Late Spring Severe Thunderstorms in Australia! (Photo Credit: Bureau of Meteorology, Tropical Tidbits)
DISCUSSION: Severe thunderstorms developed in portions of Australia the 17th and 18th of November. For eastern Australia this is quite common in late Spring. The image above shows the visible satellite during the late afternoon hours on the 17th. Cloud top temperatures are on the next image in the slideshow which represents the vertical growth, essentially the measure of the relative strength of the updrafts in these storms.
Let’s look at the setup that produced these thunderstorms. Shown above is the forecast surface map from the GFS (credit to Tropical Tidbits) around the time of thunderstorm development shown on the previous satellite images. The surface setup shows a few surface low pressure systems in northern Australia with a surface pressure trough extending inland of the coast in Eastern Australia. This provided the trigger for upward vertical motion and with moisture and instability in place (see the soundings below) diurnal thunderstorms developed in portions of northeastern inland through the eastern coastal locations of Australia, some being severe.
Radar image of developing thunderstorms along the coast near Brisbane and the surrounding region at 0718Z.
The forecast soundings above from the GFS display the instability (CAPE), moisture (dew point and PWAT), and vertical motion (negative Omega values on the left-hand side) present around the time of thunderstorm development from 00Z to 06Z on the 17th.
The above image is from the Australian Government Bureau of Meteorology site. Notice the severe thunderstorm warning in yellow issued at 5:46pm AEDT for large hail, heavy rain, and damaging winds. In fact, reports in portions of eastern Australia showed golf ball ~1.75 in/4.5 cm up to 2 in/5 cm hail in diameter.
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©2018 Meteorologist Joe DeLizio