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

Storm 10

Thanks MT for the reply to my query, you are correct with the Easterly wind as I recall most big thunderstorms we have had moved from East to West. Also when a storm in the winter like now goes through I notice a lot of blue lightning as the end of the storm passes, very little thunder, does that make sense to you????

M.T. Cranium

Not sure what you mean by blue lightning, can you describe?

Meanwhile the latest storm watch adjustment is towards the wait and see position, as the 18z GFS chops up the weekend storm into several meaty bits and pieces. Not really convinced any model has a handle on this situation yet.

Deep Easterly

M.T. Cranium wrote: »

Not sure what you mean by blue lightning, can you describe?

Meanwhile the latest storm watch adjustment is towards the wait and see position, as the 18z GFS chops up the weekend storm into several meaty bits and pieces. Not really convinced any model has a handle on this situation yet.

Blue lightning I witness quite regularly here in the west in winter, particularly during unstable polar maritime airflows behind an active cold front. Red lightning to, which seems to be more a January thing.

I read somewhere before that blue lightning is usually the result of wind and hail but that sounds a bit daft.

Over to those in the know....

maquiladora

Storm 10 wrote: »

Thanks MT for the reply to my query, you are correct with the Easterly wind as I recall most big thunderstorms we have had moved from East to West. Also when a storm in the winter like now goes through I notice a lot of blue lightning as the end of the storm passes, very little thunder, does that make sense to you????

Something like a blue jet?

Storm 10

Deep Easterly wrote: »

Blue lightning I witness quite regularly here in the west in winter, particularly during unstable polar maritime airflows behind an active cold front. Red lightning to, which seems to be more a January thing.

I read somewhere before that blue lightning is usually the result of wind and hail but that sounds a bit daft.

Over to those in the know....

Thanks Deep Easterly I notice this blue lightning especially in winter and always seems to be at the end of the storm or when we get hail with squally winds and its always sheet lightning not always followed by thunder.

Thanks maquiladora for the very detailed chart for the lightning

Deep Easterly

Storm 10 wrote: »

Thanks Deep Easterly I notice this blue lightning especially in winter and always seems to be at the end of the storm or when we get hail with squally winds and its always sheet lightning not always followed by thunder.

Thanks maquiladora for the very detailed chart for the lightning

Very same S10. Blue lightning always seems to accompany gale to storm force winds when the main front has passed over, often with no thunder. I often thought that friction against wind and ground/sea some times caused this phenomena, giving of a "static" blast. Probably a stupid theory though.

darkman2

Storm 10 wrote: »

Thanks MT for the reply to my query, you are correct with the Easterly wind as I recall most big thunderstorms we have had moved from East to West. Also when a storm in the winter like now goes through I notice a lot of blue lightning as the end of the storm passes, very little thunder, does that make sense to you????

I experienced the most severe lightning storm here in the East in 1999 but there was no thunder at all. It was just constant overhead flashes. I found the experience completely bizarre. But in fact these are very high intra cloud strikes that happen very frequently in Summer temperatures. The strikes are so high that no thunder is recorded to the ear. Sound travels slower then light but no sound could be heard. Basically the lightning, whilst spectacular when happening - it is at a height that thunder won't be heard at ground level. You can hear a distant rumble - yes. But no constant rumble. And certainly, despite the light show, not very loud.

M.T. Cranium

Interesting stuff -- considering that I have probably seen many more thunderstorms (living for 40 years in the Great Lakes region) than most here, I must admit that I have never seen an unusual coloration of lightning. Sometimes the sky optical effects are different, but I'm sure you're describing some real differences in the colour of the actual lightning.

One type of lightning that may explain some of the phenomena you all describe would be what I know as "sheet lightning" -- this is an illumination of some higher level of cloud from distant lightning which would explain the lack of thunder. I've seen that kind of lightning on many summer nights in Ontario, and it can be from storms 50-100 miles distant.

I've also seen continuous lightning from a tornadic storm at 0300 hours local time, and I hope never to see that again because the storm that broke out was somewhere between awe-inspiring and fearsome. We narrowly missed a direct hit from an F-2 tornado in that storm (it's part of a documented event, the July 14-15 overnight "derecho" in the Great Lakes region). As it turned out, we were living right under the track of its most intense cell.

Sometimes lightning in hot, dry weather on the west coast here has an orange tint but I have always associated that with dust suspended in the air in almost-dry or dry thunderstorm cells.

Well enough about that for now, it's on to the forecast ...

Tuesday, 17 November, 2009
____________________________

TODAY will be rather unsettled in western counties, but will start dry in many parts of the east with some morning sunny intervals. As the day progresses, some heavier showers will develop in western and central counties, and some sleet or snow could fall on peaks in Connacht, with hail possible at lower elevations. Rainfalls of 10-15 mms may occur in places but the east will only see about 3-5 mms later on this afternoon. Highs will average about 10-11 C.

TONIGHT will have some clear intervals but strong southerly winds will develop around midnight and spread cloud and then rain into southern and western counties. Lows may occur before or around midnight (3-6 C) then temperatures could rise to near 10 C by sunrise.

WEDNESDAY will be moderately windy and quite mild with intervals of rain or drizzle, hill fog or mist, and winds SSW 30-50 mph, with highs near 14 C. Rainfalls of about 20-25 mms will be fairly widespread by Wednesday night.

THURSDAY will be very windy at times (S 45-70 mph) with some occasional rain or drizzle at times but a risk of heavier showers developing, and further rainfalls of 10-25 mms. Some places are bound to see resumed flooding from all this rain. The lows near 12 C and highs near 17 C may set some records too.

FRIDAY will see the very strong winds abating somewhat during the early morning as they veer more to the SW or even W (20-40 mph) with some clear intervals but also more light rain or drizzle redeveloping at times. The day will bring variable skies and some additional showery rain with winds backing slowly to the south again, and highs near 15 C.

(There is certainly a risk of an unseasonable "second spring blooming" episode for some plants in all of this warm, muggy weather).

THE WEEKEND is not set in stone by any means, as various models struggle with the details, but it certainly looks windy at times. One scenario would be a strong low rushing through the southeast and Irish Sea on Saturday morning, to be followed by a second strong low further north on Sunday. That would create a scenario of rain followed by gusty winds and showers for most of the weekend. Another plausible scenario remains the one major windstorm for part or all of Ireland. I am inclined towards the first of the two choices but I'm far from certain about it.

What does seem apparent is that considerably colder air will try to join in the circulation by late Sunday or Monday, but will be quickly absorbed into the relentless SW flow, so any briefly colder weather would be short-lived.

Around where I live, we are dealing with a rainstorm now after the earlier strong winds, but it's still quite gusty and very mild (14 C) at 10:50 p.m., and a strong front is approaching -- I may be reporting some more storm force gusts around noon your time and 0400 here as this pushes through the west coast (currently it is 300 miles west of here but winds are slowly increasing from the SSE ahead of the front).

It continues very mild to warm in eastern parts of Canada and the USA, highs of near 75 F have been recorded in places around Washington DC and south, and close to 70 F in NYC, more like 60 in Boston.

If you recall the brief career of "Ida" the remnants of that were absorbed yesterday into the low that is approaching the central Atlantic now, so in a roundabout sort of way, the strong winds you'll see on Thursday will be associated with remnants of Ida.

M.T. Cranium

I've posted some weather pictures recently, the links for which are up at the top of this weather forum page.

Meanwhile, this is where we really like to visit when we get the chance, the heavy snow is pretty much guaranteed here in the mountains of eastern British Columbia (this is the small town of New Denver, BC, which is on a glacial lake about the size of the larger lakes in Ireland).

Tactical

Great to see the pictures. Thanks for the updates and the pics

glimmerman123

Thanks M.T for the pictures. I hope it won't be long before we see scenes like that here in Tipperary. Winds have dropped off a bit but still some very heavy showers and feeling mild outdoors.

M.T. Cranium

UPDATE _ Tuesday, 10:20 p.m.
________________________

Forecast more or less on track although I hear Galway is seeing a lot of rain from slow-moving bands (I used to play in one of those) ... and remember when I said the jet stream had fallen in love with Ireland?

(see attached radar image)

Now, the latest computer model run (18z GFS) is showing no changes to the details through Friday, but has ramped up the intensity of the Saturday storm, see my comments over in the weekend storm section. I hope this model is out to lunch because otherwise, parts of the south will be out of luck when this thing hits, the gradient is fierce with it.

Hard to assess the probability of this coming to pass, I tend to be distrustful of extreme weather events on model runs further than 72h out, and even from 48 to 72h not that ready to jump on the alarmist bandwagon ... however, given the situation in general, I would say at least a one in three risk of a severe wind storm event in Ireland this weekend.

M.T. Cranium

Wednesday, 18 November, 2009
______________________________

Although it will be quite windy today and Thursday, we are now tracking an intense storm that refuses to die on the model runs as we get closer to Saturday. There are worrying indications of storm to hurricane force winds for many parts of Ireland and only three days to see any relief in the forecast models -- essentially, if there is no downgrade later today, this storm should be regarded as an imminent danger. See my forecast below for an estimate of how it could play out.

TODAY will become increasingly windy and quite mild with this morning's steady rain possibly easing to drizzle or even a few dry intervals before more steady rain arrives from the southwest by afternoon. Highs will reach 14-15 C and rainfalls will average 20-30 mms. Winds are already SSW 30-50 mph in many southern and western counties, and these will soon spread further north, with a general increase to 40-60 mph later on in exposed areas (more like a steady 30-50 in less exposed locations). Although some periods of better visibility may develop, fog and mist may become widespread in the second half of the day.

TONIGHT will continue windy and very mild with more rain at times, fog and mist clinging to higher ground, and lows (if we can call them that) near 10 or 11 C. Expect perhaps 10-15 mms further rainfall tonight, and winds holding steady in the SSW 30-50 mph range.

THURSDAY could become a little more windy especially near the south coast, gusts to 65 mph are possible there, and 50-55 mph more generally. Highs will edge up to 15-17 C and rain will become heavy and perhaps thundery in a few places. Sorry to report that a further 30-40 mms could fall and create some localized flooding.

FRIDAY will see a little improvement as winds swing more into the WSW at 25-45 mph, with variable skies, some passing showers, even a few heavier ones with thunder or hail at first, but also some sunny breaks, with lows near 9 C and highs near 14 C.

Now, SATURDAY will at least be windy and showery with mild temperatures; about the best one could hope for given all the guidance available would be SSW winds of 30-50 mph and 10-20 mms of rain with highs near 13 C. Some of the more extreme model output would suggest a low of 948 mbs just west of the Shannon estuary causing afternoon and evening winds rising to SSW 60-100 mph, 30-50 mms of rain from early morning to mid-day sweeping north, squally and possible violent showers, as the wind veers from SSW to W -- in this worst case scenario, the very strong winds would be particularly bad in south coast and west coast to central counties but really, the whole country would be under siege from a hurricane-like storm. Like anyone making forecasts today, I'm stuck between hoping this won't happen, and trying to warn people that it may well happen. Stay tuned and look in on the other threads especially the one entitled weekend storm, because there you'll get a wider range of opinions as to what could happen here, but essentially, we are all wondering if one particular forecast system (the GFS model) has this storm "nailed down" today, whereas some other forecast models offer hope of a less violent solution.

Whatever Saturday brings, Sunday looks likely to be windy and colder with passing squally showers of hail, and snow on higher mountain peaks as temperatures up there drop to -1 to +3 C ... down near sea level it may be more like 7-9 C, so if you live fairly high up it could be 4-6 C and rather mixed as to precipitation type. Winds on Sunday are likely to be W 40-60 mph but if the major storm hits, that will be relief by comparison to the day before.

Another mild windy system threatens to sweep away the brief insertion of colder air on Monday night and then (this is starting to read like a movie plot) the models have yet another intense storm in mind for Wednesday (Connacht would be hit harder by this one).

Final thought for this segment, the risk of the intense Saturday storm is probably rising to about 50% now ... and with rather gusty winds likely on Thursday, you might want to think about what could happen if various trees fall (towards a north to northeast direction mostly) or if there were to be structural damage to any buildings near your parked car, for instance ... and take the appropriate action or at least be prepared for Saturday.

Meanwhile, it's not exactly calm here either, we've had strong winds now for two days and we're looking at two more, not as strong as what I'm forecasting for Ireland, but 40-60 mph in gusts, and with some further rainfall, as temperatures hover in the 8-10 C range.

squonk

This Blue Lightening discussion is intriguing me. Could I just clarify, when people are talking about Blue Lightening, are they talking about the purple coloured lightening you generally get? I've seen white and orange types also but I've never seen lightening that was 'Blue' in the sense that it was coloured like the flashing lights on an ambulance or something. I'm just wondering if I've missed out on a whole class of lightening!

Keeping an eye on the storm potential for Saturday and thanks for the updates and info. Should be interesting to see what comes but it has to be said, a tragic accident like the one in Galway last night puts the threat presented by 'exciting' weather in perspective. My heart goes out to the families of thos 4 ladies. Absolutely terrible.

Fulton Crown

Thanks MT for a very comprehensive view - excellent as always.

Deep Easterly

squonk wrote: »

This Blue Lightening discussion is intriguing me. Could I just clarify, when people are talking about Blue Lightening, are they talking about the purple coloured lightening you generally get? I've seen white and orange types also but I've never seen lightening that was 'Blue' in the sense that it was coloured like the flashing lights on an ambulance or something. I'm just wondering if I've missed out on a whole class of lightening!

The blue lightning I witness here most winters can be best described as the same colour as an ambulance siren alright. I know the purple and orange types but this is most definitely blue! I wonder is this an Atlantic phenomena exclusively? or is it more widespread?

squonk wrote:

My heart goes out to the families of thos 4 ladies. Absolutely terrible.

Seconded

squonk

That's interesting DE! I'm from the west myself and never have seen the 'blue' variety of lightening down there. Now, perhaps I just missed it anyway. I was always under the impression that people just called the purple lightening 'blue'! Ya learn something new every day!!!

kerry1960

Yes indeed that was a tragic night in galway which could well have been weather related , deepest sympathy .

From my own viewpoint im very much hoping for a big downgrade for saturdays potential storm , wind of this severity is not welcomed by any sane person .

BraziliaNZ

is this the wettest November in a while? I can never remember this much rain in November, you'd swear it was June or July with the amount of rain!

Drummer Mummer

Hope this storm doesn't come off, I live by the coast with not a tree for shelter and high wind scares the hell out of me, no sleep for me then! Yes, I too feel for the families of those girls who died in the accident near Galway, it will be a dreadful ordeal for them. May they find some form of comfort in the future

M.T. Cranium

UPDATE _ Wednesday, 1845h
_______________________

Here comes the heavier rain and it may indeed cause some severe flooding in places as it mounts up to eventual totals of 40-70 mms through late tomorrow (including what's already fallen).

As for the Saturday storm event, there is somewhat good news -- the latest GFS run looks more like the GEM in keeping the deep low centre a little further west through Saturday and reducing wind speed potential down into the range that would be severe in places but not on the scale of a national emergency (in other words, yet another windy day with gusts possibly as high as 80 mph). Now this situation is far from clarified, the jet stream wind forecasts remain ominous and any small changes in the energy of weak systems now approaching the Atlantic trough from eastern Canada would hold the potential of returning the forecasts to the high level of concern.

I've posted some more about this on the weekend storm thread including a map showing where this weekend storm is today (it's actually quite a weak and small low in the region south of Baffin Island in northeast Canada -- you wouldn't think it could harm a fly from today's view of it).

Meanwhile, tomorrow's wind and rain can be clearly seen in the central Atlantic where there is a deep low and strong fronts already.

Over here on the west coast of Canada (and you can check that out too on the map I am attaching here as well as the storm thread), we have our own little slice of heaven with a strong low forming up for an overnight assault on the coast, and it's already quite foul outside with periods of hail-mixed showers and gusty SW winds, but worse will develop tonight here (it's only 1045 here of course).

(map of weather systems across North America and the Atlantic, you're looking at North America, western Europe is on the right side of the map and oriented sideways in case you're having trouble finding Ireland, it's under all those isobars somewhere. )

http://www.weatheroffice.gc.ca/data/analysis/935_100.gif

M.T. Cranium

UPDATE _ Wed 1020 pm
___________________

Just a note to say the weekend storm is not showing signs of progressive weakening as new model runs come in, but rather seems to be trying to mount a comeback of sorts. The 18z GFS would suggest two rounds of strong winds, one from the south on Saturday, then one more from a westerly direction on Sunday, and this second round now looks stronger with potential for gusts to 90 mph. The Saturday round is more like 80-85 mph potential, so not exactly a vast improvement.

We are going to have to continue to regard this weekend storm potential with the utmost urgency until any last-minute reprieve which seems increasingly unlikely now.

I think we have you today on the dismal weather front, at least it's mild for you, otherwise, pretty much the same sorry picture.

M.T. Cranium

Thursday, 19 November, 2009
_____________________________

TODAY will continue very windy and wet, with the stronger winds being felt in the southeast (SSW 45-70 mph) while the west and northwest see a little reduction in their wind speeds (SW 30-50 mph), while the axis of heaviest rain slides slowly east through central counties towards the east. A further 30-50 mms of rain is possible, and the flooding potential seems evident to all. It will be muggy with all this, as temperatures stay mainly in the range of 14 to 16 C (12-14 C close to the south and west coasts).

TONIGHT the rain should become more showery although it could end with a few rumbles of thunder in the east, and eventually skies may begin to show a few clear patches with winds veering to SW 30-50 mph and becoming less gusty by morning. Lows will fall to only about 7-9 C.

FRIDAY will see a few breaks in the extensive overcast and there will be a few lingering areas of light rain or drizzle, mostly over higher parts of the west and north. Winds will continue WSW 20-35 mph then back to southerly by evening, picking up as rain moves in from the Atlantic. Highs for the day will be near 13 C and it likely won't drop much from that by nightfall.

SATURDAY looks very windy but so far, the models seem to agree, the strongest winds will wait now for round two of the weekend storm on Sunday, however, there may still be some very strong gusts in the south and southwest from this first phase, as winds rise to SSW 45-75 mph, with some higher gusts possible. Squally showers or periods of rain will develop from early morning and spread across the country, followed by variable cloudiness and more scattered showers or thundershowers. Highs will be near 14 C.

SUNDAY will perhaps see a few hours of less blustery winds in the early morning hours (still SW 30-50 mph though), then the winds will gradually increase from the SW all day to reach peak speeds of 60-90 mph across many parts of the west and south, possibly a little less extreme in the north and east (40-70 mph would still be very blustery though), and with some potential for gusts above 100 mph in exposed locations and at higher elevations. Somewhat colder air will arrive, keeping temperatures around 8-9 C and bringing more of a mixture to the form of showers, especially in elevations above 300 metres, where hail will be frequent, and with snow falling at times on higher slopes. Hail and thunder could reach lower elevations at times too. In other words, this is not the day for a picnic.

MONDAY will be slightly improved as the westerly flow relaxes to 30-55 mph with less frequent showers and a few sunny breaks, lows near 4 C and highs near 10 C.

TUESDAY is looking like yet another very strong wind event, with potential to reach SW 50-85 mph, and more rain with that.

The longer term prognosis is for this windy, wet onslaught to continue for about another week beyond mid-week, as a very deep "parent" low is going to be trapped by the larger features just southwest of Iceland, which means that every bit of energy coming along in a strong jet stream will be directed right over Ireland. It's almost as bad as the refereeing at the WC football qualifier. :eek:

munsterlegend

met eireann in their morning radio forecast did mention possibly strong winds for sunday. will saturday be more a rain event and will it make much?

M.T. Cranium

UPDATE _ Thursday, 7 p.m.
______________________

It continues to look as though Saturday will be moderately windy in all parts of Ireland and perhaps very windy at times in the southwest (gusts to 70 mph or so), as to rain potential I would say 10-20 mms generally and locally up to 30 mms. Sunday continues to look more ominous as the deep low that was always being speculated on by all models arrives off the Mayo and Donegal coasts by mid-day, bringing whatever westerly gales and storm force winds it can muster at that point, which looks more like gusts to 80 or even 90 mph in exposed locations. By that point the flow will be considerably colder as some maritime arctic air is mixing into the strong circulation.

The seeding low for this event has now reached about 41W and has dropped down from 60 N to about 53 N, just to the northeast now of St Johns Newfoundland. The central pressure has dropped from 994 to 984 mbs in the past day, which is not extreme but shows that it's gaining while the larger parent low northwest of Ireland has been steady at about 955 mbs. Eventually this new low will just take over most of the old circulation and the current low will be pulled back into the new circulation -- this is what the GFS was having its troubles with, because it wanted to race the area of strongest winds east on Friday and explosively develop off the west coast of Ireland -- now all major models seem to agree on a more gradual development that still sends out quite a strong leading wave on Saturday, so I wouldn't urge anyone to make big plans for the outdoors at any point this weekend, it's more a case of a disastrous event turning into something that can be more or less weathered, I suppose.

Speaking of which, it continues to blow from the west here and rain lightly at times, and it's about 7 C which feels quite raw in the 30 mph wind.

I may update again if the 18z GFS has new ideas, otherwise, I hope everyone stayed dry and we'll see how things look in the early morning.

Storm 10

A few minutes ago after the news the Met Office said we are in for very strong winds on Saturday and very stormy conditions on Sunday as an intense Atlantic low swings in very close to Ireland.

As usual MT you are spot on well done.

Silverado

What a day. In Waterford we had 64 knots of wind at midday and so far 49mm of rain since midnight.

munsterlegend

Storm 10 wrote: »

A few minutes ago after the news the Met Office said we are in for very strong winds on Saturday and very stormy conditions on Sunday as an intense Atlantic low swings in very close to Ireland.

As usual MT you are spot on well done.

where did the met office say that?

Deep Easterly

munsterlegend wrote: »

where did the met office say that?

Here:
http://www.rte.ie/news/2009/1119/6news_av.html?2652494,null,230

Scroll down to "Weather Forecast" with Gerry Murphy and play clip.

Storm 10

Met Eireann also said that the worst was over now and all we would get was a few coastal showers in the West tonight well looking at this latest radar its not showers but another deluge thats coming up the coast.