and impact of upstream Rossby wave action - which in turn determines the amount of potential amplification we might see in our part of the NH

 

Putting aside hypothesising about new seasonal prospects, we cannot, under the continued tropical Pacific led pattern, expect anything much more significant during the rest of official winter to develop than the boundaries of ordinary Atlantic ridging might allow under the cyclical retrogressions that occur during GWO Phases 1/2.

 

This, in essence, is the representation of Winter 2014/15 and the restrictions that this particular atmospheric cycle places on the creation of colder patterns this side of the Atlantic Ocean

 

The seasonal dominance of the Nina like -AAM cycle clearly represented here with only the recent attempts to break briefly into higher momentum

 

http://www.atmos.albany.edu/student/nschiral/research/gwo/prev60_phase.png

[Mucka]

As far as the bigger picture is concerned we are likely to see a slow breakdown of the stubborn high pressure across much of Europe - a real winter killer for the UK as far as snow chances go as it is too low latitude to give anything from the East and too stubborn to allow anything to dig down from the North.

 

This will take some time with the South having the best of the dry weather while unsettled weather tries to push in from the NW at times.

It could feel quite pleasant at times in the South next week as temps lift somewhat.

 

We are still on course for a slow pattern change into the last week of February with our old friend the Euro trough setting up. The signal for a return to cooler/colder zonal conditions to return is gathering pace a little now but hard to know how cold or prolonged it may be.

There is no sing of a true blocked cold spell setting up as yet and we will have to wait another week or so to know if that is a possibility as any potential blocking would be well outside the 10 day range.

For now it is case of seeing if this signal for the Euro trough can strengthen further and trying to nail down how far West/East it is likely to set up and how amplified the pattern behind will be.