A Canterbury Thunderstormic WE

[NZ Thunderstorm Soc]

According to forecasts given from MetService, we are in for a Thunderstormic WE here in Canterbury
Lets see what happens or
Is it CAPE - able?

JohnGaul
NZThS

[gllitz]

According to forecasts given from MetService, we are in for a Thunderstormic WE here in Canterbury
Lets see what happens or
Is it CAPE - able?

JohnGaul
NZThS

Hmmm...CAPE only showing at 50 or so...with LI around 2...not all that favourable....for CHCH, anyway...don't know about further inland...

[Myself]

According to forecasts given from MetService, we are in for a Thunderstormic WE here in Canterbury
Lets see what happens or
Is it CAPE - able?

JohnGaul
NZThS

Hmmm...CAPE only showing at 50 or so...with LI around 2...not all that favourable....for CHCH, anyway...don't know about further inland...

I hope you mean -2...or this thing is over even before it began!
Remember though GFS CAPEs are not all that trustworthy, because it can't estimate ground temperatures very well at all (assuming it uses surface based CAPE).

[spwill]

Has been looking warm in the upper levels.

[Tornado Tim]

It has a chance, but the levels are are on the low end scale.
I usually go by a rough guide for CAPE as only 1 condition req for a thunderstorm, You need to factor in the other conditions such as sea breeze conversion, cold fronts undercutting the whole thing ect.
Guides for CAPE alone:
0-75 j/kg No thunderstorm
75-150 j/kg Possible thunderstorm
151-300 j/kg Likely thunderstorm
301-750 j/kg Definite thunderstorm
750-"x" j/kg Severe thunderstorm
This is only going by what I have seen in the CAPE models compared to how many thunderstorms eventuated from the CAPE Levels alone.
As from what I have seen it is possible: But looking at the pic below to christchurch residents it does not look good 4 you.
Merge in other factors and make your own mind up..

[Myself]

Yup, they are using surface values. So really the GFS has no clue. It is not factoring in whether there will be added moisture drawn in from the sea, and I bet they underestimate the surface temperatures. So the real CAPE is probably going to be more than that.
But really CAPE is just a number. Nothing beats having a sounding in front of you and doing the trace yourself, then you see if the CAPE is capped at low levels, or a very thin one that extends up high (and hence could get high cloud tops) but probably very marginal for surface parcels to ever get up there (due to mixing out).

[NZ Thunderstorm Soc]

Has been looking warm in the upper levels.

Thats what I thought, thinking nothing much will eventuate, mind you I haven't checked MetService's Thunderstorm outlook yet, as well, so I don't really know their prospective?

JohnGaul
NZThS

[CHCH Weather Chaser]

Tomorrow any activity will only be inland as a fine sunny day is forecast here in Christchurch. Sunday maybe....

[NZ Thunderstorm Soc]

Yes, I thought the forecasts for Canterbury in this morning's PRESS sounded a bit strange for tomorrow and Sunday?
How could you get thunderstorms around midday with a 31C temperature with SW and becoming NE in the afternoon?

JohnGaul
NZThS

[mikestormchaser]

Tomorrow any activity will only be inland as a fine sunny day is forecast here in Christchurch. Sunday maybe....

Yes id agree Mark! i don't think we will get a thunderstorm in Christchurch tomorrow, but again yeah inland would be the key.
Sunday though with a colder airflow moving in yes that sounds more promising.

[NZstorm]

There will be some decent convergence running up the interior of the South Island Saturday afternoon, onshore SE/NE winds converging with inland W. But there won't be enough moisture there to produce the instability for thunderstorms.

[tich]

Yes id agree Mark! i don't think we will get a thunderstorm in Christchurch tomorrow, but again yeah inland would be the key.

Towering thunderclouds should be easily visible from the Port Hills (or from high buildings in Chch) though.

[TokWW]

Ok - looking for photos tomorrow evening guys... I mean whether there is any build up or not. There may be a convergence inland but upper temps may not be cool enough... we'll all wait and see.

[Storm Struck]

More of an inland event if anything for tomorrow as i said before, with Sunday being the pick of the litter for the rest of Canterbury and Christchurch.
A more favourable cold southerly change going up against a moist onshore NE flow as the norm goes.
Yes it will be mostly fine tomorrow and warm, but there is likely to be some cumulus about in areas i would imagine maybe leading to a shower in the evening for the CBD and other eastern areas.
Can we be cheecky and get a 3rd thunderstorm day for 2009 why not aye.
Cheers
Jason.

[NZstorm]

Problem with Sunday is the southerly change leaves the cold upper air down in the south seas. But the southerly looks to run into some quite moist air over the bottom of the North Island Sunday evening so looks to be a thundery risk there.

[mikestormchaser]

Problem with Sunday is the southerly change leaves the cold upper air down in the south seas. But the southerly looks to run into some quite moist air over the bottom of the North Island Sunday evening so looks to be a thundery risk there.

all these things i wouldn't know of NZstorm its very good to know.. so i dont get my hopes up

[Thunder]

Very warm upper etc. I don't think Sunday looks any good. Perhaps, I say perhaps if those surface moisture figures and temps overcome the warm upper air then maybe an inland thunderstorm could be on the cards.

[melja]

Very muggy here in rangiora this morning with 22deg and 80% humidity so lots of mosture around.

[Storm Struck]

I still dont understand why MS are going for a greater risk today than tomorrow, when i think the slightly better chance is tomorrow if anything.
No signs of any development inland yet although they are saying late afternoon/evening.
Cheers
Jason.

[Storm Struck]

Just had a few random spots of rain out here with some weaker CU forms about, also abit of virga in the sky.
Looks like a few showers popping up further south on the 1pm radar.
Cheers
Jason.

[tich]

Shower activity seems to be concentrated south of about Timaru instead of the Canterbury foothills so far this afternoon.

[Lacertae]

Hey guys, is that some sort of a pileus ?

pileus1.jpg

pileus2.jpg

[Tornado Tim]

Sure is...

[Skywatcher]

I noticed some as well at about 19:40, also looking north.

[NZstorm]

Great photos! Looks like some elevated convection on the front which looks to have been sliding gradually north all day. Interesting.