Model Outooks: Winter 2008/2009

forkassed

Probably down to snowbies feet on the ground approach to weather charts im a little late to jump on bandwagons in regards to weather charts more than 150 hours out.

But lets be honest here something is stirring when 180 charts fom gfs and ecm and even ukmo at 144 are following the same trends.

Fingers crossed chaps because it couldnt happen at a better time.

happy xmas and new year to all, may 2009 bring blocking highs, cold easterlys and snowfests to all:)

Pangea

Snowaddict wrote: »

Furthermore, I know many don't rate JMA, but just take a look.



And take a look at NOGAPS:



I would still remain cautious to be honest, because we could be in for a major letdown, but I will say that this is look more interesting by the hour. I will endeavour to do regular updates on this now.

SA.

What does the numbers repersent on the last chart? 476 to 600?

Snowaddict

Well well, look what we have here on 18Z GFS...

An easterly flow developing by St Stephen's day on 18Z GFS run this evening!!!

A clear snow risk in eastern Ireland over high ground on the 26th at 12:00 noon, and late on the 27th continuously into early 28th. What did I say earlier on?? :rolleyes:

Dewpoints are shown to be very favourable for snowfall.
Upper 850hPA's are shown at about -7 to -8 from midday next Saturday.

Colder air is pushed approx 150 miles further west on this run.

This is but one run, but as I have been saying, if things keep getting pushed further west.......;)

However, this is one run and is open to change, but it does look as if there is now a possibility of an EASTERLY, albeit not one with uppers of -10. However, dewpoints are very favourable. The cold continues the whole way out, with substantial snow risks for Tuesday 30th, Wednesday 31st. Must be said that the last few frames of FI not that great, but for the higher resolution more reliable timeframe, a major upgrade and even at T+384, another cold outbreak is developing from the northeast.



I know its still in FI, but if things continue to push further west, which has happened on every GFS run today.... Need I say anymore?

arctictree

The 9 panel GFS 12z is a thing of beauty:

http://www.wetterzentrale.de/pics/avnpanel1.html

Pity the interesting bits are in the second half!!

The chart for Sun 28th could be an 80's type event if it were to materialize.

Anyway, at least we have entered the time of year where charts like this can produce something exceptional.

A

Snowaddict

Indeed Artictree, I do expect GFS operational to be an outlier in the early part, and somewhat of a (mild) outlier in the latter, with several runs possibly trending below GFS operational. I would hope to see a continued westward tracking of things, because this does pose the potential for snowfall as early as the 26th/27th...

18Z GEFS Ensembles are ok, nothing spectacular, bit still a noticeable drop in upper temps is clear on that run....

Now one other thing to note is that JMA is almost 100% in agreement with ECM regarding upper 850hPA temps from next Saturday, that is... they would be very close to allowing snowfall in the east. I know many don't rate the model but I find this interesting.

One worrying trend for me in this is that the GFS perturbations seem to be out of kilter with the operational run, while the ECM ensembles are clearly showing extensive cold reaching our shores from the east by Saturday the 27th.

Its too far out to call IMO, but because of the lack of GFS ensemble agreement, I can't say I am in any way content as of yet...

Either way, I do put trust in ECM, and if these trends continue, there [could possibly] be wintry conditions developing in eastern areas by next Saturday.

My confidence remains very low on this though still, and I would not bank on it by any means.

Lets see what tomorrow's runs will bring.





Regards,
SA.

Snowbie

Pangea wrote: »

What does the numbers repersent on the last chart? 476 to 600?

This represents the geopotential height (assumes all land is flat) in meters (thickness) 476 to 600= 4760 to 6000 meters. This is the 1000mb to 500mb layer and gives a virtual temp in this pressure gradients.

Temperature and moisture affect the thickness values in the 1000 to 500mb layer, the lower the thickness values ie:528 to 524 in Ireland the better chance of precip being snow but this is not always the case and a whole lot of other factors need to be considered.

TheGreenGiant

Damn guys, these charts are looking really good...I just HOPE something decent comes from them! An easterly would work out very nicely indeed:D. Would bring a gloomy 2008 to a cheerful end:cool:

Pangea

Snowbie wrote: »

This represents the geopotential height (assumes all land is flat) in meters (thickness) 476 to 600= 4760 to 6000 meters. This is the 1000mb to 500mb layer and gives a virtual temp in this pressure gradients.

Temperature and moisture affect the thickness values in the 1000 to 500mb layer, the lower the thickness values ie:528 to 524 in Ireland the better chance of precip being snow but this is not always the case and a whole lot of other factors need to be considered.

Thanks for explaining it to me, Theses charts look very promising , I really hope it snows

Snowaddict

All I will say for the 00Z run is that its simply stunning. There is a period of 4 days during which the upper temps are -10, and yes even lower, just take a look. Now the last few frames show a breakdown to the atlantic, however I would doubt that this will occur so soon as the 2nd of Jan because the way ECMWF is trending, the pattern appears to be going to be blocked for a lot longer than that.

One would imagine that if these trends continued, the possible severe cold could stay until at least the 10th of January. Furthermore, with the NAO - North Atlantic Oscillation forecast to go negative to deeply negative during the first half of January, there is the potential and yes its only potential at the moment, but there is the potential for a very long lasting cold outbreak.

I know that this is all FI, and of course the cold could be pushed back out to nothing but a dreary high, but to see some of these charts sets the heart racing, a period of 4 days during which there is continuous heavy snowfall over Ireland with daytime maxes struggling to zero.

My confidence is still not too high, but if this continues to develop, we could potentially see weather conditions not seen here since at least January 1987, maybe even further back. If, and I say if, these charts verified, the country would be crippled.

This is truly, a beast from the east.

Note that although the GFS was definately a cold outlier for a good part of the run, there is a substantial drop of in temps as we head towards the 4th and 5th of January - this could be the point where substantial retrogression of the high takes place, however its way way too far out to make any assumptions about as of yet.

Snowbie

Now thats a nice pic to use as a screensaver.
Mike65 look away now:pac:, 1048mb is a nice block, very little modification of the air, windchill, low temps, high convective snow chance ooohh very nice. IMO thats the chart of the year.

06z rolling out now so see if it keeps the theme going.

Snowbie

Lets give the 06z a miss, nothing to see here.

Pangea

wow that is something special ,it looks like its gona be a winter to remeber.

Deep Easterly

Snowbie wrote: »

Lets give the 06z a miss, nothing to see here.

Just ran through the 06z and while not fabulous for deep freeze, it is a very easterly run all the same, which will do me. Imby I know, but I just want nice dry weather for now. Deadly to see even the 06z looking different from the normal closely parked Azores High crap.

http://theweatheroutlook.com/twodata/gfs/06_177_mslp850.png
http://theweatheroutlook.com/twodata/gfs/06_228_mslp850.png
http://theweatheroutlook.com/twodata/gfs/06_372_mslp850.png

Also, I am rather looking forward to Mike65's reports if them charts play off.

Snowbie

True DE.

Although cold has downgraded a tad with more Med influence than direct east, it does break the consistent runs of late. We do not want to see this as it is just outside reliable timeframe.

It is only one run and far from terrible but a big downgrade to SA chart from 00Z.

nacho libre

Snowbie wrote: »

True DE.

Although cold has downgraded a tad with more Med influence than direct east, it does break the consistent runs of late. We do not want to see this as it is just outside reliable timeframe.

It is only one run and far from terrible but a big downgrade to SA chart from 00Z.

I was just waiting for this sort of downgrade. getting an event on par with the 80s is just not going to happen. I really hope i'm wrong but it's just too delicate a balance required for this Island to experience a sustained snowfest over several days. Unfortunately, Mike65's smile won't be turning to a frown...

Supercell

12z up to t+108 now, interesting link up between scandy high and siberian....
Watching this keenly.

Supercell

Christmas morning looks a bit nippy!

Snowaddict

Supercell wrote: »

Christmas morning looks a bit nippy!

Indeed, I don't believe there is much to be downbeat about. An awful lot of fighting and trolling on the UK forums this morning along with a small number of wind up merchants who pounce as soon as one run shows a downgrade.

IMO. The general pattern still remains the same, blocked to very blocked, with retrogression of the high highly possible and almost likely IMO.

We are seeing very interesting synoptics and I wouldn't write off anything just yet, only that it certainly won't be mild from about the middle of next week onwards.

Supercell

This run is flat out weird :-



That just aint gonna happen, will eat my hat if it does.

Snowaddict

Not a good 12Z GFS run it must be said. Now I may be wrong, but I think I read something about 2-3 weeks stating that the data input at the weekend for the GFS was automatically done without any indivdual engaging in the process. However, I stand corrected on this one. But recently, I have noted that the GFS outputs at the weekend have been particularly poor in terms of cold.

I will do an ensemble analysis for the 12Z GFS and post shortly.
SA.

Snowbie

Snowaddict wrote: »

Not a good 12Z GFS run it must be said. Now I may be wrong, but I think I read something about 2-3 weeks stating that the data input at the weekend for the GFS was automatically done without any indivdual engaging in the process. However, I stand corrected on this one. But recently, I have noted that the GFS outputs at the weekend have been particularly poor in terms of cold.

I will do an ensemble analysis for the 12Z GFS and post shortly.
SA.

I don't know about that, we could discount the good and bad runs then fully but GFS is still on track regarding HP around the Christmas peroid over several days and is similar to runs early on Friday. It has been very consistent on my own forecast runs on my site. 3 weeks ago, GFS went offline for WXSIM personal weather site forecasting, is this what you read somewhere??

12z continues the downgrading unfortunately. Upper air temps not too cold. Med has more of an influence in mixing up the air over the continent and towards our shores.
Obviously the positioning of the HP is starting to become troublesome for GFS model and thus mixing up the air or a direct east cold blast.
ECM be out in awhile, see what that shows.

Snowaddict

Ensemble analysis for the 12Z GFS Run - 20 December 2008.

After the rather disappointing 12Z GFS run, how do the ensembles work out?
Well its comforting to know that GFS operational was quite a considerable / substantial mild outlier towards the latter part of the run. The ensembles are not bad at all, very encouraging in my opinion.



This is the mean or average upper 850 hPA temp chart for the 5th of January. Of course its open to substantial change with every run, but very encouraging IMO. Its the first time I've seen the mean 850 hPA temps drop to -4...



Now, there are some milder runs thrown in too, but here are the real interesting one's from what I can see:













Now after all of those charts, (and note that I have counted 6 others that are trending cold to very cold for the same period), there is a clear hint of retrogression of the high towards Greenland with the possibility of a wintry outbreak for Ireland. However, this depends on favourable upstream patterns, which are as of yet still uncertain. Also, the usual FI caveats apply to all of the above charts.

All in all, things have downgraded slightly for the shorter term, but clearly there are still significant signs of a blocked and potentially very wintry pattern.

Lets see what subsequent runs will bring. I remain very positive, and wouldn't rule out upgrades... However, I wonder what the ECMWF run will show?

SA.

Snowbie

The real cold is pushed more into the new year. As early as yesterday it was the 27th, then new years eve/day and the 5th January from the GFS

All still out in FI, so more twists to come.

ECM?

Snowaddict

Attention all:

Out to T+168, ECM is a fantastic run..... Don't lose hope just yet...

Snowaddict

The ECM is just a corker of a run now... CHART T+240 is a top classic... Words cannot describe it in my opinion.

I'm ramping it up now, no doubt about it, but just look at these charts...

You know what these mean.... :D They equal a sustained and potentially severe cold outbreak... Don't lose faith just yet...

If ECM tonight is to believed (Although I wouldn't put much on it just yet, just to be cautious in light of today's outputs), then cold will arrive by the 27th in the east, with a classic following on into the new year period...





The following chart is something of rarity and beauty in my opinion. It should provide cheer and hope to many on here. However even up to T+168 its stunning, best I've ever seen. With the usual caveat of most of these charts being in the unreliable.

Where do we go from here? No cross model agreement on this... Will 18Z GFS come on board? If these charts materialise, we will see the most blocked pattern in many many years.

I refuse however to believe it at this point, out to T+168 is excellent and the boundary IMO, because beyond that is a top classic.

Snowbie

At least ECM is better, it would have spelt disaster if that was inline with GFS.

This is the global ensemble run though. None of the models are agreeing.

mike65

Looking at wetterzentral its a 3/4 days wonder.

kerry1960

Excuse my ignorance SA but where is the cold in this chart ? the source of that circulation seems to me to be African/Med in origin ??? .

not questioning anyone's chart reading skills or anything , just wondering .

mike65

Well its only a moment in time, its the next chart thats more cold as the air drags across Europe fom Russia.

Danno

Looks good lads, but I fear that the High Pressure will be to, erm, High? 1032mb is not going to spark off many showers.