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Latest weather extremes prepared 1513 EST, Monday, 24 April 2017
State-by-state daily extremes Severe and noteworthy observations today
Hottest Coldest Wettest     Full list Windiest (km/h)     Full list
WA: 37.3 at 1500 WYNDHAM AERO
QLD: 35.6 at 1500 CENTURY MINE
NSW: 8.5 at 1500 THREDBO AWS
VIC: 7.6 at 1500 MOUNT HOTHAM
SA: 14.2 at 1500 MOUNT LOFTY
WA: 14.6 at 1500 ALBANY AIRPORT
NT: 25.6 at 1500 CAPE WESSEL
QLD: 20.0 at 1500 APPLETHORPE
Highest short duration falls:
8.6 in 10min to 1500
3.6 in 30min to 1500
Highest since 9am
29.2 to 1500
24.4 to 1500
38 gusting 50/ N at 1500
37 gusting 50/ENE at 1500
31 gusting 46/NNW at 1500
33 gusting 40/ S at 1500
31 gusting 40/SSE at 1500

Weather, climate
and site news

Reviews of weather events and climate news are normally written within a few days to give time for accurate information to become available, and as I have the time to research and write it. For weather news as it breaks, I've listed reliable, organised sources on AWN's Weather and Climate Media Reports page.

Sunday 23 April 2017

 Yesterday was Earth Day, and around the world scientists were protesting

On Earth Day yesterday, hundreds of thousands of scientists representing hundreds of universities, scientific organisations and disciplines took to the streets in over 600 locations across all continents bar Antarctica. This was an unprecedented outpouring from what are usually a pretty staid lot, who prefer to work quietly within their own specialist communities.

The March for Science occurred against a background of widespread rises in pseudo-science (or "alternative facts"), preferring beliefs over facts, disparagement of expertise, reduction in funding, apathy and, in some cases such as the Trump Administration, outright hostility. Scientists worry not just for the future of science itself but for the future of an increasingly threatened planet and its human population. The March's mission, from its official website is to act as:

"the first step of a global movement to defend the vital role science plays in our health, safety, economies, and governments….The March for Science champions robustly funded and publicly communicated science as a pillar of human freedom and prosperity. We unite as a diverse, nonpartisan group to call for science that upholds the common good and for political leaders and policy makers to enact evidence-based policies in the public interest."

Of the dozens of media articles and blogs I have read about the need for a March, none summarises it better than a short video by eminent American scientist Neil deGrasse Tyson. If you do nothing else today, take four minutes to watch it.

And while on climate

  • In what seems to be becoming a routine, the earth just passed its next round-number milestone. The heat-trapping carbon dioxide level measurement at Hawaii's Mauna Loa Observatory on 18 April exceeded 410 parts per million for the first time, less than two years after it exceeded 400ppm continuously in September 2016. The first time it exceeded 400ppm was in mid-May 2013, but seasonal and other fluctuations mean that it takes time to stabilise.
  • Another article from Climate Central gives a new perspective on the increasing warmth of the planet. The rather nifty infographic shows there hasn't been a month cooler than the 1881-1910 baseline average for 628 months. There hasn't been a cooler than average month for the globe since December 1964.
  • And just as the carbon dioxide level is accelerating upwards, so are temperatures. This NASA graph from Weather Underground shows the monthly temperature anomalies, compared to a 1980-2015 baseline. Notice how the lines for 2016 and 2017 stand well above those for all other years since 1880. 2016 was partly exacerbated by a strong El Niño; 2017 is not.
Saturday 22 April 2017

 More records fall in SA and VIC as rain winds down

Although the widespread rain of the past two days has finished, storms and areas of heavy rain continued in parts of SA, VIC and a small area of southern NSW in the 24 hours to 09.00 this morning. Since then, virtually no rain has fallen.

In SA, a band of rain from near Tarcoola up to near Coober Pedy then across to the Flinders Ranges had more than 25mm in the 24 hours, mostly falling from storms on Friday evening. Commonwealth Hill, 90km NW of Tarcoola, had its wettest April day in a 76-year history with 36.4mm in the gauge, while the 54.0mm recorded at Mount Eba Station, 155km SE of Coober Pedy, was its highest in a history going back to 1914. Mount Eba had already equalled its previous record of 32.0mm yesterday - not a bad effort!

A broader area of rain and storms gave 24-hour totals mostly between 10 and 40mm through central and northeastern VIC into the NSW South West Slopes, with some isolated falls west into the Riverina. The standout was Echuca where the 09.00 daily reading today was 72.0mm, the highest April fall in the station's very long 136-year history which began in 1881.

The BoM tweeted today that up to 09.00 this morning much of western VIC had already received above its April average rainfall, with a large swath through the eastern Mallee into the North Country sitting on more than twice its April average.

Friday 21 April 2017

 Widespread rain in southern SA and western VIC welcomed by croppers

Moderate to heavy, soaking rain moved from southern SA into much of VIC east to Melbourne and the Goulburn Valley overnight giving widespread falls of 20 to over 50mm.

The rain that has occurred in the past two days, and is continuing across central VIC with a little into the NSW Riverina, is well timed to start the winter cropping season across much of SA, western and central VIC and the southwest of NSW. It prepares the way for crops such as wheat, barley and canola and will also provide good subsoil moisture for grazing country on the fringes of crop areas.

It resulted from a moist infeed of tropical air from the Indian Ocean in a northwest rainband meeting an upper trough and cold pool that moved up from the southern ocean. The instability as these elements aligned overnight caused many thunderstorms and heavy falls in the Wimmera, Mallee and far SW NSW during the 24 hours to 09.00 this morning. Locations in all three states have reported twice or more their monthly average rain for April. There were about 20 record one-day falls for April across the three states including three rainfall stations, all in the Wimmera, with histories of over a century. The standout was Woomelang, 75km SSE of Ouyen, which registered 103.2mm, its highest for April since it opened in 1900.

The Wimmera Mail-Times* has a good article on the event from the farmers' standpoint, while the photos, videos and tweets in the Bendigo Advertiser* give a feel for the day and its impact on activities.

 IRI longer-term forecasts for rain and temperature in line with BoM

The latest forecasts from the International Research Institute for Climate and Society at Columbia University are in broad agreement with the BoM seasonal forecasts for coming months. In addition its predictions for El Niño, La Niña, and the Southern Oscillation (ENSO) development are in agreement. A background to IRI's climate work is given here.

IRI rainfall and temperature probability forecasts are based on multiple models and given for four three-month periods in advance, so the April issue is for May-June-July (MJJ), June-July-August (JJA), JAS and ASO. Looking broadly at Australia's precipitation, they see a 40 to 50% probability of below normal rainfall in the May to July quarter across most of eastern Australia and the SW half of WA, gradually intensifying to 45 to 60% chance of below normal rain by the August to October quarter across the whole northeastern half of the continent. In WA, only the far SW corner has such a high chance of below normal rain. The remainder of Australia is close to or a little above normal.

Temperatures are compared against those for the period 1982 to 2010, so given that global warming has gradually increased figures since then it is not surprising that most areas in the world show "above normal" temperatures as we adjust to the new normal. For Australia, IRI's mean temperature expectations are not as dramatic for the MJJ quarter as those of the Bureau, but do gradually expand in area and increase slightly in intensity through to the ASO quarter.

IRI's 4x3-month forecasts are issued soon after the 20th of each month and simple full-globe versions are here. A greater variety of more detailed maps can be accessed here, where you can also select just a map of Australia and play with how you want the probabilities displayed in many different and useful ways.

IRI uses an impressive set of global climate models to show its estimates of likely ENSO chances, including the POAMA model used by the BoM. Graphs and tables show each model individually so you can see the degree of agreement and the general trend, and you click on any of the graphs for larger versions accompanied by more specific information. The trend of almost all models is for ENSO to continue neutral at first, then move towards En Niño in our Winter and Spring.

Thursday 20 April 2017

 Main climate drivers suggest little change for northern Australia - for now

The two drivers of climate in Australia's north - the Madden Julian Oscillation (MJO) and El Niño - continue to have little effect on the country, though in the case of El Niño that could change later in the year.

The BoM's Weekly Tropical Climate Note* for 18 April says the MJO, after a period when it was hard to discern anywhere, has emerged in the western hemisphere. Models say it will stay fairly stationary, and are undecided on any future movement it may take. The norm when the MJO is absent like this is that convection is reduced over northern Australia and rainfall, particularly in NE Australia, is reduced. The current MJO situation with a clear explanation of how it works is here.

The El Niño-Southern Oscillation (ENSO) remains neutral, although sea surface temperatures remain above average in the eastern Pacific where they have been bringing disastrous rain and flooding to Peru and Colombia. They are still forecast to increase in the second half of 2017 bringing a likelihood they will cross into El Niño territory, though this still has the caveat that models have a lower accuracy at this time of year.

 Heavy rain in NT, SA and VIC from northwest rain band

Rain, with thunderstorms and some heavy falls, has been moving across SA and entered VIC today after giving parts of southwestern NT a soaking yesterday and early this morning.

Thunderstorms gave two of the sparse weather stations in NT's southwest some torrential rain yesterday evening, with Yulara Airport near Uluru catching 18mm in 14 minutes to 19.00 in an event total of 34.6mm. Wulungurru (Kintore) to its NW had a steadier drenching with 69.2mm falling in the 24 hours to 09.00 this morning, its heaviest April one-day total in a 14-year history.

The rain moved into southwestern SA late yesterday afternoon and extended east to arrive around Adelaide this morning. It gave patchy falls but many places received 10 to 30mm. Roseworthy, 45km N of Adelaide, had the top fall of 62.6mm for the event to 19.00 this evening, 30mm of that falling in in one downpour that lasted 45 minutes. As the day progressed, the rain moved into western VIC, with many stations recording between 10 and 35mm of rain to 10pm, though Walpeup, 100km S of Mildura had 48mm in the gauge.

Ahead of the rain, temperatures were way above normal in the NW airstream over TAS in a run of warm days. Cape Sorell on the West Coast set a new April record of 23.5° in a 20-year history. Weatherzone* points out that the 25.4° maximum at Launceston City was its highest for this late in the season since records began in 1980, and many other locations around the state had tops in the mid-twenties.

Wednesday 19 April 2017

 Some capital city rainfall radars get a rebuild

The main rainfall radars serving Adelaide, Melbourne, Sydney and Brisbane are to be upgraded. The main purpose of the upgrades is to give mid-life servicing which will extend their operation by another ten years, but in some cases they will gain new facilities that will help forecasters.

The first to get the treatment is Adelaide's Buckland Park radar which went offline on 11 April and is expected back in service in late May. In addition to normal servicing, it will have a vertical beam added to the normal horizontal beam which allows for the shape of precipitation to be detected, so it can distinguish for example between rain and hail. A Bureau video explaining the upgrade is available here. While Buckland Park is out of service, Adelaide's second radar at Sellicks Hill will take over duties.

Melbourne's Laverton radar, Sydney's Terrey Hills radar and the Brisbane Mt Stapylton installation will follow later, with the tentative dates of 2 August to 8 September for Melbourne and Brisbane and 24 August to 28 September for Sydney. Alternative radars are yet to be announced.

 April sunshine warms SA, NSW and NT

A combination of northerly winds from the interior and days of generous sunshine have given parts of SA their warmest April day yesterday and warmest night last night for at least a decade. The winds precede a northwest rainband that is moving into the NW half of the state today.

Maximum temperatures yesterday were between 4 and 8° above the April average across eastern SA, southeastern NT and western NSW giving some locations their warmest April day in up to 12 years for this late in the season. Overnight, the abnormally warm temperatures contracted to SA, but were between 4 and 10° above average over much of the state. Adelaide's minimum of 22.6° was 10.2 above average, and the second highest in the state after 22.8° at Marree, while Clare had its warmest night in its 23-year climatic history at 19.4°.

Tuesday 18 April 2017

Australian weather briefs

  • The BoM has produced a detailed but concise summary of TC Debbie's activities in QLD from 27 to 30 March 2017.
  • The village of Rockley, 30km S of Bathurst NSW, had a massive but very isolated thunderstorm on Thursday 6 April between about 15.30 and 16.30. Unfortunately, the BoM Hydro raingauge there was not working, but the hotel's publican measured 84mm in 45 minutes and this was verified by the Bureau's official 24-hour reading at the nearby Post Office at 09.00 next morning of 85mm. Substantial small hail fell with the storm. Other gauges in the area recorded little or nothing though radar showed it was a very small and intense slow-moving storm.
  • There's been no problem organising a picnic in Broken Hill NSW for a few months with no rain falling over the past 84 days. The long run of fine days may be ended on Thursday when a northwest rain band is forecast to arrive in the area.

 Cyclone Cook explained ... and forecast criticised

As anticipated in yesterday's AWN News, criticism has emerged of MetService's somewhat off-the-mark forecast for Cyclone Cook late last week. This, from Radio New Zealand, is an example. MetService, in its blog, has produced a detailed, and very interesting, response showing how the event unfolded and where the error occurred. If nothing else, it is a timely reminder that our knowledge of the weather is still not perfect and therefore our forecasts can't be, either.

Recent weather briefs - NORTH AMERICA

  • The United States has set a new and unenviable record with more than 100 tornadoes reported in each of the first four months of 2017, according to WeatherNation. 536 twisters have touched down so far this year, though there are two caveats to the claimed record. Firstly, with more storm chasers hunting down tornadoes equipped with better technology, radar, and satellite imagery than ever before, the chances of them being seen and documented are better than any time in history. Secondly, the early months of the year, especially January and February, are usually quiet for tornadoes which start to ramp up during April. Over half of them occur in May and June, so if those months are quiet this year, the early record could quickly evaporate. Accuweather has some thoughts on why it's been such an active season so far.
  • While on tornadoes, a supercell thunderstorm last Friday 14 April lasted for nine hours as it pushed through the Texas panhandle, spawning hail larger than baseball size then tornadoes according to Weather Underground. The largest of these, near Dimmitt TX, was on the ground for over 20 minutes with a path over 7km in length and a maximum width of 1.8km. Radar imagery of the storm is here. While there were few buildings in the rural area to help classify the strength of the tornado, it was given an EF3 (Enhanced Fujitsa Scale) rating, based on the fact it destroyed and moved a metal building over 100m, giving a wind speed as high as 225km/h. While the tornado missed Dim mitt (pop. 4,000), it damaged several houses and cars, and completely destroyed one home while the family sheltered in the basement.
  • While floods swept through southern and central Texas [Floodlist], Florida declared a state of emergency as over 100 bushfires burned the state, the worst situation in six years and focused on the south. 42% of the state is in moderate drought and 13% in a severe drought, a bad situation as it moves into the hotter, drier months of summer [WeatherNation].
  • Much of California's five-year drought is at an end following a summer/autumn of repeated flooding rain and deep mountain snow. The northern Sierra has had its snowiest/wettest July to June period on record - with over two months still left to go [Bob Henson, Category 6]. As of yesterday, 17 April, the Northern Sierra Index, an average of eight measurements of snowpack depth along the range converted to water content, sat at 2,309mm, the highest on record since the index began in the 1923-24 water year (July to June), and 208% of the average as at 17 April. The heavy snows have produced some spectacular figures for skiers at resorts, with many reporting accumulated snow depths over 700 inches (17.78m) and Sugar Bowl Resort measuring 777 inches (19.736m) [Weather Underground]. Some wind gust figures have been eye-popping, too, as the jet streams as least partly responsible for the prolific snow have descended to mountain peak weather stations: Ward Mountain recorded 320km/h on 20 February 2017 [Bob Henson and Jeff Masters, Weather Underground].

Older items are archived and indexed in the Daily Weather Summary for the relevant date.


* I link to stories and resources frequently - why re-do what has already been well done? However, a regular problem with the Internet is "link rot". There are two main causes: either the link has ceased to exist, in which case you get the dreaded "Error 404 page not found" or the link exists but the information on it has changed. Where possible, I use "permalinks", URLs which I know are likely not to change in the foreseeable future because the organisation, such as the ABC, has developed a stable link structure. Where I think a link may suffer link rot, I mark it with an asterisk but be aware that there's no guarantee unasterisked links won't evaporate given time.

Unless otherwise indicated, data and charts are provided by the

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