Moist unstable airmass NI 26-29th March

NZstorm · Unread post by **NZstorm** » Sun 26/03/2017 08:43

Starting a thread for observations next 3 days.

Today a front moving slowly south over Northland to reach Auckland midnight.

Monday afternoon should see convergence developing from Northland to central NI. GFS showing MLCAPE 500 j/kg+ .

spwill · Unread post by **spwill** » Sun 26/03/2017 16:57

One or two thunderstorms showing up over Northland last hr.

NZ Thunderstorm Soc · Sun 26/03/2017 17:45

Interesting to see what rainfall totals will be as compared to when I was up there a fortnight ago.

Probably get more thunder sounds that I heard at Kumeu.

spwill · Unread post by **spwill** » Sun 26/03/2017 18:07

NZ Thunderstorm Soc wrote:Interesting to see what rainfall totals will be as compared to when I was up there a fortnight ago.
Probably get more thunder sounds that I heard at Kumeu.

Good instability numbers tomorrow, if we can get good convergence ? we will hear thunder
MS shows Whangarei with 21.4mm recently

NZstorm · Unread post by **NZstorm** » Sun 26/03/2017 18:09

A see a PWS near Whangarei Airport showing 30mm in the last hour.

Nev · Unread post by **Nev** » Sun 26/03/2017 22:59

Great thunder a lightning show out in the Gulf atm…

David · Unread post by **David** » Mon 27/03/2017 01:27

Very heavy rain here with 30 mm last hour. Hopefully won't cause more issues in the Hunua dams

Nev · Unread post by **Nev** » Mon 27/03/2017 06:32

Some fairly heavy falls here after a great lightning show last night - ended up with 44mm in the 6 hrs to 1am this morn. Below are just the CG's Blitzortung picked up in the 15 minutes before 11pm…

Blitzortung NZ - Mar 26, 10.30-11.00pm.png

Nev · Unread post by **Nev** » Mon 27/03/2017 06:57

I see Whangaparaoa also recorded over 80mm overnight, including 36.4mm in the hour to midnight…

NZstorm · Unread post by **NZstorm** » Mon 27/03/2017 07:05

Nev wrote:I see Whangaparaoa also recorded over 80mm overnight, including 36.4mm in the hour to midnight…

Impressive totals.

I have caught 40mm here for the event.

jamie · Unread post by **jamie** » Mon 27/03/2017 07:35

Just over 20mm here last night.

Where is the best place to be this afternoon?

David · Unread post by **David** » Mon 27/03/2017 07:39

Nev wrote:I see Whangaparaoa also recorded over 80mm overnight, including 36.4mm in the hour to midnight…

69mm here with a max hourly fall of 35.2mm - pretty close to my station record of 36.4. Was intense briefly around 1.30am, weather station hit a rain rate of 189 mm/hr.

jamie · Unread post by **jamie** » Mon 27/03/2017 08:52

Sounds like the rain was heavy enough that it would have washed more sediment into the water in Hunua. I would imagine Auckland will now face further water restrictions.

Nev · Unread post by **Nev** » Mon 27/03/2017 09:24

Not often you see a moderate T-storm risk covering most of the North Island…

MetService - Thunderstorm Outlook

Valid to: Midnight Monday 27 Mar 2017
Issued at: 8:51am Monday 27 Mar 2017

A low over the Tasman Sea directs a moist northerly flow over the North Island.

Currently, convection with heavy rain and localised downpours is affecting southern Coromandel Peninsula, Bay of Plenty and Taupo and there continues to be a moderate risk of thunderstorms there this morning and afternoon, with a low risk of localised downpours of 25 to 40mm per hour.

As temperatures warm during the afternoon, a low risk of thunderstorms develops over most of the North Island and the northwest Nelson area. The low risk continues into the evening for the North Island, but eases late afternoon for Nelson. For a time in the afternoon, the risk of thunderstorms increases to moderate for areas between Whangarei and Palmerston North, with a low risk of downpours for Waikato, Waitomo and Taumarunui. If these thunderstorms occur,localised heavy rain is likely with intensities of 10 to 25mm per hour, or 25 to 40mm per hour in downpours.

No other areas of severe convection or thunderstorms are expected.

MetService T-storm Map - Mar 27.gif

NZstorm · Unread post by **NZstorm** » Mon 27/03/2017 09:27

jamie wrote:
Where is the best place to be this afternoon?

Depends on how the convergence sets up, we are looking for a NNE to converge with a NNW. While the convergence may not look that significant I would still rate today as relatively high risk for Waikato.

spwill · Unread post by **spwill** » Mon 27/03/2017 09:47

Fine conditions currently in Auckland which is always encouraging.

jamie · Unread post by **jamie** » Mon 27/03/2017 11:58

jamie wrote: Where is the best place to be this afternoon?

Looks like im in the box seat by being in Hamilton. MS have a low risk rectangle down western Hamilton. I will chase anything decent this afternoon.

Razor · Unread post by **Razor** » Mon 27/03/2017 12:25

jamie wrote:
jamie wrote: Where is the best place to be this afternoon?
Looks like im in the box seat by being in Hamilton. MS have a low risk rectangle down western Hamilton. I will chase anything decent this afternoon.

Keep it away from the cricket please

Nev · Unread post by **Nev** » Mon 27/03/2017 13:04

Yeah, I see MS have refined today's T-Storm Outlook map a little since this morn…

MetService T-storm Map - Mar 27, 11.53am update.gif

spwill · Unread post by **spwill** » Mon 27/03/2017 13:33

Certainly humid today, dp19C.
Some cumulus clouds around, photo

Tornado Tim · Unread post by **Tornado Tim** » Mon 27/03/2017 14:58

The odd bit of weak lightning coming from the cells just east of Raglan around Te Uku in the last hour or so....

spwill · Unread post by **spwill** » Mon 27/03/2017 15:38

A towering Cu line just east of here, some heavy looking showers along it, Cb off to the SE on the line

David · Unread post by **David** » Mon 27/03/2017 15:44

spwill wrote:A towering Cu line just east of here, some heavy looking showers along it, Cb off to the SE on the line

Auckland airport has picked up 11mm from that heavier one

cbm · Unread post by **cbm** » Mon 27/03/2017 17:01

Razor wrote: Keep it away from the cricket please

Amazing how the shower lines went just 5km either side earlier. Luck might have run out with this next line, looks on target. Groundsman will be fretting over the radar images right now.

EDIT: This line looks like it might just skim away to the East. If this line misses probably will get to finish out the day, light permitting.

jamie · Unread post by **jamie** » Mon 27/03/2017 17:07

Pouring here with torrential rain. Neighbour just sent a pic of a funnel cloud that would have been right over my house. Will post in a few mins.

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