Hot Blobs. These pools of severe warmth at the ocean surface have, during recent years, fueled all kinds of climate change related extreme weather ranging from droughts to floods to record hurricanes.

(Hot blob southeast of Australia features ocean temperatures as high as 8 F [4.5 C] above average. This is an extreme climate and severe weather-triggering feature related to climate change. One that has also been associated with strong, persistent atmospheric ridges and related high pressure systems. Image source: Earth Nullschool.)

The blobs themselves often form under persistent and strong high pressure systems which lock-in both heat and high rates of evaporation. These highs, sometimes called resilient ridges, are thought by a number of experts to be an upshot of changes to both atmospheric circulation and energy balance as a result of the Earth warming. They are an example of the kinds of extreme climate and related severe weather triggering outliers you would tend to expect in a warming world. A new kind of weather phenomena producing new effects.

Today, sea surface temperatures between Australia and New Zealand are ranging as high as 8 F (4.5 C) above average. A very significant warm temperature departure for this area of ocean. One that well meets the qualification for the term ‘hot blob.’ The large blocking high associated with the blob has, for some time now, been circulating very high volumes of moisture evaporating off these much warmer than normal waters over Eastern Australia. This moisture loading provides fuel for powerful storms in the form of both more explosive atmospheric lift and higher rainfall potential.

(Ridge-tough dipole triggers extreme weather in region prepped by moisture venting off an ocean hot blob. Image source: Earth Nullschool.)

All that heat and moisture bleeding off the hot blob just needed a catalyst to produce the kind of climate change related event I’ve been calling a ‘rain bomb.’ And, unfortunately for Southeast Australia, just this kind of catalyst in the form of a sharp facing trough in the Jet Stream and related upper level low forming over South Australia is on the way.

From today through late Friday, this low will generate added atmospheric energy that will produce very severe thunderstorms over Southeast Australia. Ones capable of generating extreme rainfall amounts in excess of 2 inches per hour over certain locations. With total rainfall amounts hitting between 4 inches (100 mm) and 12 inches (300 mm) between now and late Friday.

(Predicted extreme rainfall event is being fueled by very warm sea surface temperatures to the east.)

The storm system will also generate strong winds, lightning, and tidal flooding for some locales.

This is a dangerous event risking loss of property and life with a number of climate change related factors involved. Those in the areas affected should stay tuned to local weather (BOM) and government emergency management for storm and response information.

CREDITS:

Hat tip to Colorado Bob

Hat tip to Vic