Active trough for Monday

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tich
Posts: 3525
Joined: Sat 15/03/2003 18:32
Location: Christchurch (St Albans)/Akaroa

Unread post by tich »

This photo is a sign of how cold the upper atmosphere has been over the South Island last couple of days. The Invercargill soundings indicated the freezing level around the 1000m level down there. But in your photo, the fzl looks to have been lower.
If the freezing level was lower than 1000 metres in Chch on Tuesday, the lapse rate (I think that's what it's called, in other words how quickly the free-air temperature drops with altitude) would've been very sharp, as temps were probably in the mid teens about that time in Chch.
Thunder
Posts: 2068
Joined: Wed 12/03/2003 19:47
Location: Mt Somers

Unread post by Thunder »

Like Ben I saw other bigger clouds that day with bigger virga type trails like can be seen in the pic above, pretty much most of them seemed to do this big rain (snow) swath stuff that day with only drops of rain reaching the ground, they were of biggish size but it wasn't intense by any means.
Image
Aaron Wilkinson
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NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland

Unread post by NZstorm »

Re the lapse rate.

Yes, you can get a very sharp lapse rate in a cold atmosphere at this time of year. I remember Gary reporting a maximum temperature of 23C from Omarama when the freezing level was quite low, from memory about 1300m(at Invercargill), earlier in Febuary.

Its been a cold month down south. I think the wine growers in Central Otago might lose out this year. The Queenstown area is very marginal for wine growing as it is.