Ex Katia storm thread - TECHNICAL DISCUSSION, FORECASTS AND OBSERVATIONS ONLY!

ninebeanrows

A severe storm but luckily it stays out to sea so the worst effects along northern and northwestern coasts and western Scotland.

Gusts likely to 80 knots in Malin.

munsterlegend

maquiladora wrote: »

At 72 hours its further northeast than the 06Z. Thats two runs in a row that has tracked it further away from Ireland.

More intense than the 06Z though. Could be why it went further north.

any likelihood that its overdoing the push north east? amazing how these storms even going by america last week can take unplanned for tracks.

ninebeanrows

The main factor for moving the storm northwest is that GFS interacts and intensifies the storm quite early and thus as with all storms moves it to the left as it intensifies.

If you want the storm to hit further south one would want the storm to intensify later than progged on GFS.

- GFS paints dangerous picture for northern areas with gust potential to 85 knots in coastal regions of the north and upto 90 knots along western Scotland. So gusts above 90mph more than possible.

JanuarySnowstor

Ukmo is vastley different.
Much closer but also much weaker, giving the south the worst of it.
Where to from here....

ninebeanrows

JanuarySnowstor wrote: »

Ukmo is vastley different.
Much closer but also much weaker, giving the south the worst of it.
Where to from here....

The global UKM has the low at just sub 975mb at T48 while the NAE more resolved shorterm UK has it at 968mb at this time. I reckon there is a resolution problem affecting the UKM global model.

And the end result is not much different. Although a swathe of strong winds would cross the country.

Deep Easterly

View of Eddie Carroll - Chief forecaster at the UK Met Office:

http://www.metoffice.gov.uk/news/releases/archive/2011/stormy-september-weather

smallwonder

With the high tides should us folk up North be preparing for flooding as well as dismantling the trampolines??

M.T. Cranium

The current track on GFS appears to reduce the potential for damaging winds in Dublin to some extent but I don't think that most other regions would see a change in the predicted wind speeds in our posted forecast, noting that these included peak gusts of only 55 knots for Cork. The maps clearly show potential between 60 and 90 knots as you go north along the west coast, and I think the wording from Met-E about "south and west coasts" is meant to include northwest coasts, if not, it certainly should because the strongest winds will hit Mayo and then Donegal on the current track (as was always expected here).

The deeper trend on GFS largely offsets the slight nudge north, check the 925-mb wind panel for 09z Monday (on wetterzentrale).

What is not too clear yet is any fine-tuning of the rapid occlusion phase and locally intense wind streaks that may develop for regions between Galway and Meath - Duiblin. At this point I would suggest that wind damage is probably least likely in the inland southeast rather than Dublin. Moderate wind damage and coastal flooding issues remain very much on the table for counties from Clare north and including any inland parts of Connacht that are well exposed to a southwest to west direction (and all of Donegal).

Final point, differences between UK and Ireland "official alerts" or whatever are entirely (in my view) caused by different criteria for the timing of such alerts and very likely do not reflect any real differences in how the two agencies are viewing the storm's track or intensity. But in any case, an advance alert is warranted (again in my view) for coastal regions from Clare to Donegal and for a zone further east and south including Kerry I would suggest the frequent crossing of fingers because this will not be a non-event so much as a marginal-to-damaging wind potential situation, there will almost definitely be widespread gusts near 50 knots from this, and with trees in full leaf and somewhat saturated ground conditions, trees can rather easily come down in such winds (as demonstrated with Irene in New York state and some other places recently).

Will post any comments on GEM which should be in now, in a separate post.

The UKMO maps seem almost out of touch with the reality of Katia to my eye at least, they have seldom shown a storm within 20 mbs of other models' central pressures while crossing the Atlantic, so would be taking that model input very lightly compared to GFS, GEM or ECM.

M.T. Cranium

The GEM model continues its earlier trend of being similar to the GFS except for a slightly closer track and also clearer indications of a spread out wind field due to the phasing of the storm with an intense jet stream. Comparing regional and global GEM gives only a 2 mb intensity factor today compared to 5 mb yesterday -- but given the 950 mb prediction from GFS, if we take a GFS-GEM compromise I would consider the map to deliver strongest winds well into the land area of northwest Ireland instead of taking them out to sea.

Awaiting the ECM now with great interest.

The NHC track from 15z (as noted by other posters) seems to have been nudged south from previous outlook also, the linear extrapolation takes it over 55N 17W but assuming a slight curve that could be more like 55N 15W as shown on the GEM.

Bottom line is this -- if you live in Clare, Galway, Mayo, Sligo, Donegal, Derry, north Antrim or nearby parts of other counties, and not in some deep valley with hills off to your southwest, you should expect storm or hurricane force wind gusts between 0600 and 1500 hours on Monday. If you live in a region including most of Ulster, Leinster north and west of Dublin, or west Munster, you should be on alert for gusts between gale and storm force in a slightly later time frame. If you live in the southeast, you may be off the hook for now.

gbee

60 mile an hour gusts ~ Only MT

Redsunset

Yes track getting more precise now,or perhaps we'll get another spanner in the works

Pangea

It's the story of our lives isn't it checking threads to see if Ireland can get some interesting bit of weather, nothing is ever certain when you leave on an island on the peripheral of Europe. Looking forward to the storm now, its like waiting for the Greenland express. Those were the days.

fizzycyst

I may be mistaken, but did Jean just say that seas would be higher on the east coast than south and west during the Katia event?

Pangea

fizzycyst wrote: »

I may be mistaken, but did Jean just say that seas would be higher on the east coast than south and west during the Katia event?

You are mistaken.

redsteveireland

Pangea wrote: »

It's the story of our lives isn't it checking threads to see if Ireland can get some interesting bit of weather, nothing is ever certain when you leave on an island on the peripheral of Europe. Looking forward to the storm now, its like waiting for the Greenland express. Those were the days.

" all aboard":D

It's a real edge of the seat thriller at the moment.

JanuarySnowstor

ECM says no and keeps it offshore
I've seen enough evidence now today to be pretty certain this will be an average storm confined to the NW.
Next.....

M.T. Cranium

You can follow Katia's progress east to the south of the Canadian coastline on this link:

http://www.weatheroffice.gc.ca/data/satellite/goes_ecan_1070_100.jpg

and an animated loop can be found here:

http://www.weatheroffice.gc.ca/satellite/animateweb_e.html?imagetype=satellite&imagename=goes_ecan_1070_m_..................jpg&nbimages=1&clf=1

The current position (18z) is approx 40N 64W.

Agreed that ECM is nothing too dramatic compared with the other models discussed.

On subject of coastal water levels, have been informed that low tides along the west coast generally occur around noon on Monday, with high tides close to 0600 and 1800h. This should result in a high tide at 0600 being extended and about 0.5 metres above normal, not much of a drop to the expected time of low tide as any storm surges will replace the normal drop in water levels to some extent, then another period with water levels rising to 0.5 metres or so above normal high tides late afternoon. There may be some minor flooding as a result but I would expect the main risk to be battering waves in areas open to a southwest direction as large swells combine with 10-15 metre waves.

One thing is for sure, all ships to port Sunday afternoon on the west and northwest coasts. South coast will see slight rises in tidal levels throughout the day and east coast only marginally different, some low tides could be unusually low with water driven out by strong west winds.

dsmythy

Pangea wrote: »

It's the story of our lives isn't it checking threads to see if Ireland can get some interesting bit of weather, nothing is ever certain when you leave on an island on the peripheral of Europe. Looking forward to the storm now, its like waiting for the Greenland express. Those were the days.

When it comes to windstorms we are invariably disappointed

Pangea

Looks like things have gone a bit sour in here...

Harps

I've been away for most of the past 2 weeks so not really followed this aside from checking here once or twice so its a nice surprise to find that we might actually get a decent storm! A quick look at the models and it seems to be tracking further north than before but still a notable event either way

200motels

I don't think it's going to be the storm that some had hoped for but sure you never know.

Iancar29

I COME HOME FROM WORK AND EVERYTHING GOES DEAD!..... WHAT DID YA'S DO THIS TIME!?>.....

slowburner

The swallows started a massive southward migration from Ireland to day. I think it's about a month earlier than usual (maybe more).

I suspect they know something that we don't.

Pangea

M.E has got the finger out.

Weather Warning

Issued at 09 September 2011 - 20:00
Weather Advisory
Stormy weather expected on Sunday night and Monday with southwest winds gusting to between 100 and 130 km/hr - strongest in coastal counties of Connacht and Ulster.
Extremely high waves expected on southwest, west and north coasts with wave heights of between 6 and 10 metres possible.

Valid from :11/09/2011 21:0
Until :12/09/2011 21:0

Iancar29

Pangea wrote: »

M.E has got the finger out.

Weather Warning

Issued at 09 September 2011 - 20:00
Weather Advisory
Stormy weather expected on Sunday night and Monday with southwest winds gusting to between 100 and 130 km/hr - strongest in coastal counties of Connacht and Ulster.
Extremely high waves expected on southwest, west and north coasts with wave heights of between 6 and 10 metres possible.

Valid from :11/09/2011 21:0
Until :12/09/2011 21:0

Woah! ... never seen a warning from them given so far out! haha

Pangea

What were the highest gusts last year?
I think I remember seeing 120 or maybe 130 kmph on a met eireann forecast last year (mid November).
If top wind gusts are 130 it wont be anything I haven't seen before but maybe it will get stronger.

fizzycyst

I think the 18z has put the mockers on everyone I think, lets wait for the 00z and i bet it'll be an upgrade again. Oh how this reminds me of last winter:pac:

Iancar29

Pangea wrote: »

What were the highest gusts last year?
I think I remember seeing 120 or maybe 130 kmph on a met eireann forecast last year (mid November).
If top wind gusts are 130 it wont be anything I haven't seen before but maybe it will get stronger.

Ye i think it was 76 ( mph ) ... THat was during the Carmen storm that mise and winger_pl went to "welcome to ireland" ha

snow ghost

As dusk began to fall this evening I witnessed terrifying spectacle I have rarely encountered before – an ominous sign of impending doom – people everywhere were staring above them as a black dense cloud of tens of thousands of crows streamed from the coast inland. It was like a milky way of black crows; a crow highway that I thought would never end.

If the crows are fleeing, I think we could be in for a major storm that will probably cause widespread devastation.

Iancar29

snow ghost wrote: »

As dusk began to fall this evening I witnessed terrifying spectacle I have rarely encountered before – an ominous sign of impending doom – people everywhere were staring above them as a black dense cloud of tens of thousands of crows streamed from the coast inland. It was like a milky way of black crows; a crow highway that I thought would never end.

If the crows are fleeing, I think we could be in for a major storm that will probably cause widespread devastation.

Seriously?.... why not take a pic????????????