General February Weather

tich · Unread post by **tich** » Thu 29/01/2015 21:29

Looks like a significant different weather set up for the first week of February. Strong southwesterlies likely over NZ (looking quite chilly for the South Island), a sharp contrast to the humid east/northeasterlies at present.

melja · Unread post by **melja** » Fri 30/01/2015 04:50

Yes but still very dry for cantertbury with all the sheltering from the W-SW.

treetop · Unread post by **treetop** » Fri 30/01/2015 07:06

Southwesterlies may not be around for longer than 2 days [wed/thurs] if we have the squeeze put on us form the lows to the north which would bring in a strong SE flow from Friday or Sat. The current rain scenario continues to be pushed back.

Dean. · Unread post by **Dean.** » Sat 31/01/2015 10:42

Weakening event now on most of the models,very SW and most action will be out east.

03Stormchaser · Unread post by **03Stormchaser** » Sat 31/01/2015 11:10

Dunedin might get a storm tomorrow. Dont see it spreading into Canterbury though.

Razor · Unread post by **Razor** » Sat 31/01/2015 16:05

Looks hot tomorrow, mid 30's to kick off the month

treetop · Unread post by **treetop** » Sat 31/01/2015 21:34

Models all over the place on Thurs, Metvuw has widespread NW rain for the NorthIsland, Metsrvice just fine with strong SW winds. Around 25mm in places behind Tauranga this morning

Orion · Unread post by **Orion** » Sun 01/02/2015 06:34

Extraordinary sky to the west at the moment: dull orange beneath a vast high rainbow.

David · Unread post by **David** » Sun 01/02/2015 07:04

An overnight low of 20.8C to start February. Overcast skies this morning.

treetop · Unread post by **treetop** » Sun 01/02/2015 07:25

Interesting watching the live rain radar over the last 2 days [BOP] .Shows small intense cumulous showers moving westward [under 4000m] while above, areas of patchy rain moving eastward and crossing each other with no interferance. Very evident this morning, must be some good shear at that mid level.This is quite common but very clearly defined at the moment.

jamie · Unread post by **jamie** » Sun 01/02/2015 07:27

That rain out west the last few days is just teasing. It's like it is allergic t the land

David · Unread post by **David** » Sun 01/02/2015 07:47

jamie wrote:That rain out west the last few days is just teasing. It's like it is allergic t the land

It's just started raining here

Nev · Unread post by **Nev** » Sun 01/02/2015 09:05

It's not too often you see almost all of the South Island (excluding the Kaikoura Coast) with at least a low-risk of T-storms. High-risk for eastern Southland and Otago, and Fiordland and south Westland.

MetService - Thunderstorm Outlook

Valid to: Midnight Sunday 1 Feb 2015
Issued at: 8:34am Sunday 1 Feb 2015

A weakening front is moving up the South Island west coast this morning with a the odd thunderstorm over north Westland. Further south a trough will move onto Fiordland this morning and then affect Westland this afternoon. A second trough will move onshore over these areas later this afternoon maintaining deep instability. So, there is a high risk of thunderstorms over Fiordland and southern Westland this morning and afternoon and generally a moderate risk on the west coast south of Westport today. Rainfall rates may be boosted locally to 20mm/hr.

In the south and east of the South Island... Over eastern parts of Southland and Otago, there is a high risk of thunderstorms this afternoon and evening with a moderate risk that a few of these thunderstorms may turn SEVERE for a time, producing local downpours of 25-40mm/hr. These thunderstorms are expected to move offshore to the southeast during the evening. Further inland over the rest of Southland and Otago and northward to south Canterbury, there is a moderate risk of thunderstorms this afternoon. Over the rest of the South Island, excluding the Kaikoura Coast, there is a low risk of thunderstorms, but the risk over Canterbury may be a little higher.

Elsewhere, no thunderstorms or significant convection expected.

MetService T-storm Outlook Map, Feb 1.png

NZstorm · Unread post by **NZstorm** » Sun 01/02/2015 09:48

That very unstable airmass over Southland/south Otago is capped, so there will need to be a cap break. If a storm does develop it will be a goodie with frequent lightning.

Also the small possibility of some elevated convection as well, perhaps over South Canterbury.

Orion · Unread post by **Orion** » Sun 01/02/2015 10:26

Anyone else noticing an odd orange cast to the sunlight this morning? Just doesn't seem quite as usual.

Captain Salty · Unread post by **Captain Salty** » Sun 01/02/2015 10:48

maybe remnant from the Flock Hill fire?

Nev · Unread post by **Nev** » Sun 01/02/2015 12:18

Updated T-Storm Outlook Map to include the omitted 'moderate-risk of severe T-Storms' for eastern Southland/Otago mentioned earlier…

MetService T-storm Outlook Map, Feb 1 (11am update).png

RichyDunedin · Unread post by **RichyDunedin** » Sun 01/02/2015 13:37

Some big thunderstorms and hail starting up now around Alexandra area. The Dunedin MS site was at 25 degrees with 72% humidity before, must be a warm dew point for down here. Cumulus clouds growing quickly now, shame about the blind spots on the radar.

03Stormchaser · Unread post by **03Stormchaser** » Sun 01/02/2015 13:54

Models throwing up some crazy indications for later this afternoon and evening, -6Li's and CAPE of up too 1600!

Paul Mallinson · Unread post by **Paul Mallinson** » Sun 01/02/2015 13:59

If we take the noon Invercargill sounding and use a sfc T of 24C and a dewpoint of 17.5C and lift the sounding a little in the low and mid levels to mimick convergence in the low levels and some synoptic lift from a short wave trough, we get:
CAPE of 2115 J/kg
LI -7.1
SLI700 -4.1 and the potential for large hail.

Paul

Paul Mallinson · Unread post by **Paul Mallinson** » Sun 01/02/2015 14:00

Forgot to mention a very tall CB formed 20-30mins ago inland Otago with strong echoes to very high levels.

Paul

Tornado Tim · Unread post by **Tornado Tim** » Sun 01/02/2015 14:07

Is the Invercargill Radar offline atm? Hanvt had an update in over 8 hours. Although if a sounding was done then I presume balloon tracking functionality of the radar is still working....

Paul Mallinson · Unread post by **Paul Mallinson** » Sun 01/02/2015 14:12

Yes, data from it has been down since last evening. I think its a coms problem. The techs are working on it now.
We got a radiosonde flight but there was no winds with it so the wind finding part using the radar is obviously still not operating.

03Stormchaser · Unread post by **03Stormchaser** » Sun 01/02/2015 14:26

Paul Mallinson wrote:If we take the noon Invercargill sounding and use a sfc T of 24C and a dewpoint of 17.5C and lift the sounding a little in the low and mid levels to mimick convergence in the low levels and some synoptic lift from a short wave trough, we get:
CAPE of 2115 J/kg
LI -7.1
SLI700 -4.1 and the potential for large hail.

Paul

That is some very impressive numbers Paul. I really should have been paying more attention to this set up, this is the type its worth to head down for. I only really had a good look this morning and by then its too late.

NZstorm · Unread post by **NZstorm** » Sun 01/02/2015 14:38

The deep layer shear down south looks to be about 30knots which is just enough for convection to get organised. But the high CAPE numbers are occuring because of the low level capping. My thinking is a temperature of 25C will be enough to break the cap in Southland.

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