Joe Courtney

For all those TC watchers out there Monty is now on its decline having crossed the coast overnight. Disappointing that we lost comms with key AWS  at Barrow Island and Mardie so accurate figures on intensity are not  available. Hopefully the data will be recovered to do a pretty good analysis wrt wind/pressure. Mean winds recorded to 80 knots at several AWS
Varanus Is, Barrow Is, North Rankin platform and a private AWS, but max winds likely to be higher confirming cat 4 status. Mardie station received the worst from a mainland point of view but damage won't be known until  comms are restored.

It was fortunate that the system bisected the towns of Onslow and Karratha  so a storm surge was not an issue.

Now the interest turns to rainfall/flooding as likely daily falls of  200-400mm near the path should add to the already flooded rivers coming off the Hammersley Ranges.

I've attached a microwave image near crossing time. Note the enhanced  convection in the offshore NW quadrant that was also a feature on radar imagery. Another Jeff Kepert-enhanced offshore flow example that is seen  quite frequently. Otherwise interesting to note the eye wall/surrounding convection was strongest/greatest in northern quadrants for over 24 hours.

By and large the models performed quite well and forecast performance,  apart from being a bit slow to latch on to TC formation on Friday, was very  good. It was a rare treat to have a system monitored from radar for such a
long time and get good surface obs.

Comments welcome on this one but a reply from me will have to wait a few days following these night shifts.

Joe

Jeff Kepert

Thanks for the comment, Joe. One of the pleasures of working in meteorology is seeing ideas go from "new and exciting", to "seen quite frequently", in the space of a year or two. Just shows how much more there is to do ...

I've sent jmb a couple of TMI images - a 37 and 85 GHz from when Monty was N of Barrow Isl.

At this time on the radar, there was (I thought) a suggestion of a small-radius inner eyewall, which disappeared and the eye opened out over the following hours. This can also be seen on the 85 GHz. Both images also show strong ice scattering in the NW eyewall, including a patch of blue in the 37 GHz ... it is relatively rare to get such strong ice scattering at this frequency.

The differences between the images are interesting - I wouldn't have immediately picked them as being at the same time. In the offshore flow, to the SW of Barrow, the warm Tb's are probably emission from low-level rain, not much ice development. Microphysical development and enhanced updraft in the eyewall then gives the strong scattering downstream. But
its hard to reconcile this view, and the 85 GHz image, with the warm (brown) band on the 37 GHz which wraps around the outside of the eyewall (and apparently into the eye) which looks like low-level warm rain with no ice above?? Any real experts on microwaves (not me) care to comment?

On the enhanced off-shore flow, I expect it would tend to produce low-level convergence consistent with this. But I'd want to model it to be sure, and given the density of obs around there, this could be a good case study. Joe, we should talk about this when you've caught up on your sleep.

Jeff