Pattern change could herald a return to very cold weather

Elmer Blooker

I am completely confused by this weather! I have NEVER in my entire life seen clear skies and hard frosts under a large stationary (winter) anticyclone that built from the southwest. We should be under a blanket of cloud or anticyclonic gloom. Frosty weather like this is always associated with a continental high building westwards or a ridge behind a cold front which usually lasts only a day or two (a toppler)
The winter that wont go away a good omen for Feb perhaps?

mike65

The winter that wont go away a good omen for Feb perhaps?

I'd have thought if this persisted it would hearld the early end to winter. You reach a point where a static high ceases to "create" cold and starts to create warmth.

snowstreams

mike65 wrote: »

I'd have thought if this persisted it would hearld the early end to winter. You reach a point where a static high ceases to "create" cold and starts to create warmth.

I wonder when would that time be? Is the rate of warming faster under a high than the rate of cooling?
Otherwise we would have to wait till the equinox to get warmth from one?

mike65

Actually you are proably right, after all the sea temperature is still falling so that isn't going to help. Anyone got the answer to when a static high pressure over Ireland turns warmer?

Elmer Blooker

mike65 wrote: »

Anyone got the answer to when a static high pressure over Ireland turns warmer?

We'll have to wait and see where the high will drift. Cold lovers would like it to drift anywhere between North west and north east but indications are it will slowly drift west or south west allowing milder and cloudier Atlantic air to topple over the top of the high. It may warm up a bit over the w/end but these highs can be very stubborn!

Elmer Blooker

Elmer Blooker wrote: »

I am completely confused by this weather! I have NEVER in my entire life seen clear skies and hard frosts under a large stationary (winter) anticyclone that built from the southwest. We should be under a blanket of cloud or anticyclonic gloom. Frosty weather like this is always associated with a continental high building westwards or a ridge behind a cold front which usually lasts only a day or two (a toppler)
The winter that wont go away a good omen for Feb perhaps?

Carefull what you wish for...
Once some atlantic flow gets into the high,which it inevitably will,you will have cloud.That may only be a matter of days away.
I'm not buying the colder hopecasting at the moment.

mike65

Elmer Blooker wrote: »

We'll have to wait and see where the high will drift.

I said static! If it just sat here for the next 3 months at what point would its influence create more warmth than cold? I'm sure one of our weather boffins can speculate.

Lets ignore the fact first that it would be impossible and assume it stuck around for 3 months in exactly the one place with no wind or influence of air from anywhere other than what is on top of us.
The cold would always be there at night with frosts but gradually washed out by warmer and warmer days as they get longer.
Theres no magic formula but for as long as you have 6- 8hrs of darkness under clear still skies,you are likely to have frost if theres no wind.
The shorter the night ,the longer the day the less cold it will be.

highdef

I agree with Black Briar. I would imagine that as the days get longer and the nights shorter, the diurnal temperature variation would also increase with the greatest change around and a little after the summer solstice. By say, end of June/early July, I would say that nights would still quite cool but the early night, a few hours after sunset, would be pleasantly warm as the ground would still be releasing it's latent heat. Days would be also be very warm inland but one thing that has not been taken into account is sea breezes. By March/April, we would be getting to the stage where the land is being heated during the day to a temperature a fair bit higher than the sea. As this warm air rises, air pressure will drop in the central parts of the country and sea breezes would develop on all coasts as a result. This would result in breezy, cool and sunny days on the coasts with calmer and warmer conditions inland.

Indeed, by high summer the land could be heating to such an extent that local downpours could result, despite the high pressure. Places like the Dingle Peninsula and other peninsulas in Kerry (as a prime example) could develop micro climates on some days. During the morning and early afternoon, very warm air would rise creating low pressure. Cool sea air would then rush in from the north and south of the peninsula creating very unstable conditions with two cool moist air masses colliding with a warm dry airmass. However, as there would be high pressure overhead, there would be a cap that would be very difficult to punch through so it would take some extreme conditions to trigger a shower or thunderstorm.

And of course at night time, after the land cools down very rapidly, land breezes will develop. By dawn, there would be a near equilibrium of temperatures between sea and land so the day would start calm and sunny in most places (with maybe some mist and fog), before the whole process starts over again.

Sorry for the rambling!!!

pistolpetes11

Deleted User wrote: »

Carefull what you wish for...
Once some atlantic flow gets into the high,which it inevitably will,you will have cloud.That may only be a matter of days away.
I'm not buying the colder hopecasting at the moment.

Do you see the warm Atlantic coming in on the models ? or is it just a hunch ?

pistolpetes11

pistolpetes11 wrote: »

Do you see the warm Atlantic coming in on the models ? or is it just a hunch ?

No one can say at the moment.
What I meant was that a maratime flow would seep in around the high eventually.
That wouldn't stop the night frosts where it remains clear,but it would limit them.
paradoxically,it would make it feel colder,there being no sun.

pistolpetes11

Deleted User wrote: »

No one can say at the moment.
What I meant was that a maratime flow would seep in around the high eventually.
That wouldn't stop the night frosts where it remains clear,but it would limit them.
paradoxically,it would make it feel colder,there being no sun.

Would that only happen if the high was to sink SE, thus giving a chance for the milder air to topple over the high ?

Ideally from a cold and snow lovers point of view which way would we like to see that high go ?

Off topic , The weather station arrived today , Walshes Weather will be online in no time !!!!

It will just gradually meander in.
A slight move and more comes in,a slight move back and that moisture is trapped.
Currently that looks like a very slow process.

nacho libre

pistolpetes11 wrote: »

Would that only happen if the high was to sink SE, thus giving a chance for the milder air to topple over the high ?



Ideally from a cold and snow lovers point of view which way would we like to see that high go ?

to go to the north west or north east

it's not going to the northwest because of the polar vortex over Greenland and the jet stream up north.

it is possible the high could link up with a siberian high that could bring in even colder air eventually.


however some of the models are hinting at the high possibly sinking south east eventually, which would allow the atlantic to power back in. at the moment the high is on a tour of ireland and uk because lower pressure over parts of europe is stopping it from sinking

je55ie

Just wondering how theres no talk at all about the temps we've been getting, i see its -8 in some places

mike65

At night, in foggy valleys. And not for much longer looks like cloudier conditions will prevail soon.

Speak Now

jessie37 wrote: »

Just wondering how theres no talk at all about the temps we've been getting, i see its -8 in some places

Because they've all been spoilt rotten and turned into snow bunnies

Very impressive frosts this weeks, getting temps that would have beaten lots of winter lows in the 1990's up to feb 2009 when we saw first signs of a change on patterns.

je55ie

yea i think spoilt for definite

BLIZZARD7

It seems this high is going to take a while to shift, cold and frosty is the theme for the next few days, maybe some milder air filtering in before colder air from the continent returns.

I feel like I'm forever chasing the next cold spell!! Keeps changing, atleast were not in raging zonality like the models were suggesting 10 days or so ago...

The ECM 12z throws us a bit of interest, vortex splits and shifts east (strato warming??) and allows pressure to ridge further north sending bitterly cold air towards us...


ECM/GFS 12z 500hpa 8-10 day charts show this very nicely-

http://www.meteo.psu.edu/%7Egadomski/ECMWF_12z/hgtcomp.html

This is only one run at present but the idea has being gaining momentum over the last few days and so might provide us cold lovers with some hope...


The models are picking up on some new signal that may prove to be a dead end, or not? MJO now on the move, in to phase 7 -

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/ensplume_small.gif

This would normally give these Synoptics in a normal la Nina winter -

http://raleighwx.americanwx.com/MJO/LaNinagt1Phase7.gif

But this has not being a normal winter and so we might see a more typical reaction to the MJO in phase 7 - (la Nina not factored in) -

http://raleighwx.americanwx.com/MJO/DJFPhase7.gif

I'm hoping that the MJO acts normally without interference from the la Nina and we see high pressure centered over the Iceland/Greenland area, like this - (ECM 12z N.Hemisphete 500mb chart +240hrs) - :cold:

http://www.wetterzentrale.de/pics/Recmnh2401.gif


Oh and a southerly tracking jet to add = blocked Atlantic. -




AO/NAO forecasts have changed again (as usual), outlook a bit more uncertain now -

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

The Stratosphere is in a cooling phase at present but is forecast to warm at the 10hpa level and to a lesser extent the 30hpa level -

10hpa level at +240hrs -



30hpa level at +240hrs -




So in summary -

Some encouraging signs today for coldies, MJO in phase 7 or strato warming forecasted are possibly what the models are starting to pick up on, this has the potential to develop quite rapidly (or slowly) but that us all it is ATM, POTENTIAL...





Dan :cool:

Aiel

I dont mind this so called "boring" weather we're having.It been making for some incredible Sun sets on Galway Bay for the last week at least and also great sunrises in the mornings on my way to work because of the clear sky's.
I do like a bit of snow aswell but you can find good in nearly all types of weather:).

darkman2

Much colder weather will become established by Tuesday with snow showers likely in the East on Wednesday and Thursday. Not likely to be significant snow atm but it is changing alot - keep up to date here. Thursday will see an unstable very cold Easterly flow.