End of October Forecast

arctictree

Weather looking very stormy for next weekend (as usual!).

Some interesting weather showing up now in FI leading up to Halloween.

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

Danno

I was looking at the GFS output this morning and some central north atlantic blocking looks like taking hold with some northerly winds coming down.

This October certainly feels alot cooler than recent ones, reminds me of the early 1990s Octobers really.

arctictree

Totally in FI but a lovely chart nonetheless:



Any opinions on whether we would get snow out of a chart like this at this time of year??!

Snowbie

Will you look at that, my guess for Halloween for the first air frost looks on.:D

Arctictree, what that spells is some potent showers or coastal Thunderstorms for the north and east.
A cold polar blast travelling over warm SSTs (October has the warmest sea temps around Ireland usually) will build CB,s quickly over sea but will die out as they travel inland as no convection and dry air overland (opposite to summer).

Very hard to tell if snow where to fall from that at this time of year but October 2003 has to be noted here. Nowcast i'm afraid.
Okay FI but very hard not to admire that kinda chart.
Where has this year gone, were back to snow watching already.:eek:

Supercell

Jaysus we are already thinking about polar lows and such, thats a very tasty chart indeed. I'd just love an october 2003 to happen again, except this time up the mountains to experience the fun.

forkassed

This looks tasty

http://91.121.93.17/pics/Recm2401.gif

Mr Benevolent

This probably sounds stupid, but what conditions need to exist for snow to form, apart from temps <0C?

forkassed

Confab wrote: »

This probably sounds stupid, but what conditions need to exist for snow to form, apart from temps <0C?

I would say snowbie's your man for the ins and outs but heres a link to a good general guide

http://www.netweather.tv/forum/index.php?showtopic=20474

Supercell

Just looking at the 12z ensembles, amazing agreement all the way out until then.
This is a crazy time of year, just about anything can happen and usually does.
Then December and endless mild returns, enjoy the next month or so !!

Snowbie

I would agree with most of that Netweather link but but an exception is the scandi HP and snowfall for our east coast.
The chance's of snow from a direct east blast from Russia is reduced further thanks to the UK. The airmass will be either:

cloudy, cold with flurries
or
clear, dry and cold.

That chap mentioned it when moisture can be lifted into the atmosphere by cold air travelling over a warmish sst's but only brings gloom with the odd flurry. This is a layer of stratus (cold inversion layer) and traps the cold beneath it to the surface.

When in the clear, dry and cold setup occurs when the cloud is broken up as the pressure gradient is tighter and the winds are stronger and a wind chill coupled with bitter air can wake you up somewhat. The air is also modified by the UK, drying the air out too so dewpoints can be very low but we need a kick start for showers to occur over the sea.....
The pressure gradient will be tighter when a LP to our south moves northwards and bumps into the HP.

This LP is key for snowfall to our east and south. This will destabilise the atmosphere and create instability (lapse rates steepening), building showers quickly over the sea.
Coasts would see snow to lower levels( as DP be subzero) but unless 850mb temps(1500m) are below -10C, snow would not settle on the coast only inland as the sea can be our friend and foe at the same time as it is warmer than the land by the resorts.

First things first, a scandi HP has to be in place and a LP to approach from the south just to create a snow chance otherwise a scandi HP is like an Azores HP steering in stratus muck obviously with temp difference. 3 out of the last 10 scandi HP has brought snow to the east and the 3 had LP moving up from the south, the other 7 where stratus muck. The last snow to the east was this year Jan 3rd and had an added little feature reforming in the N Irish sea from the North sea off the Scottish coast.

Here is proof of what happened because of that feature

this thread i posted radar shots somewhere in there

The Omega block is what we want to see forming to our north when the arctic high vacates south into the NIC or the Norway to Iceland corridor. But that is as rare as Dublin winning the all Ireland.

Supercell

arctictree wrote: »

Totally in FI but a lovely chart nonetheless:



Any opinions on whether we would get snow out of a chart like this at this time of year??!

You and I might see some, the mountains above 350 metres would be a cert for falling snow and probably 500 metres a cert for settling stuff. Lower down hail and some sleet in the really heavy showers would be my guess.
Thunder likely too, its a really tasty chart!

Supercell

Snowbie wrote: »

Here is proof of what happened because of that feature

this thread i posted radar shots somewhere in there

The Omega block is what we want to see forming to our north when the arctic high vacates south into the NIC or the Norway to Iceland corridor. But that is as rare as Dublin winning the all Ireland.

Epic tread that, nice just rereading it.
Only October and we are already starting snow treads, lets hope theres another six months of potential on the charts!

Mr Benevolent

Thanks for the detailed explanation Snowbie, the whole process makes a lot more sense

Scubadevils

Wow, thought I'd stop by and see where we are at and if any talk of the elusive 'snow'. I joined boards almost 4 years ago now after doing a search on google for 'chance of snow' or something to that effect... it was a rollercoaster couple of weeks then leading up to what became a somewhat white Christmas. Anyway, hopefully this year will deliver!

Deep Easterly

I expect Snowbie and Supercell will be quite pleased with the latest ECM teaser:





I am even more pleased, for it will be spectaculary dry and a frosty wind if them charts play out anything like that.

arctictree

All the models I have seen are in rough agreement for northerlies backing north easterly for mid next week into and beyond halloween.

Will be great to have this kind of weather around then. Sure beats mild muck!!

Seeing how this evolves over the next couple of days will be interesting!!

A

Snowbie

If this where 'Play Your Charts Right' i'd stick on the bottom one

Nice one Pat, i was loading the GFS today at around 1715 and it got as far as Tuesday and an arctic LP system was streaming south towards us, i wonder is that the same LP there, must go and check when this forever taking PC back up finishes:(

Deep Easterly

Give me a mo

hERE YOU GO KARL. ENJOY.

GFS 12z Tuesday:


WEDNESDAY:


THURSDAY:


SATURDAY:


REST OF RUN KEEPS A NICE COOL THEME:

Snowbie

Sweet, if only it where Monday, we could really admire those charts. I'd say the 528 DAM thickness is well south of Ireland but only just. Notice the warm sector in and around of the core, roughly -10C to -12C 850mb temps.

Afterall it's only October and the real cold air is a couple months away. That in January/Febuary be fantastic.

Cheers Pat.

Danno

Christ! Pat, are them charts genuine? I hope they're not PhotoShoped!

nacho libre

i'd say sleet is the best we can hope for on a low ground out of this:(

i bet we won't get charts as good as those at the optimum time of year!

Supercell

Eh..AT..next round is yours
Thursday and Friday look potential packed around these parts.

Snowbie

GFS has backed off slightly for us. 18Z but Still FI.

LP coming out of Svalbard creates a polar low or comma cloud(as it looks like a comma on satellite) comming out of Iceland. This is not impossible as cold winds over warmish water(warmer than the air above it) around north Atlantic is not uncommon for this set up at this time of year.

This PL stays to the NE of Scotland and runs down the east UK with the main parent LP now moving into Norway. This setup is not a complex system as both systems are moving to the SE direction so chances of the Norway(parent) LP retrogressing back west looks unlikely.

Looks to be fairly mild around the core (Scotland sea level, snow for their MTS no doubt) so closer to the centre of the PL will be noticeably less cold but with troughs moving south right down over us (if PL track remains the same). Interesting.

Snowbie

To and fro'ing, GFS a nice upgrade today in FI land still.

Deep Easterly

Unfortunately, there is more froing than to-ing tonight Karl. Massive downgrades in all of the models. Downgrades that don't even decend into anything interesting, but just anticyclonic westerlies with embedded warm fronts.

Anyways, before then, we still might scrape a couple of wintry type showers during next week if the latest ECM run works out.



First blues of the season over the northern third of Ireland, so some hope for hail/sleet and the odd snow flurry perhaps before the horror arrives (already can be seen over the mid atlantic :mad:)

If only some major troughing would occur to the South of Iceland and become caught up on the Jet stream....

Snowbie

First time i think i ever seen this with GFS (18Z) generally having a cool possibly cold spell throughout the runs up untill the 8th Nov. No hint of a SW and even progs a scandi HP 3/4 way through. Odd but nice but chances are...

Pat i think a cool theme from this Sunday through to Wedensday instead of cold unfortunately. However 18Z last night downgraded also but near reliable timeframe now.

Danno

Daytime maxes for early next week remain below 10c, with night time minima below zero inland. Interesting setup so early in the season.

arctictree

Looks like an upgrade across all the charts this morning. ECM is still showing a cold halloween followed by cold weather lasting a few days:

Gonzo

Met Eireann have mentioned a threat of wintry showers for high ground areas next week. This whole October has been really cold for me I think, coldest October I can remember in a long time, if only this was January.

Snowbie

ATM (06Z) 528 Dam thickness flirting with Ireland (needs to be at or below this thickness for snow chance) Charts have well improved over the last two 18Z runs. GFS has nearly 36hrs of a direct N'ly source for Tuesday and beyond.

nacho libre

hopefully there will be an air frost before the end of October:D