Storm Struck wrote: ↑Sun 17/12/2023 20:18
Unsure why every time there is a thunderstorm there is a warning issued? The real question is what is the difference between an average thunderstorm and a severe one .
For example today wouldn't stick out to me to be a severe day for storms. Perhaps it is severe in terms of the heavy rain in isolation causing localised flooding.
Could spend awhile dissecting this .
Yes. I have wondered about this, To me a severe thunderstorm would have damaging tornadoes associated with it from a large supercell and gorilla shaped hailstones which could cause lots of damage and maybe seriously injure a person or animal if hit by one and very vivid lightning to ground strikes that would set off fires, etc.
The warnings seem to correlate to how "tight" the core of white and above colours look and the speed at which it appears. Perhaps metservice are trying to get the word out that people should watch out for storms on a day where they seem unlikely and then appear suddenly?
I concur with what John said. Anything less than gorillas and it's just not dramatic enough for a stw.
Some info from the MS website about their thunderstorm criteria. I would say the vast majority of STW in New Zealand are triggered by the heavy rain aspect of the criteria.
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Warm day here with it getting up to 28.6C after some rain overnight and also some light rain late this evening, 4.2mm for today.
Not much wind here until the southerly came through at 3:40pm.
Low cloud and clagg settling in late afternoon and evening with the temperature cooling down to 13.9C at 10pm.
darcyplumb wrote: ↑Sun 17/12/2023 21:00
Some info from the MS website about their thunderstorm criteria. I would say the vast majority of STW in New Zealand are triggered by the heavy rain aspect of the criteria.
It's a bit of a weak analyze for a warning for severe thunderstorms as to compared to that could be more severe.
If it is life threatening maybe but I don't think so here in NZ.
I think they should put out a hail warning potential for growers in their Severe Weather Warnings,whose crops maybe affected by hail damage in their SWW ?
NZ Thunderstorm Soc wrote: ↑Mon 18/12/2023 00:22
I think they should put out a hail warning potential for growers in their Severe Weather Warnings,whose crops maybe affected by hail damage in their SWW ?
And what do you think growers would be able to do?
NZ Thunderstorm Soc wrote: ↑Mon 18/12/2023 00:22
I think they should put out a hail warning potential for growers in their Severe Weather Warnings,whose crops maybe affected by hail damage in their SWW ?
And what do you think growers would be able to do?
They should have ( if not already) big hail nets that they can cover small to medium size crops fast enough before a storm arrives to help protect crops in vicinity of severe hail storm.
Seems their was enough heating and surface moisture to overcome the warm upper air yesterday. 500mb temp was -14 but surface temps hoverd around 28 and dew points warm at 14 yesterday. Became very unstable quickly
And what do you think growers would be able to do?
They should have ( if not already) big hail nets that they can cover small to medium size crops fast enough before a storm arrives to help protect crops in vicinity of severe hail storm.
Seems their was enough heating and surface moisture to overcome the warm upper air yesterday. 500mb temp was -14 but surface temps hoverd around 28 and dew points warm at 14 yesterday. Became very unstable quickly
Logistically impractical. Hail covers need to be permanent, because the length of time and manpower it takes to put them in place and take them down again each time hail is expected is not workable. It takes a team of workers a week or more to put netting over grapevines, and they have specialised equipment to do the job.
There are no current prevention techniques in terms of hail, apart from the hail cannons which personally I don't like the use of.
I'm sure by using these things it affects the balance of all that is naturally supposed to happen here on earth.
TonyT wrote: ↑Mon 18/12/2023 09:09
Looks like a feast of widespread thunderstorms coming up from Christmas/Boxing Day onwards. I wonder how many of them will be severe?
TonyT wrote: ↑Mon 18/12/2023 09:09
Looks like a feast of widespread thunderstorms coming up from Christmas/Boxing Day onwards. I wonder how many of them will be severe?
Hopefully works out as you say. On holiday from Friday so plenty time to chase. Look forward to watching your live stream Monday briefing tonight
TonyT wrote: ↑Mon 18/12/2023 09:09
Looks like a feast of widespread thunderstorms coming up from Christmas/Boxing Day onwards. I wonder how many of them will be severe?
NZ Thunderstorm Soc wrote: ↑Mon 18/12/2023 00:22
I think they should put out a hail warning potential for growers in their Severe Weather Warnings,whose crops maybe affected by hail damage in their SWW ?
And what do you think growers would be able to do?
Claim insurance ?
They used to have hail cannons years ago. I don't know how effective they were.
Conclusion and future work
We claim that the numerical results presented in this paper are the first three-
dimensional simulational verification of the hail cannon. We showed that repeat-
ing a sequence of shock waves for a long time significantly reduces cloud vapor.
mikestormchaser wrote: ↑Mon 18/12/2023 08:16
Seems their was enough heating and surface moisture to overcome the warm upper air yesterday. 500mb temp was -14 but surface temps hovered around 28 and dew points warm at 14 yesterday. Became very unstable quickly.
Even though it was claggy last night, the ground was still quite warm. Even today, the footpath was quite warm even after last night's rain.
TonyT wrote: ↑Mon 18/12/2023 09:09
Looks like a feast of widespread thunderstorms coming up from Christmas/Boxing Day onwards. I wonder how many of them will be severe?
TonyT wrote: ↑Mon 18/12/2023 09:09
Looks like a feast of widespread thunderstorms coming up from Christmas/Boxing Day onwards. I wonder how many of them will be severe?
2.2mm of drizzly rain overnight.
Remaining generally cloudy all day but clearing up this evening.
Mild with light easterlies. 19.6C the maximum for today.
Indeed it is looking very wet through Christmas eve into early Christmas day at this stage. However with a broad low pressure makes the forecast jump around quite a bit in the lead up to Christmas.
Very warm the next few days, is also dependent on when the N-NW moderate flow shifts in tomorrow in terms of how hot it could be for Christchurch.
The dewpoint up to 20C here today, a dewpoint 19C overnight last night.
Looks like Auckland will have some sheltering on Xmas day in the northerly flow + ridging onto the upper NI, chance of showers but still a little early for a Xmas forecast.
Big difference between the east coast and inland South Island today - only about 18C max in Chch, yet 33C in Twizel. I was in the Methven and Ashburton Lakes area today, and while it was cloudy and cool about the coast and lower plains early and late, it was sunny further inland with temps in the low 20s. Nothing like Twizel, though the lakes area is about 600-700m asl. (around 200m higher)
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