Subtropical low - effecting North Island, 19-21st April

David · Unread post by **David** » Sun 19/04/2009 13:09

Metservice are saying rain and strong winds Monday-Thursday but the models keep showing no rain on Wednesday or Thursday with each new run...

Philip Duncan · Unread post by **Philip Duncan** » Sun 19/04/2009 13:26

David I was thinking the first low will probably bring rain Mon/Tues...then perhaps a more settled spell Weds and early Thurs then the next spell of rain Thurs pm and Friday/Sat. This is a very difficult low to predict timing wise I feel.

Auckland very rarely has rain for more than 24 hours at a time though.

Thunder · Unread post by **Thunder** » Sun 19/04/2009 17:43

Thinking there could be some very heavy and thundery falls about Northland tomorrow particularly eastern areas at this stage, very high CAPE figures and low LI's, haven't seen that for a while. Lets see how it tracks, a small shift could move it out to sea.

Nev · Unread post by **Nev** » Sun 19/04/2009 21:08

2.5mm here in the last hour.

Tornado Tim · Unread post by **Tornado Tim** » Mon 20/04/2009 02:57

Seems like this low is going over the North of the NI and is bringing unstable air over to the East.
During this time rain will scattered over the NI.
Once the Low passes, GFS is suggesting another lot of unstable will cover the NI.
Update: Latest GFS Is suggesting really good CAPE Levels for the North of the NI and a LI of -3.

DP Dpr is low at the moment, only 1.5Â°C.
Indicating rain is on its way...

Willoughby · Unread post by **Willoughby** » Mon 20/04/2009 03:10

I have split posts from the GAW thread relating to this weather event.

As details on the secondary (deeper) low appear sketchy at this stage a new thread should be created by anyone that would like to speculate or forecast on that low.

Thanks

Nev · Unread post by **Nev** » Mon 20/04/2009 07:04

Good idea Foggy!

Some sporadic falls here last night, but looks like the rain has settled in now - 6.5mm so far.

I see the Kerikeri PWS is up to 38mm since midday yesterday, most of which fell this morn.

Michael · Unread post by **Michael** » Mon 20/04/2009 07:51

Just drizzle here,wind only moderate,good wind direction except that annoying decidous yellow huge tree dropping large twigs that faces due east.16Â°.

Vertigo · Unread post by **Vertigo** » Mon 20/04/2009 08:16

wow, >1000 J/kg, thats pretty good for NZ. im suprised there isnt a severe thunderstorm warning out, but i guess the conditions over land arent as favourable.

NZstorm · Unread post by **NZstorm** » Mon 20/04/2009 08:39

yes, some good CAPE numbers progged for Northland today by the gfs (1200j/kg). Have to see whether there is the low level forcing (convergence) to push up any tstorms over Northland today. Looks like Auckland misses the instability.

Tornado Tim · Unread post by **Tornado Tim** » Mon 20/04/2009 11:45

Waikato is getting a nice dumping on with rain, been quite constant since 1 AM this morning.
30.6mm in Matangi.

Manukau heads obs · Mon 20/04/2009 12:12

down in the taupo area at the moment
only spitty rain here so far

Michael · Unread post by **Michael** » Mon 20/04/2009 16:00

Coolish day here Min 14Â° max 17Â° SSE fresh at times,overcast with a few light showers.Love to pour roundup in that tree!

Dale · Unread post by **Dale** » Mon 20/04/2009 16:36

13mm since last night with 10 of that falling before 0900. Its been blowing its nuts off all day funneling through the Bombays & temp hasnt moved past 17Âºc all day. Light mizzle at present.

David · Unread post by **David** » Mon 20/04/2009 17:17

Very unexciting here with with just 12mm so far and an easterly breeze (umbrella was under no threat after all, lol). Interestingly GFS has completely removed the late week / weekend low out of the picture...

NZ Thunderstorm Soc · Mon 20/04/2009 18:21

Michael wrote:Coolish day here Min 14Â° max 17Â° SSE fresh at times,overcast with a few light showers.Love to pour roundup in that tree!

Poor Tree

JohnGaul
NZThS

Nev · Unread post by **Nev** » Mon 20/04/2009 19:45

David wrote:...Interestingly GFS has completely removed the late week / weekend low out of the picture...

Not sure which run you're looking at David, but it seems GFS has it sliding down off to the west of the country late week, then under the S.I. on Sat/Sun night.

Mostly light-rain/drizzle here today, also bringing my total to 13.3mm. SE'ers are really starting to pick up here now though. Might be a little wild tonight...

NZstorm · Unread post by **NZstorm** » Mon 20/04/2009 20:21

Yes, looks like high prressure over NZ will keep the low later in the week out in the Tasman. Looks like Monday will be the next chance for deep moist convection over the Auckland area. That instability forecast for Northland today didn't verify. The warm moist unstable air looks to have passed laregly offshore to the N of the country.

Myself · Unread post by **Myself** » Mon 20/04/2009 20:36

Yes NZstorm, from comparing what happened with the MS charts, the lightning strikes were concentrated in the narrow warm sector offshore to the east of Northland

What crossed over Northland was apparently an occluded front, and had some isolated thundery activity but nothing like what was out to sea

spwill · Unread post by **spwill** » Mon 20/04/2009 20:54

The warm moist unstable air looks to have passed laregly offshore to the N of the country.

The moist air has stayed away this Autumn, average dewpoint temps must be well down, reflected in the dry and cooler than normal Autumn we are having.
I flew into Auckland from Melbourne this evening , a very dry landscape around Melbourne while the Auckland area looked very green from the air despite rainfall being well down here for the last couple of months.

Nev · Unread post by **Nev** » Tue 21/04/2009 09:01

A little calmer here this morn, but I see Tiritiri Matangi recorded 61km/h at midnight (96km/h in the Colville Channel). Still on 12.5Â°C at 9am this morn, compared to a low of 16Â°C the previous night.

Manukau heads obs · Tue 21/04/2009 09:07

only 8C at our place first this morning, alot of cold air still to move N (but which might though stay out on the western side)
also odd that we have a ESE wind direction but Ricky is more southerly

David · Unread post by **David** » Tue 21/04/2009 09:16

Manukau heads observer wrote:only 8C at our place first this morning, alot of cold air still to move N (but which might though stay out on the western side)

Interesting...around here low was 11.6Â°C early this morning.

Razor · Unread post by **Razor** » Tue 21/04/2009 11:04

At the risk of being picky...its "affecting" on "effecting"

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Subtropical low - effecting North Island, 19-21st April

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