General July Weather

[Razor]

Magnolia's are in full bloom in Hagley Park. Early for sure!

[Bradley]

Quite a difference in between GFS and EC for the weather next Thursday-Friday for Canterbury, EC going for a fairly rigorous Souterly airflow with 10-20cm of snow down to 400m whereas GFS going for mildish temperatures and no rain at all. I see Tony has mentioned this potential snow bearing system on Facebook this morning so he must be putting some weight on EC's forecast...

Ignore the EC at your peril...

Fridays system has backed off significantly on EC, we are in for a very mild next 10 days by the looks of it, I’ve never seen such a mild June/July period with a lack of cold fronts before in Canterbury, this is going to be unprecedented by the time July ends...

[mikestormchaser]

Interesting to see on metservice the risk of thunderstorms in north Canterbury today.
Not so sure about the risks. But could be some heavy showers/ hail for a time mid afternoon?

[TonyT]

Fridays system has backed off significantly on EC, we are in for a very mild next 10 days by the looks of it, I’ve never seen such a mild June/July period with a lack of cold fronts before in Canterbury, this is going to be unprecedented by the time July ends...

The rain is still there, the cold isn't. So much for that big AAO dive. The atmosphere round here is behaving quite strangely at present.

[Bradley]

Fridays system has backed off significantly on EC, we are in for a very mild next 10 days by the looks of it, I’ve never seen such a mild June/July period with a lack of cold fronts before in Canterbury, this is going to be unprecedented by the time July ends...

The rain is still there, the cold isn't. So much for that big AAO dive. The atmosphere round here is behaving quite strangely at present.

Do you think the lack of solar activity at the moment might have something to do with the strange behaviour of our weather systems at the moment Tony? Not really understood or talked about at all solar activity and it’s effects IMO...

[TonyT]

The rain is still there, the cold isn't. So much for that big AAO dive. The atmosphere round here is behaving quite strangely at present.

Do you think the lack of solar activity at the moment might have something to do with the strange behaviour of our weather systems at the moment Tony? Not really understood or talked about at all solar activity and it’s effects IMO...

Yes, its a factor, we are near solar minimum in this solar cycle, and this solar cycle has been weak, and the next one is expected to be even weaker. This is factored into the longer range forecasting. Thats a longer term issue. But I was meaning strange in the last few weeks (and likely the next few if the way the models are currently struggling to latch onto future events is anything to go by). The only thing I can think of is the current planetary alignment (all planets on the same side of the sun since mid-July), but thats probably stretching the electric universe idea a bit too far. Even the MJO pulse and warm subsurface water which were leading us up to a Nino have backed off a little in the last week or so, its quite puzzling.

[Skywatcher]

Just had a brief heavy shower of small hail.

[Orion]

A heavy shower of rain at Orewa Beach just now, and a very bubbly white cloud towering up to the south.

[Cyclone Tracy]

Frontal squall line from central to upper NI at the moment throwing out a few sparks.

[Razor]

Hail and heavy rain in Halswell

[David]

Very heavy shower line just gone through here, rain rate peaked at 199 mm/hr on the weather station!

[Chris W]

It looked stormy all afternoon from my place but we seemed to miss it. The departing clouds made for an epic sight though.

IMG_20180729_165723_858.jpg

[NZ Thunderstorm Soc]

Nothing much here, might have counted about 5 heavy spits.

[Chris W]

It seemed to be mainly north of here plus some coastal action towards Ashburton. Pretty close to the MetService moderate risk area.

[spwill]

A pleasant day here but for the brief late heavy shower line, up to 17C.

July really lacking weather events this year. I think the slightly cooler July here has been generated by night time cooling, more light wind/ clear sky nights.

[Nev]

A pleasant day here but for the brief late heavy shower line, up to 17C.

July really lacking weather events this year. I think the slightly cooler July here has been generated by night time cooling, more light wind/ clear sky nights.

Perhaps not as cool as I first thought. I had another look at NIWA's Mangere temps and it would appear that both its T-mins and T-maxs have been running about 0.6C cooler than Akld Aero's since about mid May; they're usually roughly about the same.

While Akld Aero's average T-min this July looks like it'll end up close to normal, its average T-max looks like it'll be about 1.0C above normal, which would make it Akld Aero's 3rd-equal highest average July T-max since records began there in 1962.

[spwill]

Thanks Nev, interesting. Night cooling would produce local affects, the more inland locations having more cooling.

[Richard]

Noticed yesterday a weeping willow has green on it, this tree has never been budding out in July before.

[Cyclone Tracy]

Synoptics are starting to show a connection of sub tropical and polar air in the Oceania region within a week.

For those of you who maybe interested, here are the Global model July stats to yesterday for the southern hemisphere 500 hPa Anomaly correction up to 120 hours. Interestingly GFS has now dropped to 4th most accurate behind the Canadians. The New GFS version coming out next year is running at 87% better than the current version on 86%. Report is generated by NOAA

1.EC 92%
2.UK 89%
3.Can 87%
4.GFS 86%
5.U.S Navy 84%
6.CFS 82%

New GFS 87%

[TonyT]

Synoptics are starting to show a connection of sub tropical and polar air in the Oceania region within a week.

For those of you who maybe interested, here are the Global model July stats to yesterday for the southern hemisphere 500 hPa Anomaly correction up to 120 hours. Interestingly GFS has now dropped to 4th most accurate behind the Canadians. The New GFS version coming out next year is running at 87% better than the current version on 86%. Report is generated by NOAA

1.EC 92%
2.UK 89%
3.Can 87%
4.GFS 86%
5.U.S Navy 84%
6.CFS 82%

New GFS 87%

Another interesting idea from that graph is the variability day to day of forecast accuracy. Even the best model (EC) has a variation of about 10% - indicating that some days the models "get" the atmosphere well, and some days they dont "latch on" to that is happening to the same extent (speaking hemispherically here).

[Razor]

Its a warm month all right. GFS sticking to mainly westerly quarter after this weeks wee wet spell.

It is spring here all right, well and truly

[NZstorm]

Grey Lynn average max 16.5C, Min 7.1C. Precip 99.8mm.

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[Cyclone Tracy]

Finished here with 90.5mm for July, 35mm below the local average. Daily mean temp of 11.5, 0.6 above average.

year to date:
935mm , running 238mm above average
daily average temp 17.2, running 1.5c above average

[Richard]

Medbury 22.2 mm rainfall, a dry month. max 16.4 deg min -4.2 deg

[Skywatcher]

A mean temp here of 8C (1.7C above average), more typical of August but still not as warm as July 2013. Min of just -1.6C and only 6 air frosts.

Only 31.8mm precipitation.