Topic: General Weather Thread: QLD / NSW / ACT / NT

[Steven]

Brisbane's forecast to reach 26 tomorrow, then its all rain for the rest of the week. We'll have the rain thanks, fire danger is moderate to high.

[Mike]

Instability very slowly getting there as the days pass.  There's been some decent storms/showers overnight through the central parts of the NT towards Alice and the heat low through WA/NT is doing nicely.  Humidity levels are only around 40%, but much higher down the track - up to 70% in some areas.  There's just not enough moisture in the mids just yet to get storms and is a few weeks away yet. But the soundings are gradually showing positive signs as they do during the transition period and dew points are in the high teens to 20's now and then.  A fair cloud cover during the mornings, but burns off toward sunset and then reappears from nighttime heating around midnight onwards.

Really a lot of high based scattered CU with low tops...a bit like the pic shows - NOT!

[Harley Pearman]

A colder than normal August for Blacktown NSW

August 2008 where I live in Blacktown much like much of SE Australia will go down as a colder but relatively dry month.

Daytime temperatures were below average, averaging 17.5C with night time temperatures averaging 4.4C. This is well below the long term maximum average of 18.6C and minimum average of 6.8C.

Actually this is significantly colder than August 2007 where the average maximum was 20C and the average minimum was 8.23C.

The biggest feature for August 2008 was the lack of days where temperatures reached 20C. There were 15 such days in 2007 but this year there were 4 such days.

There were 2 days where maximum temperatures failed to reach 15C. Of interest there were 5 such days during August 2007.

The warmest day this August occurred on 26 when it reached 22C. The coldest day occurred on 22 when it reached 12C. For comparison for 2007, the warmest day occurred on 27 and 28 when it reached 27C.

The coldest night occurred on the 9 when the minimum was 1C and 1.1C occurred on the 19. For comparison for 2007, the coldest night occurred on 8 when it reached 2C and 3C on the 7.

It rained on 6 days that produced 24.9 mm. This is below the long term average of 58 mm. August 2007 saw 74.5 mm fall over 9 days. The heaviest fall occurred on 30/8/08 - 31/8/08 rain event where 13 mm fell.

One thunderstorm occurred on the afternoon of 7/8/08. However distant thunderstorms over Sydney's east were observed on 2 other occasions.

Generally August 2008 saw some colder than usual conditions which have been reported in other posts. What happened in Blacktown where I reside is a snapshot of the bigger picture where colder than normal conditions prevailed.

Harley Pearman

[Mike]

Darwin Sept6 2008

Weather is still nudging towards typical buildup days.  Today especially there were several towers to the SSE at around 17,000ft and a couple over the Tiwi's.  Stuff over the Tiwi's is a good indicator to go by as Hector convection always precedes storms inland or near Darwin and you know it's not long to go.  Last year Hector storms formed a little later in September through to the wet, so to see decent towers this early is encouraging.

Structure of the CUs seems to be good and visible height even with the ones close by.  The SOI numbers have gone through the roof for this time of year.  Last time we had numbers this positive we had decent storms early and the wet came in before xmas.

[Peter J]

Mike

I have been keeping an eye on weather up your way - humidity levels have increased quite a bit of late - I believe from a BoM report on weatherzone.com.au that Darwin sweltered through a day of 37deg C?

Big Pete
(keep that ice-jacket on, mate)

[Mike]

Hi Pete.

Indeed the last three days peaked at over 37.5 in the city!  Even BoM were perplexed as we had an afternoon sea breeze during lunchtime and I don't know what happened but the DP's went in the minus figures dramatically, temps soared to 37 and that has not happened for many, many years - not since I was born anyway!  We've been under the influence of a savage dry flow and even with some moisture coming in from the NW it did not stop whatever caused this rash heat wave.  A high pressure flow I suspect really had some impact big time for those three days.

BoM say we're def in the build up period now, but it's still 'dry' with only the odd cloud about.  All indicators are that we're in for an early wet/storm season.  We've had Hector convection twice already during the past week which is a month early for him to show his head over the Tiwi's.

Humidity is rising but you only notice it very late at night into the early hours, once the sun comes up it's almost non-existent.  Temps have returned to normal and things have 'calmed' down and that usual feel about the place.

It won't be long, but I'm going for October before any storms form and they'll form inland first anyway...still, I'm chaffing at the bit as you'd imagine!

[Richary]

Had a bit of a big night last night with a reunion and people I haven't seen for 8-10 years. So didn't surface this morning until about 11am, to find it was already 29 degrees. Hang on, this is September! It peaked at 32 here at Rydalmere, and the official temperature in Sydney matched the highest recorded this year back in January with 30.6. Certainly felt nice and summery today. Only 12 degrees above the monthly average.

Off to Perth tomorrow until Thursday for work. Hmmm, 12 degrees cooler tomorrow with showers. That's a downer.

[Harley Pearman]

Richary

Yes, I noted the temperature readings in Sydney 13/9/2008 while watching the events unfold in Texas. Yes, it did reach 31 degrees in many areas and 32 degrees in a few locations. Most of the 30 degree temperatures occurred in western Sydney for our region.

It is the first 30 degree day of the spring / summer season and the warmest day where I live since March 20 when it reached 32 Celsius.

I have noticed in recent Septembers (Did not occur last year) temperatures will reach 30 degrees on at least 0 to 3 days where I live. For example:-

2000 - 2 days
2001 - 1 day
2002 - 2 days
2003 - 3 days
2004 - 3 days
2005 - 0 days.
2006 - 4 days.
2007 - 0 days
2008 - 1 day to date.

It can occur where I live but the number of days is always limited.

Harley Pearman



MB Edit - changed 14/9 to 13/9

[Steven]

Noosa Heads reportedly had 125mm from a freak rain cell, as reported by Wz. Having assessed the radar, it's incredible how nothing else spawned except a downpour, not even lightning!

---> Gympie radar loop

There was a bit of a downpour here last night too, but not much to add up that amount. The AWS obviously wasn't under one of these things.

[Mike]

Darwin 20Sept2008

Never seen an early thunderstorm forecast this early in the piece for a long time.  BoM say inland and rural thunderstorm on the cards.  A stalled trough moving through from WA is generating some instability.  Dew points are in the 20's with temps around 33.  Sounding does not look much and even re-plotting with several numbers only changes things a little.  A dry layer at 500mb is apparent so I'm confused about that as i don't fully understand how to read them. (any advice helpful at this time as to what to look for as key indicators)

There's plenty of cloud and low based stuff also.  We had a nice CB in the rural area yesterday arvo with a hefty anvil spread.  Convection rising is no problem today as the CU's are bubbling away. I may go for a recon drive in the rural area later on once things get 'thicker' and showing signs of def towers.

We'll see what pans out - the camera is charged anyway!

[Harley Pearman]

30 Degree days in September - Sydney 20/9/2008

There are two famous winds that affect Sydney with one being "The southerly buster" that brings the summer time cool changes and the other being "The NW Brickfielder" that brings warm / hot and dry weather. The name came from a time when the hot NW winds that fanned over the city in spring and summer would loft dust from the NW and raise the temperature above the average.

Today 20/9/2008 for the second time this month the hot dry brick fielder winds fanned over the city pushing the temperature to over 30 degrees and lowering due points to very low levels.

Even though there have been 2 days this September now when it has reached 30 degrees put in context, it is only an average September temperature wise to date where I live. Out of the 20 days gone, maximum temperatures have failed to reach 20 degrees Celsius on 9 days so far. The few summer like days we have had put in context, has only resulted in an average September to date and it has not been a hot month at all. Average temperatures where I live to date are best described as average or typical for a September to date.

Some maximum temperature recordings for 20/9/2008.

Sydney Airport 33.6C - Dew Points 1.5C, WNW winds maximum of 63 km/h.
Observatory Hill 32.8C.
Sydney Olympic Park 33.8C - Dew Points 1.7C, W winds of maximum gust 50 km/h.
Badgerys Creek 32.7C - Dew Points 6.5C, W winds maximum gust 56 km/h.
Campbelltown 32.3C - Dew Points 5.8C, NW winds maximum gust 43 km/h.
Penrith 33C - Due Points 7.3C, NW winds maximum gust of 57 km/h.
Richmond 32.6C - Due Points 7.4C, WNW winds maximum gust of 50 km/h.

(Sourced from BOM weather stations / data sheets)

Most of Sydney would have had a 30 degree day and where I live it is the second such day for this month.

Harley Pearman

[Mike]

Did not even attempt going out 'chasing' today given what I observed (although some here did - I laugh!)

Weak but tall CU behind my house with a nice double rainbow and precip falling - something for the camera lens anyway.  Will upload images later..

Tuesday could see Darwin get a storm as opposed to the inland areas I see, so that would be nice.

[Harley Pearman]

Darwin - Dry season for 2008

Mike, as you live in Darwin you may be able to provide additional comments here.

An interesting weather record may have unfolded this week at Darwin Airport. I read on Weatherzone that Darwin Airport has just gone 167 days without rain.

Today I have verified that. Since the end of the wet season 2007/2008, the last fall of rain at the airport was indeed April 9 when 0.4 mm of rain fell. On the 23 September 5.4 mm of rain fell at the airport. That is indeed 167 days at the airport without a drop of rain.

I note April was a very dry month and the wet season ended early. I am reading that this is the longest and driest period ever experienced at Darwin Airport.

I lived in Darwin in 1995/1996 and during that time and based on records that I could find and despite the notion of "The dry", Darwin has never truly had a true "Dry, dry season". That is, there would always be a shower of rain at some point. That happened when I lived there.

Yet this year, the notion of a true dry, dry season appears to have almost occurred. If this is the driest period ever for this city, then I think it is truly amazing considering that Darwin is Australia's wettest capital city.

Mike, if you have any comments on this, I would be most interested especially considering that I am familiar with the climate regime in this part of Australia.

Harley Pearman

[Mike]

Hi Harley.

You are correct with the stats re the rainfall or lack of.  Now that the dry will be officially over as of Oct1 this season's dry spell was certainly dry.  We usually get the odd shower during the dry season, but this year I don't think we even got anything that registered in the gauges let alone a shower.  Whether it's a combination of the la Nina cycle moving to neutral or the MJO having stalled somewhat of late I am not sure. 

I don't take a lot of interest in stats as far as rainfall amounts or temps during both seasons here - mainly because I am more interested in chasing storms but I did find this stat...the longest period without rain being recorded in Darwin 205 days (25/4/1896-15/11/1896)


From what I have seen of the weather patterns the easterly dry winds have been vicious and strong.  The large high pressure systems that dominated the country certainly had an effect on alienating any moisture that happened to be drawn into the Top End.

I know from what the bureau has mentioned of late is that this has been quite a dry 'dry' and it's something that comes around every few years, but they don't pinpoint any particular reason for it.  Locals have all commented on it being very dry and hotter than previous years.  I've only been in the Territory 7 years and honestly, did not take much interest in the weather up until 2 years ago - so my knowledge is a bit limited re specifics.

The monsoons for 2007/8  - albeit rainfall record amounts during cyclonic activity we had - were pretty average and suddenly in April it definitely switched over to the dry season very quickly. Storm action for last season was dismal - regularly up to a week or more without storms in some months, something which had not gone unnoticed by the BoM.

I'll get some info from BoM during the week to see if they had noticed anything out of character for the dry spell which they have been able to analyze now that it's gone.

Sorry I could not give you any specifics!

[Harley Pearman]

Mike

Thank you. Your comments are terrific. I have also read that Darwin this year is facing a torrid build up being hotter, drier and with more humidity than usual.

Actually since my post yesterday, I found on the BOM site that 1976 was quite dry too, something that I was not previously aware of. Apparently in that year, the city went 164 days without rain from 7 May to 17 October. That year the build up was torrid and drier than normal. A repetition of that in 2008 is not expected but it is expected that the build up will be more torrid than normal.

I have noted that it reached 37 degrees in Darwin on the 10 September and 36 degrees on the 8 and 9. When I was there in 1995 and 1996, temperatures did not exceed 35 degrees. I have noted that inland areas are reaching 38 degrees Celsius already which may indicate a hotter and more torrid build up than normal.

October thunderstorms start to develop but they pulse up drop their moisture and decay quickly. They tease the locals and storms are usually short lived. One has to be almost underneath it to enjoy the cooling breezes that they bring. You get beautiful cloud formations though but the humidity and heat can be tough when outside getting the photographs of the storms during the daytime.

Harley Pearman

30 degree days in September - Blacktown 2008:

Another interesting weather feature for September 2008 that has not gone unnoticed is the number of 30 degree days that have occurred in September where I live. There have been 5 days to date where I live for the month occurring on the 13, 20, 22, 27 and 28. On the 28 it reached 33 degrees. This is the highest number I have experienced in September since moving to Blacktown in 1997.

What is more interesting is that 4 of those days have occurred on a weekend.

Interesting, a strong southerly change moving across Sydney at 2.25 pm saw 33 degrees in Sydney's west under north westerly winds but only 19 degrees Celsius at Sydney Airport where southerly winds were occurring. The temperature contrast between the two air masses is quite amazing to see being as much as 14 degrees across the frontal boundary.

Note:- The southerly change arrived at my place at 3.18 pm and I can feel the temperature dropping sharply.

Harley Pearman