Thunderstorms - 26-27th Jan

Tornado Tim · Unread post by **Tornado Tim** » Thu 25/01/2018 21:18

Good setup for tomorrow with east west convergence and favourable sfc moisture and temperatures.

Atmopshere unduly unstable throughout all of the Waikato into the BOP into Taupo.
Convective model parameters have remained consistent for the past 2 days which is assuring.
ML-CAPE Levels exceeding 1600j/kg, with TT 55 and solid convergence params.

SWEAT values are looking good also, some directional shear is evident through to 3 KM, though flow is relatively weak.

Karipiro is looking good Friday evening, Jamie you up for a possible chase?

Tim

jamie · Unread post by **jamie** » Thu 25/01/2018 21:21

Yep I’m definitely up for the chase if it’s firing. Baby due on 1 feb and looks like it’s prob going to be early so I just have to be on call during chasing.

jamie · Unread post by **jamie** » Fri 26/01/2018 06:46

Is this cloud representing a small cap? I can see steam rising from Huntly power station and it’s showing great signs of an unstable lower atmosphere until it reaches the cloud. This to me is a good sign to have a bit of a cap.

NZstorm · Unread post by **NZstorm** » Fri 26/01/2018 06:58

Looks to be an enhanced risk of thunderstorms over Waitomo and southern Waikato later today. The airmass is capped but the cap is likely to erode enough by late afternoon. Downpours of 50mm in an hour if cap breaks, modelling says it will.

Set up looks weaker over the North Island tomorrow Saturday and heat storms more probable over lower half of NI.

Tornado Tim · Unread post by **Tornado Tim** » Fri 26/01/2018 08:04

jamie wrote: ↑Fri 26/01/2018 06:46 Is this cloud representing a small cap? I can see steam rising from Huntly power station and it’s showing great signs of an unstable lower atmosphere until it reaches the cloud. This to me is a good sign to have a bit of a cap.

Going by Whenuapai's sounding which was taken about 7-8 hours ago, there is a cap indeed.

We dont want too much cloud as that will hinder the dtsh, but yes a cap is good at holding off the convection that doesnt have much punch.

jamie · Unread post by **jamie** » Fri 26/01/2018 08:46

It is clear to the south with cu in the sky.

Check out MS update for today. Condensed area of severe storms right over Waikato with hail to 20mm.

Chase is on! Any of you Auckland folk going to take the drive south? I suppose you will be battling the other 1m people heading south for the long weekend though.

Who from Hamilton area is up for a chase? Tim and I obviously are.

Tornado Tim · Unread post by **Tornado Tim** » Fri 26/01/2018 09:00

Yup its ON for sure!
High SWEAT Index is a big factor in the severe assesment, lots of water and possible strong downdrafts.

Metservice wrote:The combination of a very warm humid afternoon and light winds are expected to allow daytime cloud buildups to produce scattered heavy showers and thunderstorms about the central North Island and northern South Island this afternoon and evening.

The main risk of thunderstorms is about the Gisborne ranges from late morning,about inland areas from Waikato to northern Taihape, including Rotorua and Taupo,and also about inland parts of southern Marlborough, Nelson, Buller and northern Canterbury during the afternoon and evening. A low risk covers surrounding areas as indicated on the chart.

Some of these thunderstorms are expected to be severe producing localised downpours of 20-40mm/hr. Additionally, in the western North Island from Waikato to Taumarunui and northern Taihape where there is a high risk of severe thunderstorms in the late afternoon and evening, the storms may also produce hail up to 15 or 20mm diameter and wind gusts to 80km/hr.

Rainfall of this intensity can cause surface and/or flash flooding. Driving conditions will also be hazardous in heavy rain and hail.

No other thunderstorms or significant convection expected over New Zealand today.

spwill · Unread post by **spwill** » Fri 26/01/2018 09:03

I am in Hamilton today for a function early to mid afternoon. Tomorrow not looking good now up this way so I will try get out today.

jamie · Unread post by **jamie** » Fri 26/01/2018 09:15

Keen to meet up spwill?

spwill · Unread post by **spwill** » Fri 26/01/2018 10:13

jamie wrote: ↑Fri 26/01/2018 09:15 Keen to meet up spwill?

Yes, but I have a little bit of uncertainty to my day, all going well I should be free by 4pm.

NZstorm · Unread post by **NZstorm** » Fri 26/01/2018 11:04

I would chase today but I am going down to Timaru this afternoon for the weekend. Pity as it looks a good set up. You can't argue with 1800CAPE, should be some photogenic multicell storms. Cb tops to 40,000feet.

Willoughby · Unread post by **Willoughby** » Fri 26/01/2018 11:13

MetService T-storm outlook looks good: Te Kuiti - Taumarunui - Taupo triangle looks very ripe.

Tornado Tim · Unread post by **Tornado Tim** » Fri 26/01/2018 12:15

Thunderstorm Watch:

Issued by MetService at 08:49 am Friday 26 January 2018
Valid until 10:00 pm Friday 26 January 2018
This watch affects people in the following weather forecast districts:
Waikato
Waitomo
Taumarunui
Taupo
Taihape

The combination of light winds and a very warm humid afternoon are expected to allow daytime cloud buildups to produce scattered heavy showers and thunderstorms about the central North Island this afternoon and evening.

Between about 3pm and 10pm today (Friday), some of these thunderstorms may be severe about Waikato, Waitomo, Taumarunui, western Taupo and near Tongariro National Park with localised downpours of 20-40mm, hail possibly up to 15 or 20mm diameter, and wind gusts to 80km/hr.

Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.

Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain and hail.

Note: A Severe Thunderstorm Watch means conditions are favourable for severe thunderstorms in and close to the watch area. People in these areas should be on the lookout for threatening weather conditions and monitor for possible Severe Thunderstorm Warnings.

Interestingly they are reviewing at 2 PM...... looks like they leaving a little wiggle room alter the forecast in time.

Rogue · Unread post by **Rogue** » Fri 26/01/2018 14:57

Current highest temperature as per Metservice is 30.6 degrees in Taumaranui @2.57pm, which is in close proximity to a strong thunderstorm that has developed. Dew point about 22 degrees c

Willoughby · Unread post by **Willoughby** » Fri 26/01/2018 15:01

Big smuttering of bolts over northern Tongariro NP at the moment with that cell:

Capture1.PNG

jamie · Unread post by **jamie** » Fri 26/01/2018 15:02

Yea that’s a nice cell. Can see the top from the Firth of Thames.

Rogue · Unread post by **Rogue** » Fri 26/01/2018 15:10

Guessing this is thunder (or wind) being picked up on the Tongariro seismogram

2018_01_26_15_07_43_GeoNet_Volcano_Drums.png

Chris W · Unread post by **Chris W** » Fri 26/01/2018 16:46

Looks like 3 massive cells around Tongariro, Whakatane/White Island and Marlborough at the moment. The BOP 120km radar is very interesting right now, as is the Wellington one!

Thunder081 · Unread post by **Thunder081** » Fri 26/01/2018 17:17

Is anyone out chasing the north island storms?

Tornado Tim · Unread post by **Tornado Tim** » Fri 26/01/2018 17:41

In Karipiro watching cells develop to my east, convection forming to just to east, will have to wait a bit longer for the Waikato convection to fire.....

Richard · Unread post by **Richard** » Fri 26/01/2018 17:45

Looking forward to some photos you fellas

jamie · Unread post by **jamie** » Fri 26/01/2018 17:47

The air is very hazy due to the 21 dew points so hard to get clear views

Willoughby · Unread post by **Willoughby** » Fri 26/01/2018 17:49

Some lightning being picked up from that cell over the Mamakus now

Capture1.JPG

dogmelon · Unread post by **dogmelon** » Fri 26/01/2018 18:44

Three separate STW's at one. I've never seen that before. Have fun chasing and stay safe(clear air lightning).

Thunder081 · Unread post by **Thunder081** » Fri 26/01/2018 18:55

I'm looking forward to some photos too BTW if you look at the Taupo webcam on MS you can see the CB's forming near tongariro

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