Topic: Frosts and cold mornings 2008

[Harley Pearman]

Saturday morning 12/7/2008 produced another noteworthy cold morning for western Sydney including:-

1.5 C where I live in Blacktown (The coldest morning so far this year).

Penrith 1.1 C.

Richmond had -2.5 C. This is the coldest morning so far this year.

Campbelltown had -0.6 C.

Camden had -1.1 C. Not quite as cold as the 30/6/08 where the minimum temperature fell to -2.4 C.

Still there would have been morning frost in these areas. I observed frost on car windows in my locality after sun rise.

Harley Pearman

[Jimmy Deguara]

Quote from: Richary on 05 July 2008, 08:46:38 PM
From wikipedia the hottest every recorded is 50.2 C at Oodnadatta in South Australia...

Funny, I thought the hottest temp recorded was Cloncurry QLD - +51.3c (source: BoM archives)

Big Pete

Although not the focus of this thread, I thought I would touch upon the point.

Certain temperature and statistical records are being checked for their authenticity and some have unfortunately had to be laid to rest due to incorrect environments they were taken. In the case of Cluncurry, the thermometer was situated under a corrugated iron roof if I am not mistaken.

Regards,

Jimmy Deguara

[Harley Pearman]

Some very cold mornings for July 2008 - New South Wales

I have been looking at numerous centres across New South Wales finding out which town or locality has woken to the coldest morning for the month. Some places have fittingly suffered frosts and cold mornings. The coldest minimums that I can find across the state for July are as follows:-

Armidale - Located on the Northern Tablelands at an elevation of around 980 metres should be mentioned. The coldest mornings are:-

Minus 9 C on the 12, Minus 6.6 C on the 17 and minus 6 C on the 31.
The average minimum temperature for the month is Minus 0.6 C.

Goulburn - Located on the southern Tablelands at an elevation of around 630 metres received Minus 6.7 C on the 23.

Oranage Located on the Central Tablelands at an elevation of around 888 metres received Minus 5 C on the 23.

The coldest of the coldest must go to Charlotte Pass where the temperature fell below Minus 12 on the following days, 5 - Minus 12.5C, 12 - Minus 13 C, 23 - Minus 14C, 24 - Minus 15.5C, 25 - Minus 15.5C, 26 - Minus 12.5C and 30 - Minus 12.5C.

The average minimum temperature for the month was Minus 6.3C.

Note:- This does not even come close to the morning of 18 June 1994 when Minus 23 occurred which is still the coldest recorded temperature on the Australian continent at a weather station.

The morning of 31 July should also be mentioned here because some serious cold temperatures occurred. The coldest that I can find include Minus 5 at Barraba, Minus 7 at Woolbrook, Minus 6 at Armidale, Cooma and Inverell and Minus 5 at Mudgee.

Sydney:

The coldest that I can find is Minus 2.5 C at Richmond on the morning of the 12.

There were many other centres across the state that recorded low minimum temperatures for 31 July from 0 to minus 4 depending on location.

Harley Pearman

[Harley Pearman]

Some cold mornings for August 2008 - For localities in New South Wales

I have been looking at the run of minimum temperatures across New South Wales for August (Period 1 to 14 August)and so many places have had a significant run of cold mornings. Following the last frontal system and with still but clear nights with no cloud cover, minimum temperatures below 0C have been a feature across wide swathes of the state.

I would suspect too that the early morning frost that is occurring would be harming unprotected crops in the inland areas of the state. The following places are worthy of mention in this post as this is significant for August.

Armidale
The average minimum temperature for August 1 to 14 stands at minus 3.1C. On the 9, the minimum temperature fell to minus 6.6C, 10 - minus 7.8C, 13 - minus 6.9C and 14, the minimum temperature fell to minus 5.1C. The temperature has fallen below 0C on 11 out of 14 mornings to date.

This is reflected in the daytime maximums struggling to reach to 6.5C to 11.3C between 6 and 13C on the various days.

Barraba (North west NSW)
This small town has experienced 11 out of 14 nights where the minimum temperature has plunged below 0C. The coldest was on the 13 and 14 in which minus 6.1C was recorded here.

The average minimum temperature during this period stands at minus 3.1C.

Charlotte Pass (Snowy Mountains)
Cold mornings are typical here but minus 10.5C stands out on 5/8/2008. The average minimum temperature is minus 5.3C to date.

Coonabarabran (North west slopes and plains)
Special mention here given that minus 5.2C occurred on the 5/8/2008 and minus 1C occurred on 11,12 and 13.

Glenn Innes (Northern Tablelands at an elevation of 1,030 metres)
This is incredible in which 12 out of 14 mornings has seen the minimum temperature drop below 0C. The coldest being minus 5C on the 3, minus 6C on the 8 and minus 6.5C on the 9.

Goulburn (Southern Tablelands)
Worth a mention given that minus 4.7C occurred on the 4 and minus 5.6C occurred on the 5.

Guyra (AT 1,300 metres in elevation on the northern tablelands)
Not as cold as Armidale with the coldest being minus 4.3C on the 14.

Lithgow (At 930 metres on the Central Tablelands)
A reading of minus 5.4C occurred on the 4.

Tamworth (At 430 metres in elevation NW slopes)
This is amazing in its own right. A reading of minus 4C on the 9, minus 4.4C on the 12, minus 4.9C on the 13 and minus 6.3C on the 14.

The days are averaging 14C and are sunny but the nights have averaged minus 1.3C for the period.

Temora had minus 1.9C on the 14.

The run of cold nights have occurred across wide swathes of the state leading to frost. However, it is not limited to inland areas and the hills. The coast is getting it too although not as bad such as.

Richmond (NW Sydney):

A reading of minus 2.6C on the 9, minus 2.3C on the 12 and minus 2.6C on the 14 has occurred.

Murwillimbah had minus 1C on the 10 and Coffs Harbour had 1.4C on the 12, 1.3C on the 13 and barely 1.1C on the 14.

I have also read reports on Weatherzone in which some very cold nights have occurred in inland SE Queensland and even as far out as Charleville.

Where I live in Blacktown, minimum temperatures have fallen between 1C and 4C still very cold and well below the average minimum of 6.8C.

Harley Pearman

[Jimmy Deguara]

Harley,

We have had several consecutive mornings with frost here in Schofields and this includes ice having to be removed off the windows on a few of these mornings. It is the first time I recall that August have had colder and more consistently colder mornings than July.

Can anyone confirm this?

Regards,

Jimmy Deguara

[Steven]

1.8 is the coldest we've had so far this year. I don't know whether this is low enough for light frost, HOWEVER, last July brought full on frost when the temp dipped to -0.7 on the 20th.

[Jimmy Deguara]

Steven,

In response to your 1.8C temperature, this is sufficient for frost but it depends on the ground temperature which at times can be up to a few degress lower than your screen temperature. I have observed frost even when temperatures have been 5C but this is in particularly dry air situations and during periods when significant frosts have been observed prior lowering the mean ground temperature.

Regards,

Jimmy Deguara

[enak_12]

We had a few frost in Coffs over this period, not sure how many exactly but I woke up to see 3 was probably a couple more but I didnt get up for them. Took photos on the 13'th

[Michael Bath]

Been a few frosts around the Northern Rivers district over the past three weeks since the rain stopped - in fact there has been no rain since 28th July.

This is in the valley below my place on 31st July though there have been many mornings like this during August.

[James]

MB,

Thats a great example of sinking cold air and a pretty good reason why I wouldn't want to live in a valley!!

Roughly, what sort of temperature difference was there from your place to the valley in your photo? I'm interested as to how much difference there is with night time temperatures between hills and valleys.

James

[Michael Bath]

Hi James - I measured 8.8 as the min that morning. We are about 120 metres higher than the lowest part of the valley. It's typically 7 degrees warmer here than below - quite a difference. Of course that rule only applies for the clear, dry and still nights.

Lowest temp I've had this winter is 5.7 on the 12th August and the low parts of Lismore was getting minus 1.

[Steven]

Steven,

In response to your 1.8C temperature, this is sufficient for frost but it depends on the ground temperature which at times can be up to a few degress lower than your screen temperature. I have observed frost even when temperatures have been 5C but this is in particularly dry air situations and during periods when significant frosts have been observed prior lowering the mean ground temperature.

Regards,

Jimmy Deguara

Well I haven't seen many frosts at these temps (around my area especially), perhaps once before when it got down to about 2-3C and I actually braved the cold to get out.

[Jimmy Deguara]

Michael and James,

Even though the valley here in Schofields is relatively shallow - only perhaps a 20 to 30 metre drop, there is a significant difference in the frequency of frosts and their severity.

Another point worth raising is the eastward versus westward facing slopes. My parents chose this farm based on its inclination which obviously has a flow on effect on the health of plants and their growth in market gardening. Now I wonder if there is a correlation between the health of humans and animals given the above mentioned factors...

Regards,

Jimmy Deguara

[Jimmy Deguara]

Hi Steve,

I am specifically going to point out the importance of drier air and rate of cooling at the surface in the rarer cases of frost occurrences at say 4-5C. Where you are, I assume the dew points are relatively higher (moister air) so perhaps this may be the reason? Any other comments?

Regards,

Jimmy Deguara

[Richary]

With regard to height being a factor, I used to live near Gosford and would often wake up to hear on the radio it was 2 degrees or something similar in Gosford. Walked outside (aprox 80m ASL) and thought it's not that bad. As I walked down the hill to the train (about 10m ASL) you would suddenly strike a temperature change where it dropped several degrees in the matter of a few steps. Only on still days of course.

That said, where I am now at Rydalmere we are higher than Parramatta or Olympic Park weather stations by about 20m but it is often colder here than reported at those sites - I guess the proximity to the water may keep those areas a bit warmer?