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10-09-2010, 22:01   #1
 
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Thunderstorms and possible tornadoes Saturday

As discussed in the Convective thread, this one deserves its own thread.

Things could be very interesting in the eastern half of the country tomorrow, with everything pointing to frequent thunderstorms, and even a good chance of tornadoes! Surface heating under the deepening upper trough leads to CAPE in the 500-1000J/kg range, with low eq. temperatures and strong windshear meaning frequent heavy thundery showers. The chart below shows the "Significant Tornado Parameter", which takes a lot of these parameters into account and spits out where conditions are conducive for tornadoes to develop.

I'd say ESTOFEX may give a Level 1 in their forecast later.

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10-09-2010, 22:09   #2
 
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ESTOFEX 21.04 utc update:



A strong upper trough over the NE Atlantic will shift eastwards towards the British Isles, leading to cold air convection over Ireland and parts of UK. The cold front of this low pressure system seems to be not very active on Saturday but this may change on Sunday. Isolated showers and weakly electrified thunderstorms are well possible but severe weather should be unlikely.

One to watch.
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10-09-2010, 22:10   #3
 
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Estofex showing general yellow t-storm area for Ire/UK tomorrow. No level 1.
They've been wrong before though.
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10-09-2010, 22:10   #4
 
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Quote:
Originally Posted by Deep Easterly View Post
ESTOFEX 21.04 utc update:



A strong upper trough over the NE Atlantic will shift eastwards towards the British Isles, leading to cold air convection over Ireland and parts of UK. The cold front of this low pressure system seems to be not very active on Saturday but this may change on Sunday. Isolated showers and weakly electrified thunderstorms are well possible but severe weather should be unlikely.

One to watch.
OH YOU BEAT ME TO IT XD
Anyways this forecast is very lenient
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10-09-2010, 22:13   #5
 
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Originally Posted by Wertz View Post
Estofex showing general yellow t-storm area for Ire/UK tomorrow. No level 1.
They've been wrong before though.
They have, and it could well be updated later on tonight or in the morning. I have been keeping an eye on this potential myself, and it is worth keeping an eye on for sure.
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10-09-2010, 22:14   #6
 
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Hmmmm, I thought they'd say more than that. They're usually spot on, but yes, let's hope they've underestimated this one (but I betchya they haven't!)

CAPE and LI at 15Z tomorrow, showing the situation at its peak. With upper ridging approaching from the west, any showers should die out fairly quickly as the evening wears on.

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10-09-2010, 22:22   #7
Iancar29
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NOT FAIR!

IM IN WORK 12-9 2moro!!

IF ANYTHING STARTS TO HAPPEN IM GOIN OUTSIDE ON A "EXTRA LUNCH BREAK! "
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10-09-2010, 22:28   #8
 
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This looks like the usual thundery showery day Ireland usually gets in the summer imo. Might do some storm chasing tomarrow if this hits Arklow
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10-09-2010, 22:28   #9
 
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HIRLAM 18z cloud chart for tomorrow 13z:



potential still there, but what I think is keeping ESTOFEX erring on the side of caution is the timing of the ridge moving in (as Su noted). Still, could be an interesting day for some.
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10-09-2010, 23:30   #10
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Quote:
Originally Posted by Deep Easterly View Post
ESTOFEX 21.04 utc update:



A strong upper trough over the NE Atlantic will shift eastwards towards the British Isles, leading to cold air convection over Ireland and parts of UK. The cold front of this low pressure system seems to be not very active on Saturday but this may change on Sunday. Isolated showers and weakly electrified thunderstorms are well possible but severe weather should be unlikely.

One to watch.
as usual will b a non event ,on a brighter note big brother is finaly over for ever
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10-09-2010, 23:33   #11
 
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as usual will b a non event ,on a brighter note big brother is finaly over for ever

Horray
In terms of the showers there is still most likely the chance of some thundery downpours occuring except probably not as widespread.
Any thunderstorms affecting anyone yet?
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11-09-2010, 00:11   #12
 
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and I'm supposed to be taking the kids to the zoo tomorrow around lunch time.... hmmm!
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11-09-2010, 08:02   #13
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ME forecast pretty muted for today, especially if you are in the east.

Bright and breezy today with sunny breaks and occasional showers. The showers will be heavy across the midlands north and west of the country with the risk of thunder, but some parts of Leinster and east Munster will remain mostly dry.
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11-09-2010, 09:02   #14
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I can see those first showers arriving from the west. They will probably skirt past north and south of me as usual. Here's hoping for some action. For anyone.
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11-09-2010, 09:13   #15
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I think the situation is still potentially volatile today.

The first batch of showers has out-run the upper support and aside from one cell now approaching Louth, the cluster has died out. The upper trough is near 12 W at 06z and will be near 10 W by 12z, 4 W by 00z. This means it should be over eastern Ireland by 18z. The strongest convection should be just ahead of that feature in a growing area of positive vorticity. Sunshine during the morning hours will be helpful in getting the lapse rates steeper.

All things considered, I think the earlier outlook from SC and others will work out well and some heavy showers and thunderstorms will develop, but for Dublin in particular the timing would be best around 3-5 p.m., so anyone looking for an earlier opportunity to chase or take pictures might be well advised to look around Athlone to Laois or western Kildare noon to 1 p.m., that's about where I would expect some good development to take place.

There might be thunder before that in western counties, and the whole situation is mildly unstable so would not rule out other clusters further south and southeast.

Not sure how long I will be watching, my forecast thread has this potential covered but I would appreciate it, if any regulars would post updates there if storms are brewing.

The other big weather story may be the very strong winds possible on Monday night and Tuesday as the jet stream is indicated on several models as being intense across far northern Ireland and Scotland by 06z Tuesday, and then this drops further south during Tuesday. Although this is not ex-hurricane Earl, it is some of the energy that broke away from that storm which tracked up west of Greenland this week.
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