Notable Weather Events Page 30

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28-02-07 Hottest February on record.

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February 2007 was a shocker of a month. It was for me a record breaker and well and truly set the benchmark for average maximum temps. Our hottest day was 37.9 on the 4th and while not a record maximum it is in the upper range we experience at this location. 5 straight days were experienced above 33 degrees and an incredible 14 days or 50% of the month was above 30 degrees! All this gave an average maximum temperature of 28.89 degrees. Our normal average max for feb is 24.19. This makes it a ridiculous 4.7 degrees hotter than normal. Is it any wonder I felt hot every day!

Making things worse was a total lack of rainfall. Feb only gave me 1.2mm from 2 days of 0.6mm each. Such rains are insignificant and not much more than a heavy dew. Yet all around on all four sides of my location bigger falls were to be had right up to the Meadows township itself (less than 2 km away) which copped a nice little subtropical downpour on the 15th. To the end of feb it had been 38 days since the last 24 hour rain total above 2mm. The countryside is suffering for it too. In 115 years of rain data on only 8 occasions has the Feb total been lower.

02-03-07 Small lightning show.

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A weak front bought a nice little lightning show on the evening of the 2nd. Unfortunately no significant rain accompanied the front except for 3mm at Noarlunga from a cell that died as it crossed the coast. Right - Radar snippet of the cell that gave Noarlunga 3mm I managed just 0.5mm from the dregs of the cell which dried as soon as it hit the ground. Yet again another rainfall failure at this location! BUT it was moderately electrically active with beautiful sharply defined strikes in clear and good visibility conditions. I was at Victor Harbour at the time and snapped a few pics from the Bluff overlooking Encounter Bay. The images can be viewed in THIS ALBUM.

23-03-07 Another rain flop.

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System after system drops big rains over the north extending as far south as Adelaide's northern suburbs. Meanwhile down south the weather remains dry as a bone and for the first time in the history of the property our dam dries up (see some pics here). Then finally the potential of rain enters the forecast. See GFS forecast image below right.

Could it be that the we may finally see a decent drop? As the rain band approached fed by a huge tropical infeed from the north reports of heavy rains and flooding came in from the west coast. Even the press got in on the action calling this "the season break". Well it arrived in Adelaide a little late, but down came the rain. Totals grew and pretty soon most of metro Adelaide and foothills had near 15mm with one or two spots above 20mm! But what of Meadows and yours truly's location I hear you ask? Well the radar image below tells the story....

The red line signifies the direction of flow and the red dot shows my approximate location. The rain band split north and south as it rocketted overhead and continued to do much the same as shown in this radar snippet for much of the passing of this band. Extremely frustrating! By the end a nice 8.6mm had fallen at my location which is the most rain for 61 days. However yet again the best falls went north and this time south, not mention east and especially west. Even the mallee recorded nearly double my drop. This is becomming a disturbing trend, (go back through the events and this is obvious) Flop after flop. As we approach the 4th month of the year you have to wonder just when my area will manage to get a decent rain like everybody else has managed to score already in 2007? Any wonder the dam is dry?

UPDATE... The state rain map to the right well illustrates the large reduction in rainfall intensity that occurred in a narrow line in the central districts. (red arrow indicates the location in question) As indicated in the radar image above I am placed directly in the middle of this zone. Disturbingly this is becoming a trend for many in this zone and the deficiencies are visible as you drive through the area and see empty dams, dams that no longer fill after winter rains and poorly flowing creeks. It is also interesting to note that this lies in direct line with the northern coastline of the "foot" on Yorke's Peninsula. In such NW rainband flows there may be some moderate "stream" effect as is described in these pages by Ian Holton.

28-03-07 Southern Hurricane?

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An intense and powerful low pressure developed far south of the Australian mainland that culminated on the 28th March with the first ever hurricane wind warning for Southern Australian Waters! The Bureau of Meteorology issued this warning HIGH SEAS WEATHER WARNING FOR METAREA 10 ISSUED BY THE AUSTRALIAN BUREAU OF METEOROLOGY, ADELAIDE AT 0111UTC 28 MARCH 2007. HURRICANE FORCE WIND WARNING FOR SOUTH EASTERN AREA SITUATION AT 280030 UTC Low 968 hPa near 45S133E, expected near 46S135E at 280600UTC, near 46S137E at 281200UTC and near 47S140E at 290000UTC. AREA AFFECTED Bounded by 33S129E 39S141E 50S141E 50S129E 33S129E. FORECAST Clockwise winds 35/45 knots around low, increasing to 45/60 knots within 350 nm of low until 281800UTC and increasing further to 60/70 knots within 200nm of low until 280300UTC. Very rough seas, rising to high to very high within 350 nm of low until 281800UTC and to phenomenal within 200nm of low until 280300UTC. Heavy swell.

Above - satellite image of the low. Click for an animated loop

It is one of the most northerly cases of an "Ultrabomb" or "superbomb". What does this mean? To quote from Swellnet as written by Stuart Coombs of the BOM and Alex Zadnik.

"While a bombing low is defined as a drop in central pressure of 24hPa over 24 hours, a 'superbomb' or 'ultrabomb' takes into account the strength of the winds based on latitude, which is expressed in 'bergerons'. In order to upgrade the classification of a bombing low to a superbomb or ultrabomb, the intensification rate must be greater than 2 bergerons. "According to the official charts, this system comes in at 2.07 bergerons at 40 degrees south in the 24 hours ending 12UTC yesterday" said Stuart. There's a marked difference between bombing lows in the polar regions compared to the mid latitudes, with wind strengths in the polar regions usually exhibiting less strength (from a comparable pressure drop) due to the effects of latitude."
Copyright Swellnet, Stuart Coombs and Alex Zadnik.

Incredible winds to 80 knots (148 km'h) have been recorded around the lows centre! Huge swells pounded Southern Australias coast as a result.

Read the whole amazing story on SWELLNET.

Terribly Dry down South?

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The first days of April 2007 sees the extended dry in Southern SA start to show some disturbing visible effects. Stands of high rainfall stringybark scrub in the southern Mt Lofty Ranges from Belair National Park to Cherry Gardens to Meadows are under what is likely severe water stress. When viewed from afar the forest canopy is a patchwork of recently dead trees, their yellow and brown leaves smearing the normally green skyline with these unhealthy colours. This is something both I and other locals have never seen happen before in such a widespread and prolific way.

For me the last truly significant rain was in mid july 2006 a ridiculous 8 months prior. Winter 2007 will need to break all records just to begin the "repair" process to the southern ranges.

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