Sun 23 Sep 2018 Snow season second best in 14 years. Barring an unlikely late-season dump, the greatest depth of snow this winter measured by the Snowy Hydro at Spencer Creek, between Perisher Valley and Charlotte Pass, was 224.6cm on 22 August. in the past 14 seasons, only last year has seen a greater depth when a half-metre September snowfall gave an unusually late peak of 240.9cm on 20 September. The average greatest depth over the seasons from 1954 to 2017 is 197cm while the median is 186cm. Snowy Hydro measures the snow course every Thursday, and updates its full set of graphs promptly - rest your cursor on the trace for each weekly reading.

Sun 16 Sep 2018 A weekend of wild weather for southern states. The weekend of 15/16 September produced a smorgasborg of serious weather with, or in the wake of, a strong cold front that moved across the south of the continent from Friday. In the cold, dry air behind the front in WA, Saturday morning set new minimum temperature records for September (and in the cases of Ongerup and Newdegate for any month) bringing severe frosts in the South West that significantly damaged crops.

In SA and VIC, Sunday brought the coldest morning this late in the year for many years or decades as examined by Brett Dutschke on WeatherZone. Further cold records fell, as did 24-hour wind records in NSW where dust was raised in the state's west. Both Saturday and Sunday saw temperatures well above normal ahead of the front and well below normal behind, as well as some high wind gusts on the Saturday as it passed through SA and the southeastern states. The Guardian noted that the Snowy Mountains Highway on Sunday had the dubious distinction of being closed at one end by bushfire while nearly shut down at the other end by snow.

 Bushfires rage in WA, NT, QLD and NSW
Thu 20 Sep 2018

The Australian northern fire season runs from April to November, while the southern fire season runs from October or November (sometimes earlier) to April. We're now in the overlap season, where fires can be burning anywhere in Australia; in fact, all states and territories except the ACT have had bushfires during the past 48 hours.

Fires have been burning the full length of the coast and nearby ranges in New South Wales over the past week, exacerbated by warm, dry, windy weather ahead of several fronts. The largest is the Yankees Gap Road fire 25km NW of Bega. It has been burning for a month in the South East Forest National Park near Bemboka and as of mid-afternoon today had burnt through 19,118 hectares (191 sq km). The fire was at emergency level on Sat 15^th, closing the Snowy Mountains Highway overnight into the 16^th.

In Queensland, fires have also been burning the length of the coast from Brisbane to Cooktown. Two reached Prepare to Leave level today. ABC News reported that QLD Fire and Emergency Services have attended over 2,500 bushfires since the beginning of August. With drought conditions across large parts of QLD, fire authorities say there will be more instances of "subterranean fires", where a possibly small surface fire smoulders in a tree trunk then burns slowly through its root system. These fires are hard to find, hard to put out, and are likely to pop out days or weeks later and start another fire.

There have been dramatic fires on long fronts in Western Australia, such as this one (and here) south of Broome which briefly closed the Great Northern Highway on Tue 18^th. Fires continue to burn in the Kimberley, Pilbara, Interior and the state's South West.

In the Northern Territory, as in large parts of QLD and northern WA, it is the dry season, and enormous scrub fires are part of life. About half the land between Darwin and East Arnhem Land burns every year, Joshua Fischer from Bushfires NT tells ABC Darwin in this detailed article on the north's dry-season fires. There have been total fire bans from Darwin south to Litchfield and sometimes SE to the Gulf of Carpentaria each day this week except Wednesday.

 Bushfire links to bookmark
Thu 20 Sep 2018

Here are a national set of bushfire warning and information sites. They are permanently available in the links section of AWN, along with links on bushfire management and histories of major bushfires under Severe Weather > Bushfires.

Latest official bushfire warnings and information are available here: ACT | NSW | VIC | TAS | SA | WA | NT | QLD.

My Fire Watch is an Australia-wide map showing current fires, past burnt areas and recent lightning strikes. It, and its summary of national fire alerts, is not intended to replace the detailed and timely warnings from state authorities, but gives a useful national overview. It is the result of research collaboration between Landgate (the Western Australian Land Information Authority) and Edith Cowan University.

Another good resource is NAFI, the North Australia and Rangelands Fire Information website. It provides detailed maps of recent and past fire scars as well as current and recent hot spots in QLD, NT, and most of WA and SA. It has many excellent tools derived from satellite technology.

1845AEST Mangkhut crosses Luzon and heads for China. Category 5 Super Typhoon Mangkhut crossed the far NE coast of Luzon in Cagayan province at 0400 AEST, 0200 Philippines time, this morning with winds at landfall averaging 260km/h with gusts to 320km/h according to JTWC estimates. The typhoon crossed the island remaining inland and parallel to the north coast before entering the South China Sea about 8 hours later. This satellite animation from Andrew Miskelly shows Mangkhut from 2100AEST Wednesday 12^th, maintaining a near-perfectly circular eye right up to landfall after which the eye rapidly filled and the deep convection surrounding it began to seriously degrade as the typhoon crossed the island.

Initial press reports (Reuters, AFP) gave some information, though focussed on backgrounders due to a lack of hard detail because of communications loss with areas closest to the typhoon. A government official in Tuguegarao, the capital of Cagayan, told Reuters "Almost all of the buildings here have been damaged, the roofs were blown away. There has been no electricity supply ... communications [are] also down. We’ve received reports that many trees were uprooted and electric posts toppled and are blocking the roads. This makes the clearing operations really difficult." It will be some time before a detailed picture of damage emerges.

The darkness of approaching night is advancing from the right in this visible image of Category 5 Super Typhoon Mangkhut at 1720AEST Friday 14th. The northern Philippines island of Luzon, on which Manila is located bottom left, will see the arrival of Mangkhut around sunrise on Saturday, when it crosses the NE coast before moving west and parallel to the north coast through the day. JMA Himawari 8 processed by Weatherzone.

2350AEST Super Typhoon Mangkhut close to landfall. While US media presence has seen Florence grabbing most of the headlines, Typhoon Mangkhut is by far the more powerful and dangerous cyclone, and will be landing on the eastern shores of Luzon, the main northern island of the Philippines, early Saturday 15^th morning AEST. The image at left shows the sun setting on Friday on the huge eye of the cyclone, which I estimate as 65km in diameter, as it churns relentlessly towards the northern tip of Luzon. The Philippine capital, Manila, is in the bottom left of the image.

This morning, NASA posted this visible light image of Mangkhut at sunrise, while this infrared image of the typhoon, showing its progress in the 8 hours up to sunrise, clearly shows its dramatic and perfectly-formed eye.

Major press today have covered preparations in the Philippines and the arrival of cyclonic weather. Among the stories are these from AFP, Reuters and Al Jazeera. Apart from winds gusting to 250km/h and torrential rain, a storm surge "that could reach four storeys high" is expected in places, a spokesman for local civil defence authorities, Michael Conag, told AFP. He added this combination "could destroy houses, especially the makeshift houses. Those are the ones most common in coastal areas."

Press estimates of the number of people at risk vary wildly, from 4 million in Fairfax Media to 10 million, sourced to "authorities", in Al Jazeera. The Global Disaster Alert and Coordination System (GDACS) puts the exposed population* at a much higher 58.6 million, but that includes all countries touched by the typhoon.

Hurricane Florence at 2302AEST Friday 14th , about two hours after it made landfall just east of Wilmington, North Carolina. It is tracking WSW, parallel to the coast before turning to the W. Movement is expected to continue very slowly, before it turns N. NWS

2330AEST Florence makes landfall. Hurricane Florence made landfall at 2115AEST Friday (0715 Friday local time) at Wrightsville Beach, a suburb of Wilmington, North Carolina. Wilmington's population is 120,000. The barometer fell to 958hPa at Wrightsville Beach as the Category 1 hurricane passed. Reuters noted this in this 2300AEST article, saying that the National Hurricane Center (NHC) indicated sustained winds near the centre were 150km/h. 440,000 properties were without power.

NWS cautions that, despite its low category rating, Florence's sheer size and slow movement will produce "feet of rain with inland flooding and up to 13 feet of storm surge". As of now, National Weather Service (NWS) radar estimates that 100 to 300mm of rain had fallen so far in coastal areas from the South Carolina border north to Cape Hatteras. Bands of heavy rain are pushing inland and have now reached about 200km towards the Appalachian Mountains in the west of the state.

1600AEST Hurricane Florence close to landfall. A weakened yet still dangerous Hurricane Florence is edging very close to landfall on the southern North Carolina coast just north of Wilmington, as shown by the Newport/Moorehead radar. On the same radar, if you choose Storm Total, under Rainfall, you will see that radar-derived rainfall totals have already hit 4 to 6 inches (100 to 150mm) along the coast NE from Wilmington to Cape Hatteras, with over 10 inches (250mm) in places. The rain is pushing steadily inland toward the Appalachian Mountains to the NW. For a broader view, use the loop under Long Range Images.

2000AEST Super Typhoon Mangkhut remains Category 5 as it approaches the Philippines. Mangkhut appears to have peaked around 0700AEST this morning 13^th with sustained winds (one-minute average) estimated at 290km/h and gusts to 350km/h. It was over open water at that time, and is expected to reduce intensity to Category 4 when it hits the northern end of Luzon, Philippines, during Saturday morning AEST. Sustained wind shortly before landfall is forecast to be 250km/h with gusts to 300km/h. Interaction with Luzon will reduce wind speeds to 205 with gusts to 250 by late morning as the typhoon is passing over the island, dropping it to Category 3.

The UK Met Office posted this animation of Mangkhut, known in the Philippines as Ompong, about 3 hours ago and this image showing where it is headed just now. Again, the size of the typhoon will cause widespread harm as it is 700 to 900km across. The Red Cross (IFRC) posted this Information Bulletin on the situation and the preparations it is making yesterday. There are good summaries of the situation on ABC News and in The Guardian.

1900AEST Dramatic imagery from NOAA of Florence. NOAA's latest Loop of The Day features this dramatic animation of Hurricane Florence's advance on the US east coast yesterday morning 12^th local time. The scale of the hurricane compared to the Carolinas it is approaching is awe-inspiring in this imagery from the USA's GOES-16 satellite.

1505AEST Hurricane Florence update. The latest NHC Forecast Discussion issued 1300 Australian EST indicates storm surge and flood rainfall forecasts remain the same, but significant changes in the structure and environment of Florence have weakened it to a borderline Category 2/3 system. The good news is that landfall is likely to be delayed until late Friday morning and winds will be relatively lighter at that time (sustained speeds of 150km/h, or strong Category 1), though cover a larger area. The changed track of the Hurricane makes landfall more likely in southern North Carolina.

Edited details are:

1230AEST Seasonal Outlook Update out. The BoM's mid-month update and video for the Seasonal Outlook is now available, and unfortunately promises more of the same:

• Below-average rainfall likely for large parts of the country
• Day and night-time temperatures likely to be warmer than average
• While the El Niño–Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) are currently neutral, observations and model outlooks indicate El Niño and a positive IOD could develop in spring

If you're reading this after September, the archive summary version is here. The BoM's Climate Outlooks are now produced using the much higher-definition ACCESS-S model, developed by the Bureau in collaboration with the UK Met Office. Here's an interesting blog on the improvements you'll see.

1100AEST Hurricane Florence. The good news in the NHC Forecast Discussion issued 0700 Australian EST is that Florence has somewhat weakened rather than strengthened, but the bad news is that at the same time it has become larger. Here's the main part of their notes. The latest Forecast Discussion for Florence is here. EDT in the USA is 14 hours behind Australian EST.

If you're not up to speed on developments, see the analysis I posted yesterday.

 Near record number of tropical storms cause alarm in Asia and USA
Wed 12 Sep 2018

A near record number of simultaneous typhoons, hurricanes and tropical storms currently nearly circle the globe from the Sea of China, across the Pacific and Atlantic to close to the African mainland. Two of these are in the highest categories on the Saffir-Simpson scale and are expected to strengthen.

The UK Met Office Twittered a good animation on 10 September showing where they were then. Their strengths have varied since, but all the storms are still active. Typhoons, hurricanes and Cyclones are all the same beasts, while Tropical Storms are below cyclone strength but can still produce damaging winds, and Tropical Depressions are another step down again and both can deliver flooding rain.

From the west, Tropical Storm Barijat is moving westwards to the south of Hong Kong, then will skirt the south China coast during Thursday and Friday before moving into northern Vietnam. It will be China's 23^rd typhoon or storm this year. Rain will be the main problem, though wind will gust 80-90km/h for the next few days. It hasn’t reached Category 1 and isn’t expected to.

Low-angled light of approaching sunset sharpens both the dramatic and the delicate cloud features of Super Typhoon Mangkhut at 1710 AEST on 11 September. Guam is shown on the far right. JMA Himawari 8

Typhoon Mangkhut, at category 5, is classified as a super typhoon and threatens the northern Philippines, Hong Kong and mainland China. The Joint Typhoon Warning Center (JTWC) at 1900 AEST today 12^th described it as moving west at 19km/h and being "a symmetric and highly consolidated system with deep feeder bands spiraling tightly into a sharply-outlined 30NM [55km diameter] eye". Sustained winds are currently estimated to be 275km/h with gusts to 335km/h, and the size of the typhoon, measured across its area of gale-force and higher winds, is just over 800km although the total system width is much larger. Its latest estimated central pressure is 905hPa.

JTWC expect Mangkhut to clip the northern tip of Luzon, north of Manila and south of Taiwan, late Saturday morning AEST with winds gusting to 270km/h. It then weakens due to interaction with land and reducing upper outflow, passing close to Hong Kong on Saturday afternoon AEST with gusts to 200km/h, and crossing the coast of China about 12 hours later. The Global Disaster Alert and Coordination System (GDACS) estimates 42.6 million people will be exposed to risk from the typhoon.

Moving farther east in the Pacific, Olivia, a Category 4 hurricane on 7 September, has fortuitously weakened to Tropical Storm status as it grazes the south of Hawaii today, but heavy rain is still expected. Farther east again, Paul, a Tropical Storm well west of Mexico, has weakened to a Tropical Depression as it moves slowly west.

Category 4 Hurricane Florence in the western North Atlantic is looking to be the most dangerous hurricane to hit the US east coast in living memory. The sea surface temperatures that it passes over right up to landfall are 1 to 3° above normal, giving it abundant energy and huge amounts of moisture. The upper winds above the hurricane are also favourable for it to maintain its power, and likely strengthen during Thursday 13^th, but will cause it to slow considerably late Thursday 13^th local time as it approaches the North and South Carolina coasts. It seems likely to make landfall overnight Thursday/Friday. Like Mangkhut, it is an enormous cyclone (compare its size with Florida, at left). GDACS estimates 1.3 million people will be exposed to risk.

Hurricane force winds are expected as Florence arrives on shore, but the gravest dangers come from the storm surge and rainfall. Storm surges of 1 to 3m are forecast on the southern side of Florence, locally higher and driven well inland by hurricane-driven waves. The surges come on top of a general 30cm rise in water level in the past 30 years due global warming, and will be worsened if time of arrival coincides with high tides. Mandatory evacuations of over a million people have been ordered in the last few days, mainly in coastal parts of South and North Carolina and Virginia, and a massive, co-ordinated effort is under way to get people out of the area.

The unusual circumstances that slow the hurricane in its approach may cause it to stall inland after it arrives, prolonging torrential rain. At present, the National Hurricane Center (NHC) is forecasting 500 to 750mm with isolated totals of 1000mm along coastal North Carolina, with 125 to 250, isolated 500mm, in South Carolina and W and N North Carolina. The NHC says "This rainfall would produce catastrophic flash flooding and significant river flooding." Should Florence stall inland, amounts could be much greater. In similar circumstances after Hurricane Harvey struck Houston in August last year, falls of 1100 to over 1500mm were recorded during the week after landfall, with the highest coming in at 1538.8mm. This and another very close reading were the highest single-storm readings ever recorded across the 50 United States, and helped Houston on its way to a one-in-a-thousand year flood.

The World Meteorological Organisation (WMO) issued this news bulletin late today 12^th, giving additional information on Florence and Mangkhut. The SMH [partial paywall] also covered the two in this story.

Moving east again, Isaac, also fortunately, has weakened from Category 1 on 10 September to a Tropical Storm, but will still bring rain and sustained winds of 80-100km/h to the Leeward Islands on Thursday 13^th with heavy rain threatening up to 840,000 people according to GDACS. These were the islands that bore the brunt of multiple major hurricanes last year.

Finally Helene is currently Category 2 as it curves from NW to NE through the eastern Atlantic, but is likely to be comfortably within Tropical Storm or Depression status by the time it moves west of the Azores in about 5 days.