Notable Weather Events Page 37

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19-23 December 2007 widespread rain

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Could this finally be the rain event we have all been hoping for? After just 8.5mm in an amazing 45 days the countryside was parched in conditions that should only be seen in February. The models seemed to think that up to 40mm was possible from the approaching vigorous front and NW infeed of moisture. 40mm! Such a fall would be an enormous deviation from recent happenings and very very much out of character for the year. It started when 4am on the morning of the 21st I was woken by a long deep rumble. A check of the radar revealed a number of cells rocketing in from the northwest. Some of these were electrically active as was evidenced by my local thunderclap. This cleared until sunrise when the real deal approached.

The thunder was ominous, but my view was blocked by fog streaming in from the east. Then for a minute it cleared to reveal a nasty angry sky. The radar (see image to the right) showed just why it looked so nasty. A bolt of lightning shot earthwards just a few kms away in the Kuitpo valley. It looked FANTASTIC! I snapped an image in the fog break which can be seen here. The rain arrived with a torrential (but short burst) as lightning and thunder abounded. The WX captured the arrival of the rain - see graph below.

As can be seen from the weather station graph )above left) the rain then set in and proceeded to fall steadily but not heavily for ~ 6 hours!! The totals accumulated beautifully and by evening nearly 30mm was in the gauge. Amazing and it looked like the models were on the ball. However as always the most significant falls were to be seen elsewhere.

But all was not "just light rain" elsewhere. Mt Barker copped some torrential and unending downpours that saw paddocks running river and localised flooding within the town. The same could be seen in a line that followed the freeway back to the plains and then back to the Port Adelaide area. Localised flooding and traffic distruptions were seen in Adelaide in this line. The map to the right shows the distribution of the rain (supported by radar loops) with some VERY impressive falls above the 50mm mark to be seen and as always the best was north fading as you went south. Another front arrived overnight bringing more decent falls and by the end of the event I had recorded a not too shabby 44mm. Some of the higher parts of the Lofties had received an amazing 70mm!! The rain extended all the way to the riverland with falls at or above 15mm for some spots. Yet in the southeast it all fizzled away to be just a few scattered mm and was most disappointing from their point of view. I did capture a few pics of the approaching line and surrounds in the few minutes of clear before I was all rained out. They can be seen in THIS GALLERY.

New Years Eve Heatwave

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Perhaps not officially a heatwave, but hot enough anyway! The rains and cool mentioned above simply switched off and the heat returned with an uncomfortable vengeance boiling away any trace of the moisture!

Have a look (see data to the right) at the steady progression from the cold of the 22nd to the ridiculous heat of the 29th. Even more heat is on the way with temps expected to launch into the 40's for New Years Eve! NOTHING GOOD COMES FROM SUCH HEAT AND DRY

22.12.2007 - 14.5 23.12.2007 - 13.9 24.12.2007 - 16.7 25.12.2007 - 23.0

26.12.2007 - 26.1 27.12.2007 - 30.6 28.12.2007 - 32.4 29.12.2007 - 35.2

The top of 35.2 on the 29th is the highest temperature of the new summer period. It is unusual for us to reach this temperature and falls within the top 10% of temperatures we experience.

UPDATES 2nd January 2008.

The shocking heat continued past the 29th and into New years day 2008. The 30th saw temperatures rise even higher in my area to reach 36.8 degrees. On the 31st (new years eve) it climbed to a very rare 37.3!! The 1st of January was cooler with an approaching wind change from a weak front but even so still rose to 30 dgrees! The 2nd january broke the cycle with just 23 degrees in the influence of very strong and cold southerlies. The exposed hilltops above the house and weather station struggled to reach 18! An amazing turnaround considering the previous week or so. The cool did not however penetrate very far north on the 2nd with high 30's commonplace north of the Adelaide region. My area experienced an incredible and extremely unusual 6 straight days above 30 and an almost unheard of 3 straight days above 35!! In fact in the years of recording data at this site only once before in January 2006 have we recorded 3 consecutive days above 35 when it reached 36.1, 37.5 and 35.7 on the 20th to 22nd.
The 30th saw an incredible (used this word a lot in this report) 23.5 temperature variation! 20degrees of this variation happened in just 5 hours where the temperature could be felt rising a degree a minute for a short time. This is not a record though, my greatest daily variation was in 2003 when my Maximum Daily Variation was a huge 24.90 on the 19/01/03. Can I say "incredible" again?
So was this current heat event extreme - you betcha!!

Adding to the list of crazy temps - New Years Eve saw Mt Gambier reach an incredible 43 degrees! Hotter than Adelaide on the same day which is as rare as an honest politician! Overnight on the 31st the minimum temp of 29.9 set a new December record for Kent Town, breaking the old of 29.3 set on 12th Dec 1998. From the 29th december The city also recorded 3 days in a row above 40 degrees - Icky!!

The whole of South Eastern Australia sweltered on New Years Eve 2007/08

UPDATE 10th January 2008.

The heat goes on and on! The period from December 1st to January the 10th has now set my local benchmark for HOT! This period has the highest ratio of days above 30 and above 35 of any previous year. The summer of 06/07 during this period had more days above 30, but only 3 of these were above 35. 2002/03 was a shocker also with less total days above 30, but an equal top with this years amount above 35. The average number of days above 30 is 8.3 and of these falling above 35 just 2.5.

Will be interesting to compare this graph at the end of January and then the end of summer in february. Keep watching for updates on this.

18th january 2008 Localised high precipitation storms

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Strictly speaking this is not an event specific to my location with not the slightest effect in my area despite its proximity, happened within spitting distance. Tropical moisture and instability moving in from the east on the morning of the 18th dropped some nice falls in the South East district with nearly an inch at Coonawarra. This line progressed very slowly reaching a line NS from Tailem Bend before fizzling away. Was that to be it then? Hardly!

When weather moves in from the west, usually the western range front receives the best. When it comes in from the east usually the eastern ranges do best. Normally. This event was to rub salt into the wounds of more than a decade of failed severe rainfall events down my way. The moist easterly flow skipped over the top of the eastern ranges to collide with a seabreeze convergence over - yes you guessed it - the western range front and Adelaide Plains! The convection started mid morning developing into a line of dark bases stretching north south along the western range front and back into the Mt Lofties. The rain echoes started near Clarendon and suddenly exploded into severe rain cells. The radar image to the right shows the intensity of the line and the accumulated rain can be seen to the far right. The Bureau issued several STA'S. It came down in buckets! Flooding was reported from Parafield and surrounds and local roads under all affected areas were under water. Burnside 26mm in 30 minutes, parafield over 20. Most extreme falls were down south were a private gauge near Chandlers Hill and Clarendon recorded an incredible 54.5mm and unconfirmed reports of 56mm at Blewitt Springs!!!! The cut off was extremely sharp. Withing a few hundred metres it went from flood damaged to bone dry. My location did not even receive a drop despite the closeness of the cells!

Visually it was quite spectacular witht he intense rain foot from the cells. Unfortunately I was stuck at workl and could only watch events from the computer! My webcam did however catch the edge of the events. While not a quality image it shows the intensity of the rain foot from the southern cell and just how close it came to home.

Thus far in the last few months there has been significant falls above the 50mm mark in 24 hours along the south coast (Victor Harbor), Longwood to Mt Barker and now this amazing little cluster of storms dumping amazing rain from near McLaren vale to Clarendon. Its slowly completing the circle with 3 out 4 sides copping a beauty. Just one to go! Am I sounding cynical. Well yes. There has been no significant summer rain fall here at my spot since 1992. And only 1 fall above 50mm in a 24 hour period at ANY time of the year in the last 5 years!
Pretty sad considering some of my annual totals.

UPDATE 28-01-08

Site subscriber Josh Hagger from near Willuga copped one of these storms. His weather station shows how dramatically and suddenly the rain hit! See the graph below. Some interesting stats from the data.

10mm of rain fell in the first 6 minutes, 20mm of rain fell in just 15 minutes, 40mm fell in an hour, rainfall rates peaked at a torrential 109mm/hour, dewpoint and humidity spiked with the rain arrival while the temp plummeted, dewpoint reached a muggy 20.1 degress at the height of the rainfall.
Its an amazing data set and many thanks to Josh for making the data available!

Should I mention again that such a rainfall event has not been seen in my spot since 1992. The highest rainfall rate I have recorded at this location was just 60mm/hour which in itself is pretty darned heavy, but nothing compared to this type of event. While EXTREMELY rare here at this location we should cop similar about once a decade. Somewhat overdue at this stage!

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