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Possible Thunderstorms, Eastern NI, 31st December

Posted: Thu 30/12/2010 23:13
by Tornado Tim
Looks a moderate to high risk for some Thunderstorms around the BOP area and Eastern Waikato on the 31st December.

The 00 GFS Run, has a nice and healthy amount of CAPE around the area and outlines winds will come from the WNW to NNW.
Shear seems non existent so this is a pulse thunderstorm setup (unless a decent sea breeze occurs).

Ideal Location for a thunderstorm based on what I have seen i would say Kaimai Ranges through to Rotorua.

Since the Upper atmosphere at 500mb isnt that cool, a decent amount of DTSH will be required for setup to kick off.

RH and DP's are expected to be more than suffice for convection.

So we will have to see how it pans out :)

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 06:01
by Manukau heads obs
southerly wind has arrived here already
at the surface anyway....clouds are not moving much above that...
so there could be some convegence occur in the waikato even today?

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 08:53
by NZstorm
Problem with today is we have drier air invading the NI and pushing into the BOP late afternoon. Previous runs of the gfs where suggesting a slower incursion of the drier air. I think if a storm does manage to develop today it will be in the ranges between Whakatane and Gisborne. There is a 300mb jet (60-70kts) there which will help fire up any cb that does develop.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 08:56
by spwill
See what pops up on the afternoon convergence over the eastern high country.
Cooler SW conditions here in Auckland, less humid. 19C, dewpoint17C.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 09:06
by NZstorm
The next run of the gfs will be interesting.

I remember doing a New Years Eve chase over the central North Island a few years back. Got a nice storm with even a tornado and also with 1cm hail. The tornado was in the distance, when I first saw it I couldn't believe it and it took a few minutes to find a vantage point to photograph it. By then it had weakened to a funnel. The instability didn't come in until after 6pm and the mid level winds where strong making for some good shear.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 09:09
by tgsnoopy
The car is full of gas & the batteries charged. Most promising day so far from my perspective, but it's looking to me like I'm going to have to travel to it. Just trying to shake my overhang.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 10:24
by Tornado Tim
Some Altocumulus Castellanus here.

Thats a good sign :)

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 11:18
by David
spwill wrote:Cooler SW conditions here in Auckland, less humid. 19C, dewpoint17C.
Dewpoint 19C here now ;) Just as humid as yesterday

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 11:59
by Michael
SW hasnt really kicked in here yet,so quite humid here too,guess it will come up in the arvo,always between 2 and 6pm when it does.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 13:00
by Tornado Tim
Nice 20°C DP atm :D

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 14:30
by NZstorm
The 18Z gfs didn't look positive with nothing developing over BOP or Gisborne.

The air looks particularly stable over Auckland with some very flat stratocu, pretty much as expected.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 14:39
by Manukau heads obs
DP is actually slowly dropping here with the onshore southerly
now only 13C or so here

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 15:53
by tgsnoopy
Nothing happening that I consider worth chasing around here unfortunately.

Have started my next overhang so no chasing possible now, knowing my luck it'll spark up now.

Still a couple of weeks from the usual storm mid January.

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 16:09
by Tornado Tim
tgsnoopy wrote: Still a couple of weeks from the usual storm mid January.
Yup January seems to be the month for storms :)

Of note: A convergence line seems to be over Northland atm, wonder if anything will come of it?

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 18:10
by Tornado Tim
Heavy Showers developing in Southern Waikato now :)

Re: Possible Thunderstorms, Eastern NI, 31st December

Posted: Fri 31/12/2010 23:00
by tgsnoopy
Nothing happened over my side of the Kaimais. Dew point dropped away, temp was high. No convection worth looking at that I could see.