HERE’S the weather forecast for northern Australia: a high chance of chaos with an 85 per cent chance of get-me-the-hell-out-of-here for at least the next couple of days.

OK, so you won’t find that on any official Bureau of Meteorology bulletin, but that’s pretty much the outlook for the Top End of the Northern Territory and much of Queensland for the next few days.

An ominous satellite picture currently reveals a two-pronged threat. There’s Tropical Cyclone Lam in the Timor Sea just off the NT’s Gove Peninsula, and there’s also Tropical Cyclone Marcia lurking in Queensland’s Coral Sea, which looks likely to deliver severe flooding and worse.

media_camera It’s not unusual to have two massive tropical storms within coo-ee of each other. But it’s not exactly good, either.

First things first: this is the worrying scene on the Gove Peninsula, where TC Lam is hovering dangerously close to the NT’s fifth largest town of Nhulunbuy. Locals are already queueing for essentials and emergency shelters are open.

Long lines for fuel in #Nhulunbuy as #CycloneLam heads to the town. Thanks Dave Suter for the pic. pic.twitter.com/Su1b8hQhm7 — abcnewsNT (@abcnewsNT) February 17, 2015

News.com.au spoke to an on-duty technician at Gove Airport, 13km southeast of Nhulunbuy, a weather station which is obscured by the blue rain swirl in this image. He told us that the weather has closed in with less than a kilometre of visibility, the wind is currently around 40 km/h and it’s raining steadily, following 148mm in the last 24 hours.

media_camera Not a big storm, but definitely a bad storm. Source: bom.gov.au

None of that is too severe by Top End wet season standards, but as Darwin Office meteorologist Adam Morgan explained, TC Lam is set to intensify. Tonight, it was upgraded to a Category 3.

For the record, Category 3 cyclones have winds of between 165 km/h and 224 km/h. Cyclones in this range are also technically known as “severe” cyclones.

BATTEN DOWN THE HATCHES

HUNDREDS of people have taken shelter across the east coast of the Top End as severe tropical Cyclone Lam intensifies and shifts course, now charging directly towards Elcho Island and Milingimbi.

Bureau of Meteorology (BOM) senior forecaster Angeline Prasad said Cyclone Lam was expected to develop into category 4 intensity and make landfall “very close to Elcho Island” on Thursday evening.

The cyclone was situated about 140kms north of the Nhulunbuy Airport and 170kms north east of Elcho Island at 3pm on Wednesday.

“I would say (it will make landfall) between 9pm and midnight,” Ms Prasad said.

“Destructive winds and gusts greater than 170km per hour are expected to affect Milingimbi and Elcho late on Thursday, that’s where landfall is expected.

“The eye could possibly cross Elcho Island.

“Destructive winds may extend to Goulbourn Island and Cape Shield, including Nhulunbuy, during Thursday.

“Gales will possibly extend to Croker Island and Port Roper on Friday.”

media_camera Ambulance officer Michael Tsang helps deliver emergency supplies to the cyclone shelter Nhulunbuy hospital.

Ms Prasad said Cyclone Lam could reach category 5 intensity.

“If it stays over water longer, and continues westward, conditions are very favourable for it to develop further, but because it is curving south west towards land (on Thursday) it may not have enough time to develop into a category 5,” she said.

Ms Prasad said Cyclone Lam was a “small system” in terms of diameter but could pack a punch.

“The highest winds recorded were on Wednesday at Cape Wessel at 66 knots or 122km per hour, when it was in the eye wall of the tropical cyclone, that’s hurricane force,” she said.

“You tend to have the strongest winds in the eye wall.”

media_camera Empty shelves at Woolworths in the town centre.

Ms Prasad said Cyclone Lam may not cross directly over Nhulunbuy as originally expected but that the area would still be significantly affected.

“The eye of the cyclone might miss Nhulunbuy but there’s a good chance it will get cyclonic winds affecting it (on Wednesday night and Thursday).”

A cyclone warning remained current between Goulbourn Island and Cape Shield, including Nhulunbuy, overnight on Wednesday.

A cyclone watch has been issued for Croker Island to Goulburn Island and Cape Shield to Port Roper, including Groote Eylandt and Bulman.

NT Emergency Services and police have advised people to stay away from flooded drains, rivers, streams and waterways.

“You need to avoid driving into water of unknown depth and current,” Commander Porter said. “You need to stop children playing in or near flooded waters.”

“In the event you need to create your own sandbags for flooding (in homes), use pillow cases, shopping bags or any other item that’s capable of being filled by sand. “You need to be careful of falling powerlines in the event of gale force winds or destructive winds.

“With the current cyclonic conditions it’s highly likely there will be fallen branches and other debris scattered across roads.”

media_camera Nhulunbuy Police encourage residents in Ski Beach community to leave before the causeway becomes flooded, blocking them off from any emergency services.

Commander Porter said heavy rain over next 48 hours could result in weight restrictions on roads and road closures.

“Motorists are advised to check road reports prior to travelling at roadreport.nt.gov.au or ring 1800246199 to get current status of roads,” he said.

“Please do not attempt to cross any flooded waterways as we don’t want you to be a statistic in relation to this event.

“Residents who choose to relocate to other areas outside the warning or watch zones, please notify the police prior to your departure on 131444 so we know you’ve arrive safe.”

More information about cyclone safety securent.nt.gov.au

media_camera And then there were two.

As the above radar image and weather map shows, TC Lam is not a particularly large storm. But that’s not an indication of its destructive potential. As Darwin Office meteorologist Adam Morgan explained, Cyclone Tracy wasn’t big either, but it was super strong and it scored a bullseye hit on Darwin.

So how unusual is this set-up with two major cyclones on the Aussie weather map? (Or at least, one cyclone and one storm with the strong likelihood of becoming a cyclone).

“It’s certainly not uncommon to have that. We do see it from time to time,” Adam Morgan explains. “It depends where the monsoon trough is lying.”

The monsoon trough, for those of you who tune out when weather guys start using jargon, is the dotted line you can see clearly on the above map linking the two systems we just mentioned.

It basically indicates the boundary between two distinct climatic zones and prevailing windflows. Any time you have converging winds, you tend to get instability. Which usually means storms. Which in summer in the tropics often means severe tropical storms, Which often means cyclones, especially when the water is warmer than the 27 degrees it needs to be to. Which it well and truly is right now.

media_camera With water temps currently as high as 30, the Timor Sea is ripe for cyclone formation.

Ironically, the Queensland storm could deliver its most intense damage when it leaves the tropics. Here’s the path it’s expected to take.

media_camera Down she comes.

South-east Queensland residents have been warned to brace for a hammering, with a category-two cyclone expected to cross the coast between Hervey Bay and St Lawrence early on Thursday.

Tropical Cyclone Marcia will bring floods, gales, a tidal surge and beach erosion after the big storm late yesterday took a swerve towards the coast at 22km/h.

CLOSING IN: Cyclone Marcia bears down on Queensland

WEATHER CENTRAL: Up-to-the-moment observations

Emergency services have kicked into action, with councils filling sandbags and closing beaches as the low loomed about 900km northeast of Bundaberg.

Seas approached 6m off Brisbane and wind gusts past 80km/h were recorded at Cape Moreton.

Premier Annastacia Palaszczuk said the state disaster management committee would meet today as she warned residents to prepare.

More than 200 swiftwater rescue crews were being positioned in areas likely to flood.

Queensland Fire and Emergency Services commissioner Katarina Carroll said people should be ready to sustain themselves for a couple of days.

“This is a faster moving system so there will be a lot of rain in a shorter time frame,” she said. “But the ground is not saturated and the rain hasn’t been going on for a matter of weeks.”

Ms Carroll said dams had the capacity to handle the heavy rain expected.

Residents can expect impacts similar to when ex-Cyclone Oswald roughed up much of the Queensland coast in 2013, but without such brutal flooding.

Oswald swamped Bundaberg and Gympie and scared the pants off Brisbane residents who feared a repeat of the 2011 inundation.

Weather bureau forecaster Jess Carey said rainfall would range from 200mm to 400mm, with falls of more than 500mm likely in some places.

“Rainfall will kick off (today) in the Wide Bay Burnett and then extend right into southeast Queensland overnight and on Friday,” Mr Carey said.

“We’ve already seen what a low like Oswald is capable of.”

Mr Carey said Oswald flooded wide areas because it was slow moving and rain had preceded it, soaking catchments.

“This low will move more quickly and most of the significant weather will be done by Saturday,” he said.

“We’re looking at 24 to 36 hours of rain and the ground this time is not so wet but there will still be plenty of run-off.”

CHANCE OF THEM MERGING ‘UNLIKELY’

TC Lam is expected to reach a category four by Thursday morning and make landfall between Elcho Island and Nhulunbuy overnight.

If it does, it’ll become the first cyclone to cross the Australian coastline this season, marking an unusually late start.

Bureau of Meteorology records show that in the last 50 years only two other cyclone seasons have gotten underway later than they have this year.

The system began as a tropical low within the monsoon trough over the Coral Sea late last week.

A similar cyclone is lurking off Queensland’s coast, northeast of Bundaberg.

The BOM is warning some places could get 30cm of rain over 24 hours, on both Thursday and Friday.

Destructive winds between 90 and 125km/h are also predicted for some areas, with the potential for abnormally high tides and heavy rain to cause flooding.

The BOM says the forecast tracks of the two systems indicate they will not merge.

Last year, Tropical Cyclone Dylan and Fletcher made landfall within a few days of each other late January-early February in Queensland.

To date, there have only been two tropical cyclones in the Australian region this season, which runs from from November 1 to April 30, but neither came close to the mainland coast.

The last time the country saw such a late first crossing was in 1987-88, when Cyclone Charlie struck near Townsville on February 29.

- with Megan Palin, Brian Williams and AAP

Originally published as Cyclone sandwich triggers Top End terror