Model Output Discussion - 18z 31/10/15 onwards

[Frosty.]

Fantastic Gfs 6z develops through low res with a nationwide cold spell bringing Arctic winds and a risk of snow, even in the south and widespread frosts with daytime temps really struggling in low single digits celsius. This autumn has and still is very mild but the 6z would eventually change all that with our first cold outbreak, I will be so happy if we get something like this through the second half of November..i'm hoping that coldies will soon be able to say, mild weather, you are the weakest link..goodbye!!     

[Polar Maritime]

Lets please try and stick to Model Output Discussion in here, There are other threads for METO forecasts.

Many Thanks, PM.

[NorthYorksWeather]

6z 850hpa upper air ensemble temps in fairly good agreement upto around the 15th November for a gradual cool down as we head deeper into the month. The mean line is in and around the 0c line meaning more average temps for the time of the year and shows a possibility for something a bit colder later in the month as shown by the op/control run and a few other ensembles.

[Bristawl Si]

Unless Ian's post from earlier proves to be inaccurate (and i dont think it will be) any eye candy in FI will remain just that.

[Iceaxecrampon]

FI at +288

 

 

You never know - I have been watching the ppn runs over the last week or so and something wintery is possible for mid November.

Fairly confident for Scottish uplands.

[MPG]

Unless Ian's post from earlier proves to be inaccurate (and i dont think it will be) any eye candy in FI will remain just that.

Big call Bristle Boy. Its just another model Ian is using, so why should that be right?

 

Bristle Boy's comment is a prime example of 'discussion killing'. A post from a person giving information from a source not available to members here.

 

Because Ian has posted that comment, it now means people will be unwilling to discuss the GFS output.

Edited November 6, 2015 by MPG

[Iceaxecrampon]

Much better from a coldies point of view later on the Ecm 00z compared with the 12z last night with a cold unsettled end to the run with N'ly winds, both the gfs and ecm 00z show rather colder w'ly/nw'ly winds later next week, occasionally cold enough for sleet / snow on high ground further north...I know it's only early november but it's about time coldies had something to look forward to following a very mild autumn so far!.  

 

Agree Frosty  - fairly confident for mid November - something has to give sooner or later as average law goes.

[fergieweather]

Unless Ian's post from earlier proves to be inaccurate (and i dont think it will be) any eye candy in FI will remain just that.

 

Actually you'll see a change in emphasis emerge in forecast wording. The 00z EC ENS clusters and stamps - much like 00z EC DET and 06z GFS (which is more extreme) - offer sufficient weight to greater possibility of a chillier phase circa mid-month (via Pm, possibly even Am flow) and this will be reflected in further updates, at least tentatively, until some level of consensus either firms-up or dissipates. However, right now this still remains a lesser probability versus the continued westerly bias described in my earlier post, but not in a clear-cut sense. Note too that 00z EC Decider has also now backed-up GloSea's build of MSLP across the UK into mid-month, but this all seems fairly fleeting, before strong zonality resumes back end of Nov and on into early Dec. Nonetheless, there are clear emergent signs of greater amplification by end of days 8-10 and more so thereafter (post-d11), with potential for this to manifest as a colder phase of the month.

[ANYWEATHER]

Afternoon all. Well gfs continues to tease us and bring us some lovely Winter charts deep into FI. Lovely to see for a change because of the consistent output of horribly mild charts especially for Southern Britain in the short term....Chances of that happening though , well you know the answer!    

[london and south east kent]

So The cold charts continue if they keep trending this way some people will be getting the snow boots out soon 😊😊â„ï¸â„ï¸

[Duane S.]

Steep drop off on the latest forecast, although the Arctic pressure anomaly will be dropping off from a very high peak (if indeed it does reaches that). When was the last time +5 was hit I wonder?

 

 

Edited November 6, 2015 by s4lancia

[nick sussex]

Interesting output from the ECM today which doesn't phase that Atlantic low with low heights over southern Greenland, looking at the output that's the only way to develop colder conditions by day ten.

 

This allows the Canadian high to exit and head towards Greenland. The GFS typically after liking the Canadian high has gone off the idea.

 

Looking at the ECM T192 and T216hrs you can see the critical point.

 

 

 

 

Circled red is the Atlantic low and those low heights near southern Greenland, in yesterday evenings ECM these  phased and the result was the UK stuck in that milder flow and this will determine whether theres a chance of something colder within the next ten days.

 

At least for the pattern upstream in the USA there is some good news in terms of which model is preferred. The State forecast for Ohio has the following:

 

HIGH PRESSURE WILL ATTEMPT TO RIDGE INTO THE REGION TUESDAY NIGHT
THROUGH WEDNESDAY NIGHT AS THE NEXT STORM SYSTEM TAKES SHAPE OVER
THE CENTRAL PLAINS. MODELS CONTINUE TO DIFFER WITH THIS STORM
SYSTEM. AS STATED YESTERDAY THE ECMWF TYPICALLY DOES A BETTER JOB
WITH STORM SYSTEMS EJECTING FROM THE SOUTHWESTERN US. SO WITH THAT
SAID WE HAVE GONE WITH A WPC/ECMWF BLEND FOR THE LONG TERM.

However this doesn't mean that the ECM has called the issue of phasing correctly but at least they prefer it over the USA than the GFS.

Edited November 6, 2015 by nick sussex

[knocker]

Courtesy MV

 

Alaska just under a massive upper-level cold trough in the 6-10 day driven by an upstream high-latitude NW Pac ridge

Edited November 6, 2015 by knocker

[johnholmes]

Big call Bristle Boy. Its just another model Ian is using, so why should that be right?

 

Bristle Boy's comment is a prime example of 'discussion killing'. A post from a person giving information from a source not available to members here.

 

Because Ian has posted that comment, it now means people will be unwilling to discuss the GFS output.

I take your point MPG but if we look at the statistics for 10 days, using the data seen when Gibby posts, or available off the NOAA site, then GFS and for that matter ECMWF are little better than a 1 in 3 to 4 chance of being correct. UK Met have a great deal we don’t see as you rightly comment but the input from Ian’s TV discussions with the senior man at Exeter do help throw some light on why they at times make subtle changes to their 6-15 or 16-30 day outlooks.

Today is an example, yesterday no mention of any change today, link below

http://www.metoffice.gov.uk/public/weather/forecast

But the bit which may interest those wanting cold is

‘..though tending to turn somewhat colder in the north later.’

 

All we have is the anomaly charts from various sources and looking at what the MJO, AO and NAO suggest. Within some bounds I find this input can be helpful to make me widen my checking of the data we have available to try and arrive at my own balanced view of how things may develop.

Edited November 6, 2015 by johnholmes

[bradymk]

Steep drop off on the latest forecast, although the Arctic pressure anomaly will be dropping off from a very high peak (if indeed it does reaches that). When was the last time +5 was hit I wonder?

 

 

ao-061115.gif

 

Earlier this year we had a +5.660 in March, the highest ever recorded for march and the 2nd of all time but quite rare!  Just been looking at some stuff for the coming winter, the AO has decreased to -5 or lower on 12 separate occasions since 1950. Amazingly, FOUR of these were during the 2009/10 winter which was pretty remarkable. 

 

Having been looking at the AO this morning, another interesting connection is July AO's and the following winter. This July featured the second most negative Arctic Oscillation on record, second to only 2009. Out of the top 15 most negative AO July’s on record, 14 of those 15 featured a negative AO in the winter that followed.

 

Obviously there are so many other variables, particularly this winter but interesting nevertheless.

 

Also, recently regarding the current El Nino, the water has recently started to become warmer in the central pacific than the eastern Pacific where it has cooled relatively to the past few weeks. Now this could be the start of a El Nino Modoki beginning to set up which would increase our chances of a colder winter but this looks like it may now be just temporary with Nino 1+2 warming again from the WWB in the future.

Edited November 6, 2015 by bradythemole

[Nick F]

Ensemble means from GFS and EC showing a cooling trend into the 2nd half of November, which is not hard to achieve, given how mild it is and as would be expected normally as we head towards winter.

 

Interestingly, a look at the 00z ECMWF ensembles for London below, shows the 00z GFS operational was a mild outlier between the 16th and the 20th against the EC ens spread.

 

 

However upstream, looking at some of the US NWS forecasts, like the one below, suggest confidence dropping wrt to a trough which tries to move towards the east coast of America late next week - the speed and amplitude of this trough will have knock on effects with the potential wave development downstream and ridge that develops over NW or mid N Atlantic next weekend as shown by recent runs:

 

 

WITH 06.00Z MODEL GUIDANCE SUITE
CONTINUES TO SHOW DECENT AGREEMENT THROUGH ABOUT THE MID PORTION OF
NEXT WEEK...WITH SOME...PRIMARILY TIMING DIFFERENCES LATE NEXT WEEK.
THE CURRENTLY NEUTRAL NAO/AO WILL ONCE AGAIN RETURN TO POSITIVE AS
NEGATIVE PNA CONTINUES. THIS SUGGESTS A CONTINUATION OF THE MILD WX
GIVEN THERE WILL BE A CONNECTION TO THE SUBTROPICAL RIDGING AROUND
THE SE. HOWEVER IT IS THE TROF WITHIN THE NEGATIVE PNA WHICH TRIES
TO EJECT TO THE E LATE IN NEXT WEEK THAT MODELS ARE STRUGGLING WITH.
FORECAST CONFIDENCE IS HIGH THROUGH MID NEXT WEEK BUT THEN WANES BY
THE LATTER HALF. WILL CONTINUE TO BLEND DETERMINISTIC GUIDANCE AS A
BASELINE GIVEN THE AGREEMENT OVER THE NEXT SEVERAL DAYS.

 

http://forecast.weather.gov/product.php?site=nws&issuedby=box&product=afd&format=ci&version=1&glossary=1&highlight=off

Edited November 6, 2015 by Nick F

[Daniel*]

Nice to see those hatched lines indicating snow falling over Scottish uplands the first 'significant' snowfall at +156 quite a brisk windchill too with the cold westerly Polar Maritime flow coming off chilly North Atlantic SST's and snow level may drop below 200m so it does look Scotland alongside far north of England at least is going to feel a tug of something more wintry in the not so distant future with wintry precipitation with elevation.. It has been a slow burner this Autumn with these exceptionally mild conditions it certainly will feel markedly colder in highlighted areas.

[NorthYorksWeather]

GFS NH profile at 234 hours, getting closer to the reliable timeframe. Still a long way to go,

could do with losing that pesky euro high!!!

Edited November 6, 2015 by vizzy2004

[Stormyking]

Very Interesting RUN, seems to be a trend recently with high pressure towards greenland in the last 2 days, this run is a lot more solid, though wrong side of the low at this point, of coarse its FI, but its nice to a trend

 

[knocker]

I think the 12z gfs can be summed up brifly by 'Atlantic depressions'  By T186 a deep slow moving low mid Atlantic fills slowly but another low moving up from the SW phases in with it and forms another low which ends up just west of Ireland dragging some warmer air up from the south.

 

One thing perhaps worth noting is a possible pattern change upstream with a trough plunging cold air down over North America.

http://www.tropicaltidbits.com/

Edited November 6, 2015 by knocker

[nick sussex]

The GFS would have looked a lot more interesting if that Atlantic low didn't deepen rapidly, this causes it to move more ne and stops the high from ridging further south. That low needs to be as weak as possible and track more east/se.

[Iceaxecrampon]

 

12z seeing sense at +288 nevertheless it will be interesting to see if

anything comes off mid November.

 

Cold air less of a far fetched (maybe?) incursion.

 

Cairngorms should still do well for it's first real blast of Winter.

 

Ian

[london and south east kent]

Hi all this low will go south and east in time then the door will open more runs needed 😊â„ï¸â„ï¸

Edited November 6, 2015 by abbie123456

[phil nw.]

Hi all this low will go south and east in time then the door will open more runs needed â„â„

Still the colder air is easing closer as the jet trends further south towards mid-month.Not an Arctic blast but certainly a more normal feel to late Autumn.

It would be good if you would put your location in your avatar abbie.

Edited November 6, 2015 by phil nw.

[Ravelin]

The GFS would have looked a lot more interesting if that Atlantic low didn't deepen rapidly, this causes it to move more ne and stops the high from ridging further south. That low needs to be as weak as possible and track more east/se.

It goes from a pretty flabby 990mb to a tightly wound 960mb in the space of 24hrs (between 162 & 186hrs). Credible?