Your daily forecasts from Boards.ie weather forum (NO CHAT)

loup

muckety wrote: »

I had palpitations when I couldn't see this morning's weather forecast... until I found it stickied!! Phew and thanks for the great work mtcranium!

Me three!! MT thanks for your sterling work over the past year, looking forward to more of it over the next year!:D

In_tuition

Really appreciate your insight on a daily basis.

Thank you very much and keep up the fantastic work.

lubie76

Thanks MT. Great to have a (better) alternative to Met Eireann!

YESROH

Another new person here and have been reading your weather forecast since the big freeze and find it the best.

eoinor

Always enjoy the forecast M.T.!! Thanks!

wild handlin

Yeah, I'd also like to add my thanks to M.T. Cranium for the superb daily forcasts posted here.

Many thanks for taking the time to post em here, great reading on what the next few days are likely to bring.

Keep up the great work

gonker

Thank you MT (I love your name btw). Recommend you to loads of people. My favourite post on boards. Keep up the good work, and thank you.

MollyZ

Just want to add my thanks for the great forecasts over the past year MT. This is the first place I look when I want to see what the weather has in store and your work is greatly appreciated. All the very best to you.

M.T. Cranium

Friday, 4 June, 2010
____________________

TODAY, some cloud and light rain will spread across western counties during the morning but may not reach the east coast before breaking apart, allowing some mid-day and afternoon hazy sunshine to warm temperatures up to around 19-21 C.

TONIGHT will be misty and locally foggy with just a slight chance of a shower, and lows of about 6-8 C.

SATURDAY will be partly cloudy with isolated showers developing, rather light winds so that once these showers develop, they may tend to stay confined to one or two locations (more likely to be in the inland south and southeast perhaps). Highs will be around 18-20 C.

SUNDAY will be cloudy with some sunny intervals and somewhat more widespread showers developing, although some places could remain dry. Winds will become moderate SE to E 10-20 mph, and the temperature range will be from lows of 5-7 C to highs of 16-18 C.

MONDAY still looks rather unsettled although some indications now that the rain will be more likely to be persistent in the south than other parts of Ireland. At best, it will be mostly cloudy, and some of the rain may fall in heavy and locally thundery showers. Highs will be about 15-17 C after a morning low of 8-10 C. Winds will be moderate SE backing to NE 10-20 mph.

TUESDAY will remain about the same, rather unsettled with the main part of the rainfall shifting slowly eastward as winds back further NE to N 10-20 mph. Highs will be about 15-17 C.

Later next week, it should gradually clear again and remain rather cool compared to this week.

Here, we enjoyed our first long sunny interval in many days from mid-afternoon to sunset, after a cloudy morning. The high was about 19 C.

With the weekend weather apparently dominated by rather slow-moving weak features, you may want to check the other threads about this weekend's weather as it develops to get the latest weather forum thinking.

redalicat

Congrats, MT! I look forward to your forecasts each day, forwarding them to friends who want a reliable forecast. Your hard work and diligence is much appreciated. Keep up the good work!
--From a fellow North American

SeaFields

Fair play to you MT, takes a lot of commitment to do what you do.

Look forward to another year again. Well done

Great to see this getting the sticky, big thanks for the forecasts and hard work MT

M.T. Cranium

Saturday, 5 June, 2010
______________________

TODAY most places should remain dry and there will be some sunny intervals although more cloud around than the past few days. However, one or two areas of shower activity may develop in a slow-moving north-south trough feature that could produce locally persistent rainfalls in one or two places, these most likely to be in south central counties towards the southeast later, and possibly another area in the northwest. Away from these areas of rain the highs today should reach 20 C again.

TONIGHT a few more showers will develop but these will continue to be somewhat isolated, with other places remaining dry. Lows will be about 8 C.

SUNDAY will probably see more cloud but still some bright intervals and the extent of showers may remain limited until late in the day when rain begins to develop more widely in western counties. Highs will be about 17-18 C.

MONDAY will bring more frequent showers or longer intervals of rain (these more likely in the south) with moderate southeast winds backing to easterly at about 10-20 mph. The temperature range will be narrow, from lows around 8-10 C to highs around 14-16 C.

TUESDAY the rain will continue much of the day and could be rather heavy at times in the central and southeastern counties, as winds continue to back around to the NE at 15-30 mph. Temperatures will be steady in the range of about 11-14 C.

The models have changed more in the period from Wednesday to Friday now, suggesting that this low will come to a halt over southern England and allow unsettled weather to continue for much of the week, but it should at least become more showery with a few brighter intervals developing in a NE to N flow. Temperatures later in the week appear likely to stay just a bit below average by day although nights will continue mild. I'm thinking that the longer this disturbed spell lasts, the longer the next settled warm and dry spell is likely to be, so there is that compensation.

Today (being Friday the 4th) here was yet another rather cloudy day with just slight amounts of rain early and again this evening, nothing more than 1 or 2 mms, but highs were held down to about 16 C by this cloud. The long spell of very warm weather in the northeast U.S. seems likely to end with a bang over the weekend as severe storms develop along a strong cold front later today in Ohio, reaching the northeast coastal cities on Sunday.

M.T. Cranium

Sunday, 6 June, 2010
________________________

TODAY, periods of rain have developed in central Ireland and although this may begin to lose intensity after mid-morning the rain will continue to move slowly east into the Dublin region for late morning and mid-day. Amounts are likely to be 5-10 mms with this area of rain. Further west there will be intervals of cloud and sunshine for the first two-thirds of the day and areas of showery rain moving in from the Atlantic by late afternoon. Winds will generally be rather light throughout, a brief period of northerly winds will accompany the rain in the east (8-12 mph). Highs today will be 16-18 C.

TONIGHT the western counties will see further rain and any clear intervals in eastern Ireland should be followed by mostly cloudy skies before dawn. Lows will be 6-8 C.

MONDAY will see periods of rain developing again from west to east and these may be rather heavy in southern to south-central inland counties. The rain may not quite reach northern parts of Ulster, and some sunny breaks could persist there. Highs will be 14-16 C in most places and winds will pick up to ESE 10-25 mph.

TUESDAY will be cloudy with further rainfalls, the two-day total will be about 20-30 mms for some, and temperatures will be steady in the 11-14 C range with winds ENE 15-30 mph.

WEDNESDAY will brighten as rain tapers to isolated showers, and winds will be rather brisk NE 20-35 mph, with highs around 16 C.

THURSDAY, there could be a renewed interval of rain in the southeast as the slow-moving low redevelops over southern England. Otherwise most places will remain in the partly cloudy, showery northeast flow but with rather gusty winds 20-40 mph.

FRIDAY and SATURDAY should see this pattern very slowly relaxing with lighter northeast winds and possibly some longer sunny intervals but there will still be some cloud and showers around. Highs will be 17-19 C.

By the following week, a fairly warm and dry pattern is expected to return.

Meanwhile, where I live, the day (Sat 5th) was sunny and about 17 C with a strong NW breeze keeping it rather cool in exposed areas, but out of the wind it felt quite warm. Heavy storms have developed in the lower Great Lakes region and are moving towards NYC and Boston for Sunday.

mrsdewinter

Hi MT,
Just wanted to add my own congratulations to the list. Only got into your forecasts during the big freeze in the New Year but I'm hooked on them now. Many many thanks - and keep it up!

lucernarian

This terrible morning here has taken me completely by suprise. Were there many indications that there would be persistent rainfall still hanging over the country this morning? Windspeed is so low also, which I always felt was a particularly strong indicator of a stable atmosphere.

If anyone wants to shed light on this pesky front which is even now being understated by most models, please do!:D

Redsunset

Had periods of downpour around 6 this morning,and yesterday evening GFS had it fairly right.




And come midday louth holding on to the heavy precip.





Congrats on the win in football yesterday.good scoring

lucernarian

I didn't actually check the GFS model, only UKMO and Met Éireann forecasts. And the NAE model. That's one up for GFS so! I still can't identify what feature is causing this rainfall but I assume there is a trough of some sort, as M.T. Cranium outlined.

redsunset wrote:

Congrats on the win in football yesterday.good scoring

Thanks, I've been waiting quite a while to see a good performance sustained for the whole 70 minutes. Louth were an utterly different outfit to the one which scraped past Longford. It's only a LFC quarter final though so they shouldn't revel in this victory too much.

Su Campu

To_be_confirmed wrote: »

I didn't actually check the GFS model, only UKMO and Met Éireann forecasts. And the NAE model. That's one up for GFS so! I still can't identify what feature is causing this rainfall but I assume there is a trough of some sort, as M.T. Cranium outlined.

The NAE and HIRLAM had this feature nailed too. Here's yesterday's NAE 12Z run for this morning.



It's linked to strong positive vorticity advection (PVA) ahead of a deep upper trough (see 300hPa below). Divergence above means lift from below, and it's this lift that has caused the precipitation.

Here is the ECMWF output for 06Z, showing the 300hPa trough and associated divergence.

owenc

Su Campu wrote: »

The NAE and HIRLAM had this feature nailed too. Here's yesterday's NAE 12Z run for this morning.



It's linked to strong positive vorticity advection (PVA) ahead of a deep upper trough (see 300hPa below). Divergence above means lift from below, and it's this lift that has caused the precipitation.

Here is the ECMWF output for 06Z, showing the 300hPa trough and associated divergence.

Well, it was wrong for here because i never had any rain and i havn't had any since april.

lucernarian

The NAE 18z didn't appear to have those features in any significance, which is what my comments were based upon. It did show heavier rainfall by 1pm, but off the wexford coast. GFS had called the timing and location much more accurately from what I saw on the radar when I reviewed it after redsunset's post. I do think it was being predicted in charts, but I didn't hear much from forecasters themselves about it. I was under the impression that some overnight showers might pay a visit during the night. Shows how much I know:p

I did check surface level pressure which indicated a col over Ireland. I didn't see the upper level charts.

And this is where my confusion lies. There didn't seem to be any symbols for an upper level trough on FAX charts either.

Aside from the GFS convection index charts and CAPE charts, how does one forecast for those sort of troughs? Basically I'm not fully grasping the mechanics of how this sort of trough materialises.

Su Campu

To_be_confirmed wrote: »

The NAE 18z didn't appear to have those features in any significance, which is what my comments were based upon. It did show heavier rainfall by 1pm, but off the wexford coast. GFS had called the timing and location much more accurately from what I saw on the radar when I reviewed it after redsunset's post. I do think it was being predicted in charts, but I didn't hear much from forecasters themselves about it. I was under the impression that some overnight showers might pay a visit during the night. Shows how much I know:p

I did check surface level pressure which indicated a col over Ireland. I didn't see the upper level charts.

And this is where my confusion lies. There didn't seem to be any symbols for an upper level trough on FAX charts either.

Aside from the GFS convection index charts and CAPE charts, how does one forecast for those sort of troughs? Basically I'm not fully grasping the mechanics of how this sort of trough materialises.

You may be slightly confusing surface and upper troughs. Any trough is an elongated minimum in either pressure or geopotential height. Surface troughs are minimima of surface pressure, and are depicted on a surface chart as they can contain bands of showers, and so are important features.

An upper trough is an elongated minimum in geopotential height, as in the chart above. You can see it running NW-SE from Galway, southeast through Cork and through Biscay. The jetstream will follow the height lines, therefore will run from the northwest on the west flank, and to the northeast on the east flank. As it is curving around the base of the trough, this generates vorticity in the atmopshere, which causes upward movement of the air from below.

Check this and this out for a proper explanation.

beco

Can anyone see whats in the charts for tomorrow at 3pm onwards in dublin for the women's mini marathon?
Thanks

pauldry

Dont have the charts to hand at the moment but it looks like a complete washout tomorrow in the South and East

10 to 20mm of rain possible:(

lucernarian

@Su Campu

That's not quite what I was getting at. I'm quite familiar with what a trough is in the first instance. I know of upper troughs but not as well as a typical surface trough. What I'm wondering is why there was not some sort of surface trough associated with the upper trough feature. Also, it took me a while to figure out exactly what the chart you referred to was which didn't help matters. The chart shows the height of the jet stream at 300hPa in dm, I assume.

So I'm not so confused now as I was earlier. I now wonder what caused the upper trough to be separated from any surface trough/shallow low in the first place. Is this a more regular occurrence than I am giving credit for?

Su Campu

To_be_confirmed wrote: »

@Su Campu

That's not quite what I was getting at. I'm quite familiar with what a trough is in the first instance. I know of upper troughs but not as well as a typical surface trough. What I'm wondering is why there was not some sort of surface trough associated with the upper trough feature.

But there was a surface trough associated with it - that's what gave all the rain!! (marked as an occlusion on today's FAX). In general, surface troughs are supported by upper features - without support from above, the surface activity cannot be sustained. So when you see a surface trough on a chart, you can be fairly sure there's something driving it from the upper atmosphere through the factors explained before.

Also, it took me a while to figure out exactly what the chart you referred to was which didn't help matters. The chart shows the height of the jet stream at 300hPa in dm, I assume.

The chart show the height of the 300hPa pressure level (blue lines, in dm), plus advection of positive vorticity (yellow area). It doesn't actually show the jet, but its path will follow the isolines.

So I'm not so confused now as I was earlier. I now wonder what caused the upper trough to be separated from any surface trough/shallow low in the first place. Is this a more regular occurrence than I am giving credit for?

Upper dynamics are responsible for most surface systems, be they lows or highs. In our latitudes, many atlantic depressions form under areas of upper divergence, and anticyclones form under upper convergence. Better explanation here

Deep Easterly

Su Campu wrote: »

But there was a surface trough associated with it - that's what gave all the rain!!

What would be the typical weather type for an unsupported surface trough? When I lived by the coast in Salthill I did notice we would occasionally get sudden increases in wind for short periods, (day or night, and often than not within a cloudy warm sector), these were often accompained by a small, barely detectable drop in pressure for a short period without any notable change in weather. Would this be an example of a surface trough without upper support?

Su Campu

Deep Easterly wrote: »

What would be the typical weather type for an unsupported surface trough? When I lived by the coast in Salthill I did notice we would occasionally get sudden increases in wind for short periods, (day or night, and often than not within a cloudy warm sector), these were often accompained by a small, barely detectable drop in pressure for a short period without any notable change in weather. Would this be an example of a surface trough without upper support?

It could be anything. Such mesoscale features could be a due to many things, seabreezes, terrain, etc. so it's difficult to say without knowing the exact setup on the day. A drop in pressure and rise in windspeed usually means a seabreeze circulation, which acts independently of upper features (being only around 6000ft deep). Downslope flow from the mountains to the north could be another factor.

I think maybe we're hijacking MT's thread a bit, should we start a new one?

Deep Easterly

Su Campu wrote: »

It could be anything. Such mesoscale features could be a due to many things, seabreezes, terrain, etc. so it's difficult to say without knowing the exact setup on the day. A drop in pressure and rise in windspeed usually means a seabreeze circulation, which acts independently of upper features (being only around 6000ft deep). Downslope flow from the mountains to the north could be another factor.

I think maybe we're hijacking MT's thread a bit, should we start a new one?

Yep, I did suspect sea breezes but these little wind bursts could happen at any time and often under cloudy conditions, and usually from a SW or W direction.

Your right, thread is being spoiled. New thread that deals with niggly little questions like "what is the difference between an upper and surface low" sounds like a good idea. Go for it!

lucernarian

It seems I'm not clarifying what it is I don't understand. I'll leave it at that, as posting in this or a new thread won't change any misunderstandings. Suffices to say, a quick google could have told me the differences in an upper or lower trough. I was asking a very specific question about this morning's rain, that was all.