Re: General September Weather
Posted: Sat 16/09/2017 13:35
Its rumbling around the Tasman - active multi cell clusters travelling eastward.
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Re: General September Weather
Posted: Sat 16/09/2017 16:34
The NW wind that returned mid afternoon killed any chance of showers, but i see there were some weakish cb's to the south and huge smoke cloud near Hanmer. Monday is looking good for a descent amount of rain though
Re: General September Weather
Posted: Sat 16/09/2017 19:10
Nice fine day here with some weak but interesting Cu humulus to the west/NW, but nothing much to "wet your pants" about. 
Re: General September Weather
Posted: Sat 16/09/2017 21:01
Tasman sea lively with thunderstorms tonight .See Metservice have put risk of small tornadoes for the West Coast for tomorrow morning
Re: General September Weather
Posted: Sun 17/09/2017 07:47
Front due across Auckland early evening today with some heavy squally rain. My expectations for a thunderstorm however are lower now than a day or two ago due to fairly weak lapse rates on the front.
Looking like a good soaking tomorrow for Canterbury. Been a wet season down there for sure.
Looking like a good soaking tomorrow for Canterbury. Been a wet season down there for sure.
Re: General September Weather
Posted: Sun 17/09/2017 08:23
Re: General September Weather
Posted: Sun 17/09/2017 13:17
Electrical activity is ramping up to the west 
Re: General September Weather
Posted: Sun 17/09/2017 14:15
Heavy rain and thunderstorm with small hail 1130-1200 .Got 10mm of rain in 10minutes .Was wondering at one point whether the house was going to be hit by a tornado .Steering at the anemometer at the time, nope only 34 knots there so just a squall- straight line winds going through
Re: General September Weather
Posted: Sun 17/09/2017 14:37
Yea those forecasted lapse rates have weakened significantly over the last few days.
Still should be a fairly good chance of a storm tonight. Northland has the best divergence and better lift.
I see Metservice has issued a Severe Thunderstorm Watch - mainly outlining the risk for severe squalls.
Metservice Severe Convection Desk wrote: This watch affects people in the following weather forecast districts:
Northland
Auckland
Great Barrier Island
Coromandel Peninsula
Waikato
Waitomo
Taumarunui
Bay of Plenty
Rotorua
Taranaki
An active front is expected to reach Taranaki late this afternoon and then cross the North Island during the evening. Thunderstorms are likely with and following the front, these thunderstorms will bring heavy rain or showers, strong winds gusting 100 km/h, hail and the risk of a small tornado. There is also a moderate risk that a few of these thunderstorms could become SEVERE, producing damaging winds of 110 km/h or stronger or a damaging tornado.
Wind gusts of this strength can cause some structural damage, including trees and power lines, and may make driving hazardous. If any tornados occur, they will only affect very localised areas.
Re: General September Weather
Posted: Sun 17/09/2017 15:42
Been a partly cloudy day in Auckland and currently 19C. No sign of any frontal cloud yet. But front showing up well on radar!
Re: General September Weather
Posted: Sun 17/09/2017 15:55
Very active squall line now on the west side of the North Island. Just counted around 200 CG's and anvil crawlers in the last 60 minutes. Lift index has been underestimated by most of the models at this point in time IMO. Cloud tops have increased to around -50c on the squall line, probably a few good water spouts will spawn from the current observations.
Re: General September Weather
Posted: Sun 17/09/2017 16:32
Some pre-frontal cells just coming across New Plymouth atm I see, Lightning activity fairly average atm, with a good proponderance of +CG, meaning the charge distribution is getting away from the main cell, most probably due to the Jet.
Will be interesting to see the progression of the front into tonight.
Frontal lift is usually underestimated by models as the index only takes into account the surface. Better to use B4LLI, MLCAPE and TT in combo rather than use soley SFC based indexes.Cyclone Tracy wrote: Lift index has been underestimated
Will be interesting to see the progression of the front into tonight.
Re: General September Weather
Posted: Sun 17/09/2017 19:22
A sudden downpour with the front, rain rate up to 130mm/hr. Thought I heard one distant rumble but not 100% sure.
Re: General September Weather
Posted: Sun 17/09/2017 19:48
Just on phone to my Silverdale Spy, heard several very heavy downpours taking place there while we were speaking.
Re: General September Weather
Posted: Sun 17/09/2017 21:14
The front was a flop Lightning wise, hopefully the beefy showers behind have a bit more spark....
Re: General September Weather
Posted: Sun 17/09/2017 21:49
Had a couple of sparks here, 16mm and a bit of hail. Some decent gusts on the squall line.
Re: General September Weather
Posted: Mon 18/09/2017 02:48
Steady rain atm. Back from Europe now so will be more active. May also explain why I'm up at 2:47am... 
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Re: General September Weather
Posted: Mon 18/09/2017 06:43
Heard a rumble to the west about 5.15am. Looking like a cold day with max 14C and scattered wintry cb.
Re: General September Weather
Posted: Mon 18/09/2017 07:01
Certainly wet here. 21mm so far and still steadily bucketing down
Re: General September Weather
Posted: Mon 18/09/2017 09:41
great storms that rolled in yesterday evening. loudest cracks of thunder but overall the last few weeks have had lots of storm days. 
Re: General September Weather
Posted: Mon 18/09/2017 10:56
Something big is brewing in my opinion towards the end of September, early October. Antarctic surface temps are dropping like a stone, tropics are holding above average. Keep an eye out on the models for a mid latitude cold core cyclonic gyre in the 960's to 970's hPa to attack NZ in the next few weeks.
Re: General September Weather
Posted: Mon 18/09/2017 11:15
Sounds interesting 
Rain has got quite heavy here in the last half hour
Rain has got quite heavy here in the last half hour
Re: General September Weather
Posted: Mon 18/09/2017 11:40
Cold core systems are usually higher pressure, and that fits better with the current weather intelligence, so I would suggest higher than usual air pressures south of NZ in the next few weeks and frequent breakdowns in the westerly flow over the country.Cyclone Tracy wrote: ↑Mon 18/09/2017 10:56 Something big is brewing in my opinion towards the end of September, early October. Antarctic surface temps are dropping like a stone, tropics are holding above average. Keep an eye out on the models for a mid latitude cold core cyclonic gyre in the 960's to 970's hPa to attack NZ in the next few weeks.
Re: General September Weather
Posted: Mon 18/09/2017 11:58
What is MS seeing in regards to tomorrows thunderstorm outlook? I've only peeked at GFS quickly but cant see anything to justify a huge moderate risk area of afternoon buildups.
Re: General September Weather
Posted: Mon 18/09/2017 12:17
26mm of rain since 6am here to midday. Still chucking it down. Street flooded a bit again.