Tasman Low- Storms and Rain - 4th to 9th Nov

Tornado Tim · Unread post by **Tornado Tim** » Sun 03/11/2013 16:19

Further Discussion about the Developing Tasman Low can go here..............

jamie · Unread post by **jamie** » Sun 03/11/2013 21:17

Looking forward to this week. Our first real summer set up of the season.

David · Unread post by **David** » Sun 03/11/2013 21:29

GFS showing Lifted Index -2 to -3 and CAPE above 500 Wednesday afternoon, but it's looking to be cloudy and wet so not much daytime heating...

treetop · Unread post by **treetop** » Mon 04/11/2013 06:35

king country across to East cape more likely a focus for storms, given the increased heating /assisted lift and convergence.

NZstorm · Unread post by **NZstorm** » Mon 04/11/2013 07:01

Thunder looks likely over Northland/Auckland/Coromandal with the front late Tuesday into early Wednesday.
The upper air is cold 500mb-23C/lase rates 7C and strong forcing so that should produce lightning. Small hail possible.

Western Waikato looking good Wednesday afternoon. Just need to get the heating which should happen.

jamie · Unread post by **jamie** » Mon 04/11/2013 07:50

This sort of setup is reminding me of one in about October or November 2004-ish. We had a brilliant storm over western Waikato build over the hills and then sweep eastward over the basin. That setup had a similar low (probably slightly tighter low and possibly deeper) mover across the north island.

Tornado Tim · Unread post by **Tornado Tim** » Mon 04/11/2013 09:56

Manuwatu is another place that looks favourable for storms later on this week. High Cape and low shear meaning there is the potential for severe muticell storms (strong outflow gusts and assoc microbursts which contain very heavy rain)

Nev · Unread post by **Nev** » Mon 04/11/2013 15:21

NZstorm wrote:Thunder looks likely over Northland/Auckland/Coromandal with the front late Tuesday into early Wednesday.
The upper air is cold 500mb-23C/lase rates 7C and strong forcing so that should produce lightning. Small hail possible.

Not surprisingly, MS in fill agreement

MetService - Severe Thunderstorm Outlook

Valid to: Midnight Tuesday 5 Nov 2013
Issued at: 10:42am Monday 4 Nov 2013

An active front is expected to move over the top of the North Island late on Tuesday. There is a high risk of thunderstorms ahead of the front over Northland late afternoon and evening, spreading down to Auckland in the evening and overnight. These thunderstorms are expected to be accompanied by heavy rain and strong wind gusts around 110km/h. There is also a low risk that severe thunderstorms may develop with tornadoes and wind gusts in excess of 110km/h.

Elsewhere, no risk of thunderstorms or significant convection.

MetService Severe T-storm Outlook Map - Is. Nov 4, 10.42am.png

Tornado Tim · Unread post by **Tornado Tim** » Mon 04/11/2013 20:34

Wednesday is still looking positive for storms for Waikato with high numbers of CAPE and good moisture and lift.
The forecasts soundings are suggesting there is the potential for good shear however the steer or mid level flow is weak making any potential sufficient shear non existent (hence why the SHEAR values on sounding look weak).

Still looking like a potential severe multi cell storm day at this stage.

NZstorm · Unread post by **NZstorm** » Mon 04/11/2013 21:12

Yes, does appear that shear could be lacking Wednesday afternoon. That'll keep the hail size down although I wouldn't rule out marble.

A good shear number to use is the 0-5km shear. It is the difference between the surface wind vector and 5km wind vector and expressed in knots. The Americans use 0-6km shear also referred to 6km bulk shear.

ben g · Unread post by **ben g** » Tue 05/11/2013 07:15

Lots of moisture pouring in on the nor easterly from over the Hauraki gulf this morning

ImageUploadedByTapatalk1383588868.009923.jpg

Manukau heads obs · Tue 05/11/2013 07:26

thunderstorm and race day!

spwill · Unread post by **spwill** » Tue 05/11/2013 08:17

Guy Fawkes night tonight

The dewpoint temperatures are not particularly high with this system, dewpoints 12 -13C but the upper air is quite cold. I see next week we could see higher dewpoints , 17C around a High, would be our first taste of Summer here.

Orion · Unread post by **Orion** » Tue 05/11/2013 08:20

ben g wrote:Lots of moisture pouring in on the nor easterly from over the Hauraki gulf this morning

Great picture - very soggy-looking

Tornado Tim · Unread post by **Tornado Tim** » Tue 05/11/2013 08:51

Latest Outlook:

Metservice wrote: An active front is expected to sweep southeast over Northland and Auckland this afternoon and evening. There is a high risk of thunderstorms slightly ahead of the front and with the front in the far north this afternoon and then extending south over the north of Auckland this evening. These storms could be accompanied by heavy rain 15-25mm/hr, strong wind gusts 90 to 110 km/h and possibly small tornadoes.

There is a moderate risk of SEVERE thunderstorms slightly ahead of and with the front over the east of Northland this afternoon and evening and the northeast of Auckland this evening as indicated on the map. These storms could be accompanied by damaging wind gusts in excess of 110 km/h, tornadoes and downpours, 25 to 35mm/hr.

Daytime heating is likely to generate some showers over the Tarararua Ranges this afternoon and there is a low risk that some of these could be thundery with hail.

Elsewhere, no thunderstorms expected.

The front is still active according to NZAPStrike/Blitzortung, will see how the situation pans out for you Auckland folk

David · Unread post by **David** » Tue 05/11/2013 08:52

Latest outlook has the risk slightly more north, i.e north of central Auckland now...

tilly123 · Unread post by **tilly123** » Tue 05/11/2013 10:07

This looks interesting, if only I lived in Auckland

jamie · Unread post by **jamie** » Tue 05/11/2013 11:08

tomorrows outlook looks fairly decent too.

spwill · Unread post by **spwill** » Tue 05/11/2013 11:51

Tornado Tim wrote: will see how the situation pans out for you Auckland folk

A case of just watching now. Some low level instability around Auckland this morning with some showers developing. 18C, dp 14C.

KiwiWeather · Unread post by **KiwiWeather** » Tue 05/11/2013 11:59

Some activity in Dargaville right now.

Manukau heads obs · Tue 05/11/2013 13:36

have had a couple of good heavy shower lines come through here

spwill · Unread post by **spwill** » Tue 05/11/2013 16:58

A couple of gusty showers here.
Some isolated storm activity over the top Northland last hr

littleheaven · Unread post by **littleheaven** » Tue 05/11/2013 19:03

Crikey, the Metservice thunderstorm outlook for tonight contains the text "damaging tornadoes possible" which I don't think I've ever seen before.

Manukau heads obs · Tue 05/11/2013 19:17

I have seen that wording before

the front on the sat image has been looking much better compared to the rain radar...
i.e cold cloud tops....but not much under those blown off anvils

David · Unread post by **David** » Tue 05/11/2013 19:23

Just cleaned my rain gauge before the rain arrives tonight, the spiders sure go crazy with their webs at this time of year! Some fireworks already being set off... I prefer nature's fireworks (thunder and lightning just in case I have to make that clear

)

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