ASWA Victoria - March 2000 Forecast Outlook, Discussion & Report Page

Updated 1015AEST - 30th March 2000 - J ONeill
March 2000 Forecast Outlook, Discussion & Report Page ASWA Victoria
Date	Name	Information
30	Clyve Herbert (NMP Forecast)	Interesting aspects to the current synoptic situation. Over recent days there has been an almost spectacular cloudband extending from the Indian Ocean to Australia. This is a major moisture infeed to our locality. The synoptic conditions developing over the Australian region today with the high pressure system moving well south of WA, continued upper level jet over WA, are pointing towards the possibility of a moderate to good rainfall situation developing over south eastern Australia over the next seven days. Although this is early at this stage, the developing changes in the synoptic scale are different to what we have seen for many months especially for Victoria. Summary of developments: anticyclone well south of WA in a position to assist in the movement of cold air northwards towards Australia, the infeed of middle and upper level moisture from the Indian Ocean - the interaction of this development may result in major cyclogenesis potential over the southern Australian region. Also watch for a strengthening long wave trough over WA & SA and south eastwards into the Southern Ocean.
27	Clyve Herbert	Large area of middle & upper level cloud associated with upper jet over South Australia extending into Western Victoria today. Strengthening ridge into the western Bight area tonight should send pressure surge towards Victoria tomorrow. Risks: general light rain extending to most parts of Victoria especially the western & mountain areas tonight & tomorrow. Possibility of moderate totals in areas where light rain is prolonged.
22	Clyve Herbert / Jane ONeill	Interesting flow pattern across Victoria today preceding the trough & front - speed declines with height. 50knots at 925hPa declining to less than 25knots at 300hPa. Unusually there has been very little mixing down from 850hPa and this has meant that temperatures have not climbed as far as expected & the 850hPa temperature gradient preceding the front has held its steepness. Could become rather interesting before the front gets to Melbourne sometime around midnight.
22	Clyve Herbert	Cold front & associated trough expected to enter western Victoria tonight. Moisture loading of this prefrontal northerly is quite good. Front should cross Victoria tonight and tomorrow. Risks: trough & front should be accompanied by widespread showers, possibly heavy (mainly in the west along the ranges). Notes: the northerly airstream has been effected by several days of rain over interior NSW. This is not a situation that is overly common. Convective activity and orographic forcing of this airstream over the divide may trigger some showers through the day with a slim chance that some of these may spread into southern area.
18	Jane ONeill	ASWA meeting - 18th March 2000 - Pancake Parlour, Doncaster
17	Clyve Herbert	Trough and cold front approaching Victoria. Favourable alignment of the upper trough and jet with the cold front. This is favourable for a large scale uplift situation - there is no shortage of moisture in the middle and upper layers, although the system may weaken as it moves east as it encounters the east coast ridge. Risks: general light rain across across Victoria late Friday & Saturday, scattered moderate falls possible particularly about the ranges, isolated heavy falls mainly near the NE ranges, also the risk of isolated heavy falls near thunderstorm activity elsewhere. Footnote: the strengthening of the upper jet and combination with atmospheric moisture may lead to enhanced falls across the NE high country due to orographic effects.
9	Clyve Herbert	Interesting observations - Central Victoria midday. Cirrus moving from approx 45deg at up to 80knots - rare for Victoria. Probably reflects the deepening upper low north of Mildura & a vigorous surface low south of Sydney. Keep an eye on it! Risks: moderate / heavy rain in East Gippsland - some possibly extending as far west as the east central district, although there is marked subsidence over western Victoria at present.
6	Clyve Herbert	Vorticity west of Sydney looks interesting. Also an upper feature south of Broken Hill. Potential: low pressure system developing east of Sydney & intensifying. Risks: moderate to heavy falls along central & southern coast of NSW. Other possibility is that the system may be slow moving and attracted to the upper feature near Broken Hill. Looks like Steve will move south and provide a massive injection of moisture across WA, which could cause further problems for areas which have already received record falls of rain this summer.
5	Clyve Herbert	Thunder probability in Victoria for Sunday 5/3/2000: NE Victoria: between 4/10 & 5/10 rest of Victoria: 1/10
5	Jane ONeill	With the further development (since 29th February) of the jet surrounding the low pressure area analysed at 300hPa currently moving south over the coast of N NSW, and the surface area of low pressure in the Coral Sea beginning to mirror the 300hPa low in its southward development - I think we may be in for a fairly intense east coast low developing off the coast east of the Sydney - Newcastle area. The 300hPa jet currently across southern NSW will strengthen and aid in the development of this system.