Prolonged cold spell on the way

Su Campu

JanuarySnowstor wrote: »

Please guys C'mon what lies ahead is a bit better than 'start to get colder'
I back weathercheck on this, looks plenty cold enough for snow.
Dew points SU ??????

Yes, plenty cold enough for snow at high levels, as I said this morning, but for the vast majority of the popluation that lives below a couple of hundred metres, there should be nothing more than sleet I'd say.

It's looking like any precipitation this week will be in the form of lake-effect showers, which will affect coastal areas of the northeast, east, and north Mayo. These will quickly die out as they move inland due to lack of instability. Remember we'll be under the influence of a large high to our northwest, so that will be trying to warm upper levels, and put cap on convection. The models hint that a low will push in from our east, which would enhance activity, but I think the stinker will be the sea surface temperatures. I don't trust the GFS dewpoints, which are being forecast down to almost minus double figures, and 850 Theta-W down to 1 or 2°C. That would give snow, yes, were it to happen - I just don't think it will.

I certainly think we'll see white tops on the mountains, but there'll be no snow lying at low levels.

ninebeanrows

Su Campu wrote: »

Yes, plenty cold enough for snow at high levels, as I said this morning, but for the vast majority of the popluation that lives below a couple of hundred metres, there should be nothing more than sleet I'd say.

It's looking like any precipitation this week will be in the form of lake-effect showers, which will affect coastal areas of the northeast, east, and north Mayo. These will quickly die out as they move inland due to lack of instability. Remember we'll be under the influence of a large high to our northwest, so that will be trying to warm upper levels, and put cap on convection. The models hint that a low will push in from our east, which would enhance activity, but I think the stinker will be the sea surface temperatures. I don't trust the GFS dewpoints, which are being forecast down to almost minus double figures, and 850 Theta-W down to 1 or 2°C. That would give snow, yes, were it to happen - I just don't think it will.

I certainly think we'll see white tops on the mountains, but there'll be no snow lying at low levels.

Very strong statement.

I disagree, think snow should fall to low levels from Friday and into the weekend.

This is of course if the current charts are correct.

And not the ECM, ECM delays the cold but offers good long term potential. An Outlier i would suggest, over-egging the shortwave over N Norway.

darkman2

Su Campu wrote: »

but I think the stinker will be the sea surface temperatures..

They will drop very quickly though with the airmass off the continent - first over the North sea, then the Irish sea. Once the SST goes below 5C in the Irish sea and land temperatures during the day are hovering close to freezing then there won't be enough modification to prevent coastal snow. Does not matter what time of year it is this is an exceptionally cold airmass coming.

maquiladora

Su Campu wrote: »

I certainly think we'll see white tops on the mountains, but there'll be no snow lying at low levels.

A brave call Su! Just to get it in the right context, does your feeling that there will be no snow lying at low levels extend for however long the cold spell lasts or up to some particular point in time such as next Sunday for example?

Looks like we have a good old weather debate about this upcoming spell here now.

I think it's too early to call one way or the other yet myself.

maquiladora

darkman2 wrote: »

They will drop very quickly though with the airmass off the continent - first over the North sea, then the Irish sea. Once the SST goes below 5C in the Irish sea and land temperatures during the day are hovering close to freezing then there won't be enough modification to prevent coastal snow. Does not matter what time of year it is this is an exceptionally cold airmass coming.

What are the SSTs for the Irish Sea at the moment, around 12 or 13? Can they really drop to below 5 that quickly?

darkman2

maquiladora wrote: »

What are the SSTs for the Irish Sea at the moment, around 12 or 13? Can they really drop to below 5 that quickly?

Yes. It takes longer then land temperatures (and even longer if there is a strong wind) but depending on the depth of cold and the source they can drop quickly enough and not too far behind the land temps - a continental flow which has a cold source is the best option for this rather then a sea based one.


GFS is a case is point when you have the right conditions progged.

BEASTERLY

maquiladora wrote: »

What are the SSTs for the Irish Sea at the moment, around 12 or 13? Can they really drop to below 5 that quickly?

Yep, bouy m2 is recording a sea temp if 13 degrees atm. I think they were around 6 during last years cold spell.

Well, snow settled without any problems at low levels here in wexford in late november 2005, so whats different this year were the synoptics are alot better?

Su Campu

darkman2 wrote: »

They will drop very quickly though with the airmass off the continent - first over the North sea, then the Irish sea. Once the SST goes below 5C in the Irish sea and land temperatures during the day are hovering close to freezing then there won't be enough modification to prevent coastal snow. Does not matter what time of year it is this is an exceptionally cold airmass coming.

Exactly what sort of drop are you expecting in the space of a few days? The Irish Sea's 11-12°C now, you're expecting it to cool by around 1 degree per day? That will not happen darkman, the sea is water, not acetone.



Maq, I've been talking about up to the end of this week. Obviously the longer it continues the easier snow becomes, but it will take a long spell for the seas to cool enough for the January-like conditions that people are throwing around.....

maquiladora

BEASTERLY wrote: »

Well, snow settled without any problems at low levels here in wexford in late november 2005, so whats different this year were the synoptics are alot better?

25th Nov 2005?

This is the archive chart for that day. -8 upper temps extending down over much of the country for a few hours in a northerly flow :



And this is the Met Eireann warning for that period :

Issued at 23 November 2005 - 13:00Severe Weather Warning for Snow

Frequent snow showers are likely to give accumulations of between 3 and 8 cm below 250 metres during the period 1200 hours Thursday to 2400 hours Friday in counties Donegal, Mayo, Sligo, Leitrim and parts of Cavan. Strong to gale force Northerly winds will occur during the same period, giving blizzard conditions at times and causing some drifting.

Su Campu

BEASTERLY wrote: »

Yep, bouy m2 is recording a sea temp if 13 degrees atm. I think they were around 6 during last years cold spell.

Well, snow settled without any problems at low levels here in wexford in late november 2005, so whats different this year were the synoptics are alot better?

How low is low?

ninebeanrows

I think the M2 buoy will be looked at with great interest at the end of next week.

What we look for from the M2 buoy is a DP below 0c, preferably around -1/2c with a temp of no more than 4/5c.

BEASTERLY

Su Campu wrote: »

How low is low?

There was a picture on the front of the independant i think of decent snow cover in kilmuckridge, it's at about 45m asl and around 2.5km from the coast. So a proper low lying coastal location.

But i didn't realise the synoptics were as good as they actually were, thanks for the chart maq and SSTs could well have been lower.

darkman2

Su Campu wrote: »

Exactly what sort of drop are you expecting in the space of a few days? The Irish Sea's 11-12°C now, you're expecting it to cool by around 1 degree per day? That will not happen.

Wanna bet? I will happily go for a 6 or 7C drop in SST's in the Irish Sea based on current projections. Obviously if something radically changes synoptically then it does not apply.

ninebeanrows

darkman2 wrote: »

Wanna bet?

Darkman, don't confuse the SST with the air temperature at the Buoy.

There is no way the SST will fall from 11c to 5c in 10 days.

The Buoy Temp could definitely fall from 11c to 5c though.

Su Campu

darkman2 wrote: »

Wanna bet?

You're on. The Irish Sea will not cool by a whole 6°C by next Friday! I say 1, maybe 1.5 at most.

darkman2

Im gonna stick that in my sig....you can put my prediction in your sig.

Su Campu

darkman2 wrote: »

Wanna bet? I will happily go for a 6 or 7C drop in SST's in the Irish Sea based on current projections. Obviously if something radically changes synoptically then it does not apply.

You are referring to water temperatures, aren't you?? You are trying to defy the laws of the Universe of you say the temperature of the water will fall by 6 or 7°C in less than a week!!! It won't happen, so pay up now!!

Of course I see the little disclaimer you put in at the end there. I though you said you were 100% confident???

gally74

all in all im delighted, i love cold "continenatal" type weather, fresh in the morning and dries everything up, not too concerned if we get snow or not, but nice n dry with frost is jsut lovely,

mayve with the imf the weather will be more "continental" like,

darkman2

Su Campu wrote: »

You are Referring to water temperatures, arent you? You Are Trying to defy The Laws of the Universe of You Say the temperature of the Water Will Fall by 6 or 7 ° C in Less than a week! It Will not Happen, so pay up now! : D

Of course I see the little disclaimer you put in at The End There. I though You Said You Were 100% confidant ???[/ QUOTE]

I am.


If the M2 buoy shows a 6C + drop I win.: Pac:

Su Campu

darkman2 wrote: »

Su Campu wrote: »

You are Referring to water temperatures, arent you? You Are Trying to defy The Laws of the Universe of You Say the temperature of the Water Will Fall by 6 or 7 ° C in Less than a week! It Will not Happen, so pay up now! : D

Of course I see the little disclaimer you put in at The End There. I though You Said You Were 100% confidant ???[/ QUOTE]

I am.


If the M2 buoy shows a 6C + drop I win.: Pac:

So you say the M2 will register a sea water temperature of at most 6.9°C by next Friday (it currently at 12.9°C)? You're barking mad!

For your info, the specific heat capacity of water is 4180J/kg/K......you want one last chance to redo your calculations??!!!!

maquiladora

Maybe darkman means the 2m temperature over the Irish Sea rather than the sea water temperature?

*puts on his blue UN helmet*

Anyway...18Z GFS incoming...

Su Campu

maquiladora wrote: »

Maybe darkman means the 2m temperature over the Irish Sea rather than the sea water temperature?

*puts on his blue UN helmet*

That's what I'm trying to ask him. I think he must, even though I've mentioned water temperature several times!

DOCARCH

Have to agree with Su on this one - no way SSTs could drop that much in one week - would defy the laws of physics! As Su says, maybe 1c or 2c at very most.

M.T. Cranium

Yee-haw. That's all I have to add.

I think most of the regulars here have entered, but if you're getting excited about winter, there's a winter forecast contest on the forum. Entries can be submitted to end of Sunday.

He clearly meant 2m temps.
I've no doubt,they will eventually drop below 5c fairly quickly if the current predicted set up is sustained.
If sustained,I'd expect that on sunday rather than friday as the cold digs in deeper.

The most crucial thing is dewpoint and Scandi and ne of scandi is a great source of negative dp air.
If dp is sub zero next weekend,then there will be sea level snow as the dryer rh's won't dry out the air suffecient to stop the showers with super chilled -8 and below 850's.

Su Campu

Deleted User wrote: »

He clearly meant 2m temps.
I've no doubt,they will eventually drop below 5c fairly quickly if the current predicted set up is sustained.
If sustained,I'd expect that on sunday rather than friday as the cold digs in deeper.

It won't happen by Sunday either. You'd need a few more weeks for that to happen. I stand to be corrected, but I don't remember water temperatures ever being recorded below 5°C in the Irish sea, even in January-March??

EDIT: Actually, I think you too were referring to air temperatures when you said below 5??? Sorry!

WolfeIRE

A word of caution for anyone reading this thread hoping to get some 'snow days' next week.

expect chilly but bright days next week if you live away from east and north facing coasts. Frost will be most severe in the west and south west with freezing fog lingering in some places here throughout the day.

Widespread snow will not be a feature of the weather next week but high ground in eastern and northern coastal counties, along with inland Ulster, will see some snow.

Widespread snow will only become a reality when the easterly/northeasterly flow becomes a little more unstable and/or the atlantic decides to get in on the act. That will only happen when the high currently over Iceland retreats towards and over Greenland. Should this happen, and the models indicate it will, we will see some more widespread showery activity next weekend and into the following week.

The retreat of that high north over greenland, however, also will bring the atlantic back into the setup. This isn't necessarily a bad thing however as by the time it comes knocking on the Valentia Island Lighthouse door, cold air will have been in place over us for more than 10 days.

Therefore, this system will bring snow at first should it track NE over ireland and depending on how intense the blocking system is to our NE and NW could be forced to track back SE or S. Either way I am confident that there will be a widespread snow event resulting from the upcoming cold spell.

This event may signal the end of the upcoming cold spell but may also herald the next phase of an even longer cold spell of weather.

Just by twopence worth...

darkman2

Im talking about the air above the water - not the water itself. I always use sea surface temperatures when talking about the air above. A habit im afraid.


In fact warm water at foundation level is often more of a help then a hindrence. The differential in temperature of the airmass and that of the water produces more instability.

Su Campu

darkman2 wrote: »

Im talking about the air above the water - not the water itself. I always use sea surface temperatures when talking about the air above. A habit im afraid.


In fact warm water at foundation level is often more of a help then a hindrence. The differential in temperature of the airmass and that of the water produces more instability.

You should drop that habit then! SST always means water temperature. Air temperature means air temperature! :pac:

Maybe drop the signature too as it's null and void!

isle of man

you know i have been reading on here since the last year,

and norm i come on read all your great posts and 99% of the time your all spot on, does not matter what weather it is you all tend to get it right.
And norm you all agree on what it will be.

Now this is a confusing time as 1 or 2 of you that i follow and trust in your wise words of wisdom are not agreeing.

ooooo i just dont know who to think is right.

so i shall be over here

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sitting on the fence:D