Low risk of thunder for Canterbury Friday 15th - Sunday 17th

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NZ Thunderstorm Soc
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Unread post by NZ Thunderstorm Soc »

...another

JohnGaul
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Unread post by NZ Thunderstorm Soc »

a...another from West Melton
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Unread post by NZ Thunderstorm Soc »

a.a.a...another from outside Beckenham's Mitre 10.
The sky then cleared to totally fine conditions as the wind became more SW.

JohnGaul
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Unread post by mikestormchaser »

yeah nice pics john!. i clearly saw that last one!
Particarly over the port hills /BP way saw that very cold icy cloud.Nothing has looked very thundery to me today.
I never thought it would today ya could just feel what it was going to do.Might see the odd flicker out offshore tonight/ out to sea :( but i wouldnt think we will see anything onshore tonight. notice also the wind has gone NE
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Paul Mallinson
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Unread post by Paul Mallinson »

Interesting to see those pics John. Ah well, the development did occur in about the right place but it was probably held back not only by lowish dewpoints but the strong dry westerly flow probably continued over the top of the convection and held it back. Thats the impression I got from some of your pics.

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Unread post by NZstorm »

strong dry westerly flow probably continued over the top of the convection and held it back
I think the dry mid level air would favour convective development.

Problems in the upper air would have been thermodynamic, just not cold enough aloft to provide an unstable lapse rate. I notice things turned alot colder late in the day judging by Invercargills sounding.
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Unread post by Paul Mallinson »

Yes, you're probably right that it didn't get cold enough aloft - for the available surface moisture and strength of the surface convergence.

I see the southerly change got into Ashburton/Christchurch area about 2 hours after I had reckoned (5 and 6pm) and the surface values were: Temp about 11C and dewpoint about 6C, whereas I had gone for 14/6 at about 3pm. My earlier values may have powered the convection a little stronger but then it would have been a tad warmer aloft then! There's lots of trade offs in getting it right. (I see the southerly reached 29knots at Le Bons Bay at 5pm).

I think there is also some evidence to suggest that while there was low level convergence on the southerly (stronger over the sea) and therefore low level ascent, the dry westerly flow aloft may have had some descent in it and so acted to suppress the convection. The clouds in John's pictures did have a broad flattish look about them.

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Unread post by tich »

Sunny mild day so far out here near Akaroa - fohn effect of Alps blocking off the very cold showery weather that seems to be affecting the West Coast as well as the far south.
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Unread post by RWood »

Pristine here today, flow must be close to WSW or W. Yesterday started similarly but veered a bit towards NW after lunch and arch cloud cut off the sun after 2PM. The 10am satellite view certainly shows there are places that would be cold and showery at the time.
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Unread post by Storm Struck »

Might be an isolated shower or two this afternoon some weak CU out looks to be abit of moisture to the SW too.
Wind is currently NE and I would tend to think it will go SW later on with it being quite strong in the far south.
It never turned southerly here yesterday just westerly then NE.
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Unread post by Willoughby »

NZstorm was spot on, those thunderstorms eventuated around the Chathams this morning at around 2-3am.

Some hailstorms hitting Invercargill last night with a gale W.

NZDN and NZNV both reporting T/Cu and Cb this morning.
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Unread post by 03Stormchaser »

NZ Thunderstorm Soc wrote:....according to ECMWF, later next week looks quite interestering :)
JohnGaul
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Not any more, weak change to go thru Friday. Doesnt even look like it will produce a shower for us. Upper air getting far to warm aswell -20C.

Should be a Warm week, Gusty NW tues-thursday.
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Unread post by tich »

We're having showers out here on the peninsula this evening, but Chch could be missing out, with nothing recorded at Hillmorton so far.
Last edited by tich on Sun 17/09/2006 21:11, edited 1 time in total.
jeffsweather
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Unread post by jeffsweather »

tich wrote:We're showers out here on the peninsula this evening, but Chch could be missing out, with nothing recorded at Hillmorton so far.
Just went out to check the garage was closed and much to my surprise, ran into a few spots of rain. Seems have stopped now, didn't even wet the deck. Some stars visable so just an isolated and very light shower.
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Unread post by NZ Thunderstorm Soc »

Was out on the farm at West Melton today and there was the occasion 'few spits of rain' scenario from the rather glaciated sky that hang overhead, but there was no significant shower.

JohnGaul
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