La Nina and anticyclonic conditions

[RWood]

We shouldn't be too surprised if settled anticyclonic conditions prevail at times, even to the point of keeping the far north dry. The major La Nina episode of 1950-51 started about Dec 1949 or Jan 1950 (using NOAA's "ONI" index rather than the SOI value as the marker), and persisted as a strong episode till autumn 1951. Pressures were low in December 1949 and lowish in January 1950, but then were relatively high or very high (in central NZ) for 11 of the next 12 months. The North Island and north of the South Island had a run of very sunny months from September 1949 to March 1950, particularly so the last 3 (the January being surpassed only by 1957 in this respect). I don't have data handy for rainfalls in the N/NE of the North Island, but from memory the January-March 1950 period was generally very dry there. I do recall that May 1950 was exceptionally warm and had some heavy rainfalls in Bay of Plenty (?).

[David]

I see metservice mention Bay of Plenty and Taranaki/western Waikato as having a low risk of heavy rainfalls on 8th/9th in their severe weather outlook page. If this is the case then hopefully we'll get some decent rain out of this front.
9th day without rain here, so things are really drying up.
GFS still not showing much happening up here for the next week other than this front, sadly

[spwill]

Atleast we have had mostly nice weather through the festive period, a lot of Eastern Australia has had grim holiday weather, rain and wind there.

[NZstorm]

I see metservice mention Bay of Plenty and Taranaki/western Waikato as having a low risk of heavy rainfalls on 8th/9th in their severe weather outlook page

I don't think so. But there is still a few days for things to change I guess.

a lot of Eastern Australia has had grim holiday weather

Yes, a lot of people have had their holidays ruined by non stop rain/drizzle since Xmas day and big swells have kept the beaches closed over there. The attraction of that part of the world is the weather, without it I would say it wouldn't be a fun place to be.

[David]

a lot of people have had their holidays ruined by non stop rain/drizzle since Xmas day and big swells have kept the beaches closed over there. The attraction of that part of the world is the weather, without it I would say it wouldn't be a fun place to be.

According to TV3 news story, some places on the eastern coastline (Queensland) have been hammered by rain, apparently over 300mm in 3 hours in a few localities. Cannot find such stats for any of BOM's official recording sites though.

I don't think so. But there is still a few days for things to change I guess.

I didn't really believe it either, many GFS models aren't making much of it over the northern half of the North Island. Wouldn't mind some decent falls - looks like we'll be in a mainly dry period for a while to come yet.

[Manukau heads obs]

the news seemed to give the impression that the Gold coast was hit by TC Helen,which is now heading towards NZ,and campers need to pak up..
at least that is the take of it that one person has relayed to me!

[David]

Boy the tropics are looking active this summer!!
(looks to me like a low then a tropical storm then a tropical cyclone from west to east on that forecast chart)
Hopefully some will make its way down here this season

[janewaystv]

We shouldn't be too surprised if settled anticyclonic conditions prevail at times, even to the point of keeping the far north dry. The major La Nina episode of 1950-51 started about Dec 1949 or Jan 1950 (using NOAA's "ONI" index rather than the SOI value as the marker), and persisted as a strong episode till autumn 1951. Pressures were low in December 1949 and lowish in January 1950, but then were relatively high or very high (in central NZ) for 11 of the next 12 months. The North Island and north of the South Island had a run of very sunny months from September 1949 to March 1950, particularly so the last 3 (the January being surpassed only by 1957 in this respect). I don't have data handy for rainfalls in the N/NE of the North Island, but from memory the January-March 1950 period was generally very dry there. I do recall that May 1950 was exceptionally warm and had some heavy rainfalls in Bay of Plenty (?).

From NZ's weather summary 1950 (shortened version):-

The first 3 months of 1950 showed no marked abnormalities except for areas N of Waikato where a prolonged dry spell that began in August 1949 continued to provide much hassles for farmers. October 1949 was the warmest since Oct. 1915 with low rainfall/high sunshine (except in Westland where as much as 40 inches fell over the month with Waiho recording 19.30 in. in one day). November 1949 was very sunny with much less rain than usual. December 1949 however was cloudy, cool and unsettled. March 1950 was very unsettled in Southland. April was a month of SE winds - wet and dull in the N & E, sunny in the W and S. May 1950 was the warmest ever recorded, but very stormy during the last week with floods in the Southern Alps & Westland & also on the Canterbury Plains. 1950 for Westland and Southland saw mean temps being as much as 1oF above the average, sunshine was plentiful in Westland and Marlborough but below average by 100-200 hours in E areas from Cook Strait to East Cape as well as New Plymouth.

[RWood]

A caution on the sunshine deviations: Met Office was using unrealistic means for some sites (eg Napier included later discredited pre-1926 values), so the deficits at some sites were exaggerated. There was even an elementary arithmetic mistake or typos in the calcs. for means to 1950 - quoted Alexandra as 2170 for 1929-1950, but June's 120 should have been 102, and November's 230 was also wrong. The correct annual mean was about 2141.

PS - not sure where they got the N Plymouyth remark from, as the annula 2205 was cfairly lose to their normal for the time.

[janewaystv]

Thanks for pointing those facts out Rwood.

1950 states Alexandra's yearly sunshine total as 2207.7 hrs, New Plymouth as 2205.3 hrs and Napier with 2209.1 hrs, when I read New Plymouth's hours, I did think it odd that it was considered to be below average, I suppose around the time when the summary was being done, it was probably considered to be so (computers weren't around in those days & measuring equipment was probably of a poorer standard as well & verifying probably wasnt accurate).

[RWood]

I think the averages tables were just hand-calculated and not checked properly. But as I say, some pre-1930 records biased most of them upwards anyway. Later on they "went the other way" for a while and published averages for 1935-60, much more realistic (later on data from 1930 on was kept along with a few stations' pre-1930 data).

[RWood]

A couple of points of interest about 1950: at least since about 1905, 1950 had the highest MSLP's on record for NZ (or at least central NZ) that century, until 1999 surpassed it. From a rough calculation I did from a reasonable number of sites, in the years 1950-1995 it was second only top 1994 for sunshine, possibly even highest. 1983 was easily the cloudiest year for the South Island, and 1992 easily so for the North. 1983 was probbaly the cloudiest overall.

[Michael]

Its strange how the WmBas maps show no SW component but it always is for us up here.Anyway for the dryness it must be up with early 1978 for that as the last real lanina in 1989 was the lows were closer than they are this time.

[janewaystv]

1983 was certainly a very cloudy year especially in the south of the SI, only Rotorua and Christchruch had more sun than normal (105% of the annual average). Mt John and Alexandra had thier wettest year on record with rainfall being 150% of the average. Napier recorded only 549mm (59% of the average) - a record low. Strong W-SW winds prevailed during January, March and September, however E winds prevailed during April, June, July, october and November.

1992 - only Southland had above average sunshine. Record low sunshine was recorded at Auckland (1767 hrs), Wellington (1789 hrs), Nelson (2127 hrs) and Blenheim (2177 hrs), Palmerston North only recorded 1357 hrs with Dec. recording only 103 hrs. (1991 had 1558 hrs). Palmerston N certainly swings from very cloudy years to sunny years (1974 had a record 2179 hrs).

[RWood]

Ah - you've got the "wrong" Palmerston North for the 1974 reading. I once had a discussion with Paul(?) Heerdegen of Massey about the sunshine gradient in that region - the Palm Nth city site at the ESR (was DSIR) on the eastern flank of the city averages only about 1730, record high 2024 in 1934. But Kairanga, Palmerston North is west of the city a bit closer to the coast and in a 1970-1988 record averaged about 1975 hrs, with 2179 in 1974. Further to the west or northwest Foxton and Ohakea sites averaged over 2050 hrs - 2075 for the Ohakea record 1954-1991, with 2284 in 1974.

An irony of 1983 was that while Jan-March were windy and mainly cool, spoiling many beaches, but were sunny in most places, while the really miserable wet cloudy weather dominated the rest of the year, particularly April-October (though August wasn't bad), September-October being particularly bad in that respect (Palm. Nth had just 67 hrs sun in October).

The large sunshine deficits in the North Island and north of the SI in 1992 were overwhelmingly due to the miserable last 4 months, which all had massive deficits. While November was mildish, on a driving trip of 3 weeks around much of the North Island, we saw about 2 sunny days and 3 partly cloudy ones - the reminder were all overcast with showers or rain on many days.