ASWA Victoria - December 1999 Forecast Outlook, Discussion & Report Page


Updated 2320AEDST - 28th December 1999 - J ONeill
December 1999 Forecast Outlook, Discussion & Report Page ASWA Victoria
Date	Name	Information
28	Rod Aikman (Bendigo - report for 27/12)	Just before 14:00 congestus towers began to sprout upwards, and storm development looked imminent. I hopped in the car (the bike actually stayed in the shed yesterday) and drove to the Lightning Hill lookout at Eaglehawk. From this vantage point a decent looking storm could be seen to the southwest of Bendigo; there were also storms to the northwest and north. I decided to chase the storm to the south west, as this one looked to be the closest. I headed of towards Maldon, however the storms to the north looked more promising so I then decided to head towards Marong. I ran into heavy rain at Lockwood. By this time I was facing a dilemma, as storms were sprouting up all over the place. I then decided to head back towards Maldon, where I figured that I would actually cut in at the rear of this storm, which I actually did between Lockwood and Maldon. There was no organised updraft or any thing of the like at the rear of this storm. I then proceeded to Mt Tarrengower to to hopefully get a good view of all the district. From this point it was evident that the storms were very widespread, however because there was so much low cloud about, the tops of the storms were not visible. It was becoming evident that all the storms in the area, whilst producing heavy rain, were rather featureless as far as any other phenomena were concerned. There was no strong wind or hail. It seemed that none of the storms in this area at least, exhibited much organisation at all. I then decided to head back home as a rather nice looking storm looked to be over Bendigo. On returning home I encountered the usual heavy rain as I drove into town. The heaviest deluge was actually to the east. About this time every thing seemed to dissipate into a rainy cloud mass, as light rain continued for about another 2 hours.,
23	Clyve Herbert	High west of Tasmania is strengthening & a weak pressure surge pushed through western & central Victoria overnight. This will have the effect of pushing thunderstorm activity to the east of Mansfield along the divide. Although isolated activity may develop to the east of Melbourne this afternoon / evening, this is more likely tomorrow. A deepening trough can be expected on the Christmas weekend with widespread showers and storms with the likelihood of locally heavy falls particularly on the ranges, also west & central areas on Saturday, more generally on Sunday. The chance of a cutoff low developing over this weekend may lead to widespread rain in the Gippsland area on Sunday & Monday. A cooling trend is expected Monday through to Wednesday, with high pressure building west of Tasmania & a trough continuing to effect NE NSW & eastern Queensland during that time.
22	Clyve Herbert	Trough developing from SW Queensland through NSW & into northern Victoria & probably moving into western Victoria. Anticyclone is undergoing thermal splitting with a ridge persisting to the south of Tasmania between the 2 centres. Trough should continue to deepen for the next 2 days with a marked inflow of moist air into Victoria from the NE. Upper levels remain quite cold especially at 500 & 300hPa with risks of scattered showers and thunderstorms along the divide (mostly east of Ararat) with isolated heavy falls in the east of the state. Showers & thunderstorms should become more general on Thursday, although mainly on the ranges & with frequency increasing & probably becoming more widespread late Thursday & during Friday. Risks: storms becoming possibly locally severe late Friday. Potential: cut off low developing to the north of Melbourne during the Christmas weekend which may bring general rain & thunderstorms with the risk of substantial rainfalls.
21	Andrew McDonald	Tomorrow (Wed) we'll see thunderies on the ranges to the E as the BoM say with the wind coming from the ENE bringing in nice amounts of moisture over the ranges. LI's of about -2 over the far E support this development. Thursday will see a warmer day in Melbourne with the wind tending more ENE and the humidity will increase gradually as the week progresses. The trough will approach the N of the state with chance of thunderies in the N of the state and on the ranges to the E - slightly closer to Melbourne this day. LI's are more likeable too. Friday things start to get interesting with LI's of about -2 at 11am across much of Vic with the N half of the state down to -3. Thunderstorms should become more widespread in the N and W and some may extend off the ranges from the E over the outer suburbs of Melbourne (like me!!!). By 11pm Friday night LI's are down to -3 to -5 across most of Vic. Saturday (Xmas Day) will see thunderstorms in all districts with LI's of -3 across Melbourne at 11am. Once again the wind will be from the NE and full of moisture - the air could be explosive (I'm expecting DP's in the high teens by Saturday!). BoM are going for 26C in Melbourne which could see some strong - severe thunderstorms but if the temp gets up nearer to 30C we could see a decent outbreak of severe thunderstorms!!!!!!!!!!!!! Sunday the cut-off low (which develops in NW Vic sometime Saturday) will move across the state - the timing of this is very important as to the chances of severe weather on this day. One of the models had it coming across Melbourne late on Sunday night (which I think is a little later than it will happen - I'm thinking late arvo). This could still give the opportunity for some great storms. I'm going for a temp of about 25C before the change with thunderstorms clearing later in the day!!!!
21	Blair Trewin	All models show a trough of varying intensity edging across Victoria between the 24th and the 27th, with GASP and the EC both now having closed lows on the trough in its later stages (GASP has formed its by the 25th, the EC on the 26th). The EC has a low on the 27th in about the same location as the one on the same date last year - but about 30 hPa higher in central pressure!
19	Clyve Herbert	Looks like the upper cold pool east of Canberra has similarities to the one prior to April 14. Appears to be a slight risk of locally severe storms up through the Illawarra, Sydney & Central Coast of NSW today & this evening. Would be interesting to check the flow patterns at 600 & 300hPa.
15	Clyve Herbert	Although the air mass over Victoria is relatively dry, and the convective temperature is probably in the mid-30s (or less on the divide), there is a risk this afternoon of isolated showers and possible thunder, particularly along the divide and west-central district. More moisture in the east also means a higher probability of storms. The trough, due through tomorrow morning will be the favoured area for activity, particularly in the east & north. Moisture injection from TC John into the trough leads to a risk of rain areas and enhanced convection along the trough line. Risk of severe storms east of Warrigal with possible hail during the afternoon - the risk is expected to extend to the divide later this afternoon. Trend: the high will push into the Bight & the trough will linger over NSW & southern Queensland. This probably means that there will be a moist S /SW airflow effecting most of the western & southern parts of Victoria to the end of the week. The remnants of TC John will probably be caught up in the upper jet and move across northern Victoria and southern NSW.