Mike
Another interesting topic here.
I have not been into the Kimberley area however, I lived a year in Darwin 1995 / 1996 and visited the area again during the storm season in 1999. I took a decent number of storm photos and even some lightning ones around Darwin / Kakadu and managed to get out around the Top End region. Being in the Katherine region, I was not too far from the Kimberley region. Hence I was relatively close at one time during my stay.
You will find that actual thunderstorms that occur around Darwin and much of the top end will be similar to what the Kimberly region receives (Excluding monsoon bursts and tropical cyclones). They are often pulse type storms. I have to note here that the region experiences a shorter wet season to that of Darwin.
Australian Geographic has also done a good article on Hector (The storm that inhabits Melville Island and the Top End - Edition 48 - October 1997). The whole of the top end storm season is well presented in this article. Further Australian Geographic has done an article on Lake Argyle which I have and there is documentation that waterspouts have been known to occur during storms traversing over this lake.
I have watched numerous satellite photos and loops over the years and have spied storms over this region too.
Daytime storms - General Northern Australia - What I observed:
Daytime storms erupt in the early afternoon, they peak mid afternoon and decay or collapse by sunset. The storms produce heavy rain bursts for a while once mature, with brief strong winds being the downdrafts and cloud to ground lightning for a period. However, the power diminishes in intensity quite fast because they become outflow dominant rapidly. Further, the storm cells in this part of Australia just tease and they barely move. To get good photos of them with contrasts, you need to sit out doors (Under a tree) for a while and photograph the cloud towers just as they mature otherwise the opportunity for good photos will be lost.
Unfortunately, it is difficult to chase many of them due to lack of roads and storms may erupt, mature and decay in as little as 30 minutes.
This worked for me for what I wanted and I managed to capture some beautiful cloud formations this way.
These type of pulse storms are common right across northern Australia especially in the October to December period during the day.
Nightime storms:
Another favoured time for storms is around 11 pm to 4 am. Large overnight storms develop anywhere in the region but again, they do not move far from their initiation point. They develop over a locality and dump copious amounts of rain over a locality / region sometimes causing localised flooding.
I found that more rain seem to fall during the overnight storms than during the day time storms. This causes problems for chasing because flooding of outlying areas is common and outlying roads are impassible for days / weeks depending on how much rain has fallen.
Note - I am not including the impacts of tropical cyclones as I did not experience one while I was in northern Australia.
Harley Pearman