Notable Weather Events Page 27

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22-09-06 Gale force winds.

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Following on from the previous report - A series of weak fronts passing south of the continent delivered 3 days of very windy conditions. This culminated overnight on the 22nd september '06 when gusts exceeded 75km km/h for over 2 hours. The maximum gust during this time was 85.6km/h. (see weather station graph below)

Temperatures were also amazing for this time of year with it hovering around 15 degrees for most of the night. The strong winds which can be seen to abate on the graph to the left strengthened yet again during the day with regular gusts above 50km/h as a more vigorous front approached. See next report for a continuation.   left - Weather station wind graph

 

23-09-06 to 24-09-06 Rain, hail and coldies.

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A much stronger front and deep low with a nice following of cold air approached from the south west. This was the best looking of a series of fronts that had delivered little more than wind (see reports above). The models and synoptic looked promising as can be seen from the map below.

Far left - LAPS model of the system showing nice spike of cold air (blue line) Left - synoptic chart of the actual system on the morning of the 24th.

The evening of the 23rd saw the rain band arrive from the NW. Not your usual band this one displayed none of the normal rain shadow characteristics with falls actually increasing in intensity on passing over the ranges. (see radar snippet below)

The reason for the lack of rain shadow is well described by IAN HOLTON "In very strong West winds showers develop with lift on west of ranges and are moving so quickly that they dump most on east...happened in 1981 lots with very strong westerly streams is the explanation. Normally the winds aren't as strong and dumps mostly on west ranges and central ranges." The passing of the rain band saw falls as high as 9mm in some areas and 6.5mm at my location. A very nice little "front" of rain formed over the northern ranges with this initial rain band producing infrequent lightning which was visible from my spot including one almighty crack towards Mt Barker. Strong winds continued to gust through above 50km/h.

The wind change (with a drop in intensity)arrived after midnight and showers increased again as the cold air arrived. Around 4:30am I was woken by torrential rain with mixed small hail. Some thunder also acompanied this rain from what can only be described as a "coldie"! "Coldies" or cold air thunderstorms have been rarely seen during 2006 due to the dry and adverse weather patterns.

left - a "coldie cell" Temperatures dropped to 5 degrees with the cold air and hail showers were regular. right - weather station rain graph

More heavy showers with the cold air in the westerly airstream passed over and the rain total continued to climb. By 9am there was 14.5mm in my gauge and in excess of 20mm some central hills locations with an amazing 28mm at Mt Barker!

A VERY welcome system for us in the ranges and even the Strathalbyn districts and other areas just east of the ranges, But its still not really enough for the many parts of the mallee where falls were below 5mm and mostly 2-3. What next I wonder?

04-10-06 record heat.

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The dreadful season continues with a day of record heat. The mercury in Adelaide climbed to an amazing 35.4 degrees which is the hottest ever 4th october. By 9am it was a scorching 29 degrees and only dropped to 21.8 as an overnight minimum which is also a new record for Adelaide. The northern suburbs reached over 37 degrees in the hot blustery northerly. The highest wind speed recorded was a peak gust of 109 km/h at Cape Willoughby. Maximum temperatures statewide were mostly 10 to 15 degrees above average ahead of the approaching front and ranged from 40 degrees at Tarcoola to 23 degrees at Neptune Island and Cape Borda. A shocker of a day!

Up in the ranges the story was much the same. It made 29.8 at my spot after an amzingly warm night above 15 degrees for most of the night. Winds were blustery with a max gust during the day of 65.7km/h. These severe conditions with humidities in the low 20's% saw a total fire ban issued. The earliest ever issue of a complete fire ban. Despite this 30 minor fires were reported and dealt with by the CFS. The arrival of the cool south westerly with the change saw temps plummet giving an incredible 20 degree variation for the day! This is clearly visible on the temperature graph (RHS) for the day. Right - days temp graph.

11-10-06 to 12-10-06 - Hot, dry and fires.

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The season goes from bad to worse as 16 days with no rain, extreme dry and heat spark an outbreak of fires statewide. The 11th saw in excess of 40 small fires n a blustery and hot day with temps in the mid 30's around the state. The largest was near Port Lincoln and bought back memories of the January 2005 devastation. (see here for the report) Approximately 200 hectares of scrub and grass were burnt near Rustlers Gully on the outskirts of Port Lincoln. A room of a house and a few sheds were also scorched. Fire bombers from Adelaide and CFS units managed to contain and control the fire before any real damage occurred.
Three fires were also reported on on Kangaroo Island and a grass fire near Port Wakefield threatened chicken sheds. The Port Wakefield blaze is believed to have been deliberately lit.

Conditions for the 12th are even worse with even higher temps on the forecast. Add high winds as a dry front approaches and the day has the potential to spell disaster. Total fire bans have been issued for all but 2 of the states 17 districts. Incredible! UPDATES SEE BELOW.

The 11th saw some mind blowing relative humidity reports and dewpoints. The atmosphere statewide is super dry and nowhere was this more pronounced than in Ceduna and Cleve where RH dropped to ZERO and dewpoints to -40!!! See the table below for a snapshot of the conditions at Ceduna. High lighted are the DP extremes.

Date/ Time	Temp	Dew Point	Rel Hum	Delta-T	Wind					Press	Rain since 9 am
					Dir	Speed	Gust	Speed	Gust
CST	°C	°C	%	°C		km/h		knots		hPa	mm
11/17:30	35.4	-42.5	0	22.3	N	35	43	19	23	1012.2	0.0
11/17:00	35.9	-35.9	0	22.5	N	32	44	17	24	1012.1	0.0
11/16:30	36.1	-35.9	0	22.6	N	37	48	20	26	1012.2	0.0
11/16:00	36.5	-35.9	0	22.9	N	33	46	18	25	1012.0	0.0
11/15:30	36.6	-35.9	0	22.9	N	39	50	21	27	1012.2	0.0
11/15:00	37.1	-29.8	1	23.1	N	35	46	19	25	1012.3	0.0
11/14:49	36.4	-35.9	0	22.8	N	37	56	20	30	1012.4	0.0
11/14:30	36.7	-35.9	0	23.0	N	37	50	20	27	1012.8	0.0
11/14:00	36.3	-35.9	0	22.8	N	41	61	22	33	1013.1	0.0
11/13:29	35.4	-47.5	0	22.3	N	41	61	22	33	1013.6	0.0
11/13:00	34.8	-	-	-	N	41	54	22	29	1014.0	0.0
11/12:30	34.2	-42.1	0	21.6	N	44	56	24	30	1014.5	0.0
11/12:00	33.6	-42.4	0	21.2	N	43	52	23	28	1015.0	0.0

This is amazing and I don't think I have ever seen such low recordings in the height of a summer heatwave let alone in early October. It is a very sad and disturbing reflection on the current state of our weather.

UPDATED 12th OCTOBER
The forecasts for the 12th came true as the heat continued. Overnight temps were high not dropping below 18 in the hills and warmer on the plains. By 8:30 in the morning it was over 30 degrees in Adelaide and 25 at my place. Winds were also pretty fresh gusting regularly to 50km/h. Temps rose as the day progressed and Adelaide reached 37.9 degrees. This was the hottest 12th October on record, the earliest 100 on the old scale and the 3rd hottest October maximum. Its amazing when you consider that the 2 hotter Oct days happened at the end of the month (Oct 30th 1919 (38.9) and the 31st 1987 (39.0)) not in the beginning of the month! Other centres sweltered, notably 41 degrees at Port Augusta and Whyalla and 40 degrees at Elizabeth and Keith with raised dust in many areas.

Up in the ranges I reached a hot 31.5 degrees with gale force NW winds all day. The maximum gust for the day was 72.6km/h with higher recordings from Strathalbyn and other eastern ranges spots. The max temp was the highest October temperature I have yet recorded at this location. In some sort of strange irony the previous October record also happened on the 12th but in 2004 when it reached 30.9.

It was another shocker of a day for fires and yet again they sparked up around the state. The worse being in difficult terrain on Kangaroo Island where over 1500 hectares burnt. Fires were also battled at Currency creek in the SE ranges, Beachport in the SE, Onkaparinga Hills to mention but just a few. Adelaide was put on notice for the toughest ever water restrictions yet announced to take place as from the 22nd October. The arrival of a SW change in the late afternoon bought relief and a rapid drop in temperature I recorded a 2 degree drop every 5 minutes in the hills for a short time as the cool moist breeze moved over. In excess of a 20 degree variation in just over 4 hours as the temp dropped from the max of 31.5 to be below 11 degrees!!! The new doppler radar at Buckland park caught the wind change front as it hit the metro areas and well displays the sharp line highlighting the rapidity of change. (see image to the right.) Right - doppler radar image of the wind change. Displaying cool wind front rather than precipitation.

11-11-06 to 12-11-06 - Storms break the 10 month drought.

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Finally the total lack of any stormy and photogenic weather for more than 10 months is broken with a spectacular display of storms over 36 hours. Read the report and see the spectacular images HERE!

 

14-11-06 to 16-11-06 - Adelaide Hills Frosts, record cold and Queensland snow!

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A powerful front hot on the heels of the trough and instability that gave us the recent storms brought a November Cold snap across eastern Australia. A bit too far east it did not bring heavy rain to Central SA, but it did bring us cold air and together with the influence of a high and calm conditions we had a frost! Yes thats right a frost, almost unheard of at my location at any time let alone November. On the morning of the 14th the temperature dropped to be a cold 2.8 at 1.2metres above ground, but was at or below zero at gound level in a tight and narrow layer of freezing air. As a result the front lawn was crunchy, an event happening only once or twice a year at this location! (see graph below)
Then on the 15th a November Temperature record for this location! In the same cold air stream daytime temps struggled to rise to 10 degrees. It only made a very chilly 10.7 degrees at 1:50pm. As can be seen in the graph below the better part of the day was well below 10 degrees. This is the coldest November maximum I have yet recorded at this location. The previous was 11.2degrees on 22/11/03. Amazing topsy turvey weather!

Temperature Graph of the Frosty Morning

Temperature Graph of our Coldest yet November Day

This same cold snap bought hail and heavy rain to SE Australia on the 16th. Snow to the highlands in Victoria, NSW and Tasmania. Most amazingly it also delivered snow to the higher parts of the southern Queensland ranges! This is the first november snowfall in our northern state since 1941

FORECASTS FOR SOUTHEAST QUEENSLAND Issued at 4:20pm on Thursday the 16th of November 2006 for Thursday night and Friday IDQ1008001 SOUTHEAST REGION OVERVIEW Mostly fine. Isolated light snow showers about the Granite Belt overnight and early Friday. Cold overnight and early Friday over the Downs with possible light frost. Moderate to fresh SW to SE winds with a high to very high fire danger.   Above - BOM forecast Left - Synoptic of the front from the 16th

 

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