Category Archives: Rain

precipitation in the form of droplets

Violent storms, wind and fires SE Australia 11th to 13th November 2016

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Violent Storms South Australia and New South Wales 11th to 13th November 2016

A significant weather event has crossed much of southern and eastern Australia which has impacted South Australia, Victoria, Tasmania, New South Wales, Australian Capital Territory and Queensland in different ways.sydneyradar12nov6am

The system has been responsible for producing thunderstorms, some of which have caused damage, gales, outbreaks of hot weather, some heavy rainfall, fires and even snow across higher alpine regions.

South Australia

During Friday, the fast moving weather system produced a few significant thunderstorms across South Australia and there were reports of large hail across parts of north east Adelaide.

Additionally, a weather station at Pinaroo recorded peak wind gusts of 128 km/h between 6.58 pm and 7.05 pm from passing thunderstorms.

Mildura – Victoria 11/11/16

Late Friday between 8.47 pm and 9 pm, a significant thunderstorm passed over Mildura (North West Victoria) dropping 27.4 mm of rain in 13 minutes. This is significant as it represents 2 mm of rain per minute. A closer analysis of this shows that between 8.51 pm and 8.54 pm (3 minutes), 10.8 mm of rain fell or 3 mm per minute and between 8.54 pm and 8.57 pm, another 10 mm of rain fell. Hence for 6 minutes, rainfall rates were in the order of 3 mm per minute.

This was accompanied with gales of 96 km/h. This storm has caused damage across the city with a clean up occurring.

Such a storm of this intensity is unusual given the location of Mildura within a semi arid region of the state.

New South Wales

A storm system passed through the Central West and there are reports of further significant thunderstorm activity Friday night / Saturday morning. Rainfall figures reached 30 to 50 mm across some locations of the Central West.

The system passed through Sydney early Saturday morning but no significant weather occurred. A single thunderclap was heard early Saturday morning being the remnants of storm activity that had reached the coast. Rainfall was not significant with most totals in the order of 10 mm.

Following the morning rainfall, maximum temperatures reached 34 to 35 degrees across much of the city as north west winds increased through the afternoon.

A late afternoon thunderstorm developed off the coast at Broken Bay to Sydney's north but moved quickly out to sea.

Thunderstorms occurred across the North west slopes of New South Wales and the Upper Hunter Valley and a number of storms were documented by storm chasers. One particular storm passed very close to the town of Narrabri with the airport receiving three wind gusts to 128 km/h between 5.33 and 5.39 pm Saturday afternoon.

Queensland Saturday afternoon

Thunderstorms produced some strong rainfall totals across parts of Brisbane including 67 mm at Mt Nebo Alert and 65 mm at Everton Hills Alert. In Redland, an intense thunderstorm produced 51.4 mm of rain between 3.24 pm and 4 pm which is a period of 36 minutes. Redland received 53.2 mm for the 24 hours to 9 am 13/11/16.

Tasmania

The same system has produced some heavy rainfall across eastern and north eastern Tasmania with the highest figure being 171 mm at Mount St John to 9 am 13/11/16. Additionally, much of northern coastal Tasmania received 54 to 89 mm during the same period.

New South Wales Sunday 13 November

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During Sunday, significant weather contrasts featured across New South Wales. In particular, while maximum temperatures reached 28C to 30C across Sydney, very cold air passed over Southern New South Wales thus places such as Albury experienced a cold wintry weather setup with constant showers and maximum temperatures struggling to reach 13C.

The same system has produced snowfall across the Mt Kosciusko region as freezing conditions set in for the passage of the system.

While this was occurring, a large bush fire occurred near Londonderry (North West Sydney) with fire fighters spending a number of hours fighting the blaze. At one stage, a thick plume of smoke emanating from the fire passed over Blacktown and south east blocking the sunlight. The fire was fanned by strong west to south west winds that reached 70 km/h at Penrith and 74 km/h at Badgerys Creek.

The system has produced a weekend of interesting weather contrasts with the one system creating numerous weather features depending on location.

Images

1 – Sydney radar image at 5.48 am 12/11/16. Despite the radar showing this, significant rainfall amounts did not occur.

2 - The Namoi radar at 5.30 pm. The storm at Narrabri is the one of interest as it is known wind gusts reached 128 km/h.

3 - Photo - Developing storm cell of Avalon / Broken Bay. This storm formed on the coastline and developed further as it passed out to sea.

4 and 5 - Photos - Bushfire smoke plumes west from Blacktown fanned by strong winds Sunday afternoon.

Storm Chase and Hailstones 28th and 29th October 2016

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Storm Chase and Hailstones 28th October 2016

After procrastinating as to whether to take the day off and chase, the gamble was taken. It was the day before the main event situation. With cold air aloft (-16C at 500hPa level), hailstorms were likely wherever storms could produce strong updrafts.

Unfortunately, things did not clearly go to plan. Yes storms were anticipated in the Northern Tablelands. However, the North West Slopes and Plains was covered in slow moving mid-level cloud. Only a narrow window of opportunity existed as it cleared.

Just under two hours to get to Coonabarabran, it seemed any promising storms we had targeted had matured and weakened. The only option a right moving storm to the south near and north of Mendooran. Positive move! Storm became strong to severe  in the area as we neared. Multicellular in nature, the new core developed to its south and this passed over us on the road.

Hail covers the road

Hailstones fell in abundance virtually covering  the road. Although most hailstones were of the order of 1.5cm, some seemed to edge to 2cm. Outflow produced a consolidated base to the southeast - the development of a new cell was in place. Zigzagging our way to the south east via Dunedoo, we edged the core and spectacular structures. The storm though was on a downward trend over the next hour. More cells to the south near Bathurst teased an opportunity but also decayed with the lack of heating.

Hailstorms and Structure 29th October 2016

Models indicated a very complex situation and both the GFS and Access-R models seemed to deviate somewhat. It took a couple of hours to analyse the situation and possible scenario that may unfold. Target Lithgow.

After a call from Colin, Rodney and I checked radar and realised storms had already developed - south of Jenolan. Bound for Lithgow, more updrafts developed on the northern flank. On arrival, another weak cell developed near Oberon. The main Jenolan cell rumbled but the activity decreased. It seemed to have crossed the boundary.

The Oberon Cell bound for Lithgow

The Oberon cell intensified indicated by updraft and lightning activity. The south side looked ordinary so we repositioned to its north side. What a sight! Magnificent scenery and a separated base from the hail shafts. Rodney could not hold back his excitement! A bolt pierced down the right side! Inflow flowed into the base. The hail fell in bursts so it was time to reposition.

At the foothill of Hassans Walls, an inflow band connected to the menacing turbulent base. The hail core was inviting. Passing through the Hartley valley was blinding. Hail and torrents of rainfall caused severe run-off. Heading to Lithgow over the range though was astonishing!

First, copious amounts of hailstones fell building on the bonnet, the paddocks and the road! Then further up the road - nothing followed by brief burst of hailstones! Over the range though to Lithgow and it was bone dry! Not a hint of rain let alone hail! A menacing green core above the mountain edge!

Radar showed the core was still to hit the Bells Line of Road - our next target! Looking left I commented to Rodney "There is our next storm !" The storm near Bathurst showed interesting structure - the obvious choice once this cell ventured into the Wollemi National Park. No man's land!

The storm had intensified clearly on radar and had developed an ominous flanking line! Just short of Bell, the hail hit in torrents. Hail to 2.5cm fell for at least 10 minutes. Any calliper hail measurement had to wait until the rain stopped.

Tired and hungry, it was time to head to Lithgow. Unfortunately, just to our east, a car pile up. Emergency vehicles pointed to an accident (a car had rolled over). After a brief stop at Macdonalds, it was back northwest enroute to Cullen Bullen.

The storm near Bathurst looked ordinary with outflow from the core and scud under the base. Suddenly though, a core had developed to its east. Northeasterly inflow had freshened. The base organised rapidly and our repositioning placed us under the developing green base. The hail core further south indicated pea sized hailstones but it seems the main core had just moved east. No man's land once more!

Rodney suggested to head to Pearsans Lookout. Although a few kilometres away, it provided a spectacular view for time-lapse. Further time-lapse opportunities of the back updraft and base presented themselves near Kandos and Rhylstone. Sunset silhouetted on the updraft a spectacular end to a satisfying day!

Hurricane Matthew nears Western Haiti 4 and 5 October 2016

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Hurricane Matthew threatening Florida

Hurricane Matthew continues it's slow movement north towards the western portions of Haiti. The storm is moving at 9 km/h northwards as a powerful Category 4 storm sustaining winds of 120 knots at the core with higher gusts to 140 knots (Approximately 220 km/h with higher gusts to 260 km/h).
cimssmodelformatthewThis is the most powerful storm since Hurricane Felix in 2007 and news reports already confirm 3 fatalities at the present time. Further fatalities cannot be ruled out especially across Haiti.forecastcone

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Path of Hurricane Matthew

Path of Hurricane Matthew

According to the National Meteorological Centre of Haiti, the Hurricane Matthew has a central pressure of 943 hPa. Hurricane winds are occurring within 45 km of the centre and storm force wind extend outwards to 315 km from the eye.

Western Haiti affected by Hurricane Matthew

The CIMSS forecast models suggests that the eye of Matthew would pass over the far western fringe of the country placing the towns / cities of Jeremie and Les Cayes at significant risk. Other smaller towns at risk include Dame Marie, Port A Piment and Tiburon

Haiti is an impoverished country and such a storm would have a significant impact and cause major disruption to the country.

Very heavy rainfall, storm surges and landslides are being forecast given the strength of the storm. The outer rain bands are starting to impact the southern coastal fringe of the country.

The western part of Haiti does not contain too many substantial towns or cities as shown on the “Urban Extents Map” but as shown on the population density map, the western side of the country is moderately to densely populated implying the region includes numerous small villages, farms, farming communities and rural towns. In this regard, the storm will have a major impact to the country.

The storm will also have a significant impact to eastern Cuba due to the number of large towns or cities within the region.

Forecasts are being made for rainfall to reach as much as 1,000 mm in isolated locations of Haiti which would cause landslides and serious flooding.

Forecast models suggests the storm emerging into the Bahamas within two days and traversing towards or close to Florida and possible impact within the Carolina's of the United States in six days. Major uncertainty exists beyond three days but it is clear that the whole south eastern sea board of the United States including the states of Florida, Georgia, South Carolina and North Carolina is now under threat from the storm. There is a possibility of landfall in eastern North Carolina in six days but this is to early to tell at the present time.

CREDITS

1 - CIMSS - Forecast model for Hurricane Matthew acquired 4/10/2016.
2 - National Meteorological Centre Haiti.
3 - National Weather Service (USA).
4 - NASA Worldview - Population plots for Cuba, Haiti and Jamaica.

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