High Rain

Michael · Unread post by **Michael** » Sun 20/08/2006 17:57

Rain arrived at 4,30pm and over 25mm now.Whats it like else where?

Manukau heads obs · Sun 20/08/2006 19:31

this station in your area got less than 3mm
http://www.photoedit.co.nz/wx/

we got 9mm here...heavy for a time...
but the showers weakened as they moved inland

Razor · Unread post by **Razor** » Sun 20/08/2006 21:18

Certainly nowhere near 25mm here in the Waitakeres. Rained for about 20 mins, moderate intensity. I'd say no more than a few mm's

NZ Thunderstorm Soc · Sun 20/08/2006 22:11

Micheal, this posting of yours is not warrantable, so I'm going to delete it.

JohnGaul
NZTS
moderator

squid · Unread post by **squid** » Sun 20/08/2006 23:42

GraemeWi · Unread post by **GraemeWi** » Mon 21/08/2006 07:11

NZ Thunderstorm Soc wrote:Micheal, this posting of yours is not warrantable, so I'm going to delete it.

JohnGaul
NZTS
moderator

Hang on - it's not fair to delete somebody's post simply because you decide you don't like it. The spread of rainfall is hardly uniform.

There are niche micro-climates in Auckland for rainfall - for example Penrose has some real downpours as does Glenfield and Whenuapai.

G

Janos · Unread post by **Janos** » Mon 21/08/2006 07:36

I find snippits like local rainfall interesting...dont discourage.

Manukau heads obs · Mon 21/08/2006 07:46

i think you will find Michael just made that amount up , as an exageration....i.e like his SW gales exageration....

RWood · Unread post by **RWood** » Mon 21/08/2006 08:11

GraemeWi wrote:
NZ Thunderstorm Soc wrote:Micheal, this posting of yours is not warrantable, so I'm going to delete it.

JohnGaul
NZTS
moderator
Hang on - it's not fair to delete somebody's post simply because you decide you don't like it. The spread of rainfall is hardly uniform.

There are niche micro-climates in Auckland for rainfall - for example Penrose has some real downpours as does Glenfield and Whenuapai.

G

Perhaps the content of the other 3000 posts that might relate to this also...

Michael · Unread post by **Michael** » Mon 21/08/2006 09:20

Come on and move on .... I wasnt complaining about the rain.I was asking others because it bucketed down harder for an hour or so than it had in months

NZ Thunderstorm Soc wrote:Micheal, this posting of yours is not warrantable, so I'm going to delete it.

JohnGaul
NZTS
moderator

Manukau heads obs · Mon 21/08/2006 09:27

and so do you have a rain gauge or did you just guestemate the rain?

note that rain can be deceptive
large drops ...sounds heavy., but the drops can be far apart....
light drops, but dense....can lead to a higher total
etc...

RWood · Unread post by **RWood** » Mon 21/08/2006 12:30

I've noticed that the highest daily totals here are nearly always as a case
of thick, densely packed small drops - you get soaked in it fairly quickly.
One notable exception was the flooding pre-Xmas downpour here in Dec 1976 - that came down in "sheets" with some major downpours. It was a big convergence event.

janewaystv · Unread post by **janewaystv** » Mon 21/08/2006 13:47

I have a old picture book of the floods in WGT in Dec 1976, shows the Hutt River overflowing its banks in the Hutt valley eg Penrose or something like that etc. Pretty rare for WGT to get rain of this mangitude especially over the summer period. (Correct me if im wrong)

Noticed that WGT gets its majority of rain in winter is this due to southerlies prevailing? When WGT has a nor-wester, is it normally fine weather?

Manukau heads obs · Mon 21/08/2006 13:59

although the airport only got 2mm, and only 3mm or so near ardmore, and my brother just south of papakura recorded less than 1mm, he said he was on the southern motorway and the rain was heavy.....
but then thats another thing,,,,,the motorway, with all those cars and spray and large collection area, you get alot of surface water easily
next, when you are doing 100kmh you are "soaking up/collecting" alot of rain drops....which makes it much heavier than it is when you stop.....

RWood · Unread post by **RWood** » Mon 21/08/2006 14:48

janewaystv wrote:I have a old picture book of the floods in WGT in Dec 1976, shows the Hutt River overflowing its banks in the Hutt valley eg Penrose or something like that etc. Pretty rare for WGT to get rain of this mangitude especially over the summer period. (Correct me if im wrong)

Noticed that WGT gets its majority of rain in winter is this due to southerlies prevailing? When WGT has a nor-wester, is it normally fine weather?

No, southerly is not the prevailing direction in any season. Westerly types (generally bent to the northwest) dominate. There are several flavours of "Northwest" and some of them are dry, some are anything but. A substantial portion of W'gton's rain, even in winter, falls with frontal passages with NNE thru' NW winds locally. Southerly rain may be big in the right depression scenario, whatever the time of year.

I haven't seen a quotation for distribution of local rain by scenario but I know there is a paper by Salinger et. al. in the Univ. libraries somewhere - must track it down.

Winter being the wettest season is the case for a large part of the North Island, especially in the northern third. In some parts the seasonal variation is not very large at all.

The Hutt Valley event was a strong convergence right along the line of the western Hutt hills, where rainfall was up to 350 mm - about 130 mm in the city from memory. During the time of the rain there was no wind at all. The amount of rain was exceptional for any season, especially summer - but some convergence events in Dec 1939 produced W'gton's wettest ever month (386 mm in the city, with the 2 wettest days producing 6.00" and 4.84" at Kelburn). Baring Head at the lighthouse copped near 400mm in one of the events.

Pretty sure I've given Dec 1939 a writeup in an older thread...

RWood · Unread post by **RWood** » Mon 21/08/2006 19:15

janewaystv: this may be of interest. Shows for a large selection of NZ stations the rainfall ratio of the driest 3-month period to the wettest 3-month period, as a % value. It is based on 30-year rainfall means. Of course for any particular year the values could be miles from these ones, but this shows overall which "season" is wettest, which one is driest, and the degree of difference - for a good span of years. Can't give the actual rainfall values for reasons explained in an older post.

Razor · Unread post by **Razor** » Mon 21/08/2006 20:44

Showery here, but certainly not 25mm yet. You still with us Micheal????

squid · Unread post by **squid** » Tue 22/08/2006 01:18

might have scared michael off

Manukau heads obs · Tue 22/08/2006 06:44

Michael just needs a rain gauge and report accurate readings instead of just saying there was an inch of rain....

janewaystv · Unread post by **janewaystv** » Tue 22/08/2006 09:27

Thanks RWood

RWood · Unread post by **RWood** » Tue 22/08/2006 09:34

NP - you will see that there a quite a lot of flavours - eg the spring or early summer high in Alps and some W Coast, summer-type high pronounced in Central Otago, autumn max in others. Of course in many cases the ratios are not very significant, but some places are down at about 40%, eg Akaroa