tropicbreeze

Gabrielle is only a few hours away from Norfolk Is and is likely to make a direct hit. They've already recorded winds of just over 100 kph on the island. Winds at the centre are still at 110 kph, gusting to 155 kph. But strong wind shear and dry air along with lower sea temperatures are causing it havoc. It's likely now that Gabrielle has been "decapitated", the upper circulation separated from the low level circulation. It's still expected to pass over Norfolk Is at the intensity of a Cat 2 TC. Storm force winds (89 kph to 102 kph) extend about 240 kms out from the centre. It'll take a while for this system to blow itself out.

And strangely enough the tropical regions are unusually hot and dry for this time of year (wet season).

Some before and after images off the net of the flooding in south east Australia.. Lismore NSW Gympie Qld

The tropical that crossed into the NT has moved across the continent and out into the Coral Sea where it strengthened into Tropical Cyclone Seth. TC Seth is currently moving south south west off the Queensland coast. It's expected to transition into an extratropical low in a few days and drift towards the coast.

It all worked out well. The tropical low was unable to stay out far enough from land to take advantage of the very good conditions for intensification. It's crossed on shore now just bringing widespread rain . Temperatures varied from around 25 to 26 over the 24 hour period, the coldest Christmas day since records began in 1941. Most people were thankful of the colder temperatures for Christmas dinner and the end to the months of heatwave conditions.

Rabbit Flat finally finally totaled 115 consecutive days over 39C before the maximum only managed to get to 38.4C on 26 March.

Rabbit Flat in the NT has broken the Australian record for the most consecutive days over 39C. It's currently 109 days but will likely rise as the heat continues. Darwin could possibly have its driest wet season ever recorded unless it gets another 137mm rain by end of April. With TC Trevor approaching the GOC coastline it's quite possible the monsoon trough could develop over the Top End bringing the required rainfall.

Reposting the images .

Australia officially moved into spring on 1 September, in the north we've moved into the "build-up", the prelude to the wet season. Unfortunately the long range forecasts have predicted a late start to the wet season. That means without the rains temperatures will rise together with relative humidity and little chance of respite. Unless, of course, you're right on the coast and benefit from any sea breezes when they come in.

The month of May saw the dry season firmly entrench itself in the tropical north. Mid month a massive dry surge brought temperatures down to below average, Darwin Airport recording 7 consecutive days with minimums below 20 (17.9 to 19.8). That's the equal fourth longest run for the month of May. The highest minimum for the month was 25.7. The lowest maximum 30.2, highest maximum 34.9. There was no rainfall recorded in Darwin, however some rain fell along the east coasts of the Northern Territory and Queensland. Another dry surge mid week is expected to drop temperatures below average again. This "roller coaster ride" usually continues over the coming 2 months.

Dawn after TC Marcus

The official Tropical cyclone season is drawing to a close with numbers of cyclones close to average with a possibility that the average might be exceeded before the end. Extract from the Weekly Tropical Climate Note of 27 March 2018: Ten tropical cyclones in Australian region so far this season After a busy week, Australia has now observed ten cyclones during the 2017-18 tropical cyclone season, to date. This is just short of the long-term average number of eleven tropical cyclones per season across the Australian region. The tropical cyclone season runs until 30 April, so there remains a reasonable likelihood of exceeding the average number—something that has not been achieved since 2005-06. Western Australia has seen the majority of tropical cyclones, with the first seven systems of the season affecting that region. The last one, TC Nora, whilst not reaching the east coast caused heavy rain in the area. Port Douglas had 593mm rain in a 24 hour period, several other places in the area had over 300mm in the same period.

Severe Tropical Cyclone Marcus has weakened to cat. 3, central pressure 965 hPa, sustained winds 140 kph, gusting to 195 kph. Conditions are becoming less favourable and transition to a low may occur Saturday or Sunday. Ex TC Marcus may just clip the south west tip of Western Australia as it's swept eastwards. The tropical low in the Arafura Sea developed faster than anticipated and is now Severe Tropical Cyclone Nora, cat. 3. Central pressure 963 hPa, sustained winds 150 kph, gusting to 205 kph. Further intensification is likely, to cat. 4 by about mid tomorrow (Saturday). Nora is expected to continue down the west coast of Cape York as a cat. 4 but experiencing some increase in vertical wind shear, interaction with land and possibility of some dry air in the area penetrating the system.

Severe Tropical Cyclone Marcus is Cat 5 with central pressure 914 hPa, sustained winds at 230 kph gusting to 325 kph. Glad we were near the starting blocks for this one rather than near the finish. Marcus is curving around to the south and will soon begin to weaken. Another tropical low has formed in the Arafura Sea and is expected to develop into a cyclone tomorrow. This system is expected to move south east into the Gulf of Carpentaria and strengthen to Cat 3 by Sunday.

Severe TC Marcus is now cat 5 with sustained winds of 205 kph and gusting to 285 kph. Further intensification is expected before the system starts to curve to the south and run into lower sea surface temperatures and higher vertical wind shear. There is very high rainfall around the system, it will be interesting to see if this will carry through to the south west of WA. It appears that ex-Marcus may cross the coast in the vicinity of Perth.

Darwin harbour is down to 982.1 hPa and getting wind gusts of 130 kph, my place is 993.9 hPa with wind only gusting to 90 kph. Lot of trees down on powerlines and roads. Not much rain so far but should increase as the system passes. The airport is closed and flights cancelled. Lot of shipping has left the port and the Queen Mary 2 cruise ship which was due to berth in Darwin has been diverted. Power supply is failing like falling dominoes, mine has finally gone down and now I'm on my own generator supply. The power authority can't do anything until the cyclone passes. Tropical Cyclone Marcus

Tropical Cyclone Marcus has developed off the coast north east of Darwin. Currently moving eastward it's expected to turn to the south west and move over Darwin tomorrow (Saturday). Although environmental conditions are favourable for development the recent passage of an intense high pressure ridge along the south of the continent pushed a mass of dry air into the area. While in proximity to land and with the dry air, Marcus is expected to stay at cat 1 strength until it moves out into the Indian Ocean at which stage rapid intensification is likely.

January saw a strengthening of the monsoon in the north of the country with record rainfall, particularly in the Top End of the NT. A tropical low developed in the Borroloola area of the Top End and slowly drifted westwards. Although it remained inland it wasn't far from the coast and intensified to 986hPa. The greatest rainfall totals were in the western Top End of the NT. For the month of January my place recorded 1028 mm, most of that falling in the last half of the month. Friends at Darwin River recorded 1090 mm. Some remote communities were evacuated as rising flood waters bring increased risk of crocodile attack At the end of the month the tropical low moved further inland in Western Australia and weakened. Together with weakening cross equatorial flow this has dissipated the monsoon trough bringing mostly clear skies and sunny weather.

Here in the north we've officially moved into the wet season, but the dry season lived up to its name. This is BOM's summary of the dry season and a suggestion that La Niña might develop during December. Weekly Tropical Climate Note 3 October 2017 Next issue 10 October 2017 Dry season: warmest on record daytime temperatures for northern Australia The northern dry season (May–September) of 2017 was characterised by record warm daytime temperatures and below-average rainfall. Averaged across northern Australia (north of 26 °S—a line that passes through the Northern Territory/South Australia border) the mean daily maximum temperature was 2.00 °C above average, the highest in 108 years of record, and well above previous record of +1.52 °C (2013). In all months of the 2017 dry season, daytime temperatures were at least 1 °C above the long-term average, and a number ranked in their respective top ten for northern Australia. These include: the warmest July (3.02 °C above the July average), 3rd-warmest August, 4th-warmest September, and 6th-warmest May on record. Additionally, the mean temperature (average of the maximum and minimum) in July also ranked as highest on record for July, with a monthly mean temperature anomaly of 2.41 °C. The significant heat was largely from the daytime temperatures, with the mean minimum temperature averaged across northern Australia during the dry season marginally above the long-term average. The dry season is characterised by little rainfall across the northern regions of Australia. For 2017, rainfall across northern Australia was below average during the dry season (53% of the long-term average). There were two notable rainfall events in the period. A surface trough over northeastern Australia was associated with very heavy rainfall over the southern Cape York Peninsula and the Gulf Country of Queensland on the 18 and 19 May. Unseasonal rainfall was also observed on 9 and 10 July when a cloudband produced widespread rainfall totals in excess of 50 mm in the southern half of the Northern Territory. Many northern Australian locations had their lowest rainfall on record for the 2017 dry season. Most notably, Darwin Airport had nil rain in the 5-month period, the first time since records commenced in 1941. Cooling across tropical Pacific Ocean For the past few months there has been sustained cooling of sea surface temperatures (SSTs) across much of the equatorial Pacific Ocean. In recent weeks, SSTs have been cooler than average in the eastern half of the equatorial Pacific Ocean, and close to average in the central to western equatorial Pacific. However, SSTs are still well within the neutral El Niño–Southern Oscillation (ENSO) range. All international climate models surveyed by the Bureau of Meteorology suggest further cooling of the tropical Pacific Ocean is likely. Five of the eight models suggest SSTs will cool to La Niña thresholds by December 2017, but only four maintain these values for long enough to be classified as a La Niña event. It is not unprecedented for La Niña to develop this late in the year, however it is unusual. Of the four late-developing La Niña events on record, three have coincided with above-average wet season rainfall across northern Australia.

No snow forecast for this part of Australia yet.

In the north weather for the dry season (May to September) has been drier than average and temperatures marginally above. Apart from the east coast, rainfall in the northern dry season is almost negligible so slight changes can statistically seem very large. For Darwin (July figures 5 days only): Minimums May av. 22.2C May2017 22.6C Jun av. 19.9C Jun2017 20.0C Jul av. 19.3C Jul2017 22.1C Maximums May av. 32.0C May2017 32.9C Jun av. 30.7C Jun2017 31.3C Jul av. 30.6C Jul2017 32.5C

In the north west of the continent the dry season has really sunk its teeth in. Broome has had several days with winds coming out of the desert and dropping the minimum temperatures into the low teens. Maximums have mainly been in the low 30's with relative humidity dropping into the 20's. North west of the Northern Territory after a few cool mornings has been mainly hot with mild mornings. My place yesterday maximum was 36.1C, minimum this morning was 20.8C with relative humidity bottoming out at 24%. Darwin itself (airport) had a maximum of 34.5C yesterday and minimum of 22.5C this morning, relative humidity bottoming out at 23%. The north east of the Northern Territory however, has been milder with higher humidity and the odd sprinkle of rain.

Officially the last day of our dry season and it's very much like the dry season already. However, over the past week a tropical low developed off the West Papua coast and moved across the Arafura Sea. As it moved into the Timor Sea it intensified rapidly into a category 3 cyclone and was named TC Frances. Vertical wind shear was around 10 to 15 knots with sea surface temperatures 30-31C and strong upper outflow. A subtropical ridge over the continent kept the system off the coast. The surge of dry air from the ridge began to wrap into the system and Frances dissipated very rapidly. Although I only got 3 mm rain from the system, it was far more generous with the Tiwi Islands where Pirlangimpi got 233 mm. Extended models are showing some activity around the Solomon Sea and with the characteristic strong ridging this time of year there's always a possibility of it being steered across the top of Australia perhaps bringing another wet season burst. Happened in late April 11 years ago when TC Monica came through as a high end category 5.

Here's the reason for the record low temperatures in Darwin yesterday. According to BOM there was strong dry south east wind blowing into the system. The heavy rain falling through it caused evaporative cooling. Basically a huge natural evaporative airconditioner. It's a very rare occurrence. Ironically, evaporative airconditioners aren't used in the tropics as they're ineffective.

Can't believe how cold it is. Don't ever remember feeling as cold as this with a tropical low or cyclone around. I'd like to know how the temp can plummet so much. The tropical low is now over Van Dieman Gulf and is expected to take 12 hours for the short distance to be directly over Darwin in the morning. That coincides with high tide which, being a spring tide, will be over 7 metres. The low will be adding a bit to that. The rain has been easing with nightfall. Mark, Ernie was well off the coast but still in the western region. There was little effect along the coastline so no watches or warnings were issued.