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22 04, 2019

2018-19 Australian Tropical Cyclone Season Summary

2019-04-22T19:30:54+10:00

The 2018-19 Cyclone Season has come to an end across the Australian forecast region and its been an interesting season to say the least as we saw multiple systems become “severe” and also make landfall, whilst delivering much needed but also in the same sentence, very devastating, floods across large parts of Northern and Western QLD as well in pockets of WA. Above image was Cyclone Veronica (the strongest 2018-19 system) at peak strength off the WA Coast. Image via RAMMB / CIRA

 

 

For the 2018-19 season (October 1st to April 30th), we (Higgins Storm Chasing) analysed the upcoming long range climate indicators along with the timing of early season tropical waves in particular, and came to the conclusion that the atmosphere was going to favour either a borderline or weak El Nino climate pattern. Historically, El Nino years have favoured below average tropical cyclone numbers. Due to this, we predicted 9 tropical cyclones which is down from the average of around 11. El Nino years however also tend to favour an increase in severe tropical cyclones due to warmer oceans being present. As a result of this, along with previous failed tropical cyclone seasons, we erred on the side of caution and went on the lower side of 50% severe strike rate with 4 severe systems. 

 

HSC Tropical Cyclone Prediction for Season 2018-19 issued back in late September 2018

 

So how did the season pan out??
“Normally” Western Australia is the first region to go before New Year. While the season is October to April, there is usually very little activity prior to New Year, with only 1 maybe 2 systems developing and for 14 of the pas 15 seasons, its been WA to take first honours. This year it was Queensland that went first with Tropical Cyclone Owen developing in the Coral Sea and meandering around open waters before making landfall, entering the Gulf of Carpentaria, then crossing back over and back into the Coral Sea. If that wasn’t enough, around New Year Cyclone Penny decided to copy Owen which gave Queensland the first 2 systems of the season. Cyclone Riley then developed mid January over the Timor Sea and surged West, becoming the second severe system, but thankfully not making landfall over WA as it pushed into the open waters of the Indian Ocean.

 

Tropical Cyclone Owen (Category 3) & Penny (Category 2) track map combination via wikipedia 

 

While it wasn’t a named system, there was a significant tropical low during the start of February over North West and Northern QLD which never reached cyclone strength. This system produced unprecedented rainfall across the Greater Townsville region where falls of 2000-3000mm were recorded over a 10-13 day period. Further significant rainfall of 500-1000mm occurred over Northern and North West QLD which lead to significant cattle losses and devastating flood heartbreak for a very drought stricken area. 

 

12 day accumulative totals for the top 5 locations + Townsville City

The much talked about Oma was next on the list, developing in Fijian waters before Australia took responsibility later in its life cycle. It didn’t produce much, but it was yet another prolonged Queensland system. By this stage, all 3 Queensland systems had lasted more than 10 days, with Oma and Owen both pushing the 2-3 week marks. There was then a lull for a month before Mid March does what Mid March does… and thats show off as the peak of the cyclone season. First it was Savannah in the Indian Ocean that reached Category 4 strength. Then it was Trevor that went Category 4 as well before making landfall over the Southern Gulf (NT) and then flooding Western and South West QLD. Next it was Veronica who went Category 4 as well – 3 Category 4 systems in the space of a week. Veronica made landfall over the Pilbara and produced historic rainfall and flooding across the region as well. Wallace then came in a week later and didn’t do much, but added to the season tally. 

Across the season all up, there were 8 tropical cyclones (9 if you include Kenanga which happened earlier in the season, but I believe thats questionable as to whether or not it moved into Australian waters). Of those 8, 6 of them became severe with 3 Category 4 systems, 3 Category 3’s and then Penny / Oma both at Category 2. Queensland and Western Australia both tied for 4 systems each in the end (this was 1 up on our QLD prediction and 1 down on the WA prediction) while the NT also recorded 2 systems (both crossing in from QLD).

Last light on Cyclone Trevor post-landfall on March 23rd. Image via RAMMB / CIRA

 

2018-19 Australian Tropical Cyclone Season Summary2019-04-22T19:30:54+10:00
19 04, 2019

Wet Easter Forecast For SEQLD & NENSW

2019-04-19T10:32:36+10:00

Models are in agreement that like always, South East QLD & North East NSW are expecting a wet Easter for 2019 as showers and rain periods are set to increase from Friday afternoon onwards across both areas, leading to some respectable 5-day totals. Above image: ECMWF 5-day Rainfall accumulation – orange = 50mm+ (GFS is in agreement).

 

Across the Eastern long weekend, models have come into agreement that starting later on Friday and lasting until at least Tuesday, an onshore flow is expected to deepen across the South East corner of QLD and North East corner of NSW. This onshore flow is likely to combine with some weak upper level support on both Friday and Saturday, before an Inland trough develops on Sunday and lasts until Tuesday to further compliment the system. While its not expected to be a continuous non-stop rain event. Good falls are expected to develop on Friday across both NENSW and SEQLD with Coastal areas may pick up 20-40mm overnight Friday into Saturday. Rain areas should then ease a little on Saturday, although some good falls are still expected over the Sunshine Coast to Hervey Bay region.

Forecast Rainfall across South East QLD & NENSW on Good Friday – activity is expected to develop later in the day and intensify overnight into Saturday. Image via BSCH


Sunday is expected to see just some isolated to “maybe” scattered light showers across both areas and these should continue into Monday where less than 10mm is expected for most areas across the 2 days. Tuesday is bouncing around a bit, with early indicators showing 50-100mm being possible over the Northern Rivers in NENSW, but that has since backed off to less than 10mm with the better falls of 25mm+ being over the South East QLD region once again (mostly North of Brisbane) – given Tuesday is still 5 days away, this part of the forecast is expected to change around a bit.

Forecast Rainfall across South East QLD & NENSW on Eastern Sunday showing lighter activity expected. Image via BSCH

 

Across the 5 day period though, good falls of 50-80mm are expected across Coastal areas from about Hervey Bay down to Coffs Harbour. The better falls are likely over the Gympie to North Brisbane area as well as the Gold Coast Border Ranges and immediate surrounding areas. Unfortunately for those West of the Ranges, these good falls are expected to be confined to the Coast. Even Ipswich, Beaudesert, Boonah, Esk and surrounds are only going for 15-20mm across the 5 days. Toowoomba, Warwick, Stanthorpe, Kingaroy even less. There is an Inland system which is expected to develop over South West & Southern QLD on Sunday which may push through on Monday across the Darling Downs – but don’t expect a lot from this.

Current Forecast Rainfall across South East QLD & NENSW on Tuesday. Image via BSCH

Wet Easter Forecast For SEQLD & NENSW2019-04-19T10:32:36+10:00
13 04, 2019

Tornado Outbreak Possible for Southern Central United States

2019-04-13T16:58:07+10:00

Large parts of Louisiana, Southern Arkansas and Western Mississippi are forecast to be under the pump with a localised tornado outbreak expected during Saturday (local time). Above image via the Storm Prediction Center showing a categorical Moderate Risk area which could be upgraded to a “High” risk during Saturday’s outlook’s.

 

A low pressure system is forecast to move North East across Texas and through Arkansas into Missouri and the Ohio Valley region. This low is expected to have a strong surface trough extending out to the East from it which will combine with a vigorous upper level system and potent moisture injection through areas South East of the system across Louisiana, Eastern Texas, Arkansas and eventually Mississippi, Alabama and surrounding States during Saturday and into Sunday. This combination is likely to produce potent instability and very strong wind shear which will essentially mean almost every cell that develops could become a supercell quickly. 

Quote from the Storm Prediction Center: “This combined with strong low-level shear will be favorable for supercells and tornadoes across the moderate risk area. 0-3 km storm-relative helicities are forecast to be in the 350 to 450 m2/s2 range supporting strong tornadoes with the more dominant supercells near the axis of the low-level jet. A potential for long-track tornadoes will be possible and a regional outbreak of tornadoes could occur across parts of the moderate risk area. By early evening, the cluster of severe storms is forecast to move into southwestern and central Mississippi where a potential for strong tornadoes will continue.”

 

Storm Prediction Center Tornado Risk showing a 15% contour (very high) and a very large hatched area (indicating strong tornadoes).

 

 

Models are keen on activity developing over Far Eastern Texas early in the afternoon before moving into Louisiana where activity is forecast to strengthen. This is where it gets ugly. Looking deeper into models, it appears as though a line of potent supercells are expected to move East across Louisiana and Southern Arkansas in the South East quadrant of the low. Wind shear will allow virtually all of these cells to become tornado warned with a “likely” risk of several tornadoes occurring across Louisiana and Southern Arkansas, and some of these almost likely to become strong and long lived. There is every chance that this could end up being a very localised major tornado outbreak across the region. As a result of that, there is every chance that the Storm Prediction Center “could” upgrade to a high risk which is fairly rare – only one or two happen per year at the absolute most.

Simulated Radar (Left) and Significant Tornado Potential (right) from the HRRR model (highest resolution in America) showing a line of supercells moving through a maximised (blue colouring) SIG TOR region at peak time (5pm). Images via COD Weather

 

As the severe weather moves East, its forecast to consolidate into an extensive squall line where damaging winds will be the main threat. Unfortunately this area from Eastern Texas into Alabama and Western Georgia is heavily populated but also heavily covered by trees and hills. It makes storm chasing very difficult, but living there is even worse as you can sometimes have very little warning of a tornado only a few miles away. We can only hope that all chasers, residents and tourists remain safe and adhere to the warnings and have safety measures in place for such a volatile day.

NAM (North American Model) 3km resolution (high resolution) radar simulation for Sunday showing a line of storms surging East across SE USA. Image via COD Weather

Tornado Outbreak Possible for Southern Central United States2019-04-13T16:58:07+10:00
4 04, 2019

Cyclone Wallace LIKELY To Develop

2019-04-04T13:21:15+10:00

Tropical Cyclone Wallace looks likely to develop either Friday night or Saturday morning North of the Kimberley in WA waters. This will make Wallace the 8th tropical cyclone of the 2018-19 season, very close to what we predicted back in September. 

TROPICAL CYCLONE FORECASTS & TRACK MAPS AVAILABLE HERE

 

 

A large cluster of thunderstorms is continuing to develop along a weak monsoon located between Australia and Indonesia / Papua New Guinea. This cluster of thunderstorms has consolidated over the past 24-36 hours with a weak tropical low now located (Invest 97S) active. Over the next 24 hours, this tropical low is forecast to become more defined and tighten along the monsoon trough as it drifts West to South West into a more favourable environment.

Models remain in agreement that tropical cyclone formation (where Wallace will be named) seems likely either later on Friday or early on Saturday with the system at this stage located over the North East Indian Ocean. From there, models are tending to agree on the strength with the system intensifying into either a high-end Category 2 or low-end Category 3 system. The impacts of Wallace over WA will be highly reliant on what happens with a large high pressure region moving across the Southern half of AUS.

 

A high is expected to move across the Southern half of WA during the weekend, with another high trailing in about 3-4 days later. Wallace is likely to squeeze between these 2 high’s and ‘make landfall’ somewhere over WA, but the timing of that interaction is vital. If Wallace follows the ECMWF track which has a slower moving high, then its not expected to make landfall until its an Ex-TC which could be anywhere from Exmouth to Perth down the West Coast. If Wallace follows the GFS track which has a slightly faster moving high, then the channel between high’s which Wallace can turn towards the Coast will happen sooner and this could pose a threat for areas from Shark Bay to Karratha which would also mean Wallace should be a Category 2 or 3 system as it makes landfall, not an Ex-TC. 

Other models are differing also which doesn’t make the long term tracking any easier.. but we are confined that Wallace will at least be named either Friday or Saturday, and a landfall as either an Ex-TC or TC seems probable at some stage next week.

Monday morning wind forecast showing some model differences based on the timing of a high over Southern WA. ECMWF on the left, GFS on the right. This difference is vital as to who could be impacted. Images via Windy

Cyclone Wallace LIKELY To Develop2019-04-04T13:21:15+10:00
2 04, 2019

Possible Cyclone Brewing For WA

2019-04-02T18:29:57+10:00

After Severe TC Veronica produced historic rainfall and severe, dangerous flooding across the Pilbara.. it appears as though WA might need to prepare for another system which is brewing North of the NT at the moment. Above image via RAMMB – Cyclone Watch Zone is via HSC. A ‘Cyclone Watch’ refers to an area where conditions ‘may’ become favourable for tropical cyclone development – it doesn’t mean that a cyclone is guaranteed. 

 

Its common for people to believe that April isn’t a cyclone month, however this is simply untrue and 2019 may prove that once again. Historically, some of the strongest cyclones ever recorded have occurred in April (even late April) and in 2019, while a ‘major’ cyclone isn’t on the cards at this stage, we are monitoring a cluster of thunderstorms situated across the Arafura and Timor Sea’s North of the NT which is currently being forecast by several global models to consolidate over the next few days into a weak tropical low. This will inevitably produce increased showers, rain periods and thunderstorms across the QLD Peninsula and Northern NT areas. However from the weekend onwards, things are looking a little more interesting.

 

Global models are remaining in some form of agreement of tracking and intensify of the tropical low, albeit greatly varying timeframes. The majority of global models are expecting the system to intensify while tracking West to South West into the Joseph Bonaparte Gulf, West of the NT / North the Kimberley. From there, the system is currently ‘more likely than not’ to become a tropical cyclone over the Indian Ocean North or North West of the WA Kimberley. 

While a landfall location is very hard to pinpoint so far in advance, as a lot will depend on the timing of an approaching high pressure ridge – models are currently favouring the system to turn back towards the Coast which “could” mean that the Pilbara may be under threat again. At this stage, if the system were to become a tropical cyclone then models are indicating it will probably remain below ‘severe’ strength. In saying that though, sea surface temperatures are remaining extremely warm, so if a period of very little wind shear occurs, then rapid intensification cant be ruled out. Further updates will occur for the progression of this system over the next few days.

ECMWF showing a Category 2 cyclone over the Indian Ocean on Sunday night (April 7) – via Windy

 

Possible Cyclone Brewing For WA2019-04-02T18:29:57+10:00
31 03, 2019

Another Cold Night for NSW

2019-03-31T17:29:31+10:00

NSW might be having a second taste of Winter again tonight with minimums likely to plummet across the majority of the State once again thanks to mostly clear skies and cold air aloft. Above image via BSCH / OCF showing minimums for Sunday night / Monday morning.

After virtually the coldest March night / morning in 4 years across the majority of the State, and some areas challenging their March minimum records – another round of similar conditions is expected again tonight. This is largely being brought on by an expansive cold pool aloft which is sitting over the State. This very cold air aloft is combining with clear skies to allow maximum heat removal which is forcing temperatures to plummet.

Frost potential by BOM MetEye for 4am Monday morning

We should see the coldest temperatures along the Ranges with frost being possible along isolated parts of the Northern Tablelands and more scattered parts of the Central Tablelands and Blue Mountains. These areas are likely to drop below 4ºc once again and may even nudge 0ºc (about 1-2ºc colder than last night). The absolute coldest temperatures will of course be over the Southern Tablelands and elevated parts of the ACT, but cloud cover may prevent frost from occurring – and temperatures may drop early across these areas before cloud increases later on. 

Along the Coast (mostly through areas North of Newcastle by the looks), where cloud is evasive, we could see minimums of up to 6-8ºc below average, even for April standards. However areas South of Newcastle around Greater Sydney and the Illawarra in particular, below average minimums are expected but not quite as cold as last night.

Forecast cloud cover by Windy (EC model) for Monday morning showing large areas of clearing over the Ranges and Northern parts of the State.

 

Another Cold Night for NSW2019-03-31T17:29:31+10:00
31 03, 2019

Another Cool Night for Southern & Central QLD

2019-03-31T17:13:55+10:00

Its going to be another cool night across the Southern half of QLD again tonight with widespread below average temperatures spreading into Central QLD and isolated parts of North QLD – Above image via OCF / BSCH showing minimums for Sunday night / Monday morning.

 

Its expected to be almost a carbon copy of what Southern and South East QLD experienced on Sunday morning as clear skies combine with some upper level cooling and light South to South West winds to produce well below average minimums. It wouldnt be a shock to see some isolated areas drop to colder temperatures than what was experienced on Sunday morning, which was largely the coldest March morning in 11 years for most areas. The coldest temperatures of course are expected to be over the Granite Belt and Southern Darling Downs where single digits are likely, possibly even down to a round 5 or 6ºc at Stanthorpe given the area recorded 6ºc on Sunday morning. Even near the Coast, minimums should drop into the low to mid teens which is around 4-6ºc below average for this time of year.

OCF Forecast Minimums for SEQLD via BSCH for Sunday night / Monday morning

 

Last night, areas across the Central Highlands struggled to drop below 20ºc and the Central Western districts saw the mid teens. Tonight, temperatures should be around 3-5ºc colder with that cooler air surging North. This should allow places like Emerald to see 14ºc, Longreach 12 or 13ºc – even Mackay might finally drop below 20ºc with a sharp drop off towards the Ranges. The cool air should also reach North West QLD where minimums will be around 5-8ºc below average once again (similar to last night). 

Maximums should be slightly warmer across the State than what was experienced on Sunday, however Inland areas will once again see a lack of humidity. Closer to the Coast it could be fractionally more humid, but it’ll still be less humid than what has been experienced across the last few weeks.

 

OCF Forecast Maximums via BSCH for Monday

 

Another Cool Night for Southern & Central QLD2019-03-31T17:13:55+10:00
31 03, 2019

Freezing Temperatures Hit NSW

2019-03-31T07:57:39+10:00

Parts of NSW have recorded their lowest March temperatures on record, with many locations along and surrounding the Ranges showing the potential for their first frost’s for 2019 overnight as temperatures plummeted across the State. Above image is a stock image.  

 


Across NSW, the temperature across most locations dropped considerably compared to previous nights / mornings, with areas along the Ranges potentially recording their first frost of 2019! Generally, most locations across the State will have recorded their coldest March morning since 2015. It was the Northern Rivers as a district and Eastern or Coastal parts of NSW that went a little harder with the anomalies and records.

 

Temperatures:

• Thredbo -4.2ºc – Coldest March temperature since 1984!
• Mount Ginini -2.9ºc
• Perisher -2.6ºc
• Nullo Mountain 2.5ºc
• Mount Boyce 3.0ºc
• Armidale 3.1ºc
• Bathurst 3.1ºc
• Canberra 3.1ºc
• Glen Innes 3.6ºc
• Port Macquarie 7.9ºc – Tied March record on current site
• Casino 11.2ºc – Coldest March Morning in 11 years
• Grafton 11.2ºc – Coldest March morning in 11 years
• Newcastle 12.4ºc – Coldest March morning in 18 years
• Sydney City 12.5ºc – Coldest March morning in 14 years
• Byron Bay 15.9ºc – Coldest March morning in 11 years

 

 

Note: Large parts of Western Sydney fell to between 7 and 11ºc, with the majority of locations recording their coldest March morning in 11 years (since 2008). Parts of the Hunter fell to as low as 5ºc, with most of that district recording its lowest March temperature since about 2015. Large parts of Northern and Central Inland NSW dropped well into single digits as well, with temperatures at their coldest since about 2015 for March too.

 

Real-time temperatures as of 7:10am across NSW and VIC showing the large area of cooler minimums. Image via BSCH, data provided by BOM.

 

Freezing Temperatures Hit NSW2019-03-31T07:57:39+10:00
31 03, 2019

Temperatures Plummet across Southern QLD

2019-03-31T07:50:08+10:00

South East QLD and large parts of NSW have endured their coldest March morning for about the last decade thanks to widespread dry and cool South to South West blowing across both areas. 

 

Across South East QLD, it was noticeably colder this morning compared to the rest of Summer as the South Westerly surged in after midnight, dropping the temperature by several degrees in the space of a short period of time. The difference for many locations between about midnight and sunrise was 7-9ºc with many locations sitting in the high teens / low 20’s around midnight and waking up to the low teens or even sub-teen temperatures. Along the Ranges, areas such as Toowoomba, Warwick and Stanthorpe dropped into single digits for the first time in 2019. 


• Stanthorpe 6.5ºc – Coldest March morning in 7 years
• Toowoomba 9.3ºc – Equal coldest March morning since 1993 (26 years)
• Warwick 9.4ºc – Coldest March morning in 7 years
• Canungra 9.6ºc
• Kingaroy 9.7ºc – Coldest March morning in 7 years
• Dalby 10.2ºc
• Wellcamp 10.3ºc
• Amberley 10.4ºc – Coldest March morning in 11 years
• Oakey 10.7ºc
• Gympie 12.1ºc – Coldest March morning in 11 years
• Brisbane Airport 13.0ºc – Coldest March morning in 11 years
• Gatton 13.5ºc – Coldest March morning in 11 years
• Redcliffe 14.4ºc – Coldest March morning in 11 years
• Brisbane City 15.3ºc – Coldest March morning in 11 years

Note: For many areas, especially over South Eastern QLD, minimums this morning (Sunday morning) were around 10-14ºc colder than Saturday morning, purely thanks to the incredibly different winds and air masses that moved over the region in such a short period of time. 

Real-time temperatures as of 7:10am across Southern QLD showing the large area of cooler minimums. Image via BSCH, data provided by BOM.

Temperatures Plummet across Southern QLD2019-03-31T07:50:08+10:00
30 03, 2019

Much Cooler Night Coming For Southern & South East QLD

2019-03-30T14:20:39+10:00

Southern and South East QLD areas may need to turn the air con off tonight, possibly even pull the doona out as temperatures plummet behind a rain and storm bearing trough. Above image – OCF Minimums for Saturday night / Sunday morning via BSCH

 

Showers, rain areas and storms are dominating Eastern QLD through Sunday thanks to a trough drawing in high levels of moisture and instability. Behind this trough though, much drier and colder South Westerly winds are blowing in – teasing with the first hints of Winter being just around the corner. These winds are expected to cut the humidity and with the combination of cold air aloft and clear skies, temperatures should plummet across the majority of the Southern half of QLD. 

Trough line marked offshore and along the Coast with winds coming in behind it from the South to South West – these are drier winds.

 

 

Overnight Saturday night into Sunday morning, temperatures to drop to as low as 5 or 6ºc over the Granite Belt, single digits over the Darling Downs and maybe even below the teens across Central QLD. These temperatures, whilst not being totally uncommon for this early in the “cooler” season, will still be around 5 to 8ºc below average for this time of year. Closer to the Coast between Hervey Bay and the Gold Coast, minimums should bottom out in the mid teens which is around 4ºc below average for this time of year. 

During Sunday, whilst maximums should climb back up into the high 20’s or low 30’s for most areas – the big difference will be the lack of humidity. Humidity levels within 20-30km of the Coast way remain elevated – but these areas should also see cooler temperatures than those further Inland. Anywhere more than about 25-30km (as the crow flies) from the Coast should see humidity levels drop into the 30’s and 40% range (which is very low for 27-28ºc). As the week progresses, maximums will remain similar but the humidity will start to creep back in gradually. Back across Southern Inland QLD, maximums will be heavily influenced by the South to South West cooler flow, with temperatures potentially sitting at around 6-8ºc below average and in the low to mid 20’s all day.

OCF Forecast Maximums for Sunday via BSCH

 

Much Cooler Night Coming For Southern & South East QLD2019-03-30T14:20:39+10:00