Wintry potential December 09

darkman2

Hi, well t'is that time of year. The time when speculation begins to mount and the ludicrous incursions into fantasy land begin......so let's get to it.


The ECM seems to be providing the first chink of light of the season with signs that the train of Atlantic depression may be coming to an end.

At 72 hours - everything is pretty much as is except for a milder southerly flow but the windy damp spell continues




At 120 hrs (Saturday next) it's still dark and wet but a change is occuring as the Jet Stream weakens and starts to split slowing everything down. Pressure starts to rise to the North.

MJO entering a new phase?




At 168 hrs the scene is set as a ridge of high pressure extends from Greenland pushing the cyclogenisis south creating a kind of squeeze with which we would hope incoming Low pressure would undercut. The Jet Stream is taking a holiday to the Med.




Nothing spectacular just yet but they are the building blocks.

On to 216 hrs and we are in - we are in!




LP starts to grate against a push of very cold air out of Scandinavia and beyond. But the LP is not going anywhere. So it undercuts the high pressure to the North. Things about to get wet in Iberia and cold over Ireland and the UK.

At 240hrs the Polar Vortex (the darkblue and purple area) is completely moved from Greenland to were we want it to be - Scandinavia. Snow and raw winds await




UKMO also has a similar evolution out to 144hrs. GFS not having it atm but whilst the above may not occur it is by no means out of the question either. This is the first real sign of a pattern change this winter. Long range Christmas charts looking quite yummy for snow aswell atm but we won't go that far;)

Incidentally if the above did happen there is a real snow risk but id prefer it in December as opposed to November. Maybe a little early yet for Easterlies.

Anyway just a little something to keep the spirits up

cinnamon

darkman2 wrote: »

Long range Christmas charts looking quite yummy for snow aswell atm but we won't go that far;)

Anyway just a little something to keep the spirits up

Thank you kind sir, you've just made my night

danni2

Great post darkman2, its been rather depressing looking at the charts in the past few weeks, so nice to see things are looking brighter and hopefully we won't have to wait to long now to see some snow:D

Deep Easterly

darkman2 wrote: »

Maybe a little early yet for Easterlies.

Nonsense! Never too early or too soon for an easterly! :pac:

roryc1

So what your saying is that in around two weeks it will start snowing and not stop till april, thanks darkman now im happy

Gonzo

wouldnt mind a 2 to 3 week period of dry, crisp and sunny weather before winter sets in, so sick of the wind and rain! then snow from mid december onwards wud be nice.

ronbyrne2005

any updates? Im sick of this wet windy warm weather we're having.

patneve

YES WE CAN:D

GFS 12Z showing a nice cool down before a bit of a wintery snap (however those charts are in FI). Am 80% certain that a nice change is on the way:D

arctictree

GFS showing a very cold and wintry Saturday morning:



Temps are low:



There is precip around:



This could possibly be our first sleet/snow event of the winter. Could be a very nowcast event though.

Deep Easterly

:pac:

Gonzo

4/5C max for the weekend, could be some snow on high ground, im generally hoping for things to just stay calm and dry up.

JanuarySnowstor

I've been watching developments from afar all week and I firmly believe that Ireland is a hare's breath away from a snow event this wkd. Heavy ppn, Northeasterly winds, and 528dam air very closeby. Most importantly,a point being ignored on here, is some ferociously cold air just to our North!!
Someone will see a lot of snow

cian1500ww

God I hope we get some snow *fingers crossed*

Deep Easterly

cian1500ww wrote: »

God I hope we get some snow *fingers crossed*

Evelyn on the TV forecast tonight mentioned the possibility of some "wintry showers" in the east and south east this coming weekend. Looks like being dry here in the west which I am sure for many will be a much welcomed relief.

Drummer Mummer

Why is it we NEVER get snow on the East Meath coast? It could be snowing like mad a few miles away and still we wait.....! I could count on one hand the times it snowed here in the last 30 years. What are the chances (if any) for snow in the next few months?

loup

Does the colder weather mean it will rain less in the next while? I really hope so especially for all those in flood risk areas.

maquiladora

loup wrote: »

Does the colder weather mean it will rain less in the next while? I really hope so especially for all those in flood risk areas.

Looks like mostly showery in the near term apart from Friday night / Saturday morning when the southern half of the country could see fairly heavy rain. Next week looks fairly showery again but could see heavy rain towards the end of next week...

forkassed

:pac:

MUSEIST

forkassed wrote: »

:pac:

Lol, indeed, I saw this earlier and was going to post this.
Damm FI, i swear somebody just puts charts like that in FI to piss us off.
If only something like that happend, but we all know it w'ont:D

patneve

i will not be fcuked up the ... by GFS once again!! 100 hours is my limit!

It would be highly unusual for extremely cold air from the East to come in early december.
In my lifetime,I've only seen it happen once,thats how rare it is.
Ergo no breath holding.

Anyhow,FI is ridiculous-always was.
It's short for fantasy island because post 96 hrs , theres no many errors multiplying in gfs/nwp data sets that they become rapidly meaningless.

darkman2

Im not going to bother posting charts or even commenting on something that far out for the same reason as above. However there is an interesting situation about to occur in the Polar regions where a large area of high pressure is going to build from the Pacific right into the interior of the artic. This looks like splitting the Polar Vortex and probrably heading our direction so expect a pressure rise from the North which most models agree with. What's not known is how it will effect us. It should create an unusual change in pattern I would think in the next couple of weeks. The options would favour a colder outlook (perhaps very, very cold) but a milder one could also occur. Alot of variables to consider.

This page on the NH synoptical evolution and height disparities clearly show what I mean about the ridge going into the Artic and coming down on our side.


http://www.meteociel.fr/modeles/gfse_cartes.php?mode=0&ech=6&carte=1


Press "suite" to continue to 192+ just to illustrate.

patrick ryan

its - 2 i hope we get snow tonite?/???:)

danni2

patrick ryan wrote: »

its - 2 i hope we get snow tonite?/???:)

Don't think it will snow tonight, tempertures will rise as that band of rain will spread across the country tonight and tomorrow morning.

Hopefully we won't have to wait too long for our next cold spell with a proper northerly/easterly then we will see some snow, remember we have the whole winter ahead of us;)

patrick ryan

anybody get snow

Trogdor

Moved your posts in here as i think the old thread had run its course:)

patrick ryan wrote: »

anybody get snow

Snow's fairly unlikely tonight, the temperatures are set to rise quite a bit before any precip starts unfortunately

Supercell

Light stuff here, but not settling and probably will turn to drizzle soon as the temp is rising as is the DP

patneve

GFS 12Z - what an amazing run!!:D I tend not to comment on cards past 180 hours, but on this run there are important changes already at 150 hours (high pressure building on Ireland...all we need is that high pressure to shift and build to our north and it's bingo;) too early to say now though...

roryc1

The 12z have gone mad :eek:
but they do show a steady build up from the east,
i think i might go and find my snow boots, just in case

Kippure

roryc1 wrote: »

The 12z have gone mad :eek:
but they do show a steady build up from the east,
i think i might go and find my snow boots, just in case

Thats the best 12z run i,ve ever seen. Prue winter magic.

forkassed

As patneve said..Some nice trends developing on the GFS the last few days. It has showed an easterly on and off now for about 4 days. It all hinges on whether the high pressure over europe builds Northwards at around 144 hours, will be looking for evidence of this on the ECM this evening.

Doubtful this far out but a trend to watch all the same..

Supercell

I love this time of year

patneve

the biggest ingredient for any 'big cold snap' in Ireland is a nice high pressure partially shutting down Atlantic influence...that is step 1...so lets hope step one happens and then we can take it from there:)

patneve

patneve wrote: »

GFS 12Z - what an amazing run!!:D I tend not to comment on cards past 180 hours, but on this run there are important changes already at 150 hours (high pressure building on Ireland...all we need is that high pressure to shift and build to our north and it's bingo;) too early to say now though...

omg links to where ye get your runs plz!!

patneve

Deleted User wrote: »

omg links to where ye get your runs plz!!

http://www.wetterzentrale.de/topkarten/fsavneur.html

http://www.meteociel.fr/modeles/gfse_cartes.php

http://www.meteociel.fr/modeles/ecmwf.php

nacho libre

it's more likely there will be some type of advection cold for a couple of days out of this,then back to normal service from the wretched Atlantic. It would be quite something to get an easterly, so potent, that it eventually extended half way across the atlantic, which then resulted in a succession of active troughs moving from east to west over the country for a couple of weeks, but just like Ireland beating France, that would be too good to come true:(

yogidc26

patneve wrote: »

http://www.wetterzentrale.de/topkarten/fsavneur.html

http://www.meteociel.fr/modeles/gfse_cartes.php

http://www.meteociel.fr/modeles/ecmwf.php

Thanks for the links wont have to keep relying on you guys to post them up

Hooter23

Im no expert on weather charts but the latest run looks very for cold and snow someone correct me if im wrong

patneve

Hooter23 wrote: »

Im no expert on weather charts but the latest run looks very for cold and snow someone correct me if im wrong

you're right but the next runs will change another 100 times before we really see what's going to happen...

patneve

Amazing ECMWF run this evening, nice high running over us all the way up to Iceland and then the cold setting in from the East:cool: Haven't seen such good charts in ages Still too far out though . . .

Deep Easterly

Tonight's ECM run makes for great viewing:



If only.... :pac:

Deep Easterly

Deep Easterly wrote: »

If only.... :pac:

Orgasmic chart that.
In my several decades on this Earth living in the East though,I can't remember ever see'ing an icy snowy easterly with air fed from way up there in early december.
I've only seen it at the earliest Xmas week and usually not kicking in untill after Xmas.
That high is positioned roughly in the same place with the same air feed as the january '87 high.
That time the river avoca in Arklow froze solid with snow lying on the ice.

A tad early this time and of course it will change being FI but sweet if it comes none the less.

darkman2

ATM the change looks like it is going to have some effect on our weather making it colder with the real possibility of Easterlies during mid month. It can still go wrong for us of course but nice charts to drool over none the less.


UKMO 144hrs is the most progressive in terms of timing toward a much colder Easterly regime. It shows the cleanest connection between our interim High Pressure and the Artic high. I am sceptical about the lack of shortwaves (or small troublesome areas of Low Pressure).




ECM locks us in a pattern which won't be easy to get out of. The NAO (North Atlantic Oscillation) is quite possibly heading for it's most negative phase in at least 20 years. What this means is the jet stream taking a dive south leading to LP constantly undercutting HP at more Northern latitudes. The HP just going back and forth like a yo yo between Scandinavia and Greenland and latching on to the Artic high mentioned at the start of the thread leaving us in East or Northeasterly flows. A very desirable situation for those who like cold and snow.




The GFS 12z is even more stunning. A change of climate really.








Just an example of what could be around the corner. The building blocks are already within 168hrs for much colder weather.

Danno

Thursday 17th December looks fantastic on todays 12pm GFS output...

http://www.wetterzentrale.de/pics/Rtavn2521.png <<< Sub 1005hPa
http://www.wetterzentrale.de/pics/Rtavn2522.png <<< sub -5c air at 850hPa
http://www.wetterzentrale.de/pics/Rtavn2523.png <<< Sub 528dam air
http://www.wetterzentrale.de/pics/Rtavn2524.png <<< Plenty of precip
http://www.wetterzentrale.de/pics/Rtavn25217.png << Sub 2c temperatures
http://www.wetterzentrale.de/pics/Rtavn25210.png << Sub 0c dew points
http://www.wetterzentrale.de/pics/Rtavn25215.png << The jet heating for Morocco! And notice a NNW streak off our west coast.

SNOWFEST!

Deep Easterly

Tonight's ECM 850's at 216hrs:



Would bring wintry showers to the east, but very very very very dry conditions to the western half which I would much prefer. Would help dry up some of the absolute saturation of ground as well!

Timistry

Deep Easterly wrote: »

Tonight's ECM 850's at 216hrs:

Would bring wintry showers to the east, but very very very very dry conditions to the western half which I would much prefer. Would help dry up some of the absolute saturation of ground as well!

NOOOOOOO!!!:(

maquiladora

Amazing stuff, a shame that its still in FI. I fear gradual downgrades over the next few days but have my fingers crossed.

Deep Easterly

Deleted User wrote: »

Orgasmic chart that.
In my several decades on this Earth living in the East though,I can't remember ever see'ing an icy snowy easterly with air fed from way up there in early december.
I've only seen it at the earliest Xmas week and usually not kicking in untill after Xmas.
That high is positioned roughly in the same place with the same air feed as the january '87 high.
That time the river avoca in Arklow froze solid with snow lying on the ice.

A tad early this time and of course it will change being FI but sweet if it comes none the less.

A good way to spot where streams are coming from is looking at the 500's themselves:

(I did up a crude chart, forgive bad artistry )



500's, on the whole, show streams at that level, and generally reflect the direction in which clouds are moving to and from. In the chart above, 500 dam line streams are moving down from the direct north, curving a little to the N.E as they reach Ireland, which tends to happen when a polar airstream reaches Ireland due to the "Coriolis Effect".

Even at that stage though, there is an undercut of the "real Mc Coy" at surface level (2nd arrow), which would create shear thus setting off possible convection near east coasts.

The real deal though, is still on the eastern side of that crude cold front I drew in. This is where the hardcore cold is, with super low dewpoints/humidity. Snow showers/blizzards? for the east, but even colder, if a lot drier, in the west.

Sounds good to me

(this is why I love easterlies )

Edit: Post edited as it contained rushed but gross mistakes. Where "850's" was written, has been changed to "500's". Sorry about this as it was written in haste

Elmer Blooker

John Eagleton said on the 0755 forecast on the radio that next week will be "much colder as northerlies set in"
High pressure will build close to Ireland later in the week but a northerly suggests high pressure around Greenland doesn't it?
Interesting to note that high pressure near Ireland in mid December 1962 was very quickly replaced by HP in the vicinity of Iceland/Greenland.:cool:

maquiladora

06Z GFS....(FI)

ltdslipdiff

More of this please ! Taken 7/1/09 on the way to work.