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

Saturday, 6 November, 2010
__________________________

The new moon has just occurred at 0452h GMT and this will be a factor in producing high water levels around times of high tides on the south and west facing coasts on Sunday, and to a lesser extent on the east coast Sunday night and again Monday night and Tuesday (when winds are more into the coast from the east).

The fast-moving storm expected for late Sunday is still on the same track and its passage across Ireland is expected Sunday night. Ahead of the low, winds will rise rapidly from a SSW direction peaking about 7-10 p.m. Sunday. After that, the rather extensive calm centre of the low will drift southeast across Ireland and there could be as much as 12-15 hours with very little wind (the eye of the storm in other words) as long as the storm stays on the predicted track -- if it veered further west, for example, the stronger winds would continue as it moved by. Then when the storm is further southeast later Monday, the winds will start feeding back in from the east and could become quite strong again. Forecasts then:

TODAY ... A few bright or sunny intervals but extensive showers developing with winds NW to N 15-25 mph, rather chilly especially compared to recent days, and highs 8-10 C. Rainfalls generally about 3-5 mms.

TONIGHT ... Showers gradually ending, clearing with some icy sections developing on outlying roads, frost in some areas with lows -2 to +3 C. Fog patches by dawn, watch for very slippery roads in some areas.

SUNDAY ... Some morning sunshine and light winds until noon to 3 p.m. (from north to south) followed by a rapidly rising south to southwest wind eventually reaching 30-50 mph with some gusts to near 65 mph west and southwest coasts and to 80 mph on mountain summits (conditions will deteriorate very rapidly, even if it looks nice Sunday morning, would strongly advise against climbing, sailing etc). Periods of rain becoming heavy at times by late afternoon or evening, 20-30 mms likely by about midnight, and possibly some sleet or snow on summits. Highs 9-12 C but feeling much colder when the strong winds arrive.

SUNDAY NIGHT ... With the low over Ireland, winds will actually drop off to quite light and almost calm in places, with the rain breaking to showers or drizzle, and widespread fog or low cloud, lows near 7 C.

MONDAY ... The calm, misty and drizzly conditions may last for part of the morning in the south, while further north stronger N to NE winds develop with low cloud and rain. But by afternoon and evening all parts of Ireland should be back into strong winds and rain with high elevation sleet or snow, and quite chilly temperatures of about 8 C (near 3-4 C at high elevations). Winds will increase to ENE 20-40 mph with some gusts to 50 over the Irish Sea and east coast. MONDAY NIGHT will continue quite similar with the rain breaking into streamers and not making as much progress into the western counties, with winds NE 20-40 mph and lows near 6 C.

TUESDAY will see some of the cloud breaking but there may still be local streamers of rain or hail showers in Leinster mostly, also parts of Ulster. Winds will remain NE 15-30 mph and highs will be 9-10 C.

WEDNESDAY will have a brief interval of cool, dry weather with a morning frost, light winds during the day, some sunshine mixed with low cloud, and highs near 8 C.

THURSDAY-FRIDAY will turn milder again with stronger SW winds returning, periods of rain, and highs near 12 C. There may be some gusts to 50 mph or higher especially in Connacht and Donegal.

NEXT WEEKEND at this long range looks windy and colder again with the flow turning more to the northwest again.

Today here (Friday 5th that is) was a cloudy, mild day with a little rain at times, but it was clearing at sunset. Highs were about 13 C. Meanwhile, rain has ended in most east coast cities of the U.S. and is moving through eastern Canada overnight. The low that will arrive in Ireland is basically the one now leaving Labrador for the passage to Greenland where it will redevelop Saturday by forming a new centre west of Iceland. Then that heads your way for late Sunday. At the moment this storm is not exceptionally strong (about 990 mbs). Meanwhile, Tomas has swept past Haiti where there was some damage in far western rural areas but not too much happened in the capital of Port-au-Prince other than a few hours of heavy rain. This long-lived storm will probably have one more day as a cat-1 hurricane, then start to shear apart east of the Bahamas (or show up in Cork from what I hear).

The thread that the weather forum has going about this Sunday-Monday storm is a good resource for updates and since I can't be awake all the time, your best bet for updates during the rest of today. I'm staying alert to the idea that this storm will make some sort of last-minute course correction but so far the models have remained very consistent on what they think it will do, and that includes the rather extensive area of light winds near the centre which should last about twelve hours once they set in.

I'll certainly review the snowfall potential on Sunday morning but as of the guidance available, I can't foresee accumulating snow on either the front or the back side of the storm except above 1500 ft which is already covered in the forecast. However, hail could develop and coat some roads (at first I typed toads) :eek: especially in higher passes say between 500 ft and 1200 ft above sea level in higher parts of Donegal, Wicklow or Kerry for example.

The one thing that might prevent snow in the warm advection phase of the storm is that the precip moves in around mid to late afternoon so it won't be falling into the coldest air as would be the case with a storm arriving at night. If this storm slows down and follows the same track but arrives Sunday night then snow might be more of a factor. I've also mentioned in UK forecasts that snow is possible on higher parts of upland areas such as Dartmoor, Wales and Cumbria.

That being said, if it snows on higher ground it can always shift lower somewhere for a few hours late Sunday night or even Monday night, so I am not going to discount this possibility, and it's worth keeping a mention in the forecast package.

UPDATE _ Sunday, 10:15 p.m.
_________________________

No huge changes in forecast but I wanted to reset as the storm is reaching its peak intensity now across much of Ireland. A few western districts such as western Mayo and southwest Donegal have probably already seen the worst of the wind and rain (for them) but most other places are now getting the brunt of the storm and it won't let up for a few more hours, with winds in eastern counties likely to remain S backing to SSE 30-50 mph, similar for Ulster (local gusts to 60 mph) and across the southern half of the country, winds will now be veering somewhat SSW to SW 35-55 mph with some higher gusts. You'll know the worst has passed when winds tend to veer more westerly and drop off to about 30 mph.

The heavy rain will continue for a while longer across the south and east, with eventual total accumulations near 50 mms in some parts. This rain seems to be mixing with snow in a sleety combination at about 200m (~700 ft a.s.l.) and it turns to a heavy wet snow at some higher elevations, so these bands by elevation may come down towards sea level later tonight as the rain-snow mix is winding down, therefore don't be too surprised to see a bit of snow but it will only accumulate well above the elevation where most people live. The mountain tops will likely be white tomorrow, if you can see them between all the clouds and showers.

Temperatures are stuck at about 5-6 C in eastern counties and 7-9 C in the south, will likely stay near there most of the night. In the northwest, it could drop off to about 2-4 C especially around Knock and higher parts of the inland north, staying around 7 C on the west coast. In all areas, winds will tend to diminish well after midnight and could be quite light in some parts by morning, however, on the south coast this decrease will only come quite late and the high tides that are expected around 0300-0600 could be too high in a few cases (it would seem that your civil defense organizations are all over this situation, but clearly the combination of swollen rivers and higher than normal tides will prove to be a problem in some parts of Cork and possibly further east).

Monday, I'm expecting quite a mixed bag of weather conditions as the heart of this low plods its way through Ireland -- your barometer will be showing a very low reading and could be as low as 960 mbs adjusted to sea level. The skies will tend to be variably cloudy with some remnant fog or mist, the clouds will quickly boil up to freezing levels just above the summits of local mountains and drop hail or even wet snow in some higher places. There could be some thunder too. Winds, however, will remain rather light and cyclonic around the low pressure. Only late in the day will the winds start howling again this time from the northeast. By Monday night and into Tuesday, there could be rain and sleet or snow at high elevations, coming in on streamers from the Irish Sea. I would not be surprised if some of these are heavy in places and give coatings of hail or snow to higher parts of the Dublin region, the higher parts of Wicklow, and one or two other places further inland.

And as some have speculated on the threads, Thursday night into Friday will need to be watched now for a second windstorm event that could even top today's winds (which have so far peaked at 63 knot gusts at Malin Head and fairly widespread 45-55 knot gusts elsewhere). This storm would be a little more "ordinary" in its evolution, not dropping out of the arctic towards France, but just heading along in the more normal west to east jet stream over the Atlantic towards Scotland.

Winds aloft are extremely strong tonight, I think they may have lost contact with the balloon sounding at 1800h from Valentia once it got up above 10,000 feet or so. Jet stream winds are 150-200 knots at higher altitudes, from a NNW direction.

Meanwhile, I am lurking over in the storm thread where the folks are doing a great job and you'll get the full picture on the unfolding storm over there.

UPDATE _ Monday, 2:15 p.m.
________________________

Kerry and Cork are getting the lion's share of convective showers this afternoon with chance of hail, thunder and heavy downpours causing spot flooding. Otherwise, the expansive "eye" of the storm is over Connacht now and drifting southeast. When the easterly flow arrives late this evening and overnight, expect to find rain spreading back into eastern counties from the Irish Sea and quite a bite to the wind where it comes directly in (30-45 mph), otherwise a moderate increase to 20-30 mph for most parts.

Tuesday, 9 November, 2010
___________________________

TODAY ... Becoming windy and quite cold, with locally heavy rain mixed at times with hail (or sleet/snow at high elevations of southeast) ... some sunny intervals for parts of the west and south, although risk of some showers almost everywhere ... some thunder and lightning possible especially around Meath, Dublin and Wicklow ... winds ENE 20-40 mph with gusts to 50 mph possible at times near Irish Sea ... highs 6-8 C but possibly a bit higher between streamers if enough sunshine develops, however, temperatures more controlled by precip than air mass today (remember, the Irish Sea still near 13 C, this will turn the streamers quite unstable and there will be odd local effects with meso-scale pockets of convection and warmer air blown some distance inland). Today's rainfalls will be 15-25 mms in some eastern counties, more like 5-10 mms elsewhere. Some snow likely on summits of Dublin and Wicklow.

TONIGHT ... Winds diminishing, showers ending around midnight if not sooner, then some clearing and quite cold with frost, icy roads in places, and shallow fog patches mostly well inland. During the evening it may still be quite blustery and squally in the east, but by dawn, calm for most. Lows will fall to about 3 C around the east and south coasts, as well as outer west coast, but otherwise most rural inland locations -2 C or so.

WEDNESDAY ... sunny intervals, cold, isolated showers ... winds light except by late afternoon on west coast rising to SSW 20-25 mph. Highs generally in the 6-8 C range. Temperatures then continuing to rise overnight.

THURSDAY ... becoming quite windy early morning with periods of rain, heavy at times, winds SSW 30-50 mph, rainfalls of about 15-30 mms, temperatures peaking around 10-12 C, then partial clearing in a very strong westerly wind flow, severe gusts possible in Connacht and Donegal, generally 35-55 mph but locally 50-80 mph ... by afternoon, scattered hail showers developing as temperatures fall back to about 7 C. For Dublin, would expect morning rain, blustery winds peaking about 35 mph gusting to 55 mph, afternoon bright spells and scattered hail showers. Peak winds in the northwest would be likely around mid-day from the WSW.

FRIDAY ... variable cloud, a few more showers, less windy although a strong west to northwest breeze backing to southerly by evening with rain moving across the south overnight. Highs near 10 C.

SATURDAY ... cloudy, periods of light rain or sleet at higher northern elevations, chilly, winds W to NW 20-30 mph, highs near 8 C.

SUNDAY ... chilly and wet with some risk of snow inland north, sleety rain showers elsewhere, highs only about 6 C.

OUTLOOK ... looks raw and at times somewhat wintry in a cool northwest flow that sometimes lets an Atlantic frontal wave through, but without much warm air possibly setting up for some rain/snow mixtures at times.

My local weather has turned rather chilly, with a few scattered showers earlier (Monday 8th) and a high near 8 C. Some mixed rain and snow fell earlier in parts of New England, but otherwise, the trend across the eastern U.S. looks gradually warmer. Not much left of Tomas now, with a weak remnant low well south of Bermuda.

Wednesday, 10 November, 2010
________________________________

ALERT continued ... see previous post for details ... very strong and potentially damaging winds expected Thursday afternoon and evening.

TODAY will start out sunny with some isolated light showers near the west coast, and inland the morning chill may linger to mid-day in places with only slow warming due to light winds ... one or two fog patches could persist for a while until winds pick up ... cloud will rapidly spread into the western counties by mid-day and rain will follow by afternoon and evening. Winds there will pick up to southerly 20-30 mph. Highs 6-9 C except 10-12 C west and south coasts.

TONIGHT will become windy and wet, 10-20 mms of rain on average and near 30 mms in a few spots around south central Ireland ... winds will increase to SSW 30-50 mph, and temperatures will rise gradually to peak around 10-12 C by morning.

THURSDAY will bring some partial clearing followed by more showers (some with hail and thunder) in a very blustery SW to W wind that will eventually reach speeds of 40-60 mph in most areas and 50-85 mph in more exposed locations mainly west and north, with isolated gusts to 100 mph possible. See the alert (previous post) for more details. Temperatures will be steady near 7 or 8 C during this windstorm.

THURSDAY NIGHT will continue very windy although the more severe gusts should steadily abate in all but coastal Mayo, Donegal and some other parts of Ulster where they will subside after midnight. Winds will veer to NW 30-50 mph (gusts to 70 in exposed areas) before dropping off to about 20-35 mph by morning. Showers will also subside with more frequent clear intervals especially in the south, and it will be quite cold in the strong winds with lows of about 4 C.

FRIDAY will have a bright and much less windy start, then rain will spread in, heavy at times in the south, with highs of about 10 C.

SATURDAY will continue unsettled with periods of rain tapering to showers, some sleety or with hail and thunder possibly, across the north. Lows will be about 2-4 C and highs 6-8 C. Winds may pick up again although not to stormy levels, WNW 20-40 mph.

SUNDAY will be cloudy with rather raw, damp conditions that might include mixed wintry showers over the inland north, and cold rain or hail showers elsewhere. Lows near 1 C and highs near 7 C.

This trend will continue well into the new week with low pressure almost stationary near Ireland and not that much mild air around, so a constant swirl of this rather chilly air mass left behind by the big windstorm (from up around Iceland originally). On the longer term models, there are some very cold outbreaks suggested and a good chance for snow at times in the next two weeks.

My long-range forecast will be issued on the weekend (I don't want to clutter up the threads with this major storm brewing). It will discuss the potential for some very cold periods expected in December, among other things.

Meanwhile, today (Tues 9th) here was cloudy with some weak sunshine at times, and occasional light rain, very cool with highs only 7-8 C. The east coast has warmed up a little and there's some rather pleasant late fall weather in parts of the eastern U.S. except from Boston into Maine. Also, there's a slight risk of a 20th named storm being monitored for development south of Puerto Rico. This might take a few days to develop.

I highly recommend the forum thread discussing the windstorm potential, but will update here if the forecast seems to need amending ... the storm has been rapidly deepening all night and is now around 980 mbs at 30 W. Models are generally showing an eventual 950 mb low just north of Malin Head by mid-day Thursday. We don't tend to see pressures much lower than that, although 940 mbs has been observed in relatively recent times.

Thursday, 11 November, 2010
______________________________

ALERT renewed for very strong and potentially damaging winds by mid-day in western counties and by afternoon in eastern Ireland. This strong wind situation has slightly intensified and here is a summary of maximum wind speeds that can be expected later today:

Connacht, Clare and Donegal -- WSW 60-100 mph in exposed locations, 50-80 mph inland. Potential for some local gusts to 120 mph.

Kerry, Cork, Limerick and exposed higher elevation locations further east -- WSW 50-85 mph in most locations, potential for some local gusts to 100 mph.

Dublin and Leinster, Midlands, southeast -- WSW 45-70 mph, possible gusts to 80 in a few spots.

Ulster -- W 45-70 mph, possible gusts to 85 mph in exposed locations.

These winds are capable of blowing over large trees in a few places, bringing down tree branches quite widely and doing damage to wires and signs as well as roof tiles and poorly secured out-buildings. Would advise no road travel unless necessary and then with caution especially after dark. Strong winds will last from about mid-day to almost midnight. Also, watch for possible shoreline problems from waves crashing over seawalls and storm surge issues -- consult local forecasts from relevant authorities.

FORECASTS:

TODAY ... partly cloudy, rather windy at first, then very windy by mid-day (see alerts) with WSW winds 55-85 mph and some higher gusts with damage potential. Squally showers in various locations may bring hail or thunder. Temperatures steady near 10 C then falling slightly to about 7 C late in the afternoon. Feeling very cold in the strong winds.

TONIGHT ... windy until early morning, WNW 40-65 mph then NW 20-40 mph, partly cloudy for most, some remnant showers including hail at times, cold with lows about 2-5 C.

FRIDAY ... some morning sunshine, periods of rain developing by afternoon, southerly winds developing 20-40 mph, highs near 12 C.

SATURDAY ... windy with showers, periods of rain ... turning colder as winds veer westerly then northwest 25-45 mph. Lows near 4 C and highs near 9 C.

SUNDAY ... cloudy, cold, unsettled, mixed wintry showers in some northern inland counties, otherwise cold rain showers, lows 1-3 C and highs 6-8 C.

MONDAY ... continuing cool, showery. Lows near -1 C and highs near 7 C.

TUESDAY ... cloudy and becoming windy with showers, periods of rain later, highs near 10 C.

WEDNESDAY ... could be another windstorm timed like today only not as strong (40-60 mph), stay tuned for the details on that.

As I anticipate a very busy day on the forum, join the weather crew in the storm thread and share your observations. This will be your best source for updates on exact developments, but the main idea for today is -- batten down the hatches and expect the big winds to start blowing around late morning west, early afternoon east.

Note -- the strong wind gusts earlier tonight were from the advance frontal system and we are expecting a slight reduction now before the main winds arrive, so it hasn't "come and gone" by any means.

Meanwhile, hardly noticed but today here was sunny and cool, highs near 5 C.

Updates when necessary ... stay safe.

UPDATE _ Thursday, 2:40 p.m.
________________________

Winds have probably reached their peak intensity in most western counties but it will be a long, gradual return to anything remotely "normal" with severe gusts at times until 7-8 p.m., however, you may note a trend downward in the average wind speed. Would maintain a watch for squally showers to produce severe gusts in that region.

Eastern and southeastern Ireland, which have escaped most of the wind so far, may soon be visited by fast-moving and very gusty showers and thunderstorms marking the onset of their part of the windstorm, which in general may not be as bad as further west, but certainly squally enough at gusts to 60 mph in places. With these fast-moving showers and storms, expect some intense lightning and hail at times, but very fast changing conditions.

Meanwhile, watch out in Limerick for a trailing cell that is moving up the Shannon estuary and could bring some severe wind gusts shortly to that county.

Once again, further updates and news on the storm thread.

Saturday, 13 November, 2010
_____________________________

TODAY ... cloudy with rain spreading across the country from west to east, arriving east coast fairly soon ... rain becoming showery later, accumulations of about 10-15 mms ... cool and somewhat breezy with winds SW-W 15-30 mph ... highs about 8-10 C.

TONIGHT ... showers with some partial clearing later, risk of sleet or snow showers in north (inland) ... frost developing, icy roads in places ... lows around -3 C in some inland rural spots, to about +3 C sheltered coastal and urban locations.

SUNDAY ... cloudy with a few breaks, sleety showers developing in a rather light northerly wind flow, possible wet snow over higher northern districts ... highs only 5-8 C.

MONDAY ... clearing with frost early morning, then increasing cloud during the day, chilly with a raw SE to S breeze setting in, lows near -3 C and highs of about 7 to 10 C ... rain may arrive south, west around sunset.

TUESDAY ... becoming rather windy with periods of rain, milder. ... there would appear to be about a 30% risk of strong winds but so far nothing indicated above 40 knots except possibly western Mayo 50 knots in gusts ... highs near 11 C.

OUTLOOK ... turning colder again in stages, and model consensus now on considerably colder weather at times late in the week through the following week ...

Meanwhile, today for yours truly was partly cloudy with evening light rain showers, light winds, quite chilly near 8 C mid-day ... it continues rather bland across the continent for mid-November but much colder air is massing now over Alaska where they can see Russia from their weather stations ... and despite the dreary forecast, have a great weekend.

Long-range forecast summary

I will be posting a more detailed long-range forecast on a thread that was set up for winter discussion. But as of today, I wanted to mention that my outlook will be calling for significant cold spells in December and early January with likely above normal snowfall for Ireland in that part of the winter. Then it may turn considerably milder for a while before turning back to colder than average in February. More details on that over the weekend when I get a chance to post (have been fighting computer virus problems today).