IT is valid for the Australian Bureau of Meteorology to estimate the intensity of a cyclone using computer models when it is far out to sea. But once that same cyclone passes over a weather recording station the modelling data must be updated with real world observational data.
In the case of Marcia even after this cyclone passed over Middle Percy Island recording a minimum central pressure of only 972 hPa, maximum wind gust of 208 km/h and maximum wind speed of 156 km/h, the Bureau continued to report only on the basis of output from a computer model. The cyclone was clearly a category 3 system, yet the Bureau called it as a 5.
The Bureau has since removed the observational data that was once available on their website, I printed it off at the time and had it digitized this morning. That information is here:
It would be travesty if Marcia was recorded as a category 5 cyclone at landfall based on output from a dysfunctional computer model, rather than as a category 3 as clearly indicated by the observational data.
"Matt March 5, 2015 at 9:27 am #"
Hi Matt
Link below is a TinyPic image of the Samuel Hill data. Resolution here is poor although the original screengrab itself is quite readable.
If you are interested in 20 Feb only I can try cropping and enlarging the image to produce a more readable version?
http://tinypic.com/r/29ndt86/8
Middle Percy data still being 1984'd, BTW:
http://www.bom.gov.au/climate/dwo/201502/html/IDCJDW4145.201502.shtml
Williamson never faulted during Marcia and still continues to report observations unlike Samuel Hill which obviously lost comms once the Bayfield repeater lost power/backup much like the complete Telstra mobile network from Byfield south.
However Samuel Hill data was being logged during and after Marcia right up until the mobile system failed. One would imagine then that Williamson links to the north(?) or has a satellite link? All Williamson data remains intact.
So peak gust was 106km/h from the West @ 09:11, 9am was 61km/h from the WSW, which puts Marcia to the east of Williamson and the time matches the predicted track.
Does anybody have the Samuel data that used to be there for the 20th?
In the age of climate hype weather data is a dangerous commodity. Thanks for taking the time to save the actual data. BOM, NOAA, UKMET and others are proving themselves to be less than honest with weather data.
Hey Ken
Thanks for this information. Glad to know your OK, and have power back.
Regarding the data... Friday and Saturday is completely missing from the summary observations for Middle Percy Island. The BOM has told at least one journalist that the weather station lost power and so there is no data for this period, but as the above link shows, there is good surface observational data for the period when the cyclone passed over.
Interestingly at the Senate Estimates hearing on Monday the BOM representative said that they knew at 4am that Marcia was a Cat 5. This is about the same time they would have been seeing the actual readings from Middle Percy which showed it as a Cat 2-3.
Well done Jen! Thanks for the data, and thanks for pointing this out. Our power went off about 1000 Friday and mobile internet at about 1410, and still dodgy. (This comment has een waiting for over 24 hours due to mobile drop out and then flat battery.) Power supposed to be on next Tuesday. I was watching Marcia closely the whole time and watched on weather radar as the eye collapsed as it went over us, so it was Cat 2 or Cat 1 at Rocky. Very strong gusts here and worse on eastern slopes and hills, which is where most of Yeppoon damage happened. But Cat 5 would have completely wiped out Rocky and Yeppoon. It MAY have had very strong winds in the eyewall, but Samuel Hill was only a few kilometres east of the eyewall and had negligible winds. The eye went right over us and my guess would be 120 -130 kmh, and the winds after the eye passed were much less and faded quickly. All our neighbours and us were out in the street about 3.00pm, hardly any wind at all. It was a small, intense, shortlived cyclone which had reduced to a rain depression less than 10 hours after landfall.
By the way, there is nothing mysterious about the data disappearing, it is only there for 72 hours.
It is intriguing alright, as like you I followed Marcia all day via BOM, in particular observing wind speeds recorded at Middle Percy, Samuel Hill and Williamson. I wish that at the time I'd taken notice of the timings - as I recall there was no interruption in updates, but perhaps I recall incorrectly...
I was particularly interested given the utterly over the top media reporting and the suggestion that it was a Cat 5, given that what I knew of the cyclone at that time was it had been coming in as cat 1 or 2.