Wintry spell forecasting discussion - 25/11/2010 onwards

rilz

I am as low at sea level as you can get here on east coast so will let u know when the precip starts fallin wether it be rain-sleet or snow:o

nacho libre

Pangea wrote: »

Is there any possability that is snow by any chance?

don't think so. you'll have to wait till the showers move in after this front clears southwards.
yr.no has me down for rain this evening and snow tomorrow evening

Rougies

Rougies wrote: »

If you look at the chart snowstreams posted above you can see the wind would've been blowing over the cooler SSTs nearer the coast. That would've helped.

Thats a very tiny area though.
I'm positing that those showers driving down the irish sea this morning and now were entirely snow out at sea and if driven onto the coast if we were in an east flow would be snow too regardless of height or coastal location.

I was of Su campu's opinion and posted as such on the older thread that the sst's should be melting the snow to sleety rain on the coast but this morning cast doubt over that concern to me.

Dp seems to be over ruling sst

carlmwan

This is what my ipod is telling me it was reliable last year so lets see about this year


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WolfeIRE

Looking ahead to next week if I may, conscious that there are other people on here who may not see any snow at the weekend.

There is potential for a countrywide significant snow event on late Tuesday and Wednesday. A low pressure system will form in the mid Atlantic and track along the Portuguese coast before deepening over the Bay of Biscay. It will track northwards over western France before veering NE towards southern England and Ireland. Models show the system retreating eastwards as a blocking high over Iceland tracks south-eastwards somewhat and another low pressure system in the Atlantic deepens and moves eastwards.

Some very small alterations to the above set-up could bring some significant snowfall to Ireland. At present, much of southern England and the East and south East of Ireland will see some snow from this system. The following would result in the system tracking closer to or over Ireland: the blocking high over Iceland holding or retreating NE somewhat towards Greenland OR the blocking high over Scandinavia shifting eastwards.

TheMilkyPirate

At what times does the GFS roll out everyday i know its four times a day but what are times?

thanks.

WolfeIRE

baraca wrote: »

At what times does the GFS roll out everyday i know its four times a day but what are times?

thanks.

3.30pm, 9.30pm, 3.30am and 9.30am baraca

here
http://www.netweather.tv/index.cgi?action=nwdc;sess=

delw

carlmwan wrote: »

This is what my ipod is telling me it was reliable last year so lets see about this year


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its also telling you to charge it

Rougies

baraca wrote: »

At what times does the GFS roll out everyday i know its four times a day but what are times?

thanks.

3hr 30mins after each run starts.

eg. 12z will start rolling out at 15:30

pistolpetes11

I now these are useless but :

WolfeIRE

WolfeIRE wrote: »

Some very small alterations to the above set-up could bring some significant snowfall to Ireland. At present, much of southern England and the East and south East of Ireland will see some snow from this system. The following would result in the system tracking closer to or over Ireland: the blocking high over Iceland holding or retreating NE somewhat towards Greenland OR the blocking high over Scandinavia shifting eastwards.

The gfs is/was as you know the main driver of that scenario.
I don't see it coming close to Ireland or being as deep as the gfs suggests though based on a blend of the ukmo and ecm.
I also see it only bringing hill snow because of it's warm sector even if it heads north.

I'd take several pinches of salt on anything the models are showing beyond Saturday though as there are too many variables that can make big impacts on the specific's.
I notice though that the BBC met office forecasters [including Rob] are all not being specific when asked how long this goes on for.
The chap at lunchtime was asked about Xmas and he said he had his ski's at the ready... now that will give you a feel for what the people whose job it is to do forecasts are thinking.

Regarding saturday onwards aswell,there are likely to be areas in the East too who get little or no snow because they miss the streamers.
It's all in luck.

davehey79

sorry to go off topic but pistolpetes11 what app you using there

Trogdor

Deleted User wrote: »

Thats a very tiny area though.
I'm positing that those showers driving down the irish sea this morning and now were entirely snow out at sea and if driven onto the coast if we were in an east flow would be snow too regardless of height or coastal location.

I was of Su campu's opinion and posted as such on the older thread that the sst's should be melting the snow to sleety rain on the coast but this morning cast doubt over that concern to me.

Dp seems to be over ruling sst

Can confirm that the showers off the coast here this morning were of snow too, they never quite clipped the coast here but they came very close and you could see the bands of white precip falling out to sea.

WolfeIRE

back to tonight. don't be surprised to see 'snow' reported at ballyhaise and knock overnight. i reckon the sweep of midler air associated with this frontal system may only skirt western fringes

TheMilkyPirate

WolfeIRE wrote: »

3.30pm, 9.30pm, 3.30am and 9.30am baraca

here
http://www.netweather.tv/index.cgi?action=nwdc;sess=

Thankin you

pistolpetes11

davehey79 wrote: »

sorry to go off topic but pistolpetes11 what app you using there

Fizz weather

maquiladora

12Z NAE is going for all rain rather than snow overnight

bryaner

Gone pretty dull and grey in Navan..

nacho libre

Deleted User wrote: »

The gfs is/was as you know the main driver of that scenario.
I don't see it coming close to Ireland or being as deep as the gfs suggests though based on a blend of the ukmo and ecm.
I also see it only bringing hill snow because of it's warm sector even if it heads north.


.

yes the gfs tends to overcook lows in a blocking scenario. the ecmwf tends to be far more relibale in handling what is likely to happen in a blocking scenario. it's best to be skeptical of what the gfs shows in fi, as it can swing from full-on ramp mode in one output to the atlantic taking over in the next run.

pistolpetes11

What does the yellow stand for ? 50/50 chance ?

arctictree

maquiladora wrote: »

18Z NAE is going for all rain rather than snow overnight

That chart doesn't really make sense. Snow in the Irish sea and rain inland?

Defcol

bryaner wrote: »

Gone pretty dull and grey in Navan..

Theres a band of something, most likely rain, headed your way..

http://www.raintoday.co.uk/

Speak Now

pistolpetes11 wrote: »

What does the yellow stand for ? 50/50 chance ?

About 60/40 yeah but isn't that for 400m

maquiladora

arctictree wrote: »

That chart doesn't really make sense. Snow in the Irish sea and rain inland?

850 temps are a little cooler over the Irish Sea than over most of Ireland at that time. I guess that is what may be driving that distinction?

ninebeanrows

48 hours away, we would of chopped somebodies arm off for this before last winter, epic set up.

maquiladora

12Z GFS has a bit more precip around in the early hours of Saturday morning.

Corrected : 12Z not 18Z

arctictree

arctictree wrote: »

That chart doesn't really make sense. Snow in the Irish sea and rain inland?

Yup it's complete nonsense.
It's not the 18z either,that hasn't been run yet.

The bbc graphics are I think largely the latest nae + forecaster input that we don't see.
These even have rain over the wicklow mtns which I can tell you has to be wrong.
The bbc forecasters on news 24 [all ukmo paid and trained forecasters] are all saying though they have the graphic as rain,it could be snow , they just don't know.
I'm thinking not much precip out of it this side of the mtns but you should see some snow out of it if some precip survives.

Rougies

maquiladora wrote: »

850 temps are a little cooler over the Irish Sea than over most of Ireland at that time. I guess that is what may be driving that distinction?

Are those actual NAE precip type charts or weatheronline's own interpretation, like Netweather do with the GFS (which are useless)?

maquiladora

Deleted User wrote: »

Yup it's complete nonsense.
It's not the 18z either,that hasn't been run yet.

12Z. Typo on my part. I'll correct it now. :rolleyes:

Winger_PL

pistolpetes11 wrote: »

What time do the site update fully at with the 18Z, do they take a while to roll out from 3.30 ?

The GFS charts roll out 3.5 hours later, so 12Z are the most recent ones at this moment (as they rolled out just now, in fact probably still rolling). 18Z charts will not roll out before 21:35.