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phil nw.

Model Output Discussions 18z 31/01/2016

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1 minute ago, January Snowstorm said:

Hi John

Have you ever heard the phrase lies, darn lies and statistics. Perhaps your right but bear in mind 2 recent events.

1) all three models went for the projected very cold spell towards the end of Jan (inc their ensembles) All three were well off the mark

2) as close as only yesterday all three projected a vicious storm hitting southern areas over this coming wknd. 24hours later it's disappeared. That's less than 5 days where they called it wrong

I think you miss the point I was making JS? The overall forecast level has increased but of course individual forecasts or even runs of forecasts will be wrong. The improvement will be very slow and slight, something I have always suggested will be the case. Nevertheless these improvements will continue. Whether we as tax payers agree with the huge sums needed for a new computer at intervals is another question.

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 A very messy and complicated outlook with each output throwing up different solutions.

Although the overall NH set up is similar between runs the all important detail for the UK is all over the place. I think wet, windy at times with some snow for higher ground and perhaps the odd snow surprise for lower ground would sum things up.

 

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Some decent synoptic charts appearing on the GFS 18z run but frustratingly the airmass over the UK simply isn't cold enough for most of us to benefit.

Rtavn2041.gifRtavn2042.gif

Usual suspects i.e. high ground in the north, Wales & Scotland could see some decent falls of snow but elsewhere very marginal atbest and probably cold rain mostly.

A least we may squeeze out a few frosts to give a slightly more seasonal feel to the last winter month.

Rtavn18017.gif

lets hope GloSea5 and EC monthly decides to bounce back towards cold tomorrow - with the current setup I feel there is a great deal of uncertainty.

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31 minutes ago, January Snowstorm said:

Hi John

Have you ever heard the phrase lies, darn lies and statistics. Perhaps your right but bear in mind 2 recent events.

1) all three models went for the projected very cold spell towards the end of Jan (inc their ensembles) All three were well off the mark

2) as close as only yesterday all three projected a vicious storm hitting southern areas over this coming wknd. 24hours later it's disappeared. That's less than 5 days where they called it wrong

There has been improvements, below is an image from wxbell I found on Google Images. The points are calculated from raw forecast/analysis data so are not manipulated

EurovsGFS.thumb.png.338d4e6006fe8bc20cbb

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No idea why but ECM op yet again more or less the mildest run within the ensembles right out to day 9

ensemble-tt6-london.gif

 

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The N. Hem profile does remain very disorganised overall throughout the GFS 18z, with high latitude blocking hanging about. It's intriguing that the tropospheric PV split re-emerges late in the run despite a 30 hPa vortex sitting comfortably over Greenland days 10-16 (a marked shift from the previous three runs which had it over Siberia for that period).

It seems the influence of the stratosphere on the troposphere is rather intermittent these days. A boost to westerly momentum here and there, but nothing consistent. Brings to mind that whole mesosphere influence theory again - whoever brought that up I'm afraid I've forgotten your name :oops:

 

In other news, still some serious disagreement between GFS and ECM/UKMO at just three days range with respect to the disturbance leaving the U.S.:

h850t850eu.png ecmt850.072.png

As far as I can see, there are actually two disturbances in the GFS version, both of similar intensity, which the model is trying its best to keep from merging into one, strong system. They are closer together on the 18z than the 12z though, and merge just before reaching the UK, which is why there is more of a feature crossing the south on this run. 

ukgust.png

This projection of 80 mph gusts in the Channel is eye-opening but I do wonder if we're starting to see GFS move toward the ECM/UKMO outcome after all, which focuses the strongest winds a bit further north and for a longer duration due to the system being more mature as it reaches. The peak winds are probably not quite as high, though.

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18 minutes ago, Singularity said:

It seems the influence of the stratosphere on the troposphere is rather intermittent these days. A boost to westerly momentum here and there, but nothing consistent. Brings to mind that whole mesosphere influence theory again - whoever brought that up I'm afraid I've forgotten your name :oops:

That was @lorenzo - maybe others that I've not seen the comment.

Interesting graph from the presentation I linked in the Strat thread.

056ff490843654e80862cae2cd190be0.png

 

 

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2 hours ago, TomDav said:

There has been improvements, below is an image from wxbell I found on Google Images. The points are calculated from raw forecast/analysis data so are not manipulated

EurovsGFS.thumb.png.338d4e6006fe8bc20cbb

Looks pretty erratic

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Awful GFS 00z, just plenty of wind and rain with complex trough mixing out PM air

gfsnh-0-144.png?0gfsnh-0-162.png?0

 

UKMO a thousand times better but we know which will verify don't we?

UN144-21.GIF?04-05

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uh oh......

ukgust-2.thumb.png.30d4f0fea26197014f2a1

bye bye knocker's woodshed...

012.thumb.jpg.95972a910d396419168254cc14

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Much better ECM for a colder next week, still not cold enough for nationwide snow apart from maybe day 10.

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Observation that the upper trough does clear post 10th but as per the jan potential cold, a hang back beyond  Iceland prevents the potential mid Atlantic ridging that the ens were hinting at.  The result is that we don't force upper cold south and as such the nw euro trough isn't as cold as it was predicted to be.  Looks messy chilly and then beyond that back to zonal average. 

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Winter makes a comeback from the north on the Ecm 00z towards the end of next week and a little earlier on the ukmo 00z with frosts becoming widespread and an increasing chance of snow.:)

ecmt850.216.png

ecmt850.240.png

Rukm1441.gif

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14 minutes ago, Frosty. said:

Winter makes a comeback on the Ecm 00z towards the end of next week and a little earlier on the ukmo 00z.:)

ecmt850.216.png

ecmt850.240.png

Rukm1441.gif

Again all 8 days plus,which seems to be the theme this winter.

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I've a bit more confidence that next week will be colder as all models showing it of sorts, along with the METO. Still think the south will miss out though.

Good news for skiers though, the Alps look to be in for a hammering next week - especially the higher resorts of the Northern French and Swiss Alps. Just in time for the half term crowds.

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3 minutes ago, joggs said:

Again all 8 days plus,which seems to be the theme this winter.

Indeed, anyone notice how Mondays predicted temperatures have risen some 3-4 degrees since yesterday? I'm sure ECM will shift the whole pattern north as we get within day 4-5. Where is this Atlantic ridge we've been chasing since mid January, blown up by a stray torpedo?? Seems likely that the Atlantic onslaught will continue throughout February going by the GFS consistancy in this pattern post this weeks cooler blip. 

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GFS is shocking with wind and heavy rain pretty much all week.

UKMO/ECM look better but as Bluearmy alluded too, probs not cold enough for most.

Surely this ruddy Atlantic should be showing signs of slowing down, its only been in 5th gear since the turn of November!!!

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ECM at day 10 does look full of potential with a cut off icelandic high forcing the jet south- only trouble is ecm for a good few weeks has been offering kate moss at day 10 only for susan boyle to turn up on the date!!!

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17 minutes ago, Daniel* said:

Nasty storm is back on.

image.thumb.png.c34409313479ba321dd8fdd3image.thumb.png.bddce132419a56a2ac7854df

Some hurricane force mean wind speeds there. Once the GFS gets within T72, it's time to start taking it seriously. For the moment, it's a little on its own in terms of severity; ECM ensembles do not show any lows with the same intensity as far as I can make out:

http://old.ecmwf.int/samples/d/inspect/teasers/samplers/banner/mean_sea_level_pressure_and_temperature_at_850hpa!96!pop!od!enfo!enplot!2016020400!!/

 

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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 THURSDAY FEB 4TH 2016

THE CURRENT GENERAL SITUATION   A mild SW flow is moving NE across the UK with some rain in association with a set of fronts moving NE. Then a cold front will meander SE across the NW with more rain.

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

 CURRENT SNOW FORECAST AND FREEZING LEVEL OVER THE UK The freezing level across the British Isles has risen to near 7000ft today as warm SW winds cross the UK from the Atlantic. The level falls somewhat from tomorrow to nearer 5000ft as a cold front moves SE. Little snow is expected anywhere across the UK today.

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

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

MODELS-2 WEEK HEADLINE  Mostly unsettled and very windy with rain or squally showers. Fluctuating temperatures with some snow at times over higher ground especially in the North.

THE GFS JET STREAM FORECAST  The Jet Stream is currently taking a breather as a new surge of energy exits Newfoundland on it's way across the Atlantic to cross the South of the UK and France from the weekend and through the remainder of the run with low pressure close by over or near the UK.

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

GFS OPERATIONAL The GFS Operational Run today shows a stormy spell of weather likely across the UK later this week and into next week with severe gale or even locally storm force winds and spells of rain followed by showers, heavy, thundery and perhaps wintry in places with time. Then late next week a quieter period seems likely as a ridge crosses east over all areas followed by a return to more changeable, milder and windy conditions with rain at times especially over the North and West.

GFS CONTROL RUN The theme of the Control Run is virtually identical in theme with gales and heavy rain at times the most common theme over the two weeks with a drier interlude late next week and with a short period when the emphasis of the strongest winds and rain revert to the NW after the ridge before returning to all areas again by 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 show a large majority of members maintaining Atlantic Westerlies likely in two weeks time with Low pressure to the NW and High to the SW. 25% of members do show more of a NW'ly flow with a cooler and showery flow down over the UK. No members show anything dramatically cold this morning

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 deep Low pressure areas transferring East across Northern Britain bringing spells of gales and rain followed by colder showery weather with the showers turning increasingly wintry next week.

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

THE FAX CHARTS The Fax Charts today show a complex deep Low pressure based pattern across the UK with gales and heavy rain bands then showers affecting all of the UK over the weekend and the start of next week.

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

GEM GEM today shows wet and very windy weather too throughout the next 10 days with just the chance of a drier day or two as weak ridges between weather systems pass through. Late in the run a hint of something a little colder affecting parts of the North and East of the UK look likely as winds turn ESE.

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

NAVGEM NAVGEM today also shows incessantly windy and unsettled conditions from the weekend and through next week as pressure stays low and winds stay often very strong. Some colder weather is shown next week with some of the rain and showers turning wintry over the hills.

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

ECM ECM today shows the same theme as the rest with a good week to 10 days of deeply unsettled weather with Low pressure areas crossing over the UK through the period with spells of rain and showers for all with some of it turning more and more wintry with time as colder air becomes entrained within the low pressure complex over the UK.

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

ECM 10 DAY MEAN The 10 day mean chart today shows an unsettled pattern still across the UK in 10 days with the Jet stream to the South of the UK and by the angle of Low pressure shown entering the UK from the NW it looks like some members may be suggesting ESE moving Low pressure enhancing the risk of some cold air in the vicinity of the UK at times with some snow possible over the hills.

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

NOTABLE TRENDS & CHANGES FROM PREVIOUS RUNS The models continue to indicate total Atlantic domination over the period today with maybe some colder air in the mix later.

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 GFS and UKMO at 99.5 pts each.  At 3 days ECM is leading with 97.7 pts to UKMO's 97.0 pts while GFS lags behind at 96.7 pts. At 5 days ECM leads with 90.9 pts to UKMO at 89.6 pts and GFS at 88.8 pts. Then at 8 Days ECM has the leading spot from GFS with 69.2 pts to 66.3 pts. Finally at Day 10 ECM is ahead of GFS at 51.3 pts to 48.2 pts respectively. 

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   The weather has turned milder again today as we enter another 24-48hr long warm sector of weather across the UK. Some rain and drizzle looks likely for some before things begin to turn more lively from Saturday with probably some of the most volatile weather across the largest swathe of the UK this Winter so far. The Jet Stream bringing this change is on it's way South of the UK and while it again becomes very strong it is going to power up some very deep and active Low pressure areas which look like crossing the UK at times thereafter.  Each one of these will bring very heavy rain followed by squally showers and these could be the type that brings everything but the kitchen sink variety with hail, thunder, sleet and snow all possible as we move through next week. Winds could also be disruptive at times with gale or severe gales at times in locations yet to be determined but all areas are at risk. Then after next week things look only marginally better if at all as hints of a drier and brighter day or two towards next week is still hinted at from some output before the Atlantic powers back in thereafter with the return of wind and rain for many. There is a saying called 'February Fill Dyke' and I have a feeling many a dyke will be filled with heavy rain over the next week or two and flooding issues could be a problem for some through the period with yet again only transient snowfall looking feasible at times. In fact through the next two weeks there is still no sign of a calming of the Jet Stream to a state that can break us out of this mobile pattern and something more High pressure based and colder let alone increasing any risk of significant frost or snowfall.      

Next Update Friday February 5th 2016 from 09:00

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WOW what a depressing update from gibby, indeed it's full of depressions! However, i still think next week will be the most interesting for coldies since the last colder spell back in January...fingers crossed for something like the current Euro models to verify!:)

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5 hours ago, Ali1977 said:

I've a bit more confidence that next week will be colder as all models showing it of sorts, along with the METO. Still think the south will miss out though.

Good news for skiers though, the Alps look to be in for a hammering next week - especially the higher resorts of the Northern French and Swiss Alps. Just in time for the half term crowds.

I have re-ceding confidence in cold now.

We all try to decipher the model output to varying degrees.When the METO forecast moves from increasing chances of snow to wintry showers in 24 hrs, you know you're on to a loser.

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6 minutes ago, Frosty. said:

WOW what a depressing update from gibby, indeed it's full of depressions! However, i still think next week will be the most interesting for coldies since the last colder spell back in January...fingers crossed for something like the current Euro models to verify!:)

Not sure the euro models look all that wintry either frosty, maybe ecm at day 9 and 10 but we know from bitter experience they hardly ever verify.

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