Model Output Discussion - 05/01/2016 18z onwards

[Captain Shortwave]

Right a new thread, we do have evidence that the tide may be about to turn in terms of cold prospects for the UK, with an Atlantic ridge forecast to build towards the end of week 1.

ECM ens

So a flow from a northerly quadrant is likely in 5-7 days time. The question still remains on the longevity and potency of this upcoming spell. 

 

So usual rules apply, try to keep on topic and where possible post charts to back up your thoughts and feelings of where conditions in the UK might go.

For moans/ramps other off topic stuff can be posted here.

Enjoy and lets hope for upgrades in the days to come.

 

Edited January 5, 2016 by Captain Shortwave

[chionomaniac]

5 minutes ago, CreweCold said:

But the mean is heading in the WRONG direction Chiono?

A day or two back we had a proper Greenland high showing....here's what we have now at day 8

 

 

I haven't kept or looked at the meteociel means for the last few days - though I would like to see the T+264 from 2 days ago that you must be judging that comment on. The mean on the weatherbell charts that I have looked at past this point looks improved 850 wise from last night.

 

Has anyone kept the ECM mean charts for T+168 onwards for the last 4 days?

[Cheshire Freeze]

In response to the last few posts in the old thread- it wasn't just an ECM op run showing a Greenland high, the entire ensemble suite pretty much hinted as much. I have no idea how to find archived posts but I made reference to the mean and how I was dubious of it at the time. I'm sorry but I have absolutely no idea what the exchange between Fergie and Matt Hugo is getting at but from data freely available to us, the ensemble means point at nothing more than a transient N'ly now- it's there for all to see on Meteociel. A pretty solid degradation in the mean over what was being hinted at 48 hours ago! Yes it will turn colder and yes there will be SOME snow for a lucky few but I really cannot fathom what is showing that is making people feel a proper cold spell will arrive next week- other than a few ensemble members which are lower res than the ops!

What happens after is completely up in the air at the moment (if you'll excuse the pun!)

Chiono- if I knew how to access archived ensembles I'd show you the comparison.  

Edited January 5, 2016 by CreweCold

[Lakigigar]

I don't see it what you guys are seeing. This isn't exciting. ..

[blizzard81]

Previous ensemble means and op runs can be viewed in the archive sections on meteociel.

[i luv snow]

3 minutes ago, CreweCold said:

What happens after is completely up in the air at the moment (if you'll excuse the pun!)

Forgive me if I put a tad more credence into the thoughts of Matt and Ian than yourself... alas, it may not be a classic cold spell, but there is room for it to be more than you are suggesting. There will be countless more changes in tonight's and the rest of this week and weekends runs, some milder, some colder. And I will take the thoughts of those who have access to other models, and infinitely more knowledge and experience than most of us, any day.

Edited January 5, 2016 by i luv snow

[Singularity]

Having scanned through the past few pages, I see the idea of the models taking time to adapt to the changes has come up, from Fergie nonetheless. Thinking about how that might be possible, I learnt during my studies for a Masters in Meteorology that effective modelling of how tropical signals (from convection such as associated with the MJO) propagate to the mid-latitudes and beyond is among the most challenging aspects of numerical weather prediction, with a lot of assumptions made which inevitably lead to significant errors developing with time. This problem tends to scale with increasing convective signal so a high amplitude MJO is bound to cause issues and probably sooner than would usually be expected.

With the passing of time, more and more of the propagation of circulation anomalies from the tropics moves into reliable timeframes and then becomes reality, so reducing the overall error (but not removing it due to uncertainties with observations and perhaps even model physics to a small extent) - this is the 'catching on' period that we often see with the NWP models with respect to major pattern changes.

This is just one example of uncertainty, assumptions and error - all manner of anomalous conditions can have similar effects. It;s no wonder the model output tends to be so volatile sometimes, and this problem can be worse the higher a model's resolution, as more data points are effected meaning more errors impacting more data points and so on. This, I reckon, is why some of the biggest 48 or even 24 hour swings in recent history have been seen with ECM output as opposed to GFS, despite GFS seeming to have to make corrections more often overall.

 

I wouldn't be surprised to find ourselves a long way from tonight's ECM +192 chart when the time comes. I've sometimes done a spontaneous look back at what the models were showing for a particular day at a week or so's range and been amazed at the differences. Obviously that only happens part of the time - which is why we can never actually count on it 

[Chris K]

Sorry to be slightly off topic (it has some relevance though), but I thought I would try answer CC's question on why we do not see the harsh northerlies other regions do https://forum.netweather.tv/topic/84756-model-output-discussions-pm-311215/?do=findComment&comment=3315065.

I am an amateur in the subject, but I will try my best here as I am currently studying it as part of my degree and still learning! 

One reason is because the waters surrounding the UK generally have ocean currents that originate from the warmer climates. Even though the waters N of the UK may be cooler, there are still deep warm currents moving through that region from the SW just N of the UK.

Water takes a lot longer than the air to cool down or warm up, so even with the most severe cold uppers moving south towards the UK, the warmer ocean currents have a greater interaction with the cold air, modifying it more heavily as it pushes South. Regions that are close to the colder currents, often find the colder air isn't modified down as much, because there is less interaction between that and the cooler waters.

CC stated that he had seen the west coast of Canada/USA have severe uppers flooding South, even though it is on the eastern edge of the largest ocean on earth. If you look at this below image of the global ocean currents, you can see it is a cold current moving South along the majority of that West coast. Therefore in winter, the land mass and air will not see as much modification in their temperatures thanks to less interaction with cooler waters this time of year.

Also note how ocean currents sourced from cooler regions would move South with the Northerly air flow down the W coast of America, whereas for us it is coming up from a warmer region against any Northerly sourced air flow.

This isn't the only factor, but it will contribute to the amount of modification.

 

 

http://earth.nullschool.net/#current/ocean/surface/currents/overlay=sea_surface_temp/orthographic=-82.77,37.69,430 for above image.

Edited January 5, 2016 by Chris K

[Cloud 10]

The mighty NAVGEM trying its best for a Greenie.

 

[BLAST FROM THE PAST]

I think the GFS is demonstrating that we will not and are unlikely to get the hit in one.  For me a 2 day toppler is when the pattern topples after 2 days and a westerly regime takes over.  We aren't seeing that as we see reload one and reload two.  The ECM OP is the worst of the bunch make no bones about that but we are still talking FI.  I think that come end of Jan we will be entering a 2 week pukka cold spell with some very unusual cold temps spilling down from the arctic with polar lows but several bites are needed as the NH aligns itself [always the main target period].  BuT I think that as I have caused AGW my locale may miss out.   

Aaron It has to be the NAD why our northerlies are 'watered down' but this Atlantic cold pool we have may allow something more potent.  For me we are in the balance but not for immediate longevity of cold, but it does look like mild will be off the table at least from when we enter the first bite

 

BFTP

Edited January 5, 2016 by BLAST FROM THE PAST

[Mark Neal.]

1050 High in Artic . Navgem a favorite now lol 

Edited January 5, 2016 by Mark N

[johnholmes]

I tend to disagree with you CC in terms of the cold being fairly transient I think you are saying. Correct me if I am wrong.

To me the turning colder starts about 4-5 days from now, nothing spectacular but certainly different in terms of temperature for areas other than central/northern Scotland over the past few weeks. If you look at the first link below, UK Met Fax output, (yes like anything else not perfect) you can see how the contour values are being lowered and the 500mb trough orientating itself more nw-se rather than w-e.

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

The synoptic models will continue to switch a bit for another 48 maybe 72 hours. However looking at the much less volatile anomaly charts and they show the cold setting in, contour value wise by day 5-6. With, initially, the trough the main feature as heights drop to little more than 534DM in the far south. By day 8-14 and they are shown as increasing as the upper ridge moves in thus the ridge becomes the dominant force not the trough. The 'cold' to me, in terms of afternoon values and overnight lows looks to be a coldish feature, approximately 8/9 Jan-18/19 January. Might be even more in terms of dry cold. I leave the post 2 weeks to others more qualified to suggest what may happen. IF, note IF, the upper ridge slows down allowing the surface feature beneath it to end up first of all over central UK and then maybe a touch further ne then it may delay even further the Atlantic returning.

anomaly links

http://www.cpc.noaa.gov/products/predictions/610day/fxus06.html

http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

http://www.meteociel.fr/modeles/naefs_cartes.php?code=0&ech=240&mode=0&map=1&runpara=

and to see how the MJO is looking and being predicted, GFS version

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml

currently 7 in reasonable orbit, and predicted to go to 8 but by then with little major impact for the 500mb anomaly charts

7 suggests as linked below

So overall a very different upper air pattern for 2 weeks at least and who knows what may happen beyond this.

As to when/where/how much white stuff from the sky. As always T+24h at the most on the synoptic models, and remember predicting the above in rainfall is pretty difficult, for snow, add at least 6 other parameters needed to ensure you get snow. The chief one of course no matter how cold, how low the 850's etc is for PPN to show over your back garden.

enjoy the weather folks.

 

Edited January 5, 2016 by johnholmes

[chionomaniac]

Mike Ventrice has tweeted the Euro EPS T+360 temp anomalies here to demonstrate what I was saying earlier

 

 

Edited January 5, 2016 by chionomaniac

[Rocheydub]

Who'd be a moderator...

Anyway, the 18z GFS is rolling now, and ot be honest, the important features have been maintained. There is an Artic HP cell, a rise in pressure from the Atlantic northward, and a weakened P-Vortex. There will be run to run changes. Look at the ES and ensembles for the bigger picture. My hunch and experience says this will be a 3 or 4 day event. Maybe more as we go later into Jan. 

 

Remember, it's only a computer programme, not a design of the future!

[northwestsnow]

Nice post chino - liking the look of those anomalies very muchly !!!

[Dr. Astro]

Chris K, thanks for the answer above, this link will also help your studies 

 

http://scienceline.ucsb.edu/getkey.php?key=1962

 

Chiono, good image. Looks like Europe is going to get a cool down, not sure why some are down beat if it's cold you are after, as it isn't very far away.

[tight isobar]

Model Archive. .meteociel

Can be viewed usually far right side of heading ensembles. ..

Click -tap-date....visualise. 

[Cheshire Freeze]

1 minute ago, BLAST FROM THE PAST said:

I think the GFS is demonstrating that we will not and are unlikely to get the hit in one.  For me a 2 day toppler is when the pattern topples after 2 days and a westerly regime takes over.  We aren't seeing that as we see reload one and reload two.  The ECM OP is the worst of the bunch make no bones about that but we are still talking FI.  I think that come end of Jan we will be entering a 2 week cold spell with some very unusual cold temps spilling from the arctic but several bites are needed as the NH aligns itself [always the main target period].  BuT I think that as I have cause AGW my locale may miss out.   

Aaron It has to be the NAD why our northerlies are 'watered down' but this cold pool we have may allow something more potent.  For me we are in the balance but not for immediate longevity of cold, but it does look like mild will be off the table at least from when we enter the first bite

 

BFTP

Hi Fred.

I think maybe some crossed wires on here tonight. The first attempt at height rises in the Atlantic looks to lead to a 2 day toppler. This is what is infront of us in the reliable time frame. Yes there looks to be the chance of a second attempt but for the minute this is in FI. Obviously the Metoffice must be confident of the second bite of the cherry hence the exchange between Fergie and Matt. I fully agree that we're headed colder overall- I've been saying as much for weeks BUT we need to see some tangible evidence that the UK is going to be affected as many would like (cold and snow) and personally I'm not seeing evidence of this YET within the NWP other than hints here and there. We will go potent I'm sure but just not next week!

[Mark wheeler]

Wow this place is buzzing . Great to see and read . 

[BLAST FROM THE PAST]

1 minute ago, CreweCold said:

Hi Fred.

I think maybe some crossed wires on here tonight. The first attempt at height rises in the Atlantic looks to lead to a 2 day toppler. This is what is infront of us in the reliable time frame. Yes there looks to be the chance of a second attempt but for the minute this is in FI. Obviously the Metoffice must be confident of the second bite of the cherry hence the exchange between Fergie and Matt. I fully agree that we're headed colder overall- I've been saying as much for weeks BUT we need to see some tangible evidence that the UK is going to be affected as many would like (cold and snow) and personally I'm not seeing evidence of this YET within the NWP other than hints here and there. We will go potent I'm sure but just not next week!

Agreed but I wouldn't be surprised if there are some 'local' surprises that occur within the timeframe

 

BFTP

[Cheshire Freeze]

1 minute ago, BLAST FROM THE PAST said:

Agreed but I wouldn't be surprised if there are some 'local' surprises that occur within the timeframe

 

BFTP

Oh absolutely. In fact I'm quite hopeful should winds back sufficiently NW with -7 uppers I may even see some marginal snow here from an Irish Sea streamer. However, the snow that falls will not stick around- ground too wet/ too warm from anomalous warmth in December. What the spell may do though is lower ground temps for any further bouts of cold and/or snow. 

[nick sussex]

In terms of the upstream pattern NCEP still suggest uncertainty for how the vortex interacts with low pressure in the eastern USA and this will impact that Atlantic ridge.

THE H5 FLOW IS IN GOOD AGREEMENT THROUGH FRI...BUT DIFFERENCES
REMAIN FOR THE WEEKEND AND WILL DEPEND ON THE DEGREE OF INTERACTION
BETWEEN A LARGE CANADIAN VORTEX OVER HUDSON BAY AND REMNANT ENERGY
MOVING INTO THE PLAINS. THIS ELONGATED E-W ORIENTED VORTEX WILL
BECOME N-S ORIENTED WITH A COLDER AIRMASS DIVING INTO THE NORTHERN
PLAINS/UPPER MIDWEST/GREAT LAKES FOR THE WEEKEND. THIS VORTEX WILL
THEN MEANDER ABOUT ERN ONTARIO THROUGH THE MIDDLE OF NEXT WEEK.
NOT MUCH HAS BEEN RESOLVED OVER THE PAST 24 HOURS WITH A FAIR DEGREE
OF UNCERTAINTY REMAINING IN THE FORECAST DETAILS THIS WEEKEND. IT
CONTINUES TO LOOK UNSETTLED...BUT UNTIL THINGS ARE BETTER RESOLVED
PREFER NOT TO MAKE WHOLESALE CHANGES TO THE ONGOING FORECAST.
 

Although there are obviously some much better ECM ensembles than the operational run something has to give here and lets hope its the operational run!

[chionomaniac]

8 minutes ago, northwestsnow said:

Nice post chino - liking the look of those anomalies very muchly !!!

Worth reminding that is only 35% of the whole EPS suite!

[Captain Shortwave]

The one thing I don't see across the ECM suite is the Atlantic ridge toppling, whilst the ECM operational is pretty poor in the 7-10 range, it is more because of a poorly aligned Atlantic ridge, it has become rounded which allows a milder flow to push into the UK as opposed to polar maritime or arctic maritime air to affect the UK.

We can see the lowest heights running over that high, once that clears towards the trough already pushing through eastern Europe then we would need another ridge starting to form in the Atlantic which should allow the trough to our east to back westwards again to allow cold air to push through the UK again. As others have said the ECM op is one of the poorest members in the 7-10 day range in the suite with good support for something better.

Pub run is coming out now, lets hope for an improvement in the GFS suite before bed time.

Edited January 5, 2016 by Captain Shortwave

[SMU]

So what to make of it all tonight many will be thinking -

This from the aptly accurate NAVGEM ( more accurate than most for this week )

is the middle ground ridge- my 'best fit' run for the super ensemble mean tonight-

No greenland high but enough to get a small wedge in there to slow the jet....

its pretty identical to the UKMO@ 144  ( again just like this week ) both models were a smidge over amplified -so that just to factor in....

S

Edited January 5, 2016 by Steve Murr