[note all mean winds below are 10-min averages, and cyclone categories are for the Australian system, which isn't the quite same as the Saffir-Simpson scale--see http://www.bom.gov.au/info/cyclone/#severity.]

Recently we were lucky enough to obtain some video footage of Cyclone Ingrid as it was crossing Cape Don--that is, the westernmost tip of the Cobourg Peninsula, northeast of Darwin--on the morning of 13 March. The footage was taken by Jason Preece, a fishing charter operator based next to the lighthouse. You can see the layout from the photos at www.capedon.com.au. You can see our operational track at http://www.bom.gov.au/inside/services_policy/tc_ingrid/index.shtml.

Andrew Tupper, Australian Bureau of Met, has kindly spent some time cutting the footage down to something small enough to view over the internet. There are two versions, a longer unexpurgated one [6 MB], and a short one [2 MB]. Jenni Evans has now put the files at http://met.psu.edu/~evans/2005-TC-Ingrid so that they can be viewed outside the Bureau. (Thanks, Jenni!)

The fishing (in the long version) was filmed in the southerlies prior to the eye. Jason says they were a bit disappointed with the wind at that stage. There was then a 10-15 minute lull before the northerlies (most of the footage in the video, filmed from the other side of the building) which were "three times as strong" in his estimate.

The operational intensity estimate at that time was of a Category 4 system, with gusts to 260 km/h and central pressure 944 hPa. The system had been on a weakening trend from its Category 5 peak for some time by then, but current intensities had been held up based on Dvorak constraints (this is something which will be reviewed when the best track is prepared). Tree damage on the Cobourg Peninsula included extensive defoliation of the forest (see end of the video footage), which I believe is typical of Cat 4/5 impacts. A number of the buildings at Cape Don lost roofs.

We do have an AWS at Cape Don, but unfortunately it is an old Sutron variety which only provides hourly synops, so there are no high resolution data or max gusts available. Added to this was the inconvenient fact that its anemometer cups blew off in the middle of the event (and still haven't been found!)
Obs we did get at Cape Don 94129 were (times in UTC on 13/3):
time,pptn(mm),mean wind(kn),dirn, wx, MSLP
01:30 15 57 180 Rain 975.7
02:30 12 26 140 Rain 965.4
03:30 12 33 20 Rain 965.9
05:30 83 0 0 Rain 990.1
06:30 91 0 0 Rain 993.4

indicating the eye passage sometime between 0230 and 0330, with the anemometer failing before max winds on eastern side of Ingrid could be recorded.

The rangers at Black Point (a former coop observing site on the northern side of the Cobourg Peninsula) had the foresight to rev up their old barograph, and a preliminary investigation of the trace suggests a minimum pressure of just under 955 hPa (which using the Love/Murphy pressure-wind relationship would suggest and intensity borderline between Cat 3 and Cat 4). Obs section wants to inspect their instrument before confirming this reading, and Black Point was probably a bit north of the system centre, in which case they would not have sampled the true central pressure.

The asymmetry of the wind strengths at Cape Don is interesting. Ingrid was evidently being disrupted by passing over land, although the land effect would have been more like passage over an island than a continental landfall. It is also possible that Ingrid was beginning a short period of reintensification as it moved off the Cobourg Peninsula. When Cape Don was feeling the northerlies, most of the core of the system would have been over water again.

Here are some other significant obs during Ingrid's traversal of the north coast:

* MS Warrender (sheltering in the Wessel Islands north of Gove): mean wind 280/90kt at 11/3 2100 UTC (didn't experience eye);
* McCluer Island: max wind 344/83G107kt at 12/3 1840 UTC, max gust 112 knots at 1810 UTC, min pressure 973.3 hPa at 1758 UTC (didn't experience the eye; also note one of the anemometer cups became bent, so there may be some question as to the accuracy of the wind measurements);
* also there was a ship report from south of Croker Island of estimated winds of about 100 knots when Ingrid was approaching the island, but unfortunately the details of the ship were not recorded.

Posted 30 March 2005