Event East Coast (Qld-NE NSW) surface trough possible heavy rainfall 2-9 April 2021

Rainbomb

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Dec 3, 2019
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I found it useful to track the WV sat image with the lighting overlay as well. When there was persistent lightning the movement of the convection was more obvious than just the sat image on it's own.
Hard to say what will happen today though.

It was just speculation. I don't know if this convective area that form yesterday occurred earlier than forecast. Because from my time watching similar convective plumes they remain almost stationary in nature and may have prevented the trough/low to move further West due to it's presence. If it occurred later it may have been closer to the coast. Since it's weakening we can only hope a new one takes it's place closer if not over land.
 

Flowin

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Jul 5, 2019
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Pinjarra Hills, QLD
ACCESS-C gets its boundary conditions from ACCESS-G (used to get them from ACCESS-R when it was still running).

The other thing worth noting is that because ACCESS-G parameterises convection while ACCESS-C explicity models it, any new convection that forms after the forecast start time of ACCESS-C has to be "made" from scratch by ACCESS-C.
Thanks Ken. Question though - would that 12Z Access C run have got it's boundary condition from Access G 12Z or earlier - I suspect earlier
 

Ken Kato

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Jul 13, 2019
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Thanks Ken. Question though - would that 12Z Access C run have got it's boundary condition from Access G 12Z or earlier - I suspect earlier
Nah it gets its initial and boundary conditions from the dump file that's created by the same cycle of ACCESS-G e.g. the 12z run of ACCESS-G gives its data to the 12z run of ACCESS-C as soon as the obs data's assimilated and initalised.

I'm not quite ready to call this one yet. Call me insane but I'll wait longer then call it.
 

Paul Cirrus

Hard Yards
Oct 8, 2019
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Brisbane, Suburb is Windsor
yeah I suggested to myself last night the event is over and posted my own thoughts. Hoped to wake up this morning wrong and unfortunately aint wrong again :). This a Realtime thing now and the models don't mean anything to me mow at this stage. All the obs from wind/radar and sat and ground obs, to what i can observe ( Brisbane) tell me that i have seen these events many times and the picture aint great, meaning in my view all over. But 80mm even for Brisbane is a very very very long stretch.
 

Blowin’

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Jul 10, 2019
22
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Diamond Valley, sunshine coast
yeah I suggested to myself last night the event is over and posted my own thoughts. Hoped to wake up this morning wrong and unfortunately aint wrong again :). This a Realtime thing now and the models don't mean anything to me mow at this stage. All the obs from wind/radar and sat and ground obs, to what i can observe ( Brisbane) tell me that i have seen these events many times and the picture aint great, meaning in my view all over. But 80mm even for Brisbane is a very very very long stretch.

i tend to agree but will hold judgment until this afternoon.
 
Sep 27, 2019
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Yes, it really depends on the positioning of the surface low which is currently off the coast east of Yeppon. Some models have it moving due south (EC) or towards the coast (Access R) while GFS had it moving away. The next 24 hours will tell. Just a quick glance at the latest GFS run that is coming through and it looks like another shift back towards the coast. My head is spinning. It's little wonder the SWW is still in place.
 

whynot

Addicted
Jul 13, 2019
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So, EC on Windy is presently generating this forecast below. With most of the rain falling in the early hours of Wednesday morning. I would not relax my guard just yet. It will certainly be interesting to watch.


ec_rainacc_20210405.JPG
 

Rainbomb

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Dec 3, 2019
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I would say the next 6-12 hours will tell if a new area of heavy rain develops closer to the vincity of the low. After 24 hours the event would most likely be over for most. Does also seem the upper trough moves closer to SE QLD tonight and this is going to help things.

There is also rain areas from the north QLD moving south too.
 

Michael Hauber

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Jul 4, 2019
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Current situation - upper trough near Longreach and Low near Gladstone:

Capture.PNG


The large convective blob is not directly attached to the low, but would seem to be triggered by convergence on SE flank of low. As it moves away further SE it may allow renewed activity closer to the low.

Also of interest is the activity near Mackay and Townsville. The highest clouds are driven by higher winds which are more westerly and moving away from the coast. Lower stuff is moving more southerly and onto the coast. With the position of the upper trough this activity should be expected to move down along the coast. Certainly prospects for further rain even for the Capricorn area, although it depends on the low near Gladstone. If it strengthens and focuses rain near it, that will mean no rain for anything further north, and like rain on the coast further south. If it can't focus rain near it then it could rain further north as well.

Current 512 radar Mackay:

Capture.PNG


Latest EC has heavy rain in SE Qld late Tuesday, early Wednesday, with this forecast for Wed 6am:

EC Wed 6am.PNG


So I'd written this event off last night when it seemed that the large convective blob was closely linked to the low and clearly moving away from the coast. But now it looks very much up in the air and impossible to call either way.
 

Ken Kato

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Jul 13, 2019
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Current situation - upper trough near Longreach and Low near Gladstone:

Capture.PNG


The large convective blob is not directly attached to the low, but would seem to be triggered by convergence on SE flank of low. As it moves away further SE it may allow renewed activity closer to the low.

Also of interest is the activity near Mackay and Townsville. The highest clouds are driven by higher winds which are more westerly and moving away from the coast. Lower stuff is moving more southerly and onto the coast. With the position of the upper trough this activity should be expected to move down along the coast. Certainly prospects for further rain even for the Capricorn area, although it depends on the low near Gladstone. If it strengthens and focuses rain near it, that will mean no rain for anything further north, and like rain on the coast further south. If it can't focus rain near it then it could rain further north as well.

Current 512 radar Mackay:

Capture.PNG


Latest EC has heavy rain in SE Qld late Tuesday, early Wednesday, with this forecast for Wed 6am:

EC Wed 6am.PNG


So I'd written this event off last night when it seemed that the large convective blob was closely linked to the low and clearly moving away from the coast. But now it looks very much up in the air and impossible to call either way.
Yep @Michael Hauber as I mentioned yesterday as well, radar doesn’t show the complete picture - that big blob of convection off the coast with a bit of apparent rotation to it has been consistently flaring to the SE of the main low since yesterday. This is common with such lows where rising air and deeper convection tends to be skewed out to the SE and S due to air there running into a thermal gradient from warm air advection.

That blob is likely just one part of a belt of cyclonic vorticity in the broader deep trough lying just off the Fraser coast. That's also evident in the latest ASCAT wind pass.

P.S. it's also a bit hard to tell now whether another actual small low has formed in that MCS or not. This kind of setup with an elongated belt of vorticity with multiple embedded small areas of enhanced vorticity trying to compete with each other lends itself to unpredictability. Often see that sort of unpredictability happen along the monsoon trough where one minute, a low looks likely to become a TC in say the Gulf, then the next minute enhanced vorticity further along the monsoon trough forms a more promising low in the Coral Sea.
 

Benalla

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Dec 11, 2019
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Once again it’s been awesome reading/watching all the commentary from you guys for this event, Ken thank you and everyone else, I’m learning a lot from you guys.

A little disappointing only 33.5mm for this entire event here in Helensvale , light rain at the moment, have a felling this isn’t over for he GC yet.
 

Michael Hauber

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Jul 4, 2019
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Yep @Michael Hauber as I mentioned yesterday as well, radar doesn’t show the complete picture - that big blob of convection off the coast with a bit of apparent rotation to it has been consistently flaring to the SE of the main low since yesterday. This is common with such lows where rising air and deeper convection tends to be skewed out to the SE and S due to air there running into a thermal gradient from warm air advection.

That blob is likely just one part of a belt of cyclonic vorticity in the broader deep trough lying just off the Fraser coast. That's also evident in the latest ASCAT wind pass.

P.S. it's also a bit hard to tell now whether another actual small low has formed in that MCS or not. This kind of setup with an elongated belt of vorticity with multiple embedded small areas of enhanced vorticity trying to compete with each other lends itself to unpredictability. Often see that sort of unpredictability happen along the monsoon trough where one minute, a low looks likely to become a TC in say the Gulf, then the next minute enhanced vorticity further along the monsoon trough forms a more promising low in the Coral Sea.

Does seem unusual to have a convective blob that large and persistent that is not more directly attached to a low pressure circulation though? Perhaps I haven't watched enough low pressure systems closely enough.
 

Tsunami

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Jul 6, 2019
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Well what a sleep
Woken up when we are ment ti be in the middle of a deluge. Nope.
No one and no models have any udea what the hell is going to happen lol
Its an insane set up keeping everyone guessing
I feel its all over. Its to far east. But theirs talk of other lows. The current low moveing back towards the coast.Itt may now drag into Wednesday
I have no idea......wtf, poor bom. Workers
Another interesting day
 

GBerg

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Jul 28, 2019
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27mm to 9am (8.47am to be precise) here on the Northern Sunny Coast. Was hoping to be flooded in this morning but it's off to work instead. There has been bit of an increase in rain coming in off the ocean in the last hour and the wind has increased quite a bit so hopefully it's a sign of things to come but won't be holding my breath.
 

Ken Kato

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Jul 13, 2019
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Does seem unusual to have a convective blob that large and persistent that is not more directly attached to a low pressure circulation though? Perhaps I haven't watched enough low pressure systems closely enough.
Yeah agree, it is a bit unusual to be so detached from the centre. Typically you see at least some cloud swirling around the centre. I find this type of detachment most often happens when the low's not clearly defined and is highly convective. Strong shear and upper level winds such as that associated with the jet and ahead of upper troughs can also displace the convection away from the centre as well. If that MCS does spawn another little low in it (far from certain), that's another area of vorticity to compete with the rest of the belt and yet another spanner in the works.
 
Sep 27, 2019
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Yes, emotion, it's just the weather. I for one am glad that this event hasn't, so far, had the impact that it had the potential to cause. We did some sandbagging yesterday in anticipation as we have a creek running through our property that can unleash its fury in such events. I'm happy to see this one pass.
 

TweedStorm

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Jul 6, 2019
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Banora Point
Yes, emotion, it's just the weather. I for one am glad that this event hasn't, so far, had the impact that it had the potential to cause. We did some sandbagging yesterday in anticipation as we have a creek running through our property that can unleash its fury in such events. I'm happy to see this one pass.
I'm with you I. W.
Everything is just saturated down here. Wake up most days to miserable grey skies and showers. Unless there's some violence in it like thunder, lightning, waterspouts etc. it can all move on as far as I'm concerned. Looking forward to Winter in the hope of some fine sky. Never thought I would say I'm looking forward to Winter.
 

Stephen Kunze

Hard Yards
Jul 5, 2019
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Just like some extreme sports fanatics like the danger and thrill in that, weather enthusiasts such as myself enjoy the extremes weather has to offer. Everyone is different, and I'm a little annoyed about this event, emotional even, and that's just me. Everyone is entitled to feel however they like depending on your situation. For those who have had too much rain, I hear ya. But some of us haven't and would like one more event to finish this dismal summer off.

Drizzling all morning here so far and most of the day yesterday, but only 18mm for the 24 hours to 9am.
 

Ken Kato

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Jul 13, 2019
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18z ICON which initialised the actual areas of rainfall this morning better than most, tries to drag some of the wraparound onto the GC later on. We don't normally get a huge amount of rainfall from wraparounds though, except for your Upper Springbrooks, etc.

The centre of that offshore convective blob seems to have taken a slight SSW turn although hard to tell for sure whether it's a wraparound effect or not, while the rest of the lighter stuff continues to stream off southeastwards with the upper flow.
 
Sep 27, 2019
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18z ICON which initialised the actual areas of rainfall this morning better than most, tries to drag some of the wraparound onto the GC later on. We don't normally get a huge amount of rainfall from wraparounds though, except for your Upper Springbrooks, etc.

The centre of that offshore convective blob seems to have taken a slight SSW turn although hard to tell for sure whether it's a wraparound effect or not, while the rest of the lighter stuff continues to stream off southeastwards with the upper flow.
Yes, Ken, it appears to me the beginnings of a wraparound with a spur extending towards Rainbow Beach.
 

Paul Cirrus

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Oct 8, 2019
26
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Brisbane, Suburb is Windsor
Thought they would cancel, though 12 hours or more later than i expected. But they are still going for possible heavy falls, my view, this aint gonna happen. But they have to cover themselves. But yeah all over and hope to see the sun out and get winter in here ASAP. I do love the destructive weather, but this summer never really delivered except for that little low that bought brisbane some really crazy wind in november. So i would prefer months of benign weather instead of the teasers that come though like this one. I never really thought this one would come through anyway, as my gut feel was off the coast. Anyway boring drizzle/////////////////
 

Stephen Kunze

Hard Yards
Jul 5, 2019
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All over red rover. I know we never rely on just one model entirely, but gee wizz, EC (and the majority of major models) have been an epic failure in regards to this system. Pathetic really. Wouldn't be surprised later today that the 00Z run will still show huge falls on our coastline haha
 
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Multiversity

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Jul 29, 2019
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Will be the first to admit i know absolutely nothing about meteorology but reading what KK & others in the know are saying about this system plus looking at the wind field on nullschool and seeing how complex it looks around SEQ i thought you'd need a quantum computer modelling every variable possible just to get an idea of what is going on here right now let alone trying to forecast what's going to happen.

Yeah agree, it is a bit unusual to be so detached from the centre. Typically you see at least some cloud swirling around the centre. I find this type of detachment most often happens when the low's not clearly defined and is highly convective. Strong shear and upper level winds such as that associated with the jet and ahead of upper troughs can also displace the convection away from the centre as well. If that MCS does spawn another little low in it (far from certain), that's another area of vorticity to compete with the rest of the belt and yet another spanner in the works.
 

Bello Weather

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Jul 12, 2019
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This one, is like many similar events like a watched pan put on to boil. We've got cold air up high, very warm wet air streaming in below...and we know it's going to boil somewhere, just impossible to say where. So far the models have been off, but that's a very unstable atmosphere out there, so until the entire system moves away I'd not be writing it off entirely.
The big blob has died down, but no certainty as to what will pop up. The odds are certainly a lot lower than a couple of days ago, but these things can sometimes come back and bit you. I'm unlikely to see more than stream showers down here, but still a chance of some decent point totals for you guys further north.
 
Sep 27, 2019
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Are any of you guys watching the radar? Not all of it's moving off to the SE. For now at least anyway.
Yes, indeed, Ken, I am. There are some building banks of showers moving in. Despite the cancellation of the SWW, I do note the cautionary observation that STWs will be issued if needed given the ongoing risk of thunderstorms. There's definitely still a lot to play out before this event is over.
 

Michael Hauber

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Jul 4, 2019
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Am I overreacting to get a little excited by this blob near Childers?

Capture.PNG


Some activity further north on the central Qld Coast that seems to be pushing southwards with a bit of rain now near Rockhampton to Gladstone, whereas earlier this morning when I first commented on this it was all north of Rocky.

gladstone.PNG
 
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