A rain bomb in Victoria, Aystralia in the midst of hot water conditions in the Tasman (and a la-Nina)

Hot Blob off Southeast Australia Fuels Life-Threatening Rain Bomb Event

Robertscribbler,

30 November, 2017

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

Alert: sea surface temperatures (SST) are way hotter than normal.

Via Facebook

Here is November Sea Surface temperatures for recent years, prepared by Sarah Ugalde at IMAS, care of data from IMOS.

Context: 2015/2016 was a severe marine heatwave, off the charts, there were large scale impacts observed to natural ecological systems and to the aquaculture industries, both of which were (and are still) not equipped to adapted to the conditions they saw.

Personal opinion/guess: 2017/2018 is shaping up to be much, much hotter than 2015/2016. We could be about to witness an ecological disaster, and aquaculture might take a hit too. Let’s hope it’s possible for a cold marine system to offer some relief.

This is what we would expect, and have projected, climate change to look like - Spikes of unusual weather that systems can’t deal with, followed by ecological (or food production) collapse.

NZ Rainfall shortage 'dramatic'

Farmers are keeping a close eye on the rain radar, as soil moisture levels plummet.

Soil moisture levels have dropped considerably in a month. Photo: RNZI / Johnny Blades

Radio NZ,

30 November, 2017

Niwa's summer outlook is forecasting warmer than average temperatures for the whole country and an increase in rainfall for the top of the North Island.

Canterbury based farm consultant John Ryan said the soil moisture levels have gone from too wet to too dry in the space of a month.

"There's been a dramatic shortage of rainfall to put it bluntly. We're now facing soil moisture deficits on most properties."

Niwa meteorologist Ben Noll said farmers were dealing with much drier ground than last year.

The North Island and much of the South Island measured well below normal soil moisture levels, he said.

Dry conditions compared to this time last year. Photo: Niwa

"It's most pronounced in the west, so we're talking about places from western Northland ... down into the Wairarapa and Wellington regions, and then covering much of the South Island interior parts and particularly along the West Coast of the South Island."

Wilting point, which is the minimum amount of soil moisture needed to sustain plant growth, is also low.

"Some places are already at, or approaching, the wilting point - so this is quite significant from an agricultural perspective.

"Places like Greymouth, Mount Cook, Arthur's Pass ... places in Canterbury like Lincoln, which is tracking for its second driest month overall since records began in 1881."

Mr Noll said the dry weather was set to continue because of La Nina conditions.

"In the short term it does not look like much help will be coming for those dry soils."

Mr Ryan, who farms in Tai Tapu near Lincoln, said the lack of rain in the region was affecting growth on farms in the region.

"We've really missed out on perhaps 50 percent of the normal bulk of the spring growth because on the lighter land as soon as they come under pressure ... most grass species go immediately to sed."

Weather patterns were making some farmers plan further ahead, he said.

"I've had people de-stocking ewes and lambs all counted since early November, simply to create space and to not put themselves under market pressure later in the season."

People were not panicking yet, but should do their homework, Mr Ryan said.

"Nothing like getting two or three auctions in line for the cut-off date for various auctions, to be proactive and make a move before the situation becomes difficult."

Mr Ryan said the good news is that prices for all markets, except cross-bred wool, were well above recent years.

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On Facebook someone who is more aware than most expressed the following:

"Rainfall for Victoria lll result in major flooding for SE Australia and drought relief for western NSW and Central Victoria"

Unofortunately, with those high water temperatures in the Tasman I'm not so sure. We can easily get a one-off dump and rain and not make a dent in drought condiitons.

In the meantime, I have seen little mention of the la-Nina which should theoretically bring wetter and cooler conditions.

Meantime, where I am (in Wellington, New Zealand) it as hot and certainly drier on the first day of summer than it was at the height of summer during the height of the el-Nino a couple of years ago.

This is borne out by the comparative figures for sea temperature anomalies for the Tasman Sea, between Australia and New Zealand.