General January Weather

[TonyT]

Starting a new topic for a new month and a new year, mainly because I have never started one before.

Looking like an unstable first week of the year, with plenty of potential for afternoon showers and thunderstorms right around the country.

[NZstorm]

Big upper trough in the Tasman this week with good moisture advection from the north across NZ. Good recipe for convection with thunderstorms fairly widespread from Tuesday. The thunderstorms will be more likely over higher terrain.

The models don't agree on the evolution of the subtropical low in the north mid to late week. Have to watch that one.

[Richard]

Well done Tony speech speech.

Looking forward to this week coming weather wise, hoping we can kick off 2018 with a bang or two.

[spwill]

I'm looking forward to the humid weather this week, the balmy nights

[Richard]

Looking at this mornings model run that many areas are looking at a major reprieve from the dry spell, be great to get a large rainfall in mid summer.

[mikestormchaser]

Wensday is looking like it could be interesting convection wise inland south island. I'll be free to chase if anything happens.
I'm going into mt Somers to see Aaron wensday afternoon for a cratch up anyway so could work well!!

John you could be in the best spot! High total totals and a k index of 36 around those areas

[wembley]

What about Central Otago?

[NZ Thunderstorm Soc]

Wensday is looking like it could be interesting convection wise inland south island. I'll be free to chase if anything happens.
I'm going into mt Somers to see Aaron wensday afternoon for a cratch up anyway so could work well!!

John you could be in the best spot! High total totals and a k index of 36 around those areas

Maybe if something does happen, we could catch up somewhere

[Richard]

I would like to know why it is that so often that at the very first sign of light the sky can be clear as a bell then before the sun rises we can be in thick fog, being like that here since 5.30 yet the sun rises at 5.53am.

[melja]

The lowest temperature of the night which means the temp and dew point are likely to be close or perhaps the dew point rises a little with day break which will bring it close to air temp and is key for fog.

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[Richard]

The lowest temperature of the night which means the temp and dew point are likely to be close or perhaps the dew point rises a little with day break which will bring it close to air temp and is key for fog.

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Yer have to something along those lines, the coldest it got to last night was at 4.00am 11.1deg and 12deg at the first sign of light to the east. Its how the sun thats still half and hour from reaching the horizon can inference the dew point that i'm puzzled with.

[Cyclone Tracy]

The lowest temperature of the night which means the temp and dew point are likely to be close or perhaps the dew point rises a little with day break which will bring it close to air temp and is key for fog.

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Yer have to something along those lines, the coldest it got to last night was at 4.00am 11.1deg and 12deg at the first sign of light to the east. Its how the sun thats still half and hour from reaching the horizon can inference the dew point that i'm puzzled with.

Just my 2 cents worth, I think the type of fog you had today is advection fog. A sign that warmer moist air is moving in over cooler land. Normally gives a clue to storms and rain in the days ahead

[spwill]

I would like to know why it is that so often that at the very first sign of light the sky can be clear as a bell then before the sun rises we can be in thick fog, being like that here since 5.30 yet the sun rises at 5.53am.

Air movement pushing fog around or the coolest time of the day allowing fog formation.

[spwill]

I see EC has the low in a couple of days time moving across NZ more quickly now and away to the SE, GFS still has lingering low system.

[Richard]

The fog doesn't move into the valley, it forms where it is as its not moving. Its often forms straight after the first hint of light in the east, and that can be year round, so that rules out warmer moist air is moving in over cooler land it happens more in winter than summer.

The temperatures had been around its coolest since 11.00pm

[NZ Thunderstorm Soc]

Some light drizzle here this evening. The heaviest rainfall we have had this year

[Orion]

Dull and overcast in Ashburton at present, with falling mist/fine drizzle; dew and lots of little spiderwebs on lawn and shrubs.

[spwill]

Dull and overcast in Ashburton at present, with falling mist/fine drizzle; dew and lots of little spiderwebs on lawn and shrubs.

The dewpoint at Christchurch is 17C, explains the low cloud, mist and drizzle on the Canterbury Plains which will burn back to the coast through the morning as the day warms. The likes of Sumner may stay cloudy all day. A humid feel to Chch city weather today.

[Richard]

That low cloud is burning off here now, humid alright.

[03Stormchaser]

The dewpoint at Christchurch is 17C, explains the low cloud, mist and drizzle on the Canterbury Plains which will burn back to the coast through the morning as the day warms. The likes of Sumner may stay cloudy all day. A humid feel to Chch city weather today.

You could definitely notice it after the walk from my car to work this morning. You only really notice it a couple times a year in Christchurch

[NZ Thunderstorm Soc]

The dewpoint at Christchurch is 17C, explains the low cloud, mist and drizzle on the Canterbury Plains which will burn back to the coast through the morning as the day warms. The likes of Sumner may stay cloudy all day. A humid feel to Chch city weather today.

Yes, been overcast all morning here with some overnight drizzle. Still the same at the moment with 17.3C dewpoint and humidity around 70%. No sign of any clearance even though the temperture is a mild 20C.

[Orion]

At Sumner at the moment: sunny, breezy, warm, humid; a line of low cloud on the horizon to the north-east and incoming from the east, interesting bubbly towers away to the NW, a few mares' tails aloft.

[NZ Thunderstorm Soc]

DSC02339.JPG

Interesting clouds down here today.
Beside the Cu towers there was a nice display of Cs with a halo shining through it around the sun. This usually indicates rain within the next 24 hours.
Also there was a Kelvin-Helnholtz form to the south of here around 3pm.

[NZ Thunderstorm Soc]

Another picture

[Razor]

This was a cracking example of incoming stuff today... almost a double!