20 replies to this topic

[LaurieAG]

I have been watching the weather radar through many storms over the years but I have not really seen anything like this.

I'm right in the path so I'll find out what causes it in a couple of hours.

Attached Thumbnails

• 
• 
• 

Edited by LaurieAG, 06 December 2012 - 07:23 AM.

[LaurieAG]

http://www.bom.gov.a...loop.shtml#skip

Each finger has a slightly different driving force. The loop is good to view.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

The tail end is breaking down and it almost seems like there are three different threads with three threads each.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

Well it looks like things have petered out but the general pattern is still moving across even if there is little rain. Usually a storm front of that orientation will come in at a direction perpendicular to the front not in line with the front.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

The 64k images show that the threads are still distinguishable.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

Three tornadoes hit the New Zealand North Island the next day.

http://www.stuff.co....nado-11m-damage

While the tornado in Auckland packed winds of more than 200kmh, some of the most damaging winds were the "striaght gusts" which came immediately before and after the mini twister, MetService said.

[LaurieAG]

We've had some more wild weather here lately, first cyclone down here in many years.

We don't usually get so many tornadoes but then we don't get too many 'cyclones' that form and spend most of their time over land either.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

This is the 'cyclone's path. Normally they turn into rain depressions after they cross the coast.

Attached Thumbnails

• 

[LaurieAG]

Just so you can see the difference in the wind speed here are the doppler images. The second one was straight after they brought Mt Stapylton back online again and it went out again a couple of hours later.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

More weird weather from the past week. The cloud mass out to sea headed south very quickly.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

Here's the lows current location, the local rainfall for the past 24 hours and the forecast for next Thursday.

Attached Thumbnails

• 
• 
• 

Edited by LaurieAG, 23 February 2013 - 08:39 AM.

[LaurieAG]

Could the circled red dot be a waterspout? The doppler image may be an artefact.

Attached Thumbnails

• 

[LaurieAG]

It seems to be have been a persistent artefact on the doppler radar but these are the latest ones and it isn't really persistent.

Attached Thumbnails

• 
• 

Edited by LaurieAG, 26 February 2013 - 06:42 AM.

[CraigD]

Could the circled red dot be a waterspout?

I don’t have training or experience in reading radar returns, but I think no.

Waterspouts are tornados that occur over water and below low altitude clouds. The water that makes them visible is not sucked from the liquid water below, but condensed from the air – that is, it’s cloud-like. They tend to be weaker than over-land tornados.

Regardless of type and strength, tornados, including waterspouts, always involve high-speed wind moving in a circular path. On Doppler radar, this is indicated by high “towards radar” returns near high “away from radar” ones. Nothing like this is present in the left, “Doppler wind” image.

The doppler image may be an artefact.

I’m guessing the small “heavy” precipitation shown by the red dot in the right image could be an artifact – an error in the doppler radar image processing program output showing a strong return where there is actually nothing – but I think its more likely to be a return from a non-liquid object, such as an aircraft, that the software has failed to correctly subtract from the image.

I know practically nothing about how weather radar separates returns from precipitation from returns from the big bodies tracked by navigation radar. I expect it’s a pretty complicated, specialized subject, requiring some hardware and a lot of software knowledge, so you’d need to have a lot of specific expertise to comment accurately much more than I have above.

[LaurieAG]

I’m guessing the small “heavy” precipitation shown by the red dot in the right image could be an artifact – an error in the doppler radar image processing program output showing a strong return where there is actually nothing – but I think its more likely to be a return from a non-liquid object, such as an aircraft, that the software has failed to correctly subtract from the image.

Hi CraigD,

We've had a few waterspouts lately and a few sharp short showers but we have not had any of the tornado like weather up at Bundaberg around a month ago and down at Sydney last week. That's why I started this thread because I thought the first series of images posted looked like weird. Incidentally the first lot of images weren't tornadoes but New Zealand did get three tornadoes the next day.

Also they have tuned down the doppler sensitivity a bit this morning and the artefact (the blue long wind pattern, not the red dot) circled has disappeared although there did seem to be a persistent artefact later that day and night. The time seems to be jumping between GMT and local time too so there probably is some problem.

The UTC seems to be jumping about a bit between the different images too, the ones I put together are on the wrong day but still say UTC 000.

NZ had some radar issues a couple of days ago with regards to clouds of insects and we certainly have had quite a bit of rain lately along with plenty of insects.

Attached Thumbnails

• 
• 
• 

Edited by LaurieAG, 28 February 2013 - 02:03 AM.

[LaurieAG]

More snaky weather patterns.

Attached Thumbnails

• 
• 
• 

[LaurieAG]

more

Attached Thumbnails

• 
• 
•