Thunderstorms are likely to affect various areas of SEQLD/NENSW over the next three days courtesy of a trough approaching and then moving across our region during this period. Tomorrow and Saturday's thunderstorm potential should largely favour areas of NENSW and the Southern Downs. On Sunday, the thunderstorm potential looks like favouring much of SEQLD and far NENSW.
Thanks. @Seabreezes I see @Stumer1 got a good storm, so here’s hoping for something I haven’t had a chance to look at forecasts but will tomorrow.
Thanks @Seabreezes . K- Index values on all models are still very high in the SE QLD region for sunday. CAPE not so much if i'm reading it correctly. I don't have time today to post all the charts im referring to. However I noticed on Windy , EC isn't showing any potential storm activitiy for the Gold Coast on sunday anymore. Northern NSW and Sunny coast it does. When looking at storm forecasting there are different index to look at. Cape Lifted Index Sweat Index Precipitable Water Lightning Density CIN (most unstable layer ) Base Reflectivity Forecast soundings Out of all those, what's the main one to give you a idea without spending a whole day behind the computer trying to figure that out? Or do we leave that to Ken lol
If you’re short on time, have a look for areas where good CAPE and K-index (or even better, Total Totals) values coincide. That combo often tend to give the best results. The lightning flash density product from EC can also be helpful in flagging potential areas for further investigation especially if accompanied by some precip. I would also recommend multimodel probability of precip maps as a very accurate way of seeing where there’s better storm potential but unfortunately the ones on WATL have a threshold of 1mm so isolated activity often doesn’t show up on there. Re Windy, note that the 12z EC data doesn’t update on it until about 6 to 6:30am. Personally, I put less faith in the 00z runs of models than the 12z runs because I find the 00z runs can often be quite erratic even at shorter lead times. Who knows if it’ll be the case this time though.
Thanks @Ken Kato I had wondered what total totals was and just not had time to look it up. Anyway your post helpful on that.
Thanks so much Ken , yes the EC just been updated and storms back on the Gold Coast again . I havent really looked into the Total Totals Value so thanks for let me know about that one . Appreciate it
No worries, just remember though, I'd avoid using Total Totals by itself because it uses lapse rates in conjunction with low level moisture in its formula i.e. (850hpa temp - 500hpa temp) + (850hpa dewpoint - 500hpa temp) and lapse rates are typically a lot lower in the tropics and a lot higher in the midlatitudes... they also vary with time of year. For our particular region, look for areas where TT values exceed about 45 and ideally greater than 50, overlapping with surface based CAPE of at least a few hundred j/kg or more. Those areas tend to correlate fairly well with thunderstorm initiation. If steering winds aloft are strong, any storms that form in those areas can be advected into areas with less favourable values. That's if you're short on time. It's better to look at soundings as well to get a more accurate picture as well as taking into account what's happened in the past with the same kind of setup. There's other people on here who I think are really knowledgeable with weather and realistic with what's likely to happen, and who you could ask as well e.g. Mega, but there are others as well. You can see from the latest multimodel accumulating precip graph for Brisbane that all the models on there are currently going for at least some rainfall for Brisbane which is encouraging... for now at least anyway.
Won't dent the drought at all but may put some water in the tanks of those fortunate enough to get a decent drop. Do not know what the situation is everywhere, probably grim, but from what I have been able to extract from Lismore's Newspaper is the situation for those on tank water is desperate or worse.
God I love the level of knowledge in this forum. Fingers crossed we get a bit of rain over the next 7 days!
Another good option is after looking at all the parameters above and the steering winds is to look at the multi model chance of any rain chart to locate where the chance of precip falling is. Sometimes handy where to place yourself if your going to chase. Eg for today below
They are indeed really handy and reliable, but with the following caveat I mentioned in my earlier post " I would also recommend multimodel probability of precip maps as a very accurate way of seeing where there’s better storm potential but unfortunately the ones on WATL have a threshold of 1mm so isolated activity often doesn’t show up on there. " P.S. this also means that it often won't show quite how far out the edges of shower/storm areas extend out to.
Storms firing up in parts of NENSW this afternoon. I've seen a video of small hail at Bellingen this afternoon. Have heard some distant thunder here over the past five minutes. A humid day on the coast, with dewpoints in the low 20s.
Yes. & Whilst there forecasts some hopeful precip Sat Arv/eve particularly around ne nsw which may tip into the Sth Downs early hrs Sunday, , I'm curious to the wet patch closer to the GCoast, during Sunday Eve/night, well just below the border mainly but close enough to warrant said interest. Pic ! It's not much really, and I doubt it move 'if eventuates' in any nth direction because winds through all heights have atleast some southerly direction in them. Any storms away from the forecasts wet patch may deliver any amount of added splash - just hope it lands on a the dryer areas with out hail, I say hail because there is some chance of super cell capacity abouts. Ahh weather, or not, mind boggles )
IVT for circa 700 hPa looking better today so mid levels should remain juicy with that Vertical temp profile .
Got our first drop of rain for the entirety of November here. Just over 10mm in the last storm and currently getting moderate rain from a second smaller cell. Unfortunately looks like the last cell is dying before it reaches the firegrounds on the southern edge of the Myall Creek Rd Fire.
Yes can be very frustrating for those affected by the drought, especially in situations where a storm can dump 50mm in one place, and next to nothing 20km up the road. It's the widespread rain events is what they really need .
Great bunch of people here, I have learnt so much about the weather on this forum and when we used to be on weathezone forums as well .
The money shot on GFS. This plot basicly shows Solid divergence at upper levels and strong bouyancy punching up through 500 hPa. Click image to enlarge.
Re variables to use to assist in forecasting storms, I will be the first to admit that: - I rarely look at TTs (but I probably should) - I rarely use the K-Index (again, I probably should) - For days like Sunday where the flow tends NW'ly, I like to look at the 850hpa RH/DP/streamlines to get an idea of how moist it is in the higher portion of the lower-atmosphere. If it's really dry then there's a good chance of that dry air mixing down through the lower levels as the day wears on, especially if the the westerly flow is more brisk (if it's only light then there's less risk). - 2m/10m DP - to be used in conjunction with the above 850hpa DP/streamlines. Using surface dewpoints alone is a bad idea because you can't see what the rest of the lower-levels are doing - 500mb temps - generally the sweet spot to identify temperatures in the upper levels - MSLP + Precip - Can be useful to get an idea of how much precipitation the model is forecasting to reach the ground. If it's minimal across all models (1-5mm or something) then refer to other variables (maybe the mids are moist but the lowers have dry air through them restricting precip reaching the ground). Something to remember though is that I find each model handles this parameter quite differently? (Ken?) For example, ACCESS-C has had a few really good days this year where it'd show a good splattering of precip occurring across a region and it'd pretty much happen, all the while the others merely had 1-5mm. Then there was Wednesday when ACCESS-C again tried to do this (joined by GFS), but in the end it was EC's conservative approach that ended up being more accurate. There was also another day up here about a month ago where this turned out to be the case as well. - CAPE (obviously). - LI, although you still have to be careful not to take the pretty colours you so often see on BSCH as gospel. Be aware of other factors too because -8 LI does not necessarily translate widespread severe thunderstorms. I've seen BIG BIG LI days where absolutely nothing happens (for example, the cap might just be too strong for storms to initiate in the first place). So be very mindful when looking at LI on BSCH. - One of the most important methods for me (and I'm so glad with the use of modern technology we are able to do this) is simulated soundings. Tropicaltidbits or BSCH for GFS, Windy for EC, and if you're using Windy, click the magnifying glass to zoom in your desired sounding). There are plenty of resources out there to help you learn how to read a sounding, one of my favourite ones is a three-page thread from the guys over at ASWA (site seems to be down right now, not sure if it's returning?) http://www.australiasevereweather.com/forum/index.php?topic=1510.0. AC's thunderstorm forecasting guide is really good too: https://www.downunderchase.com/storminfo/stormguide/ I probably missed some stuff but those are some of the main things I look at with thunderstorm forecasting (and please remember I am no meteorologist, just a self-learner with a wild dream of becoming a meteorologist some day).
Just quickly regarding Sunday, jeez hasn't EC come to the party in recent runs? Where the hell did this come from? Haha. edit: and ACCESS-G also.
I assume you mean integrated vapour transport? If so I am a fan of that parameter, but vapour to liquid is still a mystery to me.
One of my go to plots on the University of Wyoming Atmospheric Science website. It depicts bouyancy at several choices of heights. you can mix and match/ customise plots. Forecasts from the GFS
After a quick look through forecasts this evening I am feeling more optimistic. Nothing especially special, but improved it has.
Missed a storm by only about a few kilometres today. We've had more rain here this month than most other places along the north coast though, so not a surprise that Mother Nature made sure to spread some liquid joy elsewhere. We're basically exactly the same, lol.
I'm no expert, but have learned/am still learning over the years. Below gives a run-down of my thinking and some of the charts I look at for storm days (really sorry if the images stuff up anyone's displays - I'll remove if told to). I also look at other models, but kept it to GFS to keep it simpler. Please feel free to correct me if I'm inaccurate or have misinterpreted anything. There are some things I like and don't like about Sunday's set-up. Some positives: Good directional sheer. Winds back with height right through the lower and mid-levels. This can be seen in first image below (helicity in the lowest 1-3 km). High helicity values = strong low-level winds and directional shear. Directional shear helps mesocyclones form within the storm and cause the updraft to rotate. This could help with the development of strong winds and hail. Potentially promising speed shear. Tonight's 06z GFS has a 14 kt Nly at surface and 35 kt W/NWly at 500 for Brisbane and a juicy 13 Nly at surface and 64 kt Wly for the Scenic Rim/Border Ranges. However, GFS has been fluctuating and the previous 00z run had 13 kt NEly at surface and 51 kt W'ly at 500 for Brisbane. Speed shear helps tilt a thunderstorm's updraft, which keeps the updraft/downdraft separated, allowing for longer-lasting storms and a stronger updraft. Fairly strong upper-level winds (Image 2). 90-100 kts at the 300 would help keep the top of the storms clear. Excellent steering winds (Image 3). I believe that weaker-storms are generally steered at the 850 while stronger storms are at the 650-700. Either way, these storms will be moving 25-35 kts (46-64 kph). Rain signals for afternoon activity on GFS, EC, and Access-R. Access-R has two bands moving through - one in the afternoon and one overnight. EC has these and a third, light band on Monday morning. And now for what I don't like. Cloud cover. Total cloud cover is quite high across SEQ in the morning and into the afternoon, even when there is no precipitation signal showing (first image). Looks like a mix of high and middle cloud. However, surface temperatures look like reaching mid-30s across SEQ (second image), so unlike most days I don't think the cloud cover will have a major negative effect on storm formation. CAPE. CAPE is around 400-800 across SEQ (third image). This is not even remotely conducive to explosive development of storms, but certainly more than enough to get them started and keep them going. I also think that the modest CAPE values will be offset by the excellent shear (see earlier). Steering direction. Steering looks like it will be generally north-westerly (see the earlier image for 700mb wind speed and stream). I always shudder when I see that for a storm day. So often this means storms sliding past Brisbane to the west and south on an endless conveyor belt into the GC Hinterland. Storms have to form over the Highvale/Mt Nebo region to track over Brisbane or become left-movers against the steering flow if they form further to the west. But this may not be a problem as we could see on Sunday. According to Harper and Callaghan (1998), severe thunderstorms within 150 km of Brisbane over a 10-year period had the following broad steering patterns: Type A: SE Change (23%) Type B: Strong NW Flow (17%) Type C: Weak NW Flow (43%) Type D: Other (17%) I remember a similar steering pattern in November 2016 which resulted in two separate storms forming NW of Brisbane and tracking over to the Bay, delivering 110+ kph wind gusts to Brisbane Airport. Early start. Unfortunately, it looks like there could be some patchy activity about in the morning and storms forming from midday onward. The models aren't entirely in agreement though and with the NW'ly steering this could mean Brisbane still doesn't see activity until later in the afternoon as the propagation/tracking lines gradually push coastward. Moisture (dewpoints) could still be a lot better. High teens at the surface at 4 pm and decreasing to low teens at the 850. What concerns me though is a tongue of dry air poking into SEQ from the north-west (fifth image). The lapse rate isn't bad nor is it amazing. It would be good to see colder mids though for large hail (sixth image). So what will happen on Sunday? My best guess is most of coastal SEQ will see storms. Severe storms are a big chance - the real trump card here is the shear. But for severe storms I would prefer to be around the Scenic Rim/GC Hinterland where the helicity, speed shear, moisture and CAPE are better. Brisbane has a fair chance of severe activity, but it will be a lot harder with the steering as mentioned earlier. Severe storms will become much less likely as the afternoon progresses when I would expect to see storms spreading into thundery rain.
Another aspect I might add is that the change/convergence doesn't come through until early Monday morning, and isn't very sharp, so lacking an obvious focal point and extra kick from convergence. Looks like there will be enough with shear and instability though without this. Flip side is higher chance of multiple storms with no definite clearance until Monday morning.
Thanks for taking the time to write this up @Nature's Fury . Yes I have been keeping a close eye on the cloud cover for several days now, both EC and GFS have patchy cloud in the morning getting thicker as the day progresses. Northern NSW looks like a hot spot as well for storm development. K Index has backed off slightly in the latest run
As for today latest 18z GFS wants to bring some precip to the coast, probs south of Brisbane. Very light signal. This could be quite abit later today or tonight. Also this mornings ACC R onboard. Which will be interesting as this mornings WATL using the earlier runs did not pick up on it so should be interesting because you'd think there would still be a low chance if atleast 1mm in the coast for some places.
Sorry, I accidentally posted my thoughts below in the day to day thread earlier this morning so will post them here (I’ve mainly focused on SE QLD for this one): “ It finally looks like those who do manage to score a shower or thunderstorm later today (but more-so Sunday) could get some reasonable rainfall out of them for once. (this potential will probably be somewhat lower in northern parts of SEQ although not out of the question). For today (Sat), the majority of activity is likely to favour inland and southern parts of SEQ where steering winds aloft are stronger..... although its remnants could reach some other sections of coastal SEQ late afternoon or overnight. For Sunday, showers and storms are likely to start redeveloping later in the morning or early afternoon (may be later if there’s more morning cloud cover than expected)... before being rapidly steered towards the coast by the strong W to NW steering winds aloft. The overnight hours into the wee small hours of early Monday morning could also see some areas experiencing showers, storms, and local rain areas persisting, due to an approaching upper level trough and cold air aloft destabilising the atmosphere (but this chance will be lower if too much previous activity stabilises the atmosphere more than expected). The reason I put Medium to High risk of a severe storm for Sunday somewhere in SEQ (rather than an all out High risk) is because of a couple of potential complicating factors, including a bit of uncertainty about any morning cloud cover/early showers or storms... and a somewhat drier W to NW wind flow coming close to the coast. However even with morning cloud cover (may be sunnier in the north), it only takes a few clearer gaps to allow enough heating for severe storms to erupt. If they do, a number of locations are likely to get a severe storm due to the strong shear with damaging winds, large hail, or intense bursts of rainfall. Risk of a storm at least somewhere in SEQ: Slight. Medium ✅ (Sat) High ✅ (Sun) Risk of a severe storm at least somewhere in SEQ: Slight. Medium ✅ (Sat) Medium to High ✅ (Sun) Rainfall amounts for the locations which are affected by storms: Low. Medium ✅ (higher under heavier storms) High. There’s also the upcoming hotter than average weather and increasing fire danger to deal with. "
That is an outstanding write-up NF, and I express appreciation to everyone's input/insight - awesome stuff ! NF: I also look at all them charts, some more than others, depends, but generally boggles my mind at times because I know Not the basic fundamentals on how all the aspects of weather/charts/Skew'T's/drivers etc relate/influence with each other to create a clear pitcher of whats actually going on in any weather event,, Its all good tho, I'll flip through them for an hour sometimes, so I did find your post very informative and helpful That said, I do have a Question in general, relating to updates on certain forecasts, models or what have you, I often read here "cant wait for the next Run" etc - an update I assume which I think can happen more than once a day, , QUESTION: Sooo, I am only wanting to know if the BSCH charts are updated more than once a day, if so, how many times and at what times - if possible ? Thanx in advance. Cheers & Looking forward to tomorow
Hey plumb bob Its updated 4 times a day. From what I understand 9am. 3pm. 9pm. 3am If you click on rainfall and look over to the left side it shows the times and you can confirm it is the current update I also find the 3pm one is the best. Dont know why
The main charts available on BSCH are from the GFS (American) model. This model updates at 2:30 pm (00z), 8:30 pm (06z), 2:30 am (12z) and 8:30 am (18z). However, sometimes BSCH does not update immediately and can take 15 min to an hour to make the most recent charts available. When I really can't wait (particularly when I want to see TC tracks or rainfall amounts) I look at Tropical Tidbits. It shows model runs immediately and even as they are being rendered (in the hour before the 'official release'). They also show ext forecasts and lots of data for multiple models (GFS, EC, CMC, NAVGEM, CFS). It's also a really good site in general - one of the other main ones I use. https://www.tropicaltidbits.com/ana..._pcpn&runtime=2015090600&fh=6&xpos=0&ypos=575 This is another great site for showing data from multiple models (EC, GFS, CMC, Access-G) and can be useful for making comparisons. You've probably seen a few posts from this site in the last few days even: https://weather.us/model-charts/euro/1555-e-265-s/accumulated-precipitation.html
Hot, cloudy with sunny breaks. No productivity to be seen atm. Himawari keeps showing cloud streaming in from the WNW but none wants to mature. Better luck tomorrow?
Give it a few more hours due to the cap. Think convection will develop to the WSW and be a slow process getting to the coast tonight....or not..
