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Thunderstorm Potential Early Dec 2009 in the North

Posted: Sat 28/11/2009 10:23
by Tornado Tim
GFS is plotting some nice unstable air out over the tasman atm, although the models are a little to far out to call it at this point of time.
A nice humid NW flow is expected to come with CAPE from the Tasman and drag itself over the north of NZ at this stage.
DPs are expected in the mid to high teens around early december with a expected cool 500mb temperature around Northland to South Waikato (around -15 to -18°C)
If some DTSH gets going we may very well have a "thunderstorm event".
I have attached a Skew-t chart for one of the "HOT" days:
Cross your fingers and lets hope it pans out... LOL

Re: Thunderstorm Potential Early December, 2009

Posted: Sat 28/11/2009 21:51
by David
Seems like instability coming up for northern area for possibly at least 4 or 5 days from 1st December. I made this meteorogram for Auckland here: http://www.ready.noaa.gov/ready/cmet.html

The text results for this output show that at the peak instability, CAPE is modeled at 1023 and 'Best 4 Layer Lifted Index' modeled at -3.4.

Let's dearly hope this remains in the models northerners :wave:
metgram28nov09.gif

Re: Thunderstorm Potential Early December, 2009

Posted: Sun 29/11/2009 09:21
by NZstorm
I like the 100kt jet stream in the north Tasman from early week. Thats always a good sign for some interesting weather over the North Island. Should see some major thunderstorm activity fire out in the Tasman next couple of days. Thunder chances reach the upper North Island Tuesday by the looks.

Re: Thunderstorm Potential Early December, 2009

Posted: Sun 29/11/2009 09:52
by tgsnoopy
Be careful, don't Jinx it... I'm not holding my breath, but it would be good to finally get a show. Pity I'm going to have a busy week by the look of things.

Re: Thunderstorm Potential Early December, 2009

Posted: Sun 29/11/2009 10:52
by Tornado Tim
As NZstorm said, A very nice Jet stream coming around soon:
That means the storms will have a bit of tilt on them, meaning that they can last longer :)

Re: Thunderstorm Potential Early December, 2009

Posted: Sun 29/11/2009 22:08
by jamie
Tazy sea is lighting up nicely tonight off the NSW coast.

Re: Thunderstorm Potential Early December, 2009

Posted: Mon 30/11/2009 08:03
by NZstorm
If there is sufficient heating tomorrow afternoon could see Isolated thunderstorms pop up from Northland to the Waikato. Surface dewpoints will be around the 17-18C mark and upper level air will show some cooling on today. I'm hoping we can get a bit of a surface NE going to converge with the general NW flow.

Re: Thunderstorm Potential Early December, 2009

Posted: Mon 30/11/2009 18:50
by KiwiWeather
Fingers crossed, Steven :-s

Re: Thunderstorm Potential Early December, 2009

Posted: Mon 30/11/2009 19:55
by jamie
whats the word on tomorrow. i dont really have time these days to go over all the models and work it out for myself. are there good chances of thunder storms developing around the waikato and other parts of the country tomorrow afternoon?

Re: Thunderstorm Potential Early December, 2009

Posted: Mon 30/11/2009 21:09
by spwill
some day time heating tomorrow would be good, see what the day brings

Re: North Island Thunderstorm Potential Early December, 2009

Posted: Mon 30/11/2009 21:11
by NZ Thunderstorm Soc
Good luck to you.

JohnGaul
NZThS

Re: Thunderstorm Potential Early December, 2009

Posted: Mon 30/11/2009 23:07
by Tornado Tim
MS have put some areas of Auckland and Waikato under a "high risk" but i am thinking that there is going to be a lack of DTSH and combined with that a warmish upper air temp. So if any CB's do develop i think it will be very hard for them to turn "lightning active".
I will have a look at morning models and then come back....
Heres a skew-t for Matangi around tomorrow at 4PM:
(it doesnt look good)

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 07:36
by NZstorm
Yes, the cloud cover puts a question mark on todays instability although it doesn't seem as bad this morning. Its good to see the surface flow NNE 10kts which is needed for convergence. Tim, given the good lowlevel moisture the upper air looks cool enough for convection. Should see isolated thunderstorms pop up this afternoon over northern regions. Trigger temperature looks to be around 23-24C mark.

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 07:38
by Manukau heads obs
unstable looking skies out to my west in the upper level clouds :)
even some Kelvin wave clouds too at one stage , good sign

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 07:43
by NZstorm
The gfs likes Northland with cape 800j/kg+ at 4pm. But cape is such a fluid number. It will come down to where the surface heating can occur.

Upper flow indicates any storms that develop will have some speed shear and will move quickly ESE.

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 07:48
by spwill
Great to see that thick low cloud has gone however a mid to high level cloud sheet is drifting down from the north , how will that affect the day.

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 08:18
by Peter
What does the acronym DTSH stand for?

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 08:52
by David
Peter that's day time surface heating ;)

Yes it's good to see the light NE breeze here this morning and brighter skies (although cloudy currently).

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 12:25
by Manukau heads obs
where do you find the thunderstorm outlook /watch on the new M/S web site now?
thanks :)

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 12:32
by David
Manukau heads observer wrote:where do you find the thunderstorm outlook /watch on the new M/S web site now?
thanks :)
http://www.metservice.co.nz/national/warnings/index
Then the various warning/watch pages are all there on the sub-menu :smile:

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 12:54
by Tornado Tim
Manukau heads observer wrote:where do you find the thunderstorm outlook /watch on the new M/S web site now?
thanks :)
Its hard to find eh Brian, heaps harder then it was b4.

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 13:52
by spwill
looks like the NW will keep any shower development east of here, some towering Cu in the east, Radar shows some weak showers Northland to Waikato.

Currently 25C dewpoint 19C , a very warm combination, not much in the way of sunshine this morn, afternoon is looking better for sunshine.

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 13:58
by Manukau heads obs
ah, I looked at the warning page but missed those links

have had a few showers here, and peaked at 22C despite cloud cover


http://www.metservice.co.nz/towns-cities/auckland

shows 1 minute updated temperature and wind info in the last 10 minutes
good :)

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 14:24
by David
24ºC here, wind is still light NE. Hopefully the NW doesn't push in all the way off the eastern coastline!

Re: Thunderstorm Potential Early December, 2009

Posted: Tue 01/12/2009 14:27
by NZstorm
The whenuapai sounding shows drier low level air than I was expecting to see. The low level dewpoint on it is 14C. Could that be an error?

Yes, the NW wind is kicking out the NE so chances of convergence look to be diminishing.