Reviews of weather events and climate news are normally written some days after the fact to give time for accurate information to become available, and as I have the time to research and write it. If you're looking for weather news as it breaks, I've listed reliable, organised sources on AWN's Weather and Climate Media Reports page.
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Ex-Hurricane Ophelia brings wild weather to British Isles
Late Monday evening, Australian Eastern Daylight Time, the remains of Hurricane Ophelia is scraping across the SW tip of Ireland. The eye of the ex-hurricane passed over Valentia Observatory, just inland from tip, at 11.00 UTC (22.00 AEDT) with a pressure of 959hPa, Fastnet Rock farther south reported a wind gust of 191km/h and Roches Point near Cork has recorded gusts to 156km/h. Major damage, blackouts and one death have been reported so far in southern Ireland before the high winds extend to the rest of the country in the next few hours.
Ophelia was a Category 3 (i.e. a Major Hurricane) on the Saffir-Simpson scale until earlier this morning AEDT, but has now become extra-tropical. No other hurricane since records began in 1851 has reached major status this far east in the North Atlantic. While the centre of the hurricane will initially keep just west of the Irish coast, the belt of strongest winds on its eastern flank, averaging over 100km/h, gusting to 150/160 and above in exposed locations, is now hitting the western part of the south coast of Ireland.
The ex-hurricane is forecast to move rapidly up the W coast of Ireland then turn NE across Northern Ireland and the north of Scotland while weakening. As it does, the band of hurricane-force winds will move east along the Irish south coast, then up into the Irish Sea, with Dublin and the east coast of Ireland as well as parts of Wales and SW England expected to cop a thrashing.
Most keenly watched for now is the very possible development of a sting jet. The reason it is called a "sting" jet is brilliantly descriptive. This remarkable and dangerous phenomenon (go here for simple, intermediate or detailed explanations) only became widely accepted after the great storm in southern Britain in 1987 which brought down an estimated 15 million trees, many centuries old, and caused 22 deaths and widespread damage. It marked one of the UK Met Office's most celebrated cock-ups when its hapless BBC presenter, Michael Fish, in response to widespread concern, forecast that there would be no hurricane tonight [video]. Both the UK Met Office and Irish Met Service are on notice! Those two links currently carry extensive warnings*.
For those that want to watch developments this evening and tonight, good sites include the Met Office and Met Service above, the live reporting in the UK edition of The Guardian*, the Irish Met Service's Twitter feed*, independent.ie's Twitter feed* and the Severe Weather Europe Facebook page*. Weather observations updated every 10 minutes are well presented at the French Meteociel* - this link bring a general intro page; click, say, wind gusts on the menu at left, and when that comes up click UK at the top. For local high resolution models, the ARPEGE one at WXCHARTS* is good - this link opens on the forecast wind gust speeds for the British Isles. Check the time the model was run top right of the image then use the controls bottom left, or scrub the time bar at bottom, to move through the forecasts.
Normal media of course will carry reports, moreso if the going gets rough. I will give a summary tomorrow.
BoM's updated outlook: normal rain, but warm in SE, far north
The BoM's recently introduced mid-month update to its monthly Climate Outlook is forecasting around average rainfall over much of the country from November to January, apart from somewhat wetter conditions in the far SE of the continent.
It's likely to be warmer than average, both by day and overnight, in the SE of the country and across the tropical north, and there's a very high chance that both maxima and minima will be well above average in TAS.
The full updated outlook, including a breakdown into forecasts for November, December as well as the 3-month period, is available here* (archive here).
More heavy rain in SE QLD and NE NSW
Moderate to heavy rain fell from Noosa QLD south to the NSW North Coast between 09.00 Saturday and Sunday evening with isolated very heavy falls.
A moist onshore stream was helped by a surface trough and cooler upper air to produce unsettled weather and patchy instability. In addition, the steep mountains around the Tweed Valley kicked in some additional lift that produced the heaviest fall in the 24 hours to 09.00 today, a staggering 284.0mm at Lillian Rock, 10km NW of Nimbin. This set a new October record for Lillian Rock, where rain has been measured since 1963, almost doubling its previous record of 151.4mm set in 1972. Other records are in the records section.
Elsewhere along the coastal strip and nearby mountains, about 60% of gauges on the BoM's Hydro network recorded 50 to 100mm in the 24 hours ended 09.00, with occasional falls over 100mm. In QLD, the heaviest were around Maroochydore where 170mm at Delaney's Creek Alert, SW the city was the highest, and there were several totals to 120mm just north of the city. In NSW, in addition to the remarkable fall at Lillian Rock there were several other totals just above 100mm in the area, while farther south Rappville (Myrtle Creek), between Lismore and Grafton, recorded 175mm and Gulmarrad, near Maclean, 120mm. There was a continuation of rain reported yesterday [AWN] in the Coffs Harbour area.
Between 09.00 and midnight in QLD, rain continued in much the same pattern with 50 to 100mm recorded at about 40% of the BoM's Hydro gauges. Upper Springbrook, behind the Gold Coast, was highest with 157mm. In NSW, the heavy falls contracted to the Tweed Valley where the heaviest were predictably in the mountains north of Mount Warning; Numinbah's 86mm was the highest. Dorrigo, farther down the coast, also recorded 86mm.
Storms bring heavy rain to central and SE QLD: There were some heavy falls of rain from a broad storm area that moved through the Central Highlands, Darling Downs and Wide Bay areas in QLD yesterday. Capella, 50km NNW of Emerald, recorded a 24-hour total of 133.0mm to 09.00 this morning, significantly beating its previous October record of 116.3 in a virtually unbroken set of readings that began in October 1898. There was a scattering of other totals over 100mm, and many falls over 50mm. Other new records set are given here.
The storms developed in a surface trough that lay from northern and central parts of the state to the southeast, dragging moisture in from the Coral Sea.
Long-standing rain records broken in WA: Thunderstorms in the Central Wheatbelt of WA broke October records there too, in some cases nearly doubling them. What is more significant is that this happened at three stations with histories going back between over 50 and over 100 years. Spring Valley recorded 51.0mm, well over its previous record in 53 years of 28.0mm; Bungulla's 45.0mm beat the old record of 27.9 in 86 years and Tammin, where rain records have been kept for over 103 years, recorded 47.4mm, 17.4 over its previous heaviest October 24-hour fall.
Torrential rain on NSW Mid North Coast: There was very heavy rain for a few hours on the Mid North Coast this morning and early afternoon. Several troughs and a nearly stationary weak front produced slow-moving lines of converging moist air between Taree and Coffs Harbour, producing thunderstorms offshore, but bringing torrential rain to parts of the coast and nearby mountains.
The heaviest rain fell in the Coffs Harbour area, starting just before dawn and continuing into the early afternoon, with the highest falls of 150 to 200mm in the hills around the city. The BoM Hydro gauge at Loaders Lane, 2km WNW of the CBD, recorded 188mm between 04.00 and 14.00, much of that falling in torrential bursts such as 68mm between 04.00 and 06.00 and 78mm between 11.00 and 13.00. The small creeks around the city rose rapidly, in some cases by 3 to 4 metres in less than half an hour.
Farther down the coast, many places recorded between 50 and over 100mm, often falling in a few hours. Some of the heavier falls were Nambucca Heads 92.0mm (to 09.00); Crystal Creek in the Bellinger River valley 62mm between 11.00 and 12.00 for an event total of 113mm; and Wittitrin, 20km WSW of Kempsey, 82mm between 04.00 and 09.00.
BoM Drought Statement shows impact of low September rainfall: As many in eastern Australia know, rainfall in September was a long way short of normal during September. In the Murray-Darling Basin it was the lowest on record for the month. Coming after a very dry winter, it has resulted in serious to severe rainfall deficiencies in most of NSW and large areas of QLD and SA as well as smaller pockets in other states. Lower-layer soil moisture is now below average across most of NSW, QLD, VIC and SA. Full details are in the Drought Statement issued yesterday.
Bureau documents extraordinary heat late last month : Between 22 and 29 September, eastern Australia experienced two pulses of heat that were exceptional for the first month of Spring. Over 20% of the country set new September high maximum temperature records during these eight days, with new state records being set for VIC at Mildura (37.7° on the 23rd), NSW at Wanaaring (41.4°, 27th) and QLD at Birdsville (42.8°, 27th). Australia as a whole had its hottest day on record on the 22nd, while in NSW the average maximum temperature statewide was nearly 15° above average on the 23rd, a record departure from normal.
A very detailed account of the event, including its causes, is in the Special Climate Statement, Exceptional September heat in eastern Australia (pdf), issued by the BoM today. The ABC, Guardian and Sydney Morning Herald [partial paywall] all produced stories with their own slants on the report, as well as interviews with BoM climatologists, though you can't go past reading the Statement itself.
|Thursday 28 September 2017
BoM Climate Outlook for October to December: fair to middling
The Bureau of Meteorology's outlook for the next three months*, issued today, shows fairly even chances of wetter or drier than median (or normal) weather across the country, while there's a strong indication it'll be warmer than normal across northern Australia, the far southeast and in TAS. The brief archive edition is here.
However, within the rather nondescript probabilities for rain there are some clear variations. In eastern Australia, although the El Niño–Southern Oscillation (ENSO) is neutral, continued cooling in the tropical Pacific Ocean is causing it to trend towards La Niña conditions which typically bring wetter conditions in the east. The BoM's interpretation is that this will result in a 55 to 65% chance of a wetter than normal October to December in southern QLD and most of NSW. However, this is largely caused by a very high probability of well above normal rain in October.
Much of the rest of the country shows an even chance of receiving its normal rainfall over the three months. This is due to patterns in the Indian Ocean which are likely to draw moisture away from Australia. As the Bureau puts it, "These influences from the Indian and Pacific oceans are likely to be competing, with a slightly drying influence in the Indian Ocean likely to be cancelling out a slightly wetter influence from the Pacific Ocean." The exception to this normality is the northern Kimberley which has a 60 to 70% chance of wetter than normal weather.
Both maximum and minimum temperatures show a broad tongue of cooler air extending from the Great Australian Bight to the NSW coast for the October to December period as well as the individual months of October and November. Outside this tongue - across northern Australia, on the southeastern mainland and all TAS - the chances are high that temperatures will be above normal. In TAS, they're expected to be well above normal. Inside the tongue, there's an equal likelihood of above or below average temps (or, to put it less precisely than the Bureau does, the chances are they'll be about normal). The exception is October when temperatures in the tongue are likely to be significantly below normal. That would be a change those in this area would welcome after the heat of the past couple of weeks.
The Bureau produces an excellent summary video to go with the Climate Outlook. It includes a water outlook in addition to the climate outlook. In addition, the Rural Bank provide this more detailed set of videos, broken down state by state. Use the menu at the right to select your state.
|Tuesday 26 September 2017
The heatwaves keep coming
The September heatwave that brought record-setting temperatures to most of VIC, NSW and southern QLD between last Saturday 23 and Monday 25 September will be described in more detail here in the next few days.
It was a remarkable event, setting new state September maximum temperature records for both VIC and NSW. Even more remarkable was the extent of the heat. You can see in this map showing departures from normal maximum temperatures that the BoM ran out of colours on the temperature scale to show just how abnormal the heat was. The scale finishes at 12°, but the greatest departure from normal for the day was a massive 19.9° above average at Point Hicks Lighthouse in eastern VIC.
The next two days this week, Wednesday and Thursday, look set to break even more September heat records, though across a smaller area of northern NSW and southern QLD. Some of these are likely to be new records set just last weekend, including possibly another new state record for NSW and a new September national record in QLD. [ABC]
The temperatures to watch for? The current NSW state record for September is 40.5° set at Wilcannia Airport last Saturday, 23 September, and the QLD state record is 42.4 set at Birdsville on 22 September 2003. The current national September record is 43.1 set at West Roebuck WA on 27 September 2003. In NSW tomorrow, Wednesday, 41° is the forecast maximum for Tibooburra, Bourke, Brewarrina and Walgett. In QLD tomorrow, 43° is the top temp forecast for Birdsville with 42 forecast for all locations in the state's southwest. That heat moves east to the coast on Thursday where records in the Brisbane area, many set last Sunday, are under threat.
I won't even mention record hot nights...
Pacific temps cooling, but not quite enough for La Niña
The BoM's ENSO Wrap-Up, issued today, says that although both sea surface and sub-surface temperatures have cooled in the central and eastern Pacific, and are expected to continue to do so, it will not be enough "to be classified as a La Niña event."
The Indian Ocean Dipole continues neutral, though there is a hint that it will become positive this season. If there is a late season positive IOD, it will be short-lived, as positive IOD events typically decay by December.
The full ENSO Wrap-Up can be found here.
Heavy rain across SW WA
Wet weather returned to southwestern WA with the fronts and troughs that crossed the state from last Tuesday to Saturday. They were brought by a succession of lows that passed close to the south coast, bringing wild weather, storms and high wind gusts as well as torrential rain as the fronts moved through.
Early Thursday afternoon a severe thunderstorm gave Albany Airport a wind gust of 139km/h while, for a time on Friday, almost all southern parts of the state were under Severe Weather Warnings. Everywhere west of a line from Jurien Bay to Wagin to Albany recorded at least 25mm during the week to 24 September with falls over 100mm in the mountains NE of Bunbury where Mount William registered 129mm over three days.
The heaviest rain fell overnight into Thursday 21 September to the south of Perth. The area between Mandurah and Bunbury saw the heaviest of it, with the BoM tweeting a warning of possible flash flooding. Wokalup, 65km S of Mandurah, had its heaviest September day's total in over 60 years of records with 53.0mm in the 24 hours to 09.00 on Thursday 21 September. In the mountains to its NE, Mount William scored 88.4mm and Dwellingup 42.0mm. Good falls spilt over the ranges into western parts of the wheatbelt giving Williams 35.2mm.
On Friday morning, 22 September, with the passage of an active frontal system, wind gusted to 100km/h at Ocean Reef in Perth's northern beachside suburbs, 96km/h on Rottnest Island, 93km/h at Cape Naturaliste and 91km/h at Busselton Jetty. In the early afternoon, Bickley saw a gust of 96km/h and Gooseberry Hill 111km/h in Perth's outer east, while Ocean Reef recorded 104km/h.
Heavy rain continued in the 24 hours to 09.00 Friday 22 September with the heaviest totals a little farther south around Collie, where Worsley Downs topscored with 58.0mm. By later Friday into Saturday, rain had moderated and moved to the South Coast as another low system moved past close to shore. In the 24 hours to 09.00 on Saturday Albany had the highest rainfall with 33.4mm followed by 24.4 at Northcliffe and 23.0 at North Walpole.
|Wednesday 20 September 2017
Australian weather briefs
- Heavy rain on the QLD Far North Coast eased off late yesterday as the trough bringing wet weather moved away to the east. The heaviest total in the 24 hours to 09.00 today was 97.0mm at Cowley Beach between Innisfail and Tully. Between 100 and 225mm was recorded in many gauges between Babinda and Tully over two days in an early start to the wet season in northern coastal QLD.
- Late dry season heat is building in northern WA with the first temperatures nationally above 40° recorded in the East Pilbara and West Kimberley today. Roebourne reported a top of 41° while West Roebuck and Port Hedland reached 40°.
- Ben Domensino notes on Weatherzone that the 0.2mm of rain that has fallen at Sydney Observatory Hill so far this month has given the city the driest start to spring since records began there in 1858. Other locations around the Sydney metro aren't faring much better. Eastern suburbs have picked up the odd coastal shower, giving Dover Heights 4.6mm and Rose Bay 5.2 while in the western suburbs very isolated showers have given Abbotsbury (Fairfield) 9.0mm and Shanes Park 13.6. No other gauges have recorded more than 1.8mm with most completely dry for the month so far.
|Tuesday 19 September 2017
Heavy rain sets records at top and bottom of the country
Unseasonally heavy rain has given some heavy totals on the QLD Far North Coast and eastern Atherton Tablelands in the 24 hours to 09.00 today and has continued through the day. The heaviest falls have been between Babinda and Tully with many gauges reporting totals between and 100 and 225mm over the 36 hours to 21.00 this evening.
The rain is being caused by a stationary or slow-moving upper trough providing instability to moisture-laden onshore winds. Babinda recorded 143mm in the 24 hours to 09.00 today, comfortably above its September monthly average of 122.4 but a long way off its record daily fall for September of 174.2 back in 1953. The nearby Clyde Road Flood Alert gauge recorded 170mm to 09.00 and has seen a further 54mm to 21.00. Babinda has been recording rain for 107 years, but many of the gauges in the area with shorter histories set new September records today.
At the bottom end of the country, as far south as you can go before you get to Antarctica, lonely Macquarie Island also set a new September rainfall record with 31.0mm. Rain has been recorded at Macquarie since 1948. This heavy fall was the result of a moist NW airstream moving down over the island ahead of a succession of fronts.
History repeats as Dominica receives direct hit from Hurricane Maria
Hurricane Maria, which intensified rapidly overnight to a category 5 on the Saffir-Simpson scale, made a direct hit on the small eastern Caribbean island of Dominica at about 13.00EST today. Dr Jeff Masters, in Category 6 on Weather Underground, reports that a US Air Force hurricane hunter aircraft reported surface winds of 257km/h and a pressure of 924hPa at landfall.
Conditions on the island of 72,000 are not yet known, but are likely to be better than those endured on the island of Barbuda after it was hit by the stronger Hurricane Irma just under two weeks ago. Barbuda is three islands north of Dominica in the arc of the Leeward and Windward Islands at the eastern end of the Caribbean Sea, north of Venezuela. All 1,800 residents of Barbuda have been relocated to Antigua, the nation of Antigua and Barbuda's larger island, as Barbuda has been left effectively uninhabitable [The Weather Network].
Hurricane Irma is expected to pass over or close to the Virgin Islands and Puerto Rico on Wednesday and Thursday Australian Eastern Standard Time (EST), then close to the north coast of the Dominican Republic before curving into the Atlantic Ocean east of the United States.
The best information on the current status and forecast movement of the hurricane comes from the National Hurricane Center of NOAA. Be sure you're on the Atlantic tab then click the red hurricane symbol. This brings you to many graphics, but the detail is in the text report links above the graphic thumbnails. Public Adv[isory] links to a summary of the current status of the hurricane and all warnings and watches which is followed by a straightforward description of the current situation and forecast. The Discussion link takes you to the forecaster's own report on the situation, including details of recent hurricane hunter aircraft penetrations and more detailed analysis of the situation.
If you want to know more about how the widely-used Saffir-Simpson scale compares to the Australian BoM scale of tropical cyclone intensity, Wikipedia has this useful article.