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

On that run, "this little lady" is actually the remains of Hurricane Katia.

Just rain and a bit windy on that run because it weakens as it approaches Ireland.

That is really far into unreliable territory though. Ex-Katia could be a thousand miles to the northwest on the next run at that tme.

Pangea wrote: »

Hats off to Tazio, your thread was ahead of its time

+1.... I think we should use this thread for next weeks event:)

Well not fine as in sunny but fine as in not very stormy

how long do you's think it will take the media to jump all over this with headlines like " Hurricane Katia to batter Ireland" etc..

Pangea wrote: »

I'm not familiar with Debbie, was the damage bad?

edit: Just found this.
http://www.met.ie/climate-ireland/weather-events/Sep1961_hurricane-Debbie.pdf

Has it any similar features with Katia or was Debbie stronger?

Double edit:
Debbies 50th anniversary next week, maybe Katia is here for the celebrations! :pac:

Debbie never headed far across the atlantic after forming and approached Ireland from the south so be hard to compare like for like I'd imagine.

I think I might extend my visit home to Belmullet this weekend :pac:

Tazio you have very interesting ideas on the weather. This is the place for you;)

Perhaps some of the others could answer your query but I think this storm is losing some of its potential already damn it.

Good luck with baby. We have 2wins and very busy. Cant tell you any more as its a weather thread

Min wrote: »

Isn't it the case that the higher opne lives above sea level the higher the wind speeds?
So how does it work for lets 100m, 200m or 300m above sea level?
Is there a general rule when it comes to increased wind speeds and elevation?

?

yes i think so.
i believe pressure gradient, the Coriolis effect(?) and friction play a part in wind strength and direction. so, yes the higher up you go the less friction there is from the surface, so the wind speed will be stronger.

howlinwolf wrote: »

hi all......just my opinion but i think katie will weaken even more before it gets here.yesterday nhc had it still as a hurricane north between iceland and ireland but today it already changed and has it as an atlantic storm hundreds of miles before it gets here,i think it will probably weaken further:(. is it possible for this hurricane to strengthen and maybe stay as a cat 1 hurricane as it reaches ireland or are our waters just too cold for that to happen?

It actually picked up a bit of strength overnight. It is a long way from Ireland yet though as you say.

nacho libre wrote: »

Yes it likely would be, because encountering land causes surfaces friction, which reduces wind speed. That is why counties further inland are usually less windy than Mayo and Donegal.

Generally though wind at height is greater because it only has to deal with molecular friction.

YEP, quite right indeed..
Generally speaking wind speed increases with height above the surface as the frictional force of surface diminishes with height. The friction imposed on air mechanically slows the wind and diverts its direction. The friction layer is the layer of air that is influenced by friction caused by the surface. The friction layer varies in height across the Earth, but for the most part lies within about a kilometer of the surface.

At 72 hours a significant storm in our southwest approaches.

And a significant remnant of a hurricane

cross-posted from Hurricane Katia thread

I have the feeling that reader interest will swing from this thread to the "Monday threat" thread so I plan to post forecast discussions related to Ireland in that thread from now on.

Katia came very close to ocean buoy 41044 last night and at one point around 06-07z the buoy was in the eastern eyewall and reporting wind gusts to 93 knots or 107 mph.

Katia seems to have regained a bit of strength in the past 18 hours and looks to be heading slightly east of due north near 70 W, about to be swept into the fast flow extending from south of Nova Scotia to north of Ireland.

The NHC gives a Monday 12z position at 59.5N 10W on its latest outlook which would place the strongest winds around 57N 8W but the GFS has the centre just about in that position which would place the strongest winds over Donegal. Since the GFS depiction may be slightly weaker than the NHC's implied map intensity (from their maximum winds) I would estimate the GFS 12z charts to be predicting sustained winds near 55 mph and gusts near 80 mph or 70 knots from 0600 to 0900 Monday. A storm as strong as the NHC forecast in the GFS position would give sustained 60 mph, gusts 90 mph or near 80 knots.

Will be making more extensive model comparisons later on this thread.

GEM shows an intense storm heading across Donegal Bay on a track about 1-2 deg south of the GFS. If it verified, it would create a severe storm across almost all of Ireland on Sunday night into Monday. Winds could gust as high as 80 mph in many regions and to 100 mph in coastal west and northwest as well as exposed higher inland sites, from the map depiction. The key element is a very strong jet stream forced south by phasing of an arctic vortex dropping southeast towards the Rockall marine zone at storm time. With the recent good form of this model, and with the GFS trending in a similar direction, the situation looks very ominous to me. Bear in mind also, comparing RGEM to GGEM (regional 48 hour on a finer scale, global on a coarser grid) the 48h pressure difference near Newfoundland is 5 mbs, meaning the actual storm captured on a finer model grid is then 5 mbs deeper. So the depicted 966 mb low for Monday 12z could be closer to 960 mbs. (position on that about 56N 7W).


UKMO due around 9 p.m.

ECM due around 9:30 p.m.

NOGAPS due around 10 p.m.

Will edit this post for GEM results but anticipating a number of other posts will post the UK, ECM and NOGAPS input together around 10 p.m.

12Z GEM...

The GEM would bring a really strong core of winds to much of Ireland and of particular note, the capital would be struck very hard.

Its position and movement is almost ideal for intense winds in the greater Dublin region.

Just one run of one model and at T+96hrs, a long way to go before it could come off.

Some people I talked to today didn't even hear about the storm coming.
If it is going to be dangerous I hope people will be aware and with the uncertainty the media might not like to put themselves out for criticism.

Somebody just said to me that there will be snow from October onwards though :rolleyes:

Damaging winds would still result from that ECM 96hr.

I would anticipate gusts to max 65mph overland and max 75mph on west coast.

An important thing to note as this system appears it will take a closer hit at the country
is that trees are still fully covered. There will be significant numbers of fallen trees even
if a weak system pushes through.

A few days ago, a number of large branches fell in the high winds. The max gust recorded
at DUB AIR was 43 knots or circa 47mph.

cherryghost wrote: »

It'll probably be reported on the RTE Weather tonight or tomorrow. Met Eireann have already forecast severe or damaging gusts countrywide for Monday.

There was a warning on Jean Byrnes forecast before 7.
She said very strong winds but didn't elaborate really.

High tide is 6.30am Monday for Donegal Bay. What can we expect as regard as storm surge ?