NZ Weather Forum

I thought it was about time someone started a topic dedicated to the likelyhood of a decent series of Tasman lows from around this Friday the 17th December onwards. Most of us have been watching the forecast charts with a tad of excitement given how long for most of its been since we last had a decent Low! 75 days for myself, not that I am counting of course!

Anyway going by what the general consensus is between the main forecast models, namely GFS, ECM and Metservice's model, it looks as though the area of high pressure that has been hanging around us is set to continue its march east (and maybe North too) and find a new hangout in the SW Pacific Ocean a good distance from us! This means the general area of low pressure that has been hammering the south East of Australia for the past few weeks will finally be able to head towards us and finally deliver a long period of wet weather. Unfortunately though for those away from the North and West coasts of both islands I feel this event will be marked more by the high temperatures you'll get rather than the rainfall.

The areas well exposed to the Northerly stream though should see heaps of rainfall from this system though and should see a vast improvement in soil moisture levels (though I'd imagine a few may swing from drought to flood given the amount of moisture expected to feed in from the NW). The main systems look like being a smallish low sucking moisture down from the Queensland coast on Friday the 17th as it heads SE from their towards our shores and then a much larger low moving ENE from the Tasmania region soon afterwards, reaching the mid Tasman by Monday or Tuesday. The Northerly flow ahead of this feature looks like developing a lot of rain to the West Coast of the South Island and given the Northerly orientation of this rain the East coast of the South Island looks like being very warm indeed on Monday and/or Tuesday, widespread temps in the mid 30's look a chance at this stage IMO. This would no doubt extend to SE regions of the North Island the following days.

As you can probably tell I am getting a wee bit excited about this event. though I have been taking the models outlooks with the obligatory bucket of salt it does look a lot more likely that we will finally see some movement from the high pressure feast we have been having to a diet consisting of more low pressure systems! Which I know is not everyones cup of tea but definitely it is for this rain starved New Kiwi who spent way too long in West Ozzie!

Tim S wrote:East coast of the South Island looks like being very warm indeed on Monday and/or Tuesday, widespread temps in the mid 30's look a chance at this stage

Also looking like northwest gales along with those high tempertures not good considering we are already quite dry. Hopfully there is a bit of spillover rain from this system. Still a few days out so things could change.

Heck!!
About time to get a low, Hopefully it stay in the models.......

it has headed south in the models now. the west coast will still get some good rain, but it wont be nearly as stormy methinks.

the next system moving off the aust coast should help it move more SE than S
the sat has been jogging position too by the looks, made it look like its moving south
alot of lee trough rain to the west of northland at the moment!
spitty rain so far only in the south waikato
dry pastures down here, must be the driest the waikato has been this early for a long time
drought declared in the waikato today...

This low is looking great for my neck of the woods, looks like the bulk of the rain will hit the western ranges due the more NE flow as the low travels closer to us but even so the warning does state 40-60mm for the Tasman bay region. Either way its good news for the Motueka and Moutere regions as these areas havent received more than around 20-30mm since September 30.

By the way, mods please feel free to change the date of the thread to start a day earlier as a lot of areas are already seeing some rain from this low it seems. (edit: I think I managed to do it myself, maybe. )

I'm just hoping that there's enough spill over that it makes it as far east as here,we can get some good rain at times from the NW but not if its more from the N.

Well looks like MS severe weather warning was spot on, currently sitting on 47mm here since it started around 1pm yesterday. Nice steady rain too, max hourly rainfall rate was only around 5mm/hr.

Going to be some massive falls on the ranges around here from this, highest I can see on the Tasman council site are just over 100mm at this stage.

64mm now.

You will be very pleased!

Sure am! 71.9mm now and looks to be almost the last of the decent stuff

I like the initial look for tomorrow!

Severe Thunderstorm Outlook wrote:Valid to: 12:00am Sunday 19 December 2010
Issued at: 11:10am Friday 17 December 2010

As a trough in the Tasman Sea moves onto the South Island the bulk of the rain should mainly affect northeastern and central areas of the North Island.
However, there is a moderate risk of afternoon and evening thunderstorms with localised heavy rain 10 to 25mm/hr inland from Northland to Manawatu, Wairarapa including Tararua District, also parts of Taranaki and Wanganui. This is surrounded by a lower risk (see chart).
A southeast change is forecast to move over Southland and eastern Otago in the afternoon and evening. It will probably bring some heavy showers but the risk of any thunderstorms is low at this stage.
No other thunderstorms are forecast although there could be a few heavy showers in inland Marlborough and north Canterbury.

tgsnoopy wrote:I like the initial look for tomorrow!

Yea! anyway couple of distant rumbles N E from here bout 15mins ago - humid as!!!! out there - sweet.

edit reason: closed quote tag.

Excellent, good to hear from you DT-NZ, it's been a while

Edit, spelling error.

Looks like the rain band is out to sea now. 6mm delivered to this area from the system starting last night. Very muggy outside and a warm afternoon in store as the sun will try to break through.

Auckland Airport is showing a dewpoint of 23C, I think the general dewpoint over the region is 20 to 21C.

Overcaste here, fresh NE, looks like heavy showers through parts of western Northland will move onto West Auckland soon.

Stopped raining here now still overcast and humid with 18 degrees and 91% humidity. Ended up with 4.5mm of rain.

spwill wrote:Auckland Airport is showing a dewpoint of 23C, I think the general dewpoint over the region is 20 to 21C.

I think that might be an error. The other day I saw 26C and 90% showing on the 1 minute conditions on the MS Auckland page. I reloaded a minute later and it said 57% (maybe their humidity sensor is playing up?)

reasonably heavy mizzle falling here which has meant all flights landing at the airport have been diverted, as I found out when my sister's flight was diverted to Wellington. Hopefully it clears soon, either that or just turns back to proper rain!

I have seen glaciated cb tops to the north this afternoon. But fairly overcaste low cloud again in Auckland.

Weak thunderstorm activity showing near Kaipara last hr and around 2pm this afternoon, nice area of rain has developed over southern parts of Northland, will be here in an hr.

IR shows cb tops to 35,000ft just north of Auckland . Very little lightning with it though.

ohh, good, that kaipara rain band should make it down onto us...
we already have had a heavy shower this arvo, so total rain is 22mm or so..and more on the way....
if we could get 50mm total that would be great!
currently in Inglewood...stready rain here today, but stopped for now

NZstorm wrote:IR shows cb tops to 35,000ft just north of Auckland . Very little lightning with it though.

http://www.metservice.com/national/warn ... torm-watch

Temperature is shooting up here now. Up over 20 with a dewpoint over 16. Sun is close to coming out now for the first time today.