General December Weather

[talbotmj15]

Interesting looking ahead GFS seems to be picking up a very deep depression getting down into the low 930s hpa up off the North Queensland coast. Certainly one to watch as it could develop into the first Cyclone of the season. At around the same time a very big low pressure system moves up and across the bight of Australia. Will be interested to see how this all plays out. Still a week away and given recent inconsistencies it will probably fall apart.

[NZ Thunderstorm Soc]

Looks likely this recent 'clagg' weather over us here in South Canterbury may clear as more anticyclones set to move in over, from the first week of December...
...but then there could be some "'rodents up your sleeve", ie Southerly changes, etc ?

[TonyT]

Interesting looking ahead GFS seems to be picking up a very deep depression getting down into the low 930s hpa up off the North Queensland coast. Certainly one to watch as it could develop into the first Cyclone of the season. At around the same time a very big low pressure system moves up and across the bight of Australia. Will be interested to see how this all plays out. Still a week away and given recent inconsistencies it will probably fall apart.

Solar equatorial coronal hole will be earth facing in a few days time, and these often seem to precede TC formation by about a week when surface conditions are right, so I suspect you are on to something. Plus add in CT's hints of action in the tropics early December and I think we might have a winner here.

[Razor]

So a continuation of the lottery we've had in November? Its been harder to pick than a broken nose lately

[David]

Metservice talking about heavy rain and gales in the upper NI on Dec 1st. Not seeing anything particularly noteworthy in either GFS or ECMWF however...

[Cyclone Tracy]

Watching this one closely. EC ensemble is fairly conservative 3 to 4 weeks out and considering the current tropical wave near the equator, Christmas to New Year is starting to look a little volatile for NZ.

[NZstorm]

Looks like Milford Sound may have todays Maximum with 26C.

[Razor]

13 of the last 14 days have received precipitation here of some sort. And 21 of the last 30.

Quite an amazing contrast to last years 50 day dry spell.

[melja]

Very la Nina

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[Razor]

Fascinating battle in our skies this morning. Blazing warm sunshine above, patch easterly clag to east and north and nice looking CB developments to the west. And large raindrops on the windscreen from that clear blue sky above on the drive into town

[NZ Thunderstorm Soc]

Horray!
At last a fine and sunny day with the NW kicking in and hitting 26C.
One or 2 Cu around but a generally fine and sunny day with heaps of blue sky which haven't been around since the 17th of last month.

[Richard]

Been a while since there's being strong NW winds, quite nice after so many days of gloom. 23 the high

[Razor]

We got to 29 here. Awesomeness

[melja]

18mm last evening I'm Rangiora.

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[Richard]

14 in total here

[NZstorm]

Looks warm to hot for inland parts of the country over the weekend and on Monday some 30C readings on the cards for inland North Island.

Cooler distured SW flow could be on the way for the middle of the month.

[cbm]

Looks warm to hot for inland parts of the country over the weekend and on Monday some 30C readings on the cards for inland North Island.

Cooler distured SW flow could be on the way for the middle of the month.

See that on the GFS but the EC has other ideas

Dec15_model_disparity.jpg

[Cyclone Tracy]

https://earth.nullschool.net/#current/w ... 64,-63.881

Low stratospheric polar vortex is breaking up as solar radiation increases. This is a normal seasonal cycle that starts dissolving the break off vortexes into the polar jet below. One interesting feature is that wind speeds are still quite high (120 to 140 km/h) in places which is most likely caused by the planetary waves propagating from the below troposphere.

Hard to pinpoint where (Maybe SE OZ to the Tasman) but IMO a large upper tropospheric cyclonic vortex is going to cut off into the mid latitudes. This is potentially what EC has been picking up on around December 16th to 24th in the Tasman. With the SST’s continuing to rise with this strong ridge moving in this weekend, warmer seas, a significant upper cold pool and moisture leaking down from the tropics is an explosive mix. Back to the popcorn

[TonyT]

https://earth.nullschool.net/#current/w ... 64,-63.881

Low stratospheric polar vortex is breaking up as solar radiation increases. This is a normal seasonal cycle that starts dissolving the break off vortexes into the polar jet below. One interesting feature is that wind speeds are still quite high (120 to 140 km/h) in places which is most likely caused by the planetary waves propagating from the below troposphere.

Hard to pinpoint where (Maybe SE OZ to the Tasman) but IMO a large upper tropospheric cyclonic vortex is going to cut off into the mid latitudes. This is potentially what EC has been picking up on around December 16th to 24th in the Tasman. With the SST’s continuing to rise with this strong ridge moving in this weekend, warmer seas, a significant upper cold pool and moisture leaking down from the tropics is an explosive mix. Back to the popcorn

I agree, but I think the timing will be a little later (impacts on NZ), around the end of the month.

[RODALCO]

Very nice structure, seen from Taharoto Rd Takapuna looking North. No activity on Blitz.

IMG_3417.JPG

Time 20:00 hours.

[David]

Took a couple of pics on my evening walk. Some nice Cumulus around. First is looking east towards Beachlands area at 7:30pm, second is looking north at 8pm.

[TonyT]

Wow!

If this comes off then we are sure in for an interesting summer. Get the umbrellas ready and the storm chasing vehicles fuelled up. And popcorn, must have popcorn handy.

[This is the latest ECMWF prediction of 500mb height anomalies for the December to February period. The intense blue colour over NZ shows significantly lower than normal predicted heights (equivalent to lower surface pressure and/or cold). It also suggests easterly anomalies, with higher than usual heights/pressure in the southern Pacific.]

[spwill]

I like interesting weather but lets hope it is settled over the Xmas /New year 10 day period.

Eastern parts of Auckland should get quite warm this weekend, mid twenties for the likes of Orewa

[jamie]

That’s interesting Tony, and is that a big shift from what you were seeing a month ago?


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[TonyT]

That’s interesting Tony, and is that a big shift from what you were seeing a month ago?


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Its a shift but if you've been following my thoughts on this summer then its really just a step further in the same direction I was already suggesting. If it comes off it would be a big shift for those expecting a classic EN summer.