Storm Aiden - Saturday October 31st

I have one like that, lab man ... they are a rough guide at best, it can rain in some situations at higher pressures than the range where "fair" is indicated, and it can clear out at lower pressures if you get into a dry slot in a complex of low pressure. A better indicator is whether your barometer after a tap is on the rise, steady or falling. With a rise you should be seeing improved conditions, with a fall there is usually rain (or snow) on the way, and with a steady barometer whatever you've currently got is likely to remain in place.

Might want to check that your barometer is set to your local "sea level" pressure, what's your elevation above sea level and rough location? One of us could let you know what your barometer should be reading. There's usually a screw in the back somewhere that lets you adjust the reading. This would be a good time to check as pressure trend is not changing very quickly.

(will post more on the actual weather situation in a few minutes, just checking some recent updates)

lab man wrote: »

I'm living right on the shannon estuary about 50 / 100 above sea level yes a rough guide is all I want there is a skrew on the back
Thanks for your help

Okay so your barometer at present should be reading 1001 mbs or 29.55" ... and if you happen to check a bit later, it should be slowly rising to reach a peak around 29.8" tomorrow mid-day, then it should fall to around 29.3" late Friday night. If you seem to be in that range you don't need to adjust.

At your elevation your actual air pressure is just slightly lower than sea level pressure. All the weather stations and weather maps you might see anywhere are converted to sea level pressures. Somebody living high up on a hill could have as much as an inch or 30 mbs lower "actual" pressure but if their instrument is set at the actual pressure it will range lower than the design values for "fair, change and stormy" or whatever they show.

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Meanwhile, had a look at latest guidance ... Zeta was whistling along even a bit faster than yesterday's model guidance had shown, the ragged centre just left the U.S. mainland around Ocean City MD ... model consensus seems to be that the core of Zeta's energy will remain intact for 48-60 hours and zoom past Donegal Bay late overnight Saturday into Sunday morning, probably leading to a peak in wind speeds from midnight to 0600h on the west coast. Before that, the low forming up in the middle of the Atlantic now will be bringing an interval of strong winds Saturday morning, these will veer westerly for a time, and some clearing will develop later Saturday, a brief break in the strong winds could mark the passage of a very weak ridge before Zeta's remains arrive.

The supporting upper low is trying to keep up but is falling behind and will force a secondary low to form in the same zone as Zeta runs through, that second low will never totally develop and will remain a trailing wave but we need to keep an eye on that plus the final stage of low pressure dropping southeast on Monday.

Still some potential for any of these to develop an intense band of strong winds as the jet stream is quite compressed. Will probably just be a long term disturbed period of weather with mostly level one alert conditions and the occasional localized level two (or orange alert if you prefer).

Gaoth Laidir wrote: »

Is it just me or are the two streamline animations in the Howling Hallowe'en discussion not loading?

not loading here also.

Cranium , it was at 1010. So have it changed to 1002 so looking forward to seeing how it goes
1 thing though the black hand does seem a bit loose thanks lab man

Some potential for model error even at this range because the core of Zeta has moved even faster into the Atlantic than models were suggesting over first 6-12 hours, which could give it less time to gain latitude (as the second round of strong winds). Not sure if this would impact any of the evolution of the first round earlier Saturday. Waiting to see if ECM has caught this because so far GEM, GFS and Arpege have not quite got the speed, it may be that cloud formations have accelerated past pressure patterns too.

Anyway, I think we need to underline the potential for last-minute changes in forecasts especially with the late Saturday early Sunday time frame.

There could also be late stage changes in the evolution of third wave in the series due to pass south coast Sunday night. Not sold on this one being suppressed as shown.

Ship report of 59 knot westerly winds at 37N 66W which is between post-tropical Zeta and the developing tail end low.

The GFS perturbations give some more intense solutions for Saturday night into Sunday morning, but not a big spread, implying moderately high confidence in the solution as presented.

However, I have to wonder if the intensity of the upper flow dynamics will merge the two storms so that the mid-day frontal passage becomes a sort of occlusion of the fast-approaching remnant low of Zeta, then a two-part windstorm ensues with peaks at mid-day Saturday and just after midnight (0300h Nov 1st).

Something to watch in future model runs. Full moon is Saturday (around 15z) so tidal surges may need to be considered for Galway Bay.

Significant looking rainfall for the southeast tonight/tomorrow morning, and then wet and wild around lunchtime tomorrow in the west, a day for the fire.

Status Orange - Wind warning for Carlow, Kilkenny, Wexford, Wicklow, Cork, Kerry and Waterford

Met Éireann Weather Warning

On Saturday morning strong southerly winds veering southwesterly associated with Storm Aiden will reach mean speeds of 65 to 80km/h, with severe and damaging gusts of 100 to 130km/h.

Valid: 05:00 Saturday 31/10/2020 to 10:00 Saturday 31/10/2020

Issued: 10:00 Friday 30/10/2020

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Status Orange - Wind warning for Donegal, Galway, Mayo, Sligo and Clare

Met Éireann Weather Warning

On Saturday morning and afternoon strong southwest to west winds associated with Storm Aiden will reach mean speeds of 65 to 80km/h, with severe and damaging gusts of 100 to 130km/h.

Valid: 08:00 Saturday 31/10/2020 to 16:00 Saturday 31/10/2020

Issued: 10:00 Friday 30/10/2020

pad199207 wrote: »

Status Orange - Wind warning for Carlow, Kilkenny, Wexford, Wicklow, Cork, Kerry and Waterford

Met Éireann Weather Warning

I still can't get over how the weather sticks to county borders.