Day to Day NE NSW / QLD weather

BrettSS

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But it's important to remember that the observed increasing trend in positive SAM phases mainly only applies to summer and not all the year round.

I've read that there's been a decreasing trend in winter rainfall over southern Australia as a result of the belt of westerly winds and associated rain bearing synoptic systems (cold fronts and mid latitude depressions) tending to be moving further south over the last few decades, and therefore dropping more of their rain on the southern ocean and less on the mainland, as the result of a combination of (increasing atmospheric levels of CO₂ and other greenhouse gases) and (the depletion of stratospheric ozone due to CFCs). My understanding has been that the SAM is an index which indicates the latitude of this belt of westerly winds and hence of rain bearing systems, with more positive values of SAM indicating higher (more southerly) latitudes of this belt. If my understanding is correct, then wouldn't that mean that the SAM has been in an increasing trend over the last few decades in winter as well as in summer? What am I missing here?
 

Ken Kato

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I've read that there's been a decreasing trend in winter rainfall over southern Australia as a result of the belt of westerly winds and associated rain bearing synoptic systems (cold fronts and mid latitude depressions) tending to be moving further south over the last few decades, and therefore dropping more of their rain on the southern ocean and less on the mainland, as the result of a combination of (increasing atmospheric levels of CO₂ and other greenhouse gases) and (the depletion of stratospheric ozone due to CFCs). My understanding has been that the SAM is an index which indicates the latitude of this belt of westerly winds and hence of rain bearing systems, with more positive values of SAM indicating higher (more southerly latitudes) of this belt. If my understanding is correct, then wouldn't that mean that the SAM has been in an increasing trend over the last few decades in winter as well as in summer? What am I missing here?
The increase in positive SAM phases has mainly been in summer but not completely restricted to it and that longer term trend is compared to its climatological position for that time of year. I probably should've rephrased what I mentioned earlier by not saying only and restricted which might give the wrong impression.
Because it's the southern fringes of Australia which get most of their rainfall in winter and early spring when the main belt of midlatitude westerlies and storm systems are at their farthest north, just a small southward shift (even if it's smaller than in summer) in this belt has a significant effect on rainfall during that period during that crucial time of year. This is in contrast to summer when rainbearing fronts and lows are less frequent in those areas anyway and the negative impacts of a more positive SAM are much less in those areas. The one exception is the west coast of TAS which is exposed to the uninterrupted westerly flow and is also still far south enough to be well within it. It's possible either increased overall water vapour content in the atmosphere, a stronger westerly flow, or a smaller scale change in the movement of local lows and fronts may be making it an exception.
 

BrettSS

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The increase in positive SAM phases has mainly been in summer but not completely restricted to it and that longer term trend is compared to its climatological position for that time of year. I probably should've rephrased what I mentioned earlier by not saying only and restricted which might give the wrong impression.
Because it's the southern fringes of Australia which get most of their rainfall in winter and early spring when the main belt of midlatitude westerlies and storm systems are at their farthest north, just a small southward shift (even if it's smaller than in summer) in this belt has a significant effect on rainfall during that period during that crucial time of year. This is in contrast to summer when rainbearing fronts and lows are less frequent in those areas anyway and the negative impacts of a more positive SAM are much less in those areas.

Thank you for your reply, Ken.

Are you saying, then, that while the increasing trend in SAM in recent decades is having a major effect on far southern Australian rainfall in winter and early spring because of the reasons you mentioned, its influence on eastern near coastal Australian rainfall is only significant in summer?
 
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Ken Kato

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Thank you for your reply, Ken.

Are you saying, then, that while the increasing trend in SAM in recent decades is having a major effect on far southern Australian rainfall in winter and late spring because of the reasons you mentioned, its influence on eastern near coastal Australian rainfall is only significant in summer?
On average, positive SAM phases have the biggest (positive) effect on rainfall in spring and summer in the lower east of Australia especially around eastern and central NSW as well as eastern VIC.
SE QLD/NE NSW is near the northern edge of that area of influence so we do experience some effects from that but often not as pronounced as those areas.
But there's other climate drivers like ENSO, the IOD (in southern parts), blocking patterns, etc that influence rainfall in eastern Australia, not just SAM so increasing positive SAM by itself doesn't automatically mean eastern Australia gets more rain in summer. Unlike winter/early spring rainfall in southwestern and southeastern Australia, trends in summer rainfall in eastern Australia have been a lot more variable with very dry periods interspersed with wetter ones.
 

Falling_Droplet

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The temperature was near average during the day and was a little variable from the mid morning to the mid afternoon. Slightly warm early tonight before easing to back to near average during the rest of tonight. Dew point was generally stable during the morning and afternoon, rose a little later the afternoon, became stable in the early evening before falling tonight and has remained close to average. Relative humidity have been near average during the day and tonight. Light ENE to SE winds in the late morning and in the afternoon, E to NE in the late afternoon and early tonight, followed by ENE to NE winds before calm winds later tonight.

Last 24 hours:

temp 2020-11-21.PNG
hum 2020-11-21.PNG
wind dir 2020-11-21.PNG
 

CirrusFibratus

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That's what no-one's certain about yet Cirrusfibratus because there's two competing factors.
One is the increasing greenhouse gas concentrations that's been making part of the stratosphere increasingly colder (extra carbon dioxide molecules up at that height tend to have greater efficiency in sending heat energy from that level up and out into space, as opposed to the molecules lower down in the much denser troposphere which tend to trap more of the warmth in there and warm up sections of it... and that also prevents more of that heat energy from coming up into the stratosphere and warming it). The coldness of the stratosphere over the polar region and the vertical temp gradient it causes is what maintains the polar vortex's strength. A colder stratosphere causes the polar vortex to strengthen but also contract further south. It also allows more polar stratospheric clouds such as Mother of Pearl clouds to form because they can only form below about -77C in the stratosphere - these clouds chemically react with ozone molecules and deplete their concentrations. It's also been manifested in various ways such as on the ground and satellite analyses of increasing wind speeds over sub Antarctic oceans and islands, increasing storminess at those latitudes, etc.

The other opposing influence is the continuing ozone hole recovery. Recovering ozone levels in the stratosphere = more ozone molecules to warm up the stratosphere when incoming solar radiation hits them = encourages the polar vortex to expand further north.
If this influence wins out (and no-one's sure if it will) and the polar vortex expands back further north, it's likely to do a lot of it within our lifetime. But even if it does do that, it'll depend on how quick the ozone hole continues to recover and if that recovery won't be intefered with. It also doesn't necessarily mean more frequent colder outbreaks because it depends on the season (e.g. strongly negative SAM in late spring can cause extreme fire weather, heat and dryness in areas like NSW and QLD) and also because the overall increase in longer term temps regardless of SAM is likely to modulate the effects as well.

But it's important to remember that the observed increasing trend in positive SAM phases mainly only applies to summer and not all the year round. So even if the polar vortex expands back further north or keeps contracting further south, it's likely that any trends won't be evident all year round. Or it could just stay within the current range of natural variability if the two opposing factors cancel each other out.
Either way, it's one of the more fascinating interplays of chemical reactions and physics which ultimately have a big effect on the weather at the surface.
Thank you for the comprehensive reply, I think I get how it all comes together now.

It's stuff like this that keeps me hooked on weather as a hobby. Even when 'nothing' is happening weather wise, understanding why that is the case is fun in itself.
 

Retired Weather Man

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WYNNUM NORTH ( 27.4S 153.2E ) - WEATHER
( DATA FROM 0900 PREVIOUS DAY TO 0900 CURRENT DAY )
22 NOVEMBER 2020
TIME....0750
CURRENT TEMPERATURE...26.1C
CURRENT HUMIDITY........64%
CURRENT DEW POINT.......19C
CURRENT WIND........NE 9Kph
CURRENT VISIBILITY.....30KM
CURRENT PRESSURE..1020.1Hpa
CURRENT CLOUD.....2/8 Cu, 1/8 Ci
CURRENT WEATHER...No significant weather
RAIN SINCE 0900 SATURDAY...0.0mm
SUMMARY LAST 24 HOURS
YESTERDAYS MAX TEMP..........30.0C
THIS MORNING'S MIN ..........18.1C
PAST 24 HOURS TEMP ANOMALY..+0.95C
THIS MORNING'S GRASS MIN.....16.1C
AVERAGE 24 HOUR DEW POINT......19C
AVERAGE 24 HOUR PRESSURE...1019.7Hpa
PAST 24 HOURS MAX WIND.....NE 24Kph 1501
PAST 24 HOURS SIG.WEATHER..No significant weather.
...............................................
NOVEMBER RAINFALL TO DATE.............18.0mm
NOVEMBER AVERAGE RAINFALL............105.0mm
2020 RAINFALL TO DATE...............1188.0mm
AVERAGE ANNUAL RAIN TO END OF NOV...1026.4mm
 

Ken Kato

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upload_2020-11-22_8-46-25.png


Speaking of storms, impressive outbreaks happening today across large parts of SE Australia as well as northwestern and central parts of the continent.
Map above is for the 10am today to 10am tomorrow period. Should be some severe cells in amongst that lot also. Magenta contours = areas with some severe storm potential, green contours = areas with ingredients present for short bursts of intense convective rainfall.
 

Bello Weather

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Lightning map from EC for the three hours to 5pm Tuesday:

xx_model-en-304-3_modez_2020112112_66_12880_548.png


Once we get through this stormy time it looks like some real heat could kick in....way off at the risky end of runs but there is consistency already between runs...on a big heat event possible next weekend - and some decent heat over the next couple of days as well. Here's the current EC run for max temps from next Friday through Tuesday. Focus at this stage looks like being NE NSW, but one to watch:

ezgif.com-gif-maker (32).gif
 

Ken Kato

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Forecast rainfall amounts themselves often aren't too great an indicator of storm potential/extent except for whether a lot of them will drop good rainfall amounts. Probability of any precip on the other hand is a fairly good indicator.
Just need to hope the change doesn't push through TOO early. If on the off chance that happens, much of the higher storm potential will shift further north even though there's still instability aloft behind the change. This change is a bit stronger than the last one we had so a bit less mixing behind the change.
Hopefully should get a better idea about Tuesday by tomorrow.
 

Mezo

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Forecast rainfall amounts themselves often aren't too great an indicator of storm potential except for whether a lot of them will drop good rainfall amounts. Probability of any precip on the other hand is a fairly good indicator.
Just need to hope the change doesn't push through TOO early. If on the off chance that happens, much of the higher storm potential will shift further north even though there's still instability aloft behind the change. This change is a bit stronger than the last one we had so a bit less mixing behind the change.
Hopefully should get an even better idea about Tuesday by tomorrow.

How often do we get a downgrade, followed by an upgrade? Hardly ever.
 

Ken Kato

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How often do we get a downgrade, followed by an upgrade? Hardly ever.
A bit more often than what many people perceive (I've kept stats on this), probably because many people tend to remember the downgrades/letdowns a lot better than an upgrade, especially if high hopes have been built up and there's lots of anticipation and scrutiny leading up to it. Large upgrades/downgrades tend to become less and less common closer to the day. And these more subtle changes closer to the day also don't tend to be remembered well by many people. But on average, downgrades still happen more often than upgrades when it comes to rainfall amounts in this region (just using EC stats), and especially at longer ranges.

What I'm more interested in is why this seems to be much more prevalent in this region compared to many others. I suspect one of the possible reasons may be the simple fact that our region often tends to be on the northern end of setups like these where the dynamics are often weaker and therefore more susceptible for something to ruin it.
 

Ken Kato

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upload_2020-11-22_9-15-47.png


@Mezo this was the last upgrade. It was only just under a week ago on the 17th.

18z ACCESS-C had an obvious hole of nothingness over the far southeast corner but then the following 00z run partially filled it. The end result was that some storms occurred in that hole and ended up being closer to the 00z upgrade. One of the storms in that hole was even identified as severe. But the upgrade seemed to go past unnoticed by many and I even saw some people still talking about how things had downgraded even after the 00z upgrade. Image via WZ.

I'm not saying for one second that the same thing will happen for Tuesday and it's still outnumbered by downgrades especially at longer ranges, but just one of the examples showing that it does happen from time to time in general.
 

Ken Kato

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Thanks for that bit of info, @Ken Kato . But, I won't hold my breath.
No worries @Mezo , yeah I haven’t held it for a very long time. I used to when the weather was a lot more exciting here back in the day. But these days, my standards are so low in this place that I just don’t get that disappointed anymore. Of course it’s a different story for those in areas where their livelihoods depend on rain. But as for this local area, my care factor has been low for a long time. I’m far more interested in the meteorology rather than hoping for so-called weather events eventuating in this place.
The only exception is when we miss out on exciting winter weather while everywhere else gets it instead. I’m just thankful I got the opportunity to travel to TAS again recently to get my fix and tide me over for awhile.
 

Nature's Fury

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@Rays74 Those are great photos. I'm actually keen to drive out there in the next few weeks now.

As for Tuesday, I'm not too interested at this point. It looks like an inland SEQ show, much like last Tuesday. I'll wait until closer before sharing more detailed thoughts though.

I certainly didn't think we'd have such a quiet November. I'm still hopeful that we'll see a more significant transition to rainy conditions next month.
 

Rays74

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@Rays74 Those are great photos. I'm actually keen to drive out there in the next few weeks now.

As for Tuesday, I'm not too interested at this point. It looks like an inland SEQ show, much like last Tuesday. I'll wait until closer before sharing more detailed thoughts though.

I certainly didn't think we'd have such a quiet November. I'm still hopeful that we'll see a more significant transition to rainy conditions next month.

Hey Nature's Fury...
If you're keen to explore , check out Fifteen and Seventeen Mile Road.

Fifteen mile road runs Hampton to Murphy's creek, all dirt.

Seventeen mile road runs from Helidon to Ravensbourne National Park, all dirt.

I don't recommend a normal passenger car.

I use 4H and it's great. Not too rutted , few blind corners and off camber sections.
But fantastic landscape to see.
 

Falling_Droplet

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Ferny Grove Weather
Date: 22 Nov 2020
Time: 11:40 AM

Min Temp since 9am yesterday: 16.7 C
Max Temp since 9am yesterday: 30.7 C
Min Ground Temp: 14 C
Rain since 9am yesterday: 0 mm

Temperature: 29.5 C
Relative Humidity: 48 %
Dew Point: 17.3 C
MSL Pressure: 1018.2 hPa
Wind Speed: 9 kph - light breeze
Wind Direction: ESE

Present Weather: State of sky generally unchanged during preceding hour
Visibility: 20km to 39km - Very Good Visibility
Cloud Cover: 1/8
Ground State: Ground dry

Notes of yesterday weather - 21/11/20: Mostly sunny with some Ci and Cu clouds. Slightly above average temperature in the early to mid morning as the temperature rose quickly. The temperature was a little variable from the mid morning to the mid morning. Slightly warm in the evening. The dew point was close to average over the entire day. The dew point was stable early in the day, rose in the morning generally stable but was a little variable from the mid morning, rose a little later in the afternoon, became stable in the early evening before falling in the evening. Relative humidity was near average early in the day while slowly rising fell quickly in the morning and became moderately low. The relative humidity was near average from the mid morning as the relative humidity fell more slowly. Calm winds early, light WSW to SSW in the early morning, then SE to NE winds with some N to NE winds earlier in the morning and then S to ENE to SE in the late morning and in the afternoon. Light E to NE winds in the late afternoon and early evening, then ENE to NE winds before calm winds later in the evening.

Today: Temperature was near average today and have been a little variable from the mid morning. Dew point have remained close to average that fell slowly in the early hours, rose in the early morning then fell before becoming generally stable since the mid morning. Relative humidity was near average in the early hours, fell quickly this morning and became slightly below average before falling more slowly later this morning while remaining slightly below average. Calm winds early before light N to ENE winds in the early morning before ESE to NE winds with some N to NE winds.
 

TweedStorm

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Hahahaha...it's SO true. My standards are so rock bottom I get excited if I see cloud building to the SW on a steamy day, I am so lame. :emoji_expressionless:
That story reminds me of the first time I went to Darwin during the buildup. I was hiring a car with a mate and the guy that ran the place said what are your plans I said we hope to see a few good storms and a bit of bushwalking etc.
He said just a minute I'll let you know if we'll get one today and he looked outside his business and said yep, well get a storm later. He said do you see that tiny bit of a cloud in the distance out to the southwest. I had to look twice because it was so small, but sure enough that evening we had a ripper Top End thunderstorm over the city . I so love that place, highly recommend Darwin for those who love spectacular thunderstorms and don't mind heat and humidity which is pretty intense up there this time of the year, but at least you get to see towering Cumulonimbus each day, unlike around here.
 

Ken Kato

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I keep hearing early December, but then there was a lot of respected people saying second half of November, as well.
I wonder if they were referring to this coming Tuesday's showers and storms. I haven't kept close tabs on any outlooks for awhile due to being wrapped up with lots of other weather stuff but I do remember around about this Tuesday is what's been showing up for ages as a bit of a jump in rainfall in the late Nov period. So makes me wonder if that's they were looking at.
 

PlumbBob

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Edit: Just seen your post @MegaMatch : Yeah I have noticed that a little, but, nothing I can do so I just carry on - it is depressing weather for some, and I'm no spring chicken these days, have learned to except on both fronts :whistle:
HavaGoodN
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Does anyone have any idea when we might move in to a wet pattern (not just random one off storm days)? I keep hearing early December, but then there was a lot of respected people saying second half of November, as well.
Anyones guess in the long term @Mezo - Models verses Reality ? ?
Have attached a couple of charts, tho I assume you know about and asking for more solid info, which is what we'd all like, One thing I do know is; don't ask a clairvoyant, fortune-teller or astrologist ;)

Z1.JPG


Z2.JPG


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Hmmm, Tuesday eh, looks interesting enough to not give up yet ?

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Anywho, I originally logged on to show a couple of interesting cloud pics from the achives I stumbling accross earlier.

1st was back in winter of 2011, over the back fence, old camera and stiching gradiants evident, some form of thin undulatus asperatus going on at a guess ?

2nd is what I call a Comet Cloud, and taken over our house 'center'. Quite an effect evident in the higher level winds and conditions.

Hope worth a Squizz...

W_0451PStM1.jpg


W_093236M1sm.jpg
 

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Nature's Fury

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Does anyone have any idea when we might move in to a wet pattern (not just random one off storm days)? I keep hearing early December, but then there was a lot of respected people saying second half of November, as well.

Thinking back to my previous discussions and the forecast modelling, it looked like a major transition to wetter conditions was on the cards in mid-October and then November and now it looks to December. Remember CFS was going for significantly above average rainfall in the "month ahead" from September. Unfortunately a few things have worked against us like the LWT positioning, MJO being active in the IO suppressing rain here, and a temporary weakening of the trades resulting in temporary warming of the Nino regions and cooling of the Coral Sea. I still think we will see a breakdown and major transition to wetter conditions, most likely in December, but obviously it will have occurred later and possibly for a shorter period of time then might otherwise have been.
 

BrettSS

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Does anyone have any idea when we might move in to a wet pattern (not just random one off storm days)? I keep hearing early December, but then there was a lot of respected people saying second half of November, as well.

I think that's what we'd all like to know, but no-one can say for certain. The average time of arrival of the monsoon in northern Australia (at Darwin) during La Years is mid December, which is earlier than the average time of arrival for ENSO neutral and for El Nino years. Also, the monsoonal moisture inflow tends to be greater in La Nina years; the stronger the La Nina, the greater the inflow, all other things being equal. The arrival of the monsoon, then, should greatly enhance the flow of atmospheric water vapour into northern Australia. This will greatly enhance the potential for rain in our region, though whether or not this potential is actually realised will depend on whether or not the local synoptic systems are such that this tropical moisture is advected southwards into our region and activated (i.e. uplifted and condensed to form clouds and rain). The last I heard, there are LWTs (long wave troughs) located at the longitudes of Western Australia and New Zealand, causing rain bearing (short wave) systems to culminate over those latitudes, leaving us high and dry. My understanding is that it is this unfavorable (for us, though south western WA also badly needed - and probably still needs more - rain) positioning of the LWTs has been the major factor inhibiting rainfall in our region this month (November 2020), though the (unfavorable) phase of the MJO has undoubtedly also played a role. As such, I think that whether or not the abundant inflow of atmospheric moisture into northern Australia which is highly likely with the arrival of the monsoon (probably some time next month) translates into good rainfall for us will depend on the positioning of any LWTs at and near Australian longitudes.

I've been trying to understand the nature and typical behaviour of LWTs since Ken Kato informed me that the positioning of an LWT over central Australia (at the time) was the principle reason for the generally dry conditions over eastern Australia during the first half of spring (2020), while central parts of the country received ample rain, but finding information about LWTs online has seemed to me to be like looking for gold nuggets. Given how important they are to our weather, I can't understand why it so hard to find information about them. My understanding is that, like most weather patterns, the positioning of LWTs more than a few days to a week or so into the future is impossible to reliably predict, so I'm not under any illusion that having a better understanding of LWTs would allow me to predict with any reliability when we will next see one positioned at eastern Australian longitudes, thereby greatly enhancing rainfall in our region. But having some idea of their typical behaviour would give me some idea of how likely it is that we may see an LWT in a position favourable to high rainfall in our region by, say, the end of the year. If, for instance, the positioning of the LWTs tends to change every few weeks, and if when it does change it does so a fair proportion of the time in such a way that an LWT becomes located in a position favourable to high rainfall in our region, then we can at least hold out hope for good rainfall here by the end of the year. But if the LWT pattern typically remains static for several months at a time, or if when it does change it seldom changes to a pattern conducive to good rainfall in our region, then we are probably screwed, not only for the remainder of the year, but for the entire remainder of this wet season, thereby effectively wasting this La Nina for us. So knowing the typical behaviour of LWTs in the Australian region would not allow me to be able to predict if and when we are likely to reap the benefit of this La Nina in SE Queensland, but it would give me some idea as to whether or not there is any real hope.

Anyway, that's where my understanding's at, and it's about as close as I can come to answering your question. I hope that helps in some way.
 

Seabreezes

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Thunderstorm activity on the eastern slopes and inland coastal plain this evening about the local region. Boonanghi, west of Kempsey, picking up 26mm. I've heard some distant thunder at times here too.

I've been lurking, and will continue to do so, but I have just one question;

But why am I called out for having a whinge about my area yet 80% of the above posts in this thread are just that, day after day after day, and nothing is said?
Because we never had an issue with your posts :):) It was just a single person (who was probably having a bad day) and doesn't even live in the area covered by this thread.
 

Tsunami

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Thunderstorm activity on the eastern slopes and inland coastal plain this evening about the local region. Boonanghi, west of Kempsey, picking up 26mm. I've heard some distant thunder at times here too.
Youre all good mega match And we / most felt youre pain

Because we never had an issue with your posts :):) It was just a single person (who was probably having a bad day) and doesn't even live in the area covered by this thread.
I aggree
We all get frustrated with the weather
Anyone who loves weather etc probably need to see a psychologist after the last few years
 

DarkandStormy

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I've been lurking, and will continue to do so, but I have just one question;

But why am I called out for having a whinge about my area yet 80% of the above posts in this thread are just that, day after day after day, and nothing is said?

I have been a long time lurker only cause of working away from home all the time so my contributions on here are very rare.
But Mega you are very switched on to the local area of the Wide Bay and Burnett, you have contributed massively to the area and I always look forward to your posts and others on here of up coming events.
I can understand the frustration of researching computer models from a few days before an event that shows quite promising to only to see on the day activity go past your area or a strong random developing ridge destroying any rain activity chance, I see it on radar quite regular that the activity comes close to the area of the Fraser Coast but just misses time after time.

I think the Fraser Coast and QLD will benefit a good drop of rain when the tropical season in the north kicks in and hopefully it will be sucked down southwards with no drama's from troughs that create wind shear.
Have not seen that famous black NE for a long time who knows it maybe this season for it well and truly overdue for it.
 

Ken Kato

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I did say it a few posts back that we'd get no more rain in November. This will be the driest November on record. 2014 Coolangatta 27.4mm. So far 2020 we've had 15.6mm. Top it off next weekend with high temps and hot dry winds.
@Warlock_01 where did you get the record low of 27.4mm from? If it was from Weatherzone which it appears to be, a lot of the record low/high rainfall and temp figures on there are invalid for the respective location, because of both outdated obs data and also data at some sites being for nearby stations.

The official record low for November there is actually 4.2mm set in 1994
http://www.bom.gov.au/climate/averages/tables/cw_040717_All.shtml
 

Warlock_01

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@Warlock_01 where did you get the record low of 27.4mm from? If it was from Weatherzone which it appears to be, a lot of the record low/high rainfall and temp figures on there are invalid for the respective location, because of both outdated obs data and also data at some sites being for nearby stations.

The official record low for November there is actually 4.2mm set in 1994
http://www.bom.gov.au/climate/averages/tables/cw_040717_All.shtml
Thanks Ken for clearing that up. I was about to look deeper into that as I presumed it wasn't correct.
 

Ken Kato

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Thanks Ken for clearing that that up. I was about to look deeper into that as I presumed it wasn't correct.
No worries, yeah I mentioned this to Vinny awhile ago as well but the obs data for many sites on the Weatherzone website also hasn't been updated since 2016 for whatever reason.

If you scroll down to the Coolangatta AP Data Availability subsection and look for the row titled Latest Entry on this webpage: https://www.weatherzone.com.au/climate/station.jsp?lt=site&lc=40717 it'll tell you when it was last updated.
They need to fix that up because as it stands, the records on there are misleading for those who aren't aware of this issue.
 

Warlock_01

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Jul 7, 2015
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Gold Coast, Bonogin
No worries, yeah I mentioned this to Vinny awhile ago as well but the obs data for many sites on the Weatherzone website also hasn't been updated since 2016 for whatever reason.

If you scroll down to the Coolangatta AP Data Availability subsection and look for the row titled Latest Entry on this webpage: https://www.weatherzone.com.au/climate/station.jsp?lt=site&lc=40717 it'll tell you when it was last updated.
They need to fix that up because as it stands, the records on there are misleading for those who aren't aware of this issue.
In my opinion, I've never trusted Weatherzone to be reliable, I think it's a give and take on whatever rain falls and temps and therefore they average it out around the nearby stations.
 

Ken Kato

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Jul 13, 2019
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I think that's what we'd all like to know, but no-one can say for certain. The average time of arrival of the monsoon in northern Australia (at Darwin) during La Years is mid December, which is earlier than the average time of arrival for ENSO neutral and for El Nino years. Also, the monsoonal moisture inflow tends to be greater in La Nina years; the stronger the La Nina, the greater the inflow, all other things being equal. The arrival of the monsoon, then, should greatly enhance the flow of atmospheric water vapour into northern Australia. This will greatly enhance the potential for rain in our region, though whether or not this potential is actually realised will depend on whether or not the local synoptic systems are such that this tropical moisture is advected southwards into our region and activated (i.e. uplifted and condensed to form clouds and rain). The last I heard, there are LWTs (long wave troughs) located at the longitudes of Western Australia and New Zealand, causing rain bearing (short wave) systems to culminate over those latitudes, leaving us high and dry. My understanding is that it is this unfavorable (for us, though south western WA also badly needed - and probably still needs more - rain) positioning of the LWTs has been the major factor inhibiting rainfall in our region this month (November 2020), though the (unfavorable) phase of the MJO has undoubtedly also played a role. As such, I think that whether or not the abundant inflow of atmospheric moisture into northern Australia which is highly likely with the arrival of the monsoon (probably some time next month) translates into good rainfall for us will depend on the positioning of any LWTs at and near Australian longitudes.

I've been trying to understand the nature and typical behaviour of LWTs since Ken Kato informed me that the positioning of an LWT over central Australia (at the time) was the principle reason for the generally dry conditions over eastern Australia during the first half of spring (2020), while central parts of the country received ample rain, but finding information about LWTs online has seemed to me to be like looking for gold nuggets. Given how important they are to our weather, I can't understand why it so hard to find information about them. My understanding is that, like most weather patterns, the positioning of LWTs more than a few days to a week or so into the future is impossible to reliably predict, so I'm not under any illusion that having a better understanding of LWTs would allow me to predict with any reliability when we will next see one positioned at eastern Australian longitudes, thereby greatly enhancing rainfall in our region. But having some idea of their typical behaviour would give me some idea of how likely it is that we may see an LWT in a position favourable to high rainfall in our region by, say, the end of the year. If, for instance, the positioning of the LWTs tends to change every few weeks, and if when it does change it does so a fair proportion of the time in such a way that an LWT becomes located in a position favourable to high rainfall in our region, then we can at least hold out hope for good rainfall here by the end of the year. But if the LWT pattern typically remains static for several months at a time, or if when it does change it seldom changes to a pattern conducive to good rainfall in our region, then we are probably screwed, not only for the remainder of the year, but for the entire remainder of this wet season, thereby effectively wasting this La Nina for us. So knowing the typical behaviour of LWTs in the Australian region would not allow me to be able to predict if and when we are likely to reap the benefit of this La Nina in SE Queensland, but it would give me some idea as to whether or not there is any real hope.

Anyway, that's where my understanding's at, and it's about as close as I can come to answering your question. I hope that helps in some way.
@BrettSS if you think that’s complex, wait til you have a look at all the research on the Global Wind Oscillation and the accompanying global synoptic dynamic model.

It’s been years since I’ve studied the GWO and I can’t remember much of the nitty gritty about it anymore (it’s an extremely complex concept to get your head around) so I’m definitely the wrong person to ask about it until I brush up on it again.

But from the basics I still do remember, it’s essentially an all-encompassing global physical process which also includes the more well known mechanisms such as the MJO, ENSO phases, Rossby Wave packets and trains which then break like breaking waves (which play a big part in changes in longwave patterns), etc and involves the transfer of momentum between the surface and atmosphere and north and southwards. Things like torque forces from big mountain ranges, dissipation of MJO pulses, etc also have a sizeable input. The large scale changes in that atmospheric angular momentum manifest themselves as different phases, kind of like what climate drivers like ENSO, SAM and the MJO do. Some phases resemble La Ninas and El Ninos as well. Certain phases also have a known very strong correlations with things like severe thunderstorm outbreaks in certain regions, stable weather in others, etc. And arguably even better correlations than those some of the more familiar phenomena such as the MJO.

The catch is, the return period of the phases is so variable that you can't really go off an average to try and predict when the next phase will be. There is a degree of predictability out to about a month using GWO forecast products which use model data but also a fair bit of uncertainty.

But it has major implications for effects on hemispheric longwave patterns because it has a big direct effect on things like how strong or weak the jets become, how meridional or zonal they get, whether blocking patterns become more likely, which areas become more prone to very hot/cold/wet/dry conditions, etc. Basically the sort of stuff that we're most affected by. That's about the limit of what I remember about it though. There should be a lot of research info about it online nevertheless.
 

BrettSS

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Sep 7, 2020
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I did say it a few posts back that we'd get no more rain in November. This will be the driest November on record. 2014 Coolangatta 27.4mm. So far 2020 we've had 15.6mm. Top it off next weekend with high temps and hot dry winds.

According to the BOM site, the record lowest November rainfall total for the official Coolangatta site is 4.2 mm in 1994 (during an El Nino and a positive IOD event), and the site has already received 15.6 mm of rain so far this November (2020).
 
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