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.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
ABOM has a habit of in filling from source data, as seen in their twisted temperature record database. They say it is warming when it is cooling and they say the weather is more extreme than it is. It’s all caused by Carbon Dioxide (the 3% humans make) and the resulting #globalwarming, don’t you know?
Thanks Jennifer….enjoying your work!
Pity the ” courier” can’t spell ones name accurately- then again what you expect with provincial hacks at the top of their game! Good work Jennifer- time to hold BoM to account for their political mischievousness !
Very important that someone is keeping tabs on what is going on and also has such a solid reputation, Jennifer, and expertise.
Thanks,
Jennifer,
the Samuel Hill weather station looks like it went through the eastern eye wall at about 9:30am on the 20th.
The Samuel Hill observations show maximum gusts to 170km/hr at 9:36am (from Unmentionable) before the winds subsided.
The BOM has the cyclone center (not the eye wall) passing ~20km to the west of the station at about 9:30am, and they show it at Cat 5 at 10:00am on the cyclone track map.
Seems a big difference.
In cricket parlance, a ‘classic catch’.
Well anticipated.
Thank you.
Thanks for your doggedness in holding an obviously corrupt BoM to account. Can we ever take this mob seriously again?
I am glad these guys at the BOM aren’t traffic cops.
The BOM has missing data for cyclone Marcia, so they have looked at nearby cyclones such as cyclone Lam and homogenized. This is the World’s Best Practice.
Dr Morahasy.
The data from Creal Reef was equally interesting. The cyclone intensified to the east of the recording station. I should have taken a screen shot, mistakenly believing the monthly summary would hold the data. Only problem is this station is not on the list.
The winds were a category 5 strength because they were able to wipe away the data so many days ago. The new man made super storms are really the worst.
The Courier Mail article quotes BoM chief Rob Webb rejecting suggestions the bureau relied solely on modelling to determine that Marcia was a Cat 5 cyclone.
“…the US Joint Typhoon Warning Centre had analysed Marcia as at least a category 4.
Forecasters were aware of the lesser wind speed (208km/hr) recorded at Middle Percy but would not downgrade the forecast because the cyclone’s strongest winds were to the east of the weather station.”
So how did the BoM know that the strongest winds were to the east of Middle Island weather station? Not using weather radar surely? Do BoM even have weather radar with a limiting Nyquist velocity that high?
The TRMM satellite data could not have been the source. The satellite passed over the eye of the cyclone some 5 hours before the centre of the cyclone passed over Percy Middle Island, and almost 12 hours before its landfall. The IR imaging scan width was about 250 km along an oblique 50 degree angle. The best that could be obtained from the satellite is a FORECAST of the rainfall intensity over Middle island and a highly subjective estimate of windspeed (Dvorak estimate) 12 hours before landfall.
Certainly not the Aqua satellite.
How then?
BTW: Is there any chance that someone conflated a Dvorak T-number with Tropical Cyclone Category- a Dvorak T-5 is expected to have sustained wind speeds of 175 km/h, an Australian cyclone scale Category 5 has windspeeds over 200 km/h?
BOM has proved to us that a CAT 5 Marcia (LOL) is no problem and so safe we can go surfing as we witnessed on the Media coverage
Hi Jen!
There is another weather station that I haven’t seen mentioned in Shoalbay. That is Williamson Airfield.
https://maps.google.com.au/maps?hl=en-AU&gbv=2&ie=UTF-8&gl=au&q=williamson+airport&ei=0y3sVPuULYnp8AXd14CYAw&ved=0CBUQtgMwAA&output=classic&dg=brw
It seems to reporting live data on this site:
http://wind.willyweather.com.au/qld/fitzroy/williamson-airfield.html
And on Wundergound:
http://www.wunderground.com/history/station/95370/2015/2/20/DailyHistory.html?req_city=&req_state=&req_statename=&reqdb.zip=&reqdb.magic=&reqdb.wmo=&MR=1
There are historical readings available on both. Suggests that the site never stopped functioning – and what readings are available, don’t suggest huge wind speads / pressure
The widget at the bottom of the first site allows a historical range to be selected. Between 19/2 and 21/2 the max wind is 105.5 km/h W on 20th February 2015
Wundergouund has a sustained wind of ~60Km/hr and ~987hpa pressure.
This is another datapoint as Magic Marcia would have passed between this site and Samuel Hill. In fact, I would guess that it was 20Km or so east of the eye. I have no idea on how to get the raw data from here… but it appears that it will be available from willyweather or from Wundergound.
cheers
Arnost
Excellent Armost!
Err Arnost.
Marciagate
Some more observational data.
TC Marcia did not pass directly of the Middle Percy weather station.
The BOM confirms Jennifer’s observational data(after all it is theirs):
“On Thursday night it turned almost due south and intensified even further, reaching category 5 at 4am on Friday 20th February. Wind gusts at Middle Percy Island reached 208 km/h as the cyclone passed to the east.”
The BOM also issued this:
TROPICAL CYCLONE ADVICE NUMBER 23
Issued at 4:01 am EST on Friday 20 February 2015
Headline:
Severe tropical cyclone Marcia has intensified to category 5, expected to continue moving southward.
Details of Severe Tropical Cyclone Marcia at 4:00 am EST:
Intensity: Category 5, sustained winds near the centre of 205 kilometres per hour with wind gusts to 85 kilometres per hour.
Location: within 9 kilometres of 21.6 degrees South 150.5 degrees East, estimated to be 130 kilometres northeast of St Lawrence and 180 kilometres north of Yeppoon
Given Middle Percy’s WS details:
Station Details ID: 200001 Name: MIDDLE PERCY ISLAND Lat: -21.66 Lon: 150.27: it would be outside the maximum wind speed zone and still a wind speed almost at Cat4.
The data is hardly indicative of what you have commented and hardly indicative of a true intensity of TC Marcia. (all sources BOM)
By the way these weather stations display intra daily observations on a rolling 72 hour basis, that’s why they are called “recent” observations. The daily aggregate of these observations was obviously impacted by the cyclone itself.
“Intensity: Category 5, sustained winds near the centre of 205 kilometres per hour with wind gusts to 85 kilometres per hour.” – sillyfilly chaff
I think you mean wind gusts to 285 km/h, silly.
That was a 4am forecast which would not have even had the satellite intensity data from the 11pm satellite overpass (TRMM reports are not real time- the data takes 6 to 8 hours to produce).
Also you make the absurd claim that no part of the cyclone passed over the weather station on Percy Middle Island. In fact the trajectory of the centre of eye between the 11pm satellite image and the landfall passes very close to the island and the 11pm image showed an eye diameter (not including the wall) of about 60 km- larger than most tropical cyclones. So some part of the the eye/eyewall would certainly have passed over the island.
The BOM maintains that the maximum windspeeds were predicted to occur outside the path of the eye and the inner eyewall to the east of the cyclone path, due to the natural asymmetry of a cycle (with higher wind on the left wrt the direction of travel) However, the satellite infra red imaging showed that the maximum rainfall intensity was ahead of the cyclone just outside the eyewall in the SOUTHWEST quadrant, and that the highest primary formation cloud heights were occurring in the northwest quadrant.
Thank you Doctor Marohasy, I really tought that I was becoming senile!! Like a lot of other people I was watching the various BOM stations during the event, a couple of sites that I distinctly remember were Samuel Hill and Williamson. Samuel hill now has no data for 3 days, I am positive the data was there when I was watching the cyclone go past, am I seeing things?? Or maybe it’s BOM that has seen things and decided to take down incriminating evidence…..??
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.
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.
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.
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.
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?
Middle Percy data still being 1984’d, BTW:
http://www.bom.gov.au/climate/dwo/201502/html/IDCJDW4145.201502.shtml
“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