Notable Weather Events Page 32

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21-05-07 Midnight Storms.

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Ahead of an approaching front was a significant line of instability that developed into a long line of storms. All the factors needed combined and some severe cells with black cored centres strengthened on approach to the metro and hills areas. The BOM issued an STA for damaging winds and hail. I moved to the hill for a better viewpoint in the Ute and was immediately buffeted by gale force and cold winds. Sp much so I had to set up camera from the Ute canopy in order to be able to set up the camera. One storm cell was already over the south coast and flashing avery 3 seconds. Unfortunately most of the bolts were up in the cloud or hidden in intense rain cores. This was going to be a storm to watch mostly and not photograph. Out west however the horizon was lightning up. The radar looked great and it was coming my way!

The radar image to the right shows the cell on collision course with my spot and its hail delivering black core. The second image to the far right is its arrival. I sat in the back of the ute watching the approach of this cell from the west. Lost of flashes, but all intracloud. It was bright enough to light up the solid rain shaft approaching and when it hit I retreated very quickly inside the vehicle and closed the doors. WHAM! It hit with torrential rain as can be seen in the image to the far right above. Then "chink -chink -bang!" HAIL! It came down hard. Mostly pea sized but the occasional

big bang on the roof had me worried about car damage. The cows could be seen hurrying for the cover of the pine trees through the lightning flashes which were now directly overhead. The rain dropped a quickfire 6mm with a rate of 48mm/h. It may have been more from hail blocking the gauge! I left the hill returning to the house just as another torrential burst with hail hit. It added another very fast 3mm and one almighty "FLANG" that shook the house from top to bottom.

Next it was the turn of the northern suburbs. A very impressive black cored (hail) cell hit them (see radar image to the right) delivering what one local chaser from the area described as "it wouldve ranked up there in my top 5 of hailstorms ever". Not as much rain fell there with average falls around the 5mm mark. Images from the event. - It was not very photgenic, too much rain and intracloud lightning. I did snap a few images and they can be seen in this gallery. A follow up cold pool (our first for the year) delivered nice heavy rains and small hail the following day with a very cold 9 degree maximum. Even the city was cold with their coldest day in 9 months.

28-05-07 Quickfire storms.

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Another approaching coldpool and front delivered yet another prefrontal electrical show! It too, as was the previous event, difficult to photograph as a profusion of very fast moving cells exploded over the hills and east of the ranges. (see radar image to the right). Firing infrequently they may have been, but the strikes were beatiful and clear nonethless. See gallery of pics HERE The follow up cold pool promised much, but was pretty much a rainfall flop for me. I received about 20mm over 48 hours and one very light hail shower. Not so for the northern hills (again!!) and particularly the northern suburbs where line after line of intense coldie action in that horrible southwest airstream drilled them with torrential cells an intensity of which I have never yet recorded at this location!! (see radar snippets below)

The rainfall distributions from the morning of the 30th well show the impact of these cells. (image bottom right) May has been the most frustrating month yet with system after system leaving me on the edge. As it stands parts of the mid north traditionally less than 50% of my annual average have recorded more rainfall than my location this year to the end of May! It has been a good start to the year for sure, but for some it has been truly outstanding!

*UPDATE* This system and subsequent low that developed near the states South East continued to leave me completely out of the rainfall loop. It certainly was NOT a local event but worth a mention as in excess of 100mm fell on the higher parts of the Mt Lofty district (Mt Lofty - Uraidla - Ashton). The best 24 hour was an amazing 67mm recorded at a couple of Stations (including Mt Lofty itself) on the 1st June. A WNS stream that persisted for days, normally a good flow for me, this time failed and kept constant steam showers over the Adelaide Plains and northern hills and suburbs. Compared to down south, 40% or more rainfall was experienced in these areas. Many stations in the city and hills also approached the 100mm mark to June 2nd. Down my spot 68mm fell from the 28th May to the 2nd June. Yes it is damp underfoot, but the best of the falls has avoided me again. The trend of frustration continues in the South Eastern Ranges.

The weekly rain bulletin from to the 1st June shows the amazing falls over higher Mt Lofty and surrounds. (this bulletin will be updated to the 2nd June when it becomes available

11-06-07 Deep South Rain Band

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A small front, pushed into a deep southerly approach by the influence of a large high pressure system in the Bight, arrives with significant rainfalls in the early hours of the morning. With a bang I receive 17.8mm of rain in a relatively short time. (19mm in the 24 hour period includes a few light falls the previous evening) My June total to the 11th now sits at 93mm! The south coast also does well with 20mm in a few locations! But good falls are not widespread. The city, in a strong rainshadow manages between 3-5mm generally. The interesting exception is Seaton which in the gulf stream effect scored 20mm from a short and heavy burst. Right - Rain Graph | Far right - Synoptic loop

24-06-07 Coldest June to date for my location.

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June 2007 has been a chilly month indeed. In fact up to the 23rd its been my coldest recorded month thus far. Previous was 2003 at a large ~1 degree warmer. Our average max temperature for this time of year is ~12 degrees. Temperatures at or below 5 degrees by 5pm each day have been commonplace. Frosts are rare at this location but elsewhere around the state widespread frosts have been common with some centres dropping to minus 5 degrees, notably the Riverland. See the stats to the right for a day to day rundown of the month thus far. Even the city has been colder than usual. The plains dwellers may even see a reocrd set down there! The Kent Town stations previous records for June are as follows. Min. 5.5 in 1982 Max. 14.3 in 1989 The Current stats are - Min. currently 6.2 Max. currently 14.4. As the cold continues a new Maximum Record may be set! Rainfall wise the south has done well with average monthly falls in a mostly south easterly stream. 127mm to the 24th. This has mostly been the result of dominating high pressure cells in the bight and while I have done OK with rains, further north they are screaming for a drink. A good solid return to big frontal systems is needed to help break the long damaging drought conditions of the previous few years. For me its also the wettest start to a year for a long time at this location. 470mm to the 24th June. Previous high was 444mm in 2003.

02-07-07 to 07-07-07 Storms, rain and fllooding. Winter is here!

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Yep, its been cold wet, windy with storms, hail and lightning that has seen fantastic rainfall recodings and Adelaides Coastline battered. Read the report of the first week of July HERE

29-07-07 Summer style fronts and rain distribution!

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The approaching front was nothing special on paper. It delivered a reasonable rain with some good news that the desperate Riverland managed between 3-10mm. Down in the central Mallee/upper southeast some falls of 15+mm were reported which is also fantastic news for these regions. As you go further south the falls fell off so that when you arrive at Mt Gambier not a drop was recorded! (Mt Gambier Airport AWS).

Locally, well, not really impressive at all. Just 13mm. Not bad you might think. But this was almost a summery system. With NO cold air accompanying the "front" rainfall distributions returned to being frustrating for me and fell back into the pattern that has dominated the recent few years leaving me in the middle or on the edge of any decent INTENSITY rains around. And this is the key - intensity. My 13mm fell from little more than regular drizzle while elsewhere heavy and solid falls accumulated. Why is this so?

I have for a long time theorised that the presence of the 540 thickness line increases my chances of decent rainfalls from nearly ALL streams, even the south-westerlies which are my traditional rainshadow. The 540 line is the blue line on the computer model and current charts indicating cold air dropping to lower atmospheric levels. See the image to the top right which has been taken from the system discussed here. The 540 line is no where near central SA and the current front, being no further north than Tasmania. This often leads to rainfall distributions which strongly favour the northern Mt Lofty ranges and miss my and some eastern ranges spots. See the map below left for a common rain distribution from this scenario.

This year (2007 has seen the return (albeit temprarily) of the cold 540 air over central SA on many occasions (see above right). In tandem I have also received decent falls of significant intensity, enough to achieve the runoff point on many occasions. In previous years this has been absent or weak and has seen my intensity of rain falls and often totals quite low in comparison to my near neighbours.

The map to the right shows a more typical rain distribution when the cold air is present. Note the location of 540 line a long way north of my location near Meadows (~ location marked with red dot) This is I must stress not as valid for the western range front above Adelaide and much of the hills north of the freeway line and seems to affect locations mostly in my area to Strathalbyn. It is interesting to watch and rather frustrating too at times.

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