Storm Lorenzo: October 3/4 2019 **Technical Discussion Only**

An Ri rua

kerryjack wrote: »

fair play guys ye called it fairly well all week I pitty any old people living alone and listening to rte the life would be frightened out of them.

While it's true that the media got carried away, it was a major news story 2 days ago, sufficient to cause the National Coordination Group to convene in the NECC.
It's a very anomalous weather event which could have had devastating effect across Ireland.
We did dodge a bullet, for all of the knocking of Joanna on the Chat thread.
Preparation and forecasting are everything, lest we have a Michael Fish moment and end up with dead citizens.
I also thought Eoghan Murphy was fudging it re school closures but, the more I thought it through, the NCG have done their job. They are not fortune tellers.

m17

Co galway 03/10/19

Graces7

kerryjack wrote: »

fair play guys ye called it fairly well all week I pitty any old people living alone and listening to rte the life would be frightened out of them.

Young person! I am nearly 80 and there is no way any weather or forecast would " frighten the life out of me" and the same applies to all the old folk I know! We have all experienced and weathered weather you can only guess at! We prepare for these events

And I hope that you are following through with your concerns and calling in on your old neighbours? Bless you for that!

Awful lot of nimbyism here. It was only ever going to be a west coast event. And be sure it is! I am west coast and we are being thrashed and battered by Lorenzo.

Have been all the night long. Still have power and my dish is still intact.. but that could change any minute.

Graces7

No easing here. Still savage gusts and loud deluges on the windows. wish I had the means to measure windspeed.. just loud and louder and very loud! VERY loud now..

west mayo offshore island

Graces7

Something just changed out here; increasingly savage gale. Dwelling shaking. Has it changed direction? Gusting dangerously.

west mayo

Something just hit the roof or came apart!

Just realised that this is Lorenzo passing nearer? Certainly far worse than before; things flying out there and the dwelling shaking. Like Callum. Ah well.. " this too shall pass."

Oscar Bravo

4am

Mace head gusting 57 knots (107 km/h)

DOCARCH

Mace Head gusting 58kts/107kmh in 0600 report. Mean of 45kts/83kmh.

That mean speed technically satisfies requirement for red warning.

M.T. Cranium

Well on the other hand some coastal conditions probably verified the orange level warning, it's up to the presenters and news media to clarify the application of warnings to counties, as everyone on this forum seems to understand that they won't always verify throughout a given county.

The centre of old Lorenzo has finally made contact with land around Donegal Bay, and once it moves inland, I think it will take 2-3 hours for the gradient to slacken then a rapid improving trend will set in for the west. The east will see a slight increase in wind speeds as what's left of the cyclone approaches from the northwest, and there will be a spell of moderate rain. The storm, such as it is for the east, will likely just dissipate rapidly around the early afternoon hours.

DOCARCH

Status Yellow - Wind warning for Longford, Westmeath, Galway, Mayo, Roscommon and Clare

Strong westerly winds persist for a time this morning, mean speeds 50 to 65 km/hr with higher gusts.

gozunda

M.T. Cranium wrote: »

Well on the other hand some coastal conditions probably verified the orange level warning, it's up to the presenters and news media to clarify the application of warnings to counties, as everyone on this forum seems to understand that they won't always verify throughout a given county.

The centre of old Lorenzo has finally made contact with land around Donegal Bay, and once it moves inland, I think it will take 2-3 hours for the gradient to slacken then a rapid improving trend will set in for the west. The east will see a slight increase in wind speeds as what's left of the cyclone approaches from the northwest, and there will be a spell of moderate rain. The storm, such as it is for the east, will likely just dissipate rapidly around the early afternoon hours.

Wind has ramped up here again over the last 2 hours with some very strong gusts atm. Unfortunately my Anemometer is down.

North Cork limerick border

Gaoth Laidir

So 58 knots is the highest gust so far. I was way out with my 75.

Looking at the buoys, Finnis Buoy, just east of the Aran Islands, was reporting gusts consistently in the mid to high 50s and then reported one isolated one of 65 kts. Ballybunion buoy was way lower.

https://twitter.com/FinnisBuoy/status/1179936632566353920?s=19

DOCARCH

At 0700....

Mace Head reporting mean of 47kts/87kmh, gusting 58kts/107kmh.
Newport reporting mean of 35kts/65kmh, gusting 57kts/106kmh.

Gaoth Laidir

ASCAT winds at 20.48Z yesterday.

Villain

New warnings issued.

Impressive that Mace Head has seen top gust of either 106 or 107kmh since 1am to 8am, Lorenzo is a consistent fella

irishgeo

DOCARCH wrote: »

Mace Head gusting 58kts/107kmh in 0600 report. Mean of 45kts/83kmh.

That mean speed technically satisfies requirement for red warning.

The alert is triggered when it says widespread mean speeds. Not one station.

DOCARCH

irishgeo wrote: »

The alert is triggered when it says widespread mean speeds. Not one station.

I know!

sryanbruen

46mm at Finner Camp in last 12 hours.

https://twitter.com/kilkennyweather/status/1180009005772660736?s=21

Gaoth Laidir

Analysis at 7 am. Centre just over Donegal town. Pressure up from 969 hPa 6 hours earlier.



AMSR2 winds just before 4 am.

MJohnston

That low pressure system pictured above will pretty much linger where it is, but it'll have a very rainy sting in its tail for us, along with another low system that'll arrive from the east coast of America overnight Sunday:



Another windy night for the west on Sunday too!

Snow Garden

Has Sryanbruen done his wind comparison table yet?

DOCARCH

Snow Garden wrote: »

Has Sryanbruen done his wind comparison table yet?

Probably not worth the hassle!

Graces7

May I offer a heartfelt thanks to the folk here who gave so wholly of their expertise and knowledge yesterday?

It was a huge support to many of us, especially in the more vulnerable situations.
So much appreciated and always relied on.

THANK YOU!

Gaoth Laidir

Interesting to see the effect of cold upwelling along Lorenzo's path over the past week.

Gaoth Laidir

ASCAT winds just before 1 pm today. Stiff gradient off the southeast coast.

Oneiric 3

My 10 min wind speeds over the last 24hrs. Got a bit on the windy side for a short while this morning but a more or less steady drop thereafter. Gust wise, a few above 40 kts around peak time but they were not that frequent. Pretty much calm out now.

Storm 10

The highest gust I recorded at my station in Galway was 60 mph, during Ophelia it was 82 mph and the gusts were very short lived unlike Ophelia where the were very sustained

Oneiric 3

Storm 10 wrote: »

The highest gust I recorded at my station in Galway was 60 mph, during Ophelia it was 82 mph and the gusts were very short lived unlike Ophelia where the were very sustained

Ophelia ended up being stronger here too, even though we largely missed out on it, with higher mean and gust speeds (think my max was around 52kts) Ophelia was also notable for its angle of attack. It seems that, here in the west of Ireland at least, trees etc 'shaped' to tolerate strong winds from a westerly quarter, but not from an easterly one. That could be a nonsense theory though but for whatever reason, strong winds from an easterly direction always seem to be stronger and more 'robust' than they would appear to be in the actual stats.

Meteorite58

For the record the Pressure readings and highest gusts for the last 24 hrs .

So the Storm took a track further out, further North and stayed over the sea a lot longer than the models were showing a few days back.The models did modify the wind speeds in the last couple of days before landfall , especially the last couple of runs. It was unusual to see such a big storm track up the coast as it did and turn back in over Ireland . Initially I said it would gust 72 knots two days ago but later models showed it unlikely to do so.

No winds of note here in Kerry overnight, just gusting 60 km/h and no rain recorded since midnight and just 0.6mm yesterday. Highest gust here for the event was 71 km/h at 07.31 yesterday morning.

Interesting study and watching the models so closely over the last 12 days or more. Great learning experience and more bits of knowledge picked up from all the other posters contributions.









https://twitter.com/metoffice/status/1180120446576013319?s=20


https://twitter.com/Buailtin/status/1180052067249004545?s=20

Danno

Lorenzo in South Laois:

Top gust of 39mph just before 11.30am on Thursday morning as it got closer to Ireland. I suspect the Nore Valley assisted in the angle of attack SSE. The top average ten minute wind speed average was 23.8mph at the same time of the top gust.
Today as the storm moved SE over Ireland the winds picked up again with a top gust of 37mph just before 11.45am. At this time the top average ten minute wind speed was 22.9mph.
Rain associated with the storm measured 4.1mm up to 10am this morning from the manual gauge (AWS 4.8mm). The AWS reports just 0.2mm since the 10am manual read, so we'll have to wait until 10am tomorrow morning (9UTC) to get Lorenzo's final tally there - that is if tomorrow's front doesn't arrive before the 10am lift!
Pressure dropped to 997.6hPa just before 10am this morning, it had dropped to 998.9hPa around 5pm on Thursday evening as Lorenzo passed up along the west coast.
The storm certainly brought a plume of mild air with it, a top temperature of 16.3c was recorded around 5pm on Thursday also, coinciding with the first low pressure measure. Temperatures gradually fell away from there with 11.0c recorded before 6am this morning and as the storm cleared this afternoon, partly clearing skies allowed the AWS to record a mild 15.8c (Suspect a ~16.0c from the manual thermometers).


Warranted Yellow Warnings?

A yellow warning was issued for both wind and rain. Taking the observations into account:
Wind Speed - 39km/h top average wind speeds recorded versus a minimum of 50km/h requirement. 11km/h short
Wind Gust - 63km/h top gust recorded versus a minimum of 90km/h requirement. 27km/h short
Rainfall - 4.3mm (included AWS) recorded versus a minimum of 20mm (6hrs) or 30mm (12hrs). 15.7mm short

Conclusion: The yellow warning was not warranted in any of the three criteria listed.


Lessons to be learned?

This is not the first time the yellow-orange-red warning system has come in for criticism. The unrelenting hype by the media is moreso to blame than Met Eireann, but there surely now must be calls for a review of the system which is nearing 5 years old now. While it is easy criticise the system, it is only a cheap shot to do so without offering alternatives. In my opinion, Met Eireann should abandon the current system and replace it with Advisory, Watch, Warning and Alert. They should also employ % chances of an event happening. In addition, the use of counties should be reduced in use (they are suitable for summer heat alerts) and a greater use of coastal margins to define storms etc... I think the four categories would allow for a greater spread of warnings, the current ones are very "straight-jacket".

Carol25

The calm after the storm in Salthill today.