It was just a few days ago that the driest part of the country- western QLD, northwest NSW and northeast SA- was being singed by a record-breaking heatwave. Today, this outback region is getting drenched by flooding rains! Urandangi in northwest QLD hasn't seen a drop in months, yet in just 24 hours a massive 42mm has fallen across the desert town.
Local flooding is already affecting southern areas of SA's Northeast Pastoral district thanks to 30-90mm of rain over the last few days. Another 50-70mm is possible by Thursday, further increasing the likelihood of flooding in the coming days.
What has caused this remarkable turn-around in the weather across the outback? There are two weather features at play. During the recent heatwave, northerly winds persistently churned extreme heat towards central Australia for about two weeks. But the hot air wasn't travelling on its own; the winds were also drawing in moisture from the tropics towards the central inland. Over the weekend, the south- eastern states got drenched thanks to a cold pool of air across the region. This cold pool has moved further north and tapped into this tongue of tropical moisture to produce flooding desert rains!
Is this normal? In one way it is. The climate of the outback is characterised by extreme variability. Prolonged dry periods followed by flooding rains are "normal" in this part of the world and that's what makes the arid zone so special. But it's quite unusual to see this much rain this early in the wet season. Flooding rains typically affect this region in December and January when tongues of tropical moisture feed into inland areas during periods of active monsoonal and tropical cyclone activity in the tropics. So this rain set-up is a little left of field for what we normally expect.
Tuesday, November 24, 2009
Monday, November 23, 2009
Southerly buster cools Sydney’s Sunday scorcher.
If I asked you what the hottest part of NSW was yesterday, you’d be forgiven for thinking it was somewhere in the outback like Broken Hill or Bourke. But it was actually Sydney Airport which reached a furnace-like 42.5ºC degrees, a massive 19 ºC above the November average! The city itself baked in its hottest day since January reaching a scorching 40ºC.
Thankfully, a southerly buster burst onto the scene at around midnight to bring some gusty relief and temperatures today are around 20ºC cooler than what they were yesterday.
While the official recorded temperatures were in the low forties, it's possible that your thermometer in the backyard could have registered an even higher temperature, especially if it was in the direct sunlight. This is because the temperatures obtained from official weather stations are recorded in what is known as a "Stevenson screen." It's a white box located about 1.25-2m off the ground which houses various meteorological measuring instruments like a thermometer. Its purpose is to shield the thermometer from outside influences like rain and direct sunlight in order to create a "standardised" environment for measuring various meteorological variables.
The fact that the air temperature is measured at height is also important for farmers when forecasting frost because the temperature on the ground itself will be around 2-3 degrees colder than what is recorded in the Stevenson screen.
Thankfully, a southerly buster burst onto the scene at around midnight to bring some gusty relief and temperatures today are around 20ºC cooler than what they were yesterday.
While the official recorded temperatures were in the low forties, it's possible that your thermometer in the backyard could have registered an even higher temperature, especially if it was in the direct sunlight. This is because the temperatures obtained from official weather stations are recorded in what is known as a "Stevenson screen." It's a white box located about 1.25-2m off the ground which houses various meteorological measuring instruments like a thermometer. Its purpose is to shield the thermometer from outside influences like rain and direct sunlight in order to create a "standardised" environment for measuring various meteorological variables.
The fact that the air temperature is measured at height is also important for farmers when forecasting frost because the temperature on the ground itself will be around 2-3 degrees colder than what is recorded in the Stevenson screen.
Wednesday, November 18, 2009
SA Heatwave reaches day 12 and spreads east
Northern SA is now in day 12 of the November heatwave with temperatures skyrocketing to as much as 14 degrees above the average. The record heat has been blistering SA soils for almost two weeks now, and today we have the added feature of strong winds which is what has lead to a Catastrophic Fire Danger in the Northwest Pastoral and Flinders districts. This is the most severe bushfire rating and under this warning, fires will be uncontrollable, unpredictable and fast- moving. This is the first time a Catastrophic Fire Danger has been issued in Australia since the bushfire warning system was revised earlier this year.
Extreme heat is also searing across NSW and QLD today with Bourke and Thargomindah set to reach 45ºC and 44ºC, respectively. The heatwave is peaking tomorrow with November heat records almost guaranteed to tumble.
Extreme heat is also searing across NSW and QLD today with Bourke and Thargomindah set to reach 45ºC and 44ºC, respectively. The heatwave is peaking tomorrow with November heat records almost guaranteed to tumble.
Monday, November 16, 2009
SA coast cools down- but not for long!
Adelaide can look forward to temperatures below 30ºC today for the first time in 10 days! This is thanks to a cool southerly change that swept across the South Australian coast last night bringing slight relief to heat- ravaged areas. But even though some places are up to 15 ºC cooler than what they were yesterday, they are still above average today. This gives you some idea of just how hot it got with a few places even reaching 45 ºC like Ceduna, Wudinna and Port Augusta.
But this drop in the mercury will only be short-lived! By tomorrow, the heat will be back with 34ºC before getting to a scorching 41ºC on Wednesday and Thursday. The “proper” cool change will arrive on the weekend in the form of a cold front that will finally drop temperatures down to the low twenties on Saturday and Sunday.
The reason why the cool change today isn’t sticking around is because it’s just a wind change from northerlies to southerlies- the actual temperature of the hot air above South Australia isn’t changing. So once the southerlies move away, the heat comes back! On the contrary, a cold front brings a wind change and cold air behind it which actually replaces the hot air and brings a longer period of cooler weather.
But this drop in the mercury will only be short-lived! By tomorrow, the heat will be back with 34ºC before getting to a scorching 41ºC on Wednesday and Thursday. The “proper” cool change will arrive on the weekend in the form of a cold front that will finally drop temperatures down to the low twenties on Saturday and Sunday.
The reason why the cool change today isn’t sticking around is because it’s just a wind change from northerlies to southerlies- the actual temperature of the hot air above South Australia isn’t changing. So once the southerlies move away, the heat comes back! On the contrary, a cold front brings a wind change and cold air behind it which actually replaces the hot air and brings a longer period of cooler weather.
Thursday, November 12, 2009
Tiger sizzles on the green!
It goes without saying that Tiger Woods is red hot on the green, but this time I mean it in a literal sense! Today, Melbourne experienced its 6th day in a row of 30 degrees or more and the heat isn't expected to let up until Monday.
But if you're feeling bad for Tiger, spare a thought for locals in Victoria's north who, like their South Australian neighbours, are putting up with the discomfort of 40-plus temperatures. The hot air is also seering through much of NSW with Ivanhoe getting up to 44 degrees.
City slickers have also been left panting for cool relief with Penrith recording 38.8 degrees this afternoon. Thunderstorms ahead of a southerly buster have just turned Sydney's blue skies into an ominous grey, and Sydneysiders will get a short break from the heat tomorrow.
But keep your swimmers and sunscreen handy! The mercury is on the rise again with the western suburbs set to sizzle in 40-degree heat by Monday!
But if you're feeling bad for Tiger, spare a thought for locals in Victoria's north who, like their South Australian neighbours, are putting up with the discomfort of 40-plus temperatures. The hot air is also seering through much of NSW with Ivanhoe getting up to 44 degrees.
City slickers have also been left panting for cool relief with Penrith recording 38.8 degrees this afternoon. Thunderstorms ahead of a southerly buster have just turned Sydney's blue skies into an ominous grey, and Sydneysiders will get a short break from the heat tomorrow.
But keep your swimmers and sunscreen handy! The mercury is on the rise again with the western suburbs set to sizzle in 40-degree heat by Monday!
South Australia smashes November heatwave record
It's official: Adelaide is sweating through it's worst November heatwave on record. At 3.30pm the city's temperature skyrocketed to 39.2 degrees, making it it's 5th day in a row above 35 degrees. The previous record of 4 consecutive days above 35 degrees was set in 1894. But the heatwave isn't over yet with the mercury expected to rise to a scorching 40 degrees by Sunday!
A cool change will eventually drop temperatures down to the high twenties/ early thirties on Monday and Tuesday but this mild relief will be shortlived. On Wednesday, locals will once again need to prepare to suffer through another spell of 35-plus temperatures.
Many inland parts of South Australia have also cracked the 40- degree mark with Murray Bridge sweating through 3 days in a row above 41 degrees.
South Australians are accustomed to prolonged heatwaves but as I mentioned in my earlier post, this pattern of sustained, well above average heat is unusual for this time of the year and, as of today, unprecedented in November.
A cool change will eventually drop temperatures down to the high twenties/ early thirties on Monday and Tuesday but this mild relief will be shortlived. On Wednesday, locals will once again need to prepare to suffer through another spell of 35-plus temperatures.
Many inland parts of South Australia have also cracked the 40- degree mark with Murray Bridge sweating through 3 days in a row above 41 degrees.
South Australians are accustomed to prolonged heatwaves but as I mentioned in my earlier post, this pattern of sustained, well above average heat is unusual for this time of the year and, as of today, unprecedented in November.
Tuesday, November 10, 2009
The Silver City melts in Spring heat
South- western parts of NSW, including Broken Hill, are baking in temperatures as high as 10 degrees above the November average. Today the Silver City is heading for 36 ºC, with the mercury expected to reach a scorching 40 ºC by Thursday. Temperatures are likely to remain at 35 ºC or more for the rest of the week.
On average, Broken Hill will swelter through around 6 days above 40 ºC but this year there have already been 16 40-plus days! Most of these temperatures occurred last Summer when locals sweated through 12 days in a row above 40 ºC in January and February! In the past 6 months, temperatures in Broken Hill have been about 1 degree above the average.
So what can we expect for the coming Summer? According to climate forecasts based on current sea surface conditions in the Pacific and Indian Oceans, Broken Hill is likely to receive below average rainfall through the summer and above average temperatures. Right now, we are in an El Nino phase which usually results in drier than average conditions. Most climate models are forecasting El Nino to persist throughout Summer.
On average, Broken Hill will swelter through around 6 days above 40 ºC but this year there have already been 16 40-plus days! Most of these temperatures occurred last Summer when locals sweated through 12 days in a row above 40 ºC in January and February! In the past 6 months, temperatures in Broken Hill have been about 1 degree above the average.
So what can we expect for the coming Summer? According to climate forecasts based on current sea surface conditions in the Pacific and Indian Oceans, Broken Hill is likely to receive below average rainfall through the summer and above average temperatures. Right now, we are in an El Nino phase which usually results in drier than average conditions. Most climate models are forecasting El Nino to persist throughout Summer.
Temperatures soar in South Australian heatwave
It’s only 9am and Adelaide is already 32 ºC! The city is heading for its third day in a row above 35 ºC today and with 39 ºC expected from Wednesday to Friday, it’s almost guaranteed that it will break the November heatwave record of 5 days in a row. Thankfully, a cool change is finally expected on Saturday- the timing is still uncertain but I’ll keep you posted.
This unrelenting heat is being caused by a near- stationery high in the Tasman that is churning a hot airmass from the northwest interior right down to the southern coastline. This type of a high pressure system is often called a “blocking high” because it blocks the usual easterly progression of weather systems. In this case, it’s stopping cold fronts from the Southern Ocean from being able to reach the mainland and cool things down.
This weather set-up is quite unusual for this time of the year. Typically, Spring sees erratic and changeable weather rather than the stagnant pattern of unprecedented heat that we’re seeing at the moment.
This unrelenting heat is being caused by a near- stationery high in the Tasman that is churning a hot airmass from the northwest interior right down to the southern coastline. This type of a high pressure system is often called a “blocking high” because it blocks the usual easterly progression of weather systems. In this case, it’s stopping cold fronts from the Southern Ocean from being able to reach the mainland and cool things down.
This weather set-up is quite unusual for this time of the year. Typically, Spring sees erratic and changeable weather rather than the stagnant pattern of unprecedented heat that we’re seeing at the moment.
Monday, November 2, 2009
Hold onto your hats at the Cup!
It might be warm today but colder weather is headed towards Melbourne with temperatures dropping and winds picking up just in time for the Melbourne Cup on Tuesday. The cool change is expected in Melbourne around midnight tonight will a few showers until around sunrise tomorrow. Most of the day should stay dry with just some isolated showers and a cooler maximum of 20 degrees. But the main weather feature will be the westerly winds which are expected to gust up to around 50 kmh. While this won't affect the field, it may send the fashions flying! So while the cooler weather will be a pleasant change for the boys in suits after Derby Day's sweat- fest, here a few tips for ladies on weather-proofing your fashions...
Locks:
Pin those facinators nice and tight and bring a few spare bobby pins to stop them from flying
A bit of extra hairspray won't go astray
And hold onto your hats!
Frocks:
Pencil skirts are not only flattering but you won't need to worry about your skirts flying up in the wind!
Bring a pashmina- 20 degrees will feel even colder with the windchill
If your outfit allows for tights or pantyhose- they will cover any goosebumps
Now that your locks and frocks are sorted, I hope you enjoy Australia's biggest race and back a winner!
Locks:
Pin those facinators nice and tight and bring a few spare bobby pins to stop them from flying
A bit of extra hairspray won't go astray
And hold onto your hats!
Frocks:
Pencil skirts are not only flattering but you won't need to worry about your skirts flying up in the wind!
Bring a pashmina- 20 degrees will feel even colder with the windchill
If your outfit allows for tights or pantyhose- they will cover any goosebumps
Now that your locks and frocks are sorted, I hope you enjoy Australia's biggest race and back a winner!
Adelaide is sweating through hottest night since February!
The temperature in Adelaide hasn't dropped below 26.4 degrees all night, forcing locals to sweat through their hottest night since February! At 6am local time, the temperature was already a steamy 28 degrees and the mercury is expected to rise to 35 degrees today. With 5 days in a row of temperatures 5 degrees above the average, the city has officially experienced a "heatwave." Today will be Adelaide's 6th day in row with temperatures above 30 degrees. But there is relief in sight! A cool, south- westerly change will arrive around lunch-time dropping temperatures by about 10 degrees. Tomorrow's forecast maximum is a much cooler 20 degrees but it will be shortlived. Winds will turn back northerly again with sunshine and temperatures in the 30's once once more delivering great beach weather for the weekend.
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