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27-09-2010, 11:42   #1
maquiladora
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Wet & Windy Days Ahead (Sept 30th onwards)

It looks like we are going to get our first proper taste of Autumn later this week and into the weekend with some wet and windy conditions possible.

It's too early to tell just exactly how wet or how windy it will be but here is how things look at the moment.

Plenty of rain, heavy at times :





Low pressure bringing breezy/windy conditions :





Met Eireann outlook mentions:
Quote:
Thursday will be breezy, with rain spreading from the southwest, accompanied by fresh southerly winds. More rain will follow Thursday night, with a risk of some heavy falls. Southerly winds will strengthen further, with a risk of gales at sea.
Thats just how it looks at the moment, those charts will proabably look different by the time we get to Thursday, but its almost certain now we will be entering a period of wet and perhaps windy conditions for a least a few days.

Last edited by maquiladora; 27-09-2010 at 11:59.
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27-09-2010, 13:40   #2
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The trees around my way are heavily laden with leaves waiting to be blown off. This sounds like just the weather to do so.
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27-09-2010, 18:39   #3
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Originally Posted by maquiladora View Post
It looks like we are going to get our first proper taste of Autumn later this week and into the weekend with some wet and windy conditions possible.
Its been autumn a long time if thats the case
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27-09-2010, 19:06   #4
 
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Friday's looking like the worst day rainwise, but with such a dynamic situation in the the breeding ground for these systems upstream off the northeast US /Canadian coast, minor shifts will have huge consequences on what we get here. I would take anything outside 48hrs with a pinch of salt this week.

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27-09-2010, 19:26   #5
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12Z ECM showing a fairly strong low but keeps it out at sea.



As Su says you have to take all these charts with a pinch, the path and intensity of these lows change a lot on each run but the general trend is for a period of wet and perhaps windy weather ahead.
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27-09-2010, 19:47   #6
 
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This week is one where the likes of yr.no and weatheronline, etc. forecasts will be chopping and changing several times a day as each model run comes out. Some people here won't like to hear that!
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27-09-2010, 21:24   #7
 
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Compare the ECMWF run above to the German GME for the same time. The GME has the low 18hPa shallower, and about 700 miles further to the northwest. And the UKMO has it in a similar position to the ECMWF but 10hPa shallower. Seeing as Met Éireann use all of these models in their forecasting, now do you all see where the skill of a forecaster comes in??


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27-09-2010, 21:48   #8
 
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Interesting set up alright.

Tonight's ECM run is showing this low deepening to the NW of Ireland by almost 30 mb in the 24hr period between 18z Thursday and 18z Friday:

Thursday evening forecast:



Friday Evening:



the same model had the same forecast low moving right in over Ireland and deepening explosively while sitting right over the country which was not plausable at all.

Will be interesting to see how this develops in reality!
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27-09-2010, 22:14   #9
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i trust the ecm model predictions over the others.
pangea, if a low of 954 mb does pass to the northwest, make sure if you go out your toupee is glued on to your head
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27-09-2010, 22:19   #10
 
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It will be interesting indeed, as the Rosenbloom Rule of forecasting states that bomb cyclones like this one will follow a track to the left of the forecast model track, so we can expect it to end up even a bit further away from us. How things can go from good to bad in the space of a few hours!!
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27-09-2010, 22:24   #11
 
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It will be interesting indeed, as the Rosenbloom Rule of forecasting states that bomb cyclones like this one will follow a track to the left of the forecast model track, so we can expect it to end up even a bit further away from us. How things can go from good to bad in the space of a few hours!!
Interesting to see that the mean ensemble run has the low tracking further to the northwest than the standard determinstic run:



all up in the air still!

Just to add to that, the deterministic run can often be more accurate, but will it this time?????????????????????????
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27-09-2010, 22:28   #12
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I wonder how much it will have changed by thurday.
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27-09-2010, 22:40   #13
 
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One positive aspect in the event that this primary low does somehow end up in a more 'nomal' position closer to Iceland might be that we would be in a better position to get hit full on by potent secondaries should they form in the mid to west Atlantic. Vigorous shortwaves are rarely picked up on by the models beyond 72hrs so maybe this might be a straw to clutch on?
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28-09-2010, 01:05   #14
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Personally I would just like the Azores high to miraculously move up over us.
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28-09-2010, 09:16   #15
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Yeah most of the models seem to be in agreement with keeping that low well off to our NW now. Still possible for the models to change and bring it closer to us again but at the moment, as DE says, there is a better chance of us getting high winds from a secondary low with this setup looking like it does.
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