Complex Trough and Thunderstorms - Apr 27-29

[Myself]

Easterly probably due to the low crossing the South Island last night. Situation is really very ugly with the other low forming to the west though. I guess the next batch of rain is in the northerly flow ahead of that new low.

[Manukau heads obs]

re the waitaki dams over flowing and 800mm of rain
due to the windflow/rain being very northerly? (more west/NW they dont get as much spill over?)?

[CHCH Weather Chaser]

Heavy to very heavy rain falling between Halswell and Rolleston. Yet here in Halswell and most of CHCH it is only light rain. We have had a sheltering affect or something most the day. I only have to drive 3 mins up the road and its pouring yet here its not even enough to register0.2mm at jeffs per 10mins. Just 4.4mm so far today in daylight hours with an additional 10mm between midnight and 5am this morning. Total -14.4mm

[Storm Struck]

Yes it is interesting how isolated the rain areas are, if you look at the radars for today the heavier rain was intially more North Canterbury before moving south of Christchurch this afternoon.
25mm since midnight here in the gauge, just a lighter rain now unlike around lunchtime.
Cheers
Jason.

[mikestormchaser]

It started out foggy here today in Christchurch with low cloud/drizzle.
It wasn't overly cold for starters but it got cold from about 10am when that S picked up.
To me was always to warm for sleet, and if it was there would of been a clear sight of a dusting on top of suger loaf hill.
Been steady rain here for most of the night, not sure if it will last though

cheers

[Storm Struck]

It started out foggy here today in Christchurch with low cloud/drizzle.
It wasn't overly cold for starters but it got cold from about 10am when that S picked up.
To me was always to warm for sleet, and if it was there would of been a clear sight of a dusting on top of suger loaf hill.
Been steady rain here for most of the night, not sure if it will last though

cheers

If going by the radars between 11am-3pm the heavier more concentrated falls were north of the city and inland, so any dusting of snow would be on the Foothills not the Port Hills which had little precipitation.
If i am correct this might have been something to do with the low wrapping in as it crossed Mid Canterbury This morning, the wind didnt turn SW here until midday along with a sharp temperature drop and what looked like very close to sleet intermixed.
Obviously Banks Peninnsula acted as a form of shelter for much of today.
Cheers
Jason.

[carrot]

-5 degrees forecast over night friday in some place, -3 for Chch forecast tomorrow night.

[Dale]

Not sure how other folks around AKL faired last night.. the runciman station up the road is only recording barely 5mm for the 24 to 0900 this morning.

10pm last night above Paerata the heavens opened with wave after wave of heavy showers, lasting near an hour & putting 25mm into the nylex. Must have been some pretty isolated stuff.. would be handy to have a radar archive of it. Have considered starting one but hourly updates are next to useless.. (when they even work)

[Manukau heads obs]

we did get some heavy rain here too, 5mm in a short period
the rain radar shows the most intense showers were indeed isolated

[Tornado Tim]

I think This Thread may need to be extended....
Im not sure about Auckland but here is getting good convergence. Cumulus Congestus popping up to the NE.
Update: Now there is definite lift in the clouds...
This is what it looks like:
Westerly has picked up and DP's have increased.

[David]

Not sure how other folks around AKL faired last night.. the runciman station up the road is only recording barely 5mm for the 24 to 0900 this morning.

0.7mm here overnight.

[Dale]

Lots of nice CJ's around the northern waikato this afternoon.. super strong updrafts & some rock solid back ends on a few of the towers which atempted to break the cap, but came forth with pileus when they did. Also noticed a couple of solid hailshafts in at least 2 of them.. with the 500 temps as they were it was no surprise really.. but the steering winds caught me unawares.

Lovely to see popcorn around today.. not from the microwave anyway.

*Ed:* Another 5mm out of one of them popcorn type thingys taking me to 31mm since around this time last night.

[NZ Thunderstorm Soc]

What are CJ's ?

JohnGaul
NZThS

[Dale]

Congestus...
Aussie slang, at least for South East Queensland storms.. see if i can find some reference on Jane's site somewhere (Melbourne Storm Chasers)

*Ed:* Could not find it on MSC but managed to on Weatherzone... in the glossary we put together going back near a decade now..

Cj
Cumulus conjestus. A particular style of cumulus cloud that gives observers great mirth. It has even been reported that groups will engage in boiterous joke telling and much laughter when conjestus is in abundance. The name is derived from the Latin and essentially translates to 'cumulus with jest' or 'cumulus with humour'.

[tich]

Dry and cloudy in Chch - no more rain (just drizzly showers in Chch) since about midafternoon. 9m Radar still shows band of precipitation inland. Mt Hutt webcam today showed quite abit of snow up there, but not as low as Castle Hill according to its webcam.

[CHCH Weather Chaser]

Rolleston weather station is forecasting a chance of snow tonight I think that can think again. Few more heavy but very small and very isolated showers showing. Little bit of formation south of the city. Only 0.8mm today and the total of this system up to around 19mm.

[NZ Thunderstorm Soc]

Rolleston weather station is forecasting a chance of snow tonight I think that can think again. Few more heavy but very small and very isolated showers showing. Little bit of formation south of the city. Only 0.8mm today and the total of this system up to around 19mm.

I recorded 23.6mm at my raingauge in Halwell for the Tuesday and Wednesday period, whereas 35.8mm fell here, so there was an ovbiously rainshadow effect from that and Jeff's rainfall readings as well. I haven't checked Bob Crowder's reading yet.

JohnGaul
NZThS