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Storm Barra: December 7/8th 2021 Technical Discussion Only

SleetAndSnow

Since the other thread is currently burying a lot of the graphs posted, I decided to make a technical thread for this storm.

Current weather warnings:

Status Red - Wind warning for Cork, Kerry

Met Éireann Weather Warning
Storm Barra: Southwesterly winds later veering northwesterly will reach mean speeds in excess of 80 km/h with severe or damaging gusts in excess of 130km/h. Due to a combination of high waves, storm surge and high tide, coastal flooding is expected. Disruption to power and travel are likely.
Valid: 06:00 Tuesday 07/12/2021 to 21:00 Tuesday 07/12/2021
Issued: 13:47 Monday 06/12/2021

Status Red - Wind warning for Clare

Met Éireann Weather Warning
Storm Barra: Northwesterly winds will reach mean speeds in excess of 80 km/h with severe or damaging gusts in excess of 130km/h. Due to a combination of high waves, storm surge and high tide, coastal flooding is expected. Disruption to power and travel are likely.
Valid: 16:00 Tuesday 07/12/2021 to 01:00 Wednesday 08/12/2021
Issued: 16:21 Monday 06/12/2021

Status Orange - Wind warning for Clare, Cork, Kerry, Limerick, Waterford, Galway, Mayo, Wexford

Met Éireann Weather Warning
Storm Barra: Southeasterly winds, later veering northwesterly will reach mean speeds of 65 to 80 km/h with severe or damaging gusts of 100 to 130 km/h, with localised stronger winds likely, with severe gusts on coasts. Due to a combination of high waves, storm surge and high tide, coastal flooding is expected. Disruption to power and travel are likely.
Valid: 06:00 Tuesday 07/12/2021 to 06:00 Wednesday 08/12/2021
Issued: 13:47 Monday 06/12/2021

Status Orange - Wind warning for Dublin, Louth, Wicklow, East Meath

Met Éireann Weather Warning
Storm Barra: Southeasterly winds will reach mean speeds of 65 to 80 km/h with severe or damaging gusts of 100 to 130 km/h, with localised stronger winds likely. Due to a combination of high waves, storm surge and high tide, coastal flooding is expected. Disruption to power and travel are likely.
Valid: 08:00 Tuesday 07/12/2021 to 13:00 Tuesday 07/12/2021
Issued: 13:47 Monday 06/12/2021

Status Yellow - Wind and rain warning for Ireland

Met Éireann Weather Warning
Storm Barra will bring widespread mean speeds of 50 to 65 km/h and gusts of 90 to 110 km/h with localised stronger winds likely. Heavy rain will also bring risks of surface flooding and, due to a combination of high waves, storm surge and high tide, coastal flooding is expected. Disruption to power and travel are likely.
Valid: 02:00 Tuesday 07/12/2021 to 18:00 Wednesday 08/12/2021
Issued: 13:47 Monday 06/12/2021

No chat in this thread please!

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M.T. Cranium

Note Valentia failed to report at 11z probably a power failure? That gust at Kerry airport tells the story. Did Kinsale energy platform close down, I noticed they weren't on the buoy reports this past year or so. Must be gusting near 100 kts out there.

Meteorite58

Picking up now

squarecircles

I wonder will Galway and Mayo go red.

The sun is out now and its very calm here in west Mayo, very deceiving for whats to arrive later.

Graces7

We have no wind out here but even for here the rain is heavy and relentless. Hour after hour

West Mayo offshore

blindsider

Yes MT, the Kinsale field has been plugged and they had a 'decommissioning plan'. I think they had planned to be finished last month, so there's not likely to be any/much activity now.

Still very gusty in Cork city - but the sky has brightened considerable in the last few minutes.

ascophyllum

Arpege also showing gusts 130 to 150 for Mayo after 6pm. A Red warning would be warranted sooner rather than later so people can get home, make arrangements etc.

lucernarian

https://www.boards.ie/discussion/comment/118282945#Comment_118282945

That's a decent height to be at, atmospheric pressure forecasts are adjusted to be for sea level, and 166m above that will shave off quite a few millibars from the sea level equivalent.

Speak Now

Waterford airport gust reports (knots)

9.30 - 57

10.00 - 54

10.30 - 45

11.00 - 55

11.30 - 53

M.T. Cranium

Seeing Valentia now gusting 70 knots, station record being what?

Danno

https://www.boards.ie/discussion/comment/118283397#Comment_118283397

In 1997 Valentia recorded a gust of 88 knots. But I've a feeling the record is higher... @sryanbruen might have the data!

ascophyllum

GFS 06Z for Southwest Mayo, a sustained wind of 96kmh.....

ednwireland

looking at ventusky and they are showing the centre of the storm over Scottish borders tommorrow morning and the north west getting 100kmh gusts. but that's on the icon run . is that an outlier or is that where its heading ?

Speak Now

Waterford airport has it's first 60kt gust in the 12.00 report.

Gaoth Laidir

https://www.boards.ie/discussion/comment/118283243#Comment_118283243

Valentia was reporting on the aviation site. Gust 70 knots in the previous hour.

PsMETAR VALE 071100Z AUTO 27046G70KT 4000NDV BR BKN017/// 07/05 0971 MSL=

ninebeanrows

Pressure still falling at Mace Head, this is a deep storm, pressure ~ 957hPa at midday, can't work out full conversion to sea level so will await official update.

Pressure has dropped 40hPa at Mace Head in 12 hours

ninebeanrows

Recent gust to 73 knots or 135km/h at Sherkin Island

SleetAndSnow

The gusts seem stronger, but look to be dropping in Cork City, down to 48kt gusts in the last hour. Latest TAF reading seems to say that the gusts will get up to 60kts between 12 and 6pm - Max 53kt gust in the last hour.

Gaoth Laidir

"Barra"metric pressure aviation warnings from Met Éireann:

EISN PR WRNG 02 VALID 070900/071500 EISN SURFACE PRESSURE IS EXPECTED TO PASS THROUGH THE VALUES 0976 HPA AND 0960 HPA IN SHANNON FIR DURING THE FORECAST PERIOD E OF W00100 FCST=

The significance of such warnings is to alert pilots to the danger of gross differences between the indicated altitude (as read from the onboard altimeter) and the actual altitude (true height above sea level, as indicated by e.g. a GPS).

As altimeters are calibrated for use at the standard 1013 hPa, when setting it to the current regional sea-level pressure (QNH) of e.g. 960 hPa, it will read around 1430 feet too high ((1013-960)x27). So if you're flying at what you think is 1500 ft, you're actually only around 70 ft above sea level (and in all likelihood digging a trench in the ground in all but coastal locations).

Gaoth Laidir

Sherkin Island 10-minute mean wind 60, gust 73 knots at midday.

PsMETAR SHER 071200Z AUTO 27060G73KT 2300NDV -SHRA BKN024/// 06/04 0975 MSL=

Waterford Airport gust 60 knots

METAR EIWF 071200Z 24039G60KT 190V270 9999 FEW006 SCT020 07/05 Q0973 R21/2/////=

Tazio

Cork Airport & Roches Point Wind speeds for today --

Cork Airport Roches Point plot at 1215h.PNG

Gaoth Laidir

https://www.boards.ie/discussion/comment/118283526#Comment_118283526

The station pressure at Mace Head at midday was 954.8 hPa, converting to 957.5 hPa at sea level. The station is 23 m above sea level.

Here are the actual station pressures. Only 936 hPa at Knock Airport (200 m amsl).

[Deleted User]

Malin Head getting some decent wind this morning 119kmh gust at 10am, 87 kmh mean 10 min speed

[Deleted User]

Was talking to someone in Glencolmkill. He was saying it was windy up there.

Last time I looked it was a steady 60 kmh at my location

Discodog

956 & rising Knocknacarra Galway. Wind had really dropped but heavy showers

Gaoth Laidir

Big dip in gusts at Kerry Airport at 12:30, down to 40 knots from 56 knots at 12:00.

METAR EIKY 071230Z 26023G40KT 240V300 7000 -RA OVC015 06/04 Q0969=

Here are the half-hourly gusts since 9 am

45 - 37 - 49 - 50 - 71 - 57 - 56 - 40

M.T. Cranium

Okay, so let's see how the models did with this from 72 hours ...

This grid with model positions for 12z today was posted in the other thread (now the COVID overflow not storming here thread) on Saturday taking down all available model predictions for the event. Just like in our forecast contests, Con Sensus is almost exactly right.

I have placed an X where the low centre was reported to be (just southwest of Mace Head) and the central pressure was probably closer to 957 than 959. Below this copy of the grid and notes, I have added some comments ...

MODEL PREDICTIONS of 12z TUES 7th DEC LOW position, central pressures

(faster models show an 06z position on the grid (in brackets, e.g. Arp) UK 06z pres likely similar c 965.

Not shown is JMA with low around 53N 18W, similar track to ICON but 12h slower.

==================================================

_ _ _ _ 11_ _ _ _ _ 10 _ _ _ _ _9_ _ _ _ _ _ 8_ _ _ _ _ _ 7_ _ _ _ _ _ 6_ _ _ _ _

_ _ _ _GEMECM _ _ |_ _ _ _ _ _|_ _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _

______956 957___________________________________________________ 55 F

GFS ICON _ _ con_ |_ _ _ _ _ _|_ _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _

961 959____X 959__________________Arp__________________________ 54 N

_ _ _(Arp 06) _ _ |_ _ _ _ _ _|_ _ _ _ _ _964 _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _

_____963_(UK)_____________________UK____________________________ 53 N

_ _ _ _ _ _ _ _ _ _ |_ _ _ _ _ _|_ _ _ _ _ _967 _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _

________________________________________________________________ 52 N

_ _ _ _|_ _ _ _ _ _ |_ _ _ _ _ _|_ _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _ _ |_ _ _ _ _

________________________________________________________________ 51 N

Some earlier model runs had tracks in the 51-52 N area cutting north around 7W,

this is basically off the south coast and then near Wexford.

I have marked a "Con" for consensus on weighted average by model reliability.

That position is near Newport. Most of these model tracks are from WSW to ENE at 12z.

---------------------------------------------------------

The outcome is that the weighted model consensus from 72 hours was very close to perfect. The model which had the least positional error was the ICON which went on to introduce a more southerly track for several runs recently. But back then it had the closest approximation although most of the others were quite good, some were a bit off to the north closer to Belmullet, and the Arpege had a fairly good track but was too fast by about 4-5 hours. The UKMO was the furthest out with a track through west Munster, something it maintained until almost the last run before the storm.

As to intensity, GEM and ECM were closest but the model consensus was also very good.

Moral of the story, take a weighted consensus whenever possible.

Little snowy old me

Surprisingly quiet in here considering....

[Deleted User]

Pressure is rising. Up to 947hpa.

Highest wind was 70 kmh.

Are we expecting more?

leahyl

Jennie O’Sullivan just said on Radio that it’s expected to get worse in Cork?

Goldfinch8

Gone very calm here near Castlebar. Reckon the eye of Storm Barra must not be too far away.

Barra certainly cuts quite an impressive picture in the 13.05 satellite image below.