The most damaging of a number of severe storm cells that developed this afternoon are shown bearing down on Muswellbrook and Taree in this 5pm radar image. Three cells display the maximum reflectivity reported by 15-level radar (a cell that brushed south of Katoomba shortly before 3pm also showed maximum reflectivity), while the Muswellbrook cell is remarkable for the size of its solid precipitation shaft -- some 20km in diameter. Weatherzone

Heavy damage from NSW severe thunderstorms

Severe thunderstorms developed over the NSW Central Tablelands this early this afternoon, then moved ENE into the Sydney metro area, Hunter Valley and Mid North Coast causing widespread and severe damage from hail and flash flooding. The storms developed in a surface trough supported by a closed low in the lower atmosphere, cooler air aloft and a broad tongue of moisture extending down to the Central Coast from the Coral Sea.

Muswellbrook in the Hunter and Taree on the Mid North Coast fared worst, with significant damage and disruption also reported from Sydney's western and northern suburbs and the Oxley region. The SES received hundreds of calls for assistance, with repair and mopping-up operations continuing through to Tuesday and additional crews brought into Taree and Muswellbrook from surrounding areas.

The Muswellbrook storm developed to the west of Mudgee soon before 2pm and rapidly gained full strength as it moved east over largely uninhabited country in the upper Hunter. For much of its life, it showed a near-circular echo of intense rainfall about 20km across on radar, with strong echoes indicating hail shafts as well. It passed across Muswellbrook around 5.30pm, bringing 10 minutes of intense rainfall and hail. There were around 400 SES call-outs in and around the town, and damage is expected to run to about $10m. Hail was the greatest cause of damage. The SES said stones were 9 to 12cm in diameter and included jagged lumps of ice formed by the fusing together of smaller stones. The roofs of about 20 homes were damaged, and extensive damage was caused to cars, especially those in car sales yards. Early estimates are that around 30% of the grape crop in the Upper Hunter was stripped of foliage by the hail. Paterson (Tocal) recorded the highest 24 hour to 9am Monday rainfall in the Hunter with a total of 40.0mm, most of which fell in the storm and 19.0mm of which was reported in 10 minutes to 6.10pm. Wind gusted to 91km/h at Williamtown at 6.28pm.

In Taree flash flooding occurred in the CBD. Portion of the roof of Coles Supermarket collapsed when hail blocked gutters and the weight of water and hail built up, requiring the store to be evacuated. A nursing home suffered water damage after hail smashed through skylights. Around 22mm was recorded at the Airport in the storm, 14.0mm falling in just 7 minutes to 7.40pm.

Around Sydney, flash flooding caused brief traffic dislocation while strong winds and lightning strikes produced some power blackouts. About 2,000 customers in Harbord and Pymble lost power for about 90 minutes. There were other local outages on the North Shore, Blue Mountains, Emu Plains, Penrith, Greystanes, Seven Hills and Fairfield. A lightning strike put signalling equipment out of action on the Blacktown line for about 40 minutes, leading to general delays of around 10 minutes to railway services. The SES received about 30 calls for assistance, mainly for lightning strikes causing tree damage. The storm dumped 17.4mm in 6 minutes to 3.47pm in Penrith Lakes AWS raingauge for a storm total of 36mm. Details of other heavy falls are given in downpours below.

Severe storm cells are frequently associated with strong windshear aloft (i.e. the upper wind is blowing at a different direction and/or speed from surface winds, aiding the development of strong updrafts), but there appears to have been surprisingly little windshear with today's storms. Winds at 850hPa were circular around the lower atmosphere low that tracked across the Central Coast, but were of the order of 20 to 30km/h. Upper winds were relatively benign westerlies of around 60km/h, with the jet stream core situated over southern QLD. The most severe storms appear to have been associated mostly with convergence into the lower atmosphere low.

Heatwave sets records, brings bushfires and storms to QLD

Daytime temperatures were from 8 to 12 above normal across much of southern QLD and parts of northern NSW today for the third day running. Winton (42.5C), Longreach (42.4) and Cloncurry (42.0) recorded the highest maxima, but the greatest departures from normal were in a triangular area from the SE Coast west to the Maranoa and north into the Central Highlands. Clermont and Springsure, two Central Highlands towns with long computerised records (around 40 years) both set new October records with top temperatures of 40.5 and 40.0 respectively. In the same area, but with shorter periods of record, Emerald and Moranbah set a new October highs of 41.3 and 40.5.

A number of bushfires flared up in SE QLD, though no significant property damage was reported. The worst fires were to the NW of Brisbane. A large blaze at Moore closed the D'Aguilar Highway, while three fires were reported around Esk. Another fire at Kilcoy burnt through 1,000ha of bushland and required water bombing to bring under control. A fire west of Dayboro was burning in inaccessible country, while grass fires were reported at Esk, Mt Binga, Tenthill, Ropeley, Flagstone Creek, Mt Whitestone, Nanango, Gordonbrook, Rosedale, Moore, Cooyar Creek, Perry River, Widgee, Lower Wonga, Gurgeena, Dallarnil and Cinnabar.

A band of thunderstorms developed to the west of Dalby mid afternoon and moved rapidly ENE, clearing the coast mid evening. The storms exacerbated the fire problem as rain was generally light from the fast-moving cells, but squally winds gusted to 113km/h at Oakey (accompanied by a temperature drop of 12.3C in 4 minutes!) and lightning strikes created fresh spot fires. Rural Fire Service district inspector Wayne Waltisbuhl told The Courier-Mail "I believe there was a shed on fire in Esk (northwest of Brisbane) which was started by a lightning strike and as crews were heading to it lighting was causing the power lines to arc and starting grass fires along the road." Golf ball sized hail fell in Toowoomba while the gusty winds raised a duststorm at Greenmount, 25km S of the city. Severe thunderstorms with hail and strong winds were also reported from Boonah and Rathdowney. Robert Bundy from the Toowoomba SES told ABC Radio "We've had a number of houses damaged in the Cambooya shire, the Pittsworth and the Tara area, some with quite severe damage, entire roofs ripped off but generally, roughly about six to eight houses in total in the Cambooya shire, which was worst hit."