Lows and cool change, Apr 26 - May 3

[Michael]

Looks as if may will start cooler especially in the South and unsettled in the west by this depression.

[NZstorm]

yes, looks like a particularly interesting set up. Looks good for heavy snow to low levels in inland Canterbury to Southland. Also some squally thunderstorms /hail over the north of the country. Early days ofcoarse.

[NZ Thunderstorm Soc]

ECMWF have a cumbersome low over us around that period, so things may be interesting

JohnGaul
NZTS

[gllitz]

Yeah, looking pretty yucky, and I am supposed to be going down south to Q'town and Dunedin during that time with family visiting from the States, too...driving back to CHCH on the 1st... Will need to keep an eye out on this one...

[NZstorm]

Very cold air looks to start affecting the South Island from Wednesday, latest GFS suggesting snow to around the 300m mark. GFS 850mb forecast temps here for Thursday 9am.

[David]

Yeah the 1st May is looking very interesting, GFS has the 500mB temps for N Island around -26C!! Upper air hasn't been that cold for some time...seems we may get the whole package of wild weather - very strong southwest winds, squally showers, and maybe thunderstorms and hail! Looking forward to it (GFS predictions better not change much!)

[NZstorm]

The GFS has a cold pool of below -30C at 500mb level west of North Island Thursday. Will this verify. We can only hope so.

[jamie]

WOW thats looking good and very nasty!!

[Manukau heads obs]

also some good weather coming down from the north over this weekened....weak tornadoes possible in the thunderstorm outlook for Northland....

[tgsnoopy]

Hmm, we have a number of very large dental caravan's to move in preperation for the coming second term on Thursday and Friday.

Let's hope the conditions wait until Saturday Then I can chase any potential stuff that's local.

[Manukau heads obs]

with the warm tasman sea temperatures and this very cold pool alot, sure looks like there will be great potential for beefy showers....as long as the airmass is not too dry though...which it will tend to be, coming from so far south...
ecmwf wants to have a more ESE flow eventualy develop , with a westerly to the north....sort of the same situation that resulted in the tornadoes in taranaki last year...

[spwill]

The GFS has a cold pool of below -30C at 500mb level west of North Island Thursday

latest run is less cold (suprise suprise) still looks like an extended period of generally unstable weather coming up, tending warm in the North to finish April

[jamie]

This looks good!!

[NZstorm]

latest run is less cold

GFS is dredging air up from high lattitudes though so I would say the very cold scenario should come back into play in future runs.

still looks like an extended period of generally unstable weather coming up,

Yes starting this weekend ion the north. Hopefully this warm front coming in over the weekend can turn thundery. GFS has LI -3 for Auckland Sunday with surface dp 19C so potential is there.

[Manukau heads obs]

I guess need a thread for the current weather....
anwyays, I think the frontal band slowly moving onto the NI is ripe to explode....once the jet stream to the north moves closer
keep your eyes on it lads

[Cameo1]

Yes its definitely looks interesting up there at the moment

[gopolks]

Whats the latest for canterbury?

[spwill]

looks active to the north of NZ currently.
Overcast 19C here

[Michael]

Whats the latest for canterbury?

NW By the looks

[gopolks]

Whats the latest for canterbury?

NW By the looks

hehehe, that changed completely from yesterday, from what they were predicting for Canterbury, for the start of may.

[David]

I see Metservice have a moderate confidence of rain reaching warning accumulations on Tuesday - for Northland, Auckland, Waikato, Coromandel, BOP and Central Plateau.

GFS has certainly downgraded the instability of the upper atmosphere for the start of May (500mB temps).

[Manukau heads obs]

was just up on the west coast hills....nice CB tops way to the NW (look better than what the rain radar shows them to be)

[spwill]

GFS has certainly downgraded the instability of the upper atmosphere for the start of May (500mB temps).

Surface moisture looks good though, will keep the thunder risk going. In for an interesting week

[NZstorm]

Yes, GFS is forecasting a dewpoint of 19C and LI -4.3 for Auckland tomorrow. I notice the dewpoint at Cape Reinga tonight is 20C. Hopefully the warm front coming through tomorrow will be the trigger for a thunderstorm or two.


Tuesdays front could be quite a thundery one also.

Still looks like its going to be an unstable start to May for the west and north of the NI despite a downgrade in the upper cold pool.

[David]

Geez what was MS thinking! They said persistent rain overnight and some heavy rain for this morning, and there was 1mm overnight - and only NOW it gets changed to a few showers. Can't see any thunderstorms eventuating out of what is on the rain radar at the moment....hopefully that all changes. A very warm night for the time of year with a low of 17 degrees.

Been checking the forecast models again, and most seem very certain at this stage of substantial rain on Tues/Wed. GFS still has the cold pool crossing over, and most of the models also predict the crossing of a less 'vigorous' low to follow late week