La Niña passed its peak?

The La Niña episode which has dominated the Australian climate for the past nine months is showing signs of weakening. Pacific Ocean temperatures, most notably below the surface, have warmed, while atmospheric indicators such as the Southern Oscillation Index (SOI), trade winds and cloud patterns have eased from their respective peaks in early January

Past Week’s Weather Feb 14 – 20

Weekly Plot

Solar Flares

On Tuesday 15the February 2011 a spectacular solar eruption in a sunspot the size of Jupiter produced a Class X flash – the most powerful of all solar events.

A sunspot is an area of highly organized magnetic activity on the surface of the sun. The new 11-year cycle, is expected to build gradually, with the number of sunspots and solar storms reaching a maximum by 2012, though devastating storms can occur at any time.

The eruption blasts a torrent of charged plasma particles, called a Coronal Mass Ejection (CME), towards Earth at about 900 kilometres per second,.

A direct hit from a CME could trigger a huge geomagnetic storm as incoming particles bounce off the Earth’s geomagnetic field, where it can bring down power grids, disrupt critical radio communications, and threaten astronauts with harmful radiation. Storms can also knock out commercial communications satellites and swamp Global Positioning System signals. Routine activities such as talking on a cell phone or getting money from an ATM machine could suddenly halt over a large part of the globe.

“Our growing dependence on highly sophisticated, space-based technologies means we are far more vulnerable to space weather today than in the past,”

On March 13th, 1989 a huge solar induced magnetic storm played havoc with the ionosphere, and the earth’s magnetic field. This storm, the second largest storm experienced in 50 years, totally shut down Hydro-Quebec, the power grid servicing Canada’s Quebec province.

Meteorological Observations in WW11

The planning of military operations was dependant on good weather forecasting and good forecasting is dependant on good weather observations to build a synoptic pattern of current weather conditions. The normal sources for collecting observations were not often available and secrecy was paramount in collecting data.

In the United Kingdom the Royal Air Force took over a major role of collecting weather data during WW11and in early 1941 established a small number of meteorological reconnaissance units that grew at its peak to eighteen squadrons with over 750 personnel. The task of gathering vital meteorological information was the first step in forecasting the weather so that allied generals could undertake military actions with increased confidence and minimum risk. The weather conditions encountered on many of the flights were very hostile and operations called for exceptional qualities of dedication and courage by the crews. Reconnaissance sorties were both flown deep into enemy territory and over the surrounding seas and hostile waters of the Atlantic Ocean.  By the end of the war 16,000 sorties had been flown and 52 aircraft failed to return.

The Handley Page Halifax bomber was the aircraft mainly used and equipped with scientific metrological equipment for observing the weather. Often the pilot had to ascend to fly at 500mbar atmospheric pressure. This was almost the maximum height for the Halifax and if cloud tops such as those of cumulonimbus were high and thick, a bumpy flight followed with oxygen masks worn by crew. Another hazard encountered at this height was the strength of the winds associated with the Polar Front jet stream.  Very little was known about jet streams in 1940’s and it was this phenomena encountered by the American Air force pilots when high level  bombing of Japan who found they could save on fuel by taking advantage of the Jet stream. A common feature of our jumbo jet passenger planes today. The Japanese also became aware of the advantages of the jet stream and used it to create alarm and dependency among the USA population by dropping incendiary bombs on American soil from balloons carried on a jet stream.

Past Week’s Weather Feb 7 – 13

Weather on the ranges was the result of three separate systems. There was an extensive high in the Tasman Sea extending a firm ridge into SE Queensland, an upper level trough in a NW cloud band and a surface trough to the west of us.

 

It’s been a muggy week with periods of short showers, heavy at times, filling gauges with 20mm of rain. Winds were light and temperatures in the mid twenties.

Weekly Plot 13.2.11

Past Week’s Weather Jan 31 – Feb6

Weekly Plot 6.2.11

Throughout the week the hinterland’s weather was influenced by a ridge of high pressure extending from a slow moving high in the Tasman Sea.  

Barometric pressure of around 1016hPa brought stable atmospheric conditions to the region.  Northerly winds were light on the Ranges with maritime isolated showers, heavy at times.  Always useful to have an umbrella handy!

This has been a week when everyone’s thoughts and prayers have been with those living in the path of the category 5 tropical cyclone. A major loss of life was averted by the state of readiness and the cyclone crossing the coast away from maximum population. Never-the-less, structural damage and loss of property was heavy.

For the record, the cyclone was born in the monsoonal trough with a low developing off Fiji, near Vanuatu on Saturday January 29, at a time when TC ‘Anthony’ menaced the north Queensland Coast.

On Sunday, the low increased in intensity and became a category one tropical cyclone named by the Fijian Meteorological Authorities as ‘Yasi’.

TC ‘Yasi’ entered into the Australian Bureau of Meteorology area of responsibility on Monday 31st January, and with winds increasing to 170km/h soon became a cyclone with a category three rating. The unknown factor was where it was going to make landfall? Some where between Cooktown and Mackay seemed most likely?  

On the following day, TC ‘Yasi’ increased its movement toward the northeast coastline of Queensland with wind gusts soaring past 225km/h, now a category four tropical cyclone.

Wednesday Feb 2 began the day with ‘Yasi’ officially a category five system with wind gusts above 280km/h and capable of causing major destruction. At about midnight TC’Yasi’ made landfall near Mission Beach, avoiding areas of dense population, with wind gusts of 285km/h and a central pressure of 930hPa.

January 2011

Maleny ~ January

2011

2010

Rainfall

902.8 mm

154.6 mm

Rain Days

21

12

Max. 24 hr rain

282.6 mm

33.8mm

Thunder heard

10

2

Annual Rainfall to date

902.8 mm

154.6 mm

Evaporation

95.6 mm

133.2mm

Mean Humidity (9.00am)

84%

76%

Mean Humidity (3.00 pm)

78%

68%

Lowest Minimum Temperature

16.0°C

16.8°C

Highest Minimum Temperature

21.8°C

20.8°C

Lowest  Maximum Temperature

22.2°C

22.6°C

Highest   Maximum Temperature

31.4°C

33.8°C

Days over 30ºC

2

6

Dom. Wind Direction

NE

N

Bright Sunshine Hours

76

229

MWS Internet Usage            Hits

354,530

194,018

MWS Internet Usage            Visits

17,537

9015