December 2000 Forecast Outlook, Discussion & Report Page

Victoria

Information

Hello all weather watchers.

A slow moving high pressure centre west of Tasmania is the main feature affecting south-eastern Australia ( 29.12.00 ) - this high pressure cell will very slowly weaken over the next 3 days as it "amoebas" eastward just to the south of Tasmania and into the south Tasman Sea by later Saturday or Sunday.  A major trough should clear the eastern side of the continent overnight Friday and Saturday. The far northern portion of this trough however looks rather interesting and appears to be showing a tendency to stall over the far north of QLD on Saturday and Sunday, there is also some weak divergence at 300hpa to the north of this tropical disturbance - interestingly this area of tropical surface convergence has persisted for a number of days and originated from the remains of tropical cyclone Sam.

Elsewhere in Australia most of the interior is experiencing mainly fine conditions under the influence of a rather strong upper ridge extending from Victoria to the west of Alice Springs - this upper ridge also has rather dry air near the surface.  A trough moving through SA Saturday and Sunday is rather weak and should reach the southeast of Australia later Sunday and Monday and remain a slow moving feature during its journey.  A high pressure system in the south Indian Ocean extends a ridge to the southwest of WA -  this ridge should remain rather weak.  A small new high should bud off this ridge later Sunday or Monday to become centred in the Australian Bight area.

TEMPERATURES......The prolonged cold spell over south-eastern Australia is now coming to a close and a warmer trend is expected from Saturday with progressively increasing temperatures to at least next Tuesday.  Very cool conditions will linger in Tasmania to at least Sunday a few frosts can be expected over inland Tasmania Saturday and Sunday. The north of Australia will see above average temperatures for most of the outlook with hot conditions moving into SA on Saturday. The southwest of WA will remain mild until Saturday and then warm to hot conditions will redevelop from Sunday as a surface ridge builds to the south of that state. The east coast of Australia will experience mainly average temperatures with a warming trend from Sunday.

RAINFALL......The only areas showing indications for heavy rainfall is the east coast north of Cardwell and the Cape York Peninsula. Some very heavy falls are possible over these regions on Saturday and Sunday with the possibility of some flooding.   No significant falls appear likely for the remainder of Australia at this stage -   the trough over SA will only move slowly over the next three days and a few afternoon showers should develop near to the trough line, as this trough moves into south-eastern Australia later Sunday,  a better moisture supply should see showers and the odd storm develop over the mountain regions of Victoria and NSW with the risk of more general storms on Monday and Tuesday.  A heat trough should also persist over eastern QLD with a few storms over the southeast and central divide of that state. The upper ridge will suppress storm activity over the Top End of the Northern Territory and the Kimberley region on Saturday and Sunday but activity should become more frequent again by Monday.

RISKS.....The area of convergence over the Cape York area continues to be of interest and should be watched over the next 24 to 48 hours..

A VERY HAPPY NEW YEAR FROM THE TEAM AT GEELONG WEATHER SERVICES

Regards from Clyve Herbert and Lindsay Smail.....(NMP)

Merry Christmas all weather lovers

A mid latitude westerly surge affecting south-eastern Australia and all of Tasmania is the main feature today Monday 25.12.00. These conditions are reflecting an active period of mid latitude cyclogenesis to the south of the Australian continent. There is however some sign of change over the next five days. The large and slow moving high southwest of Albany WA continues to push a ridge to the Australian Bight - this ridge is being eroded over south-eastern Australia due to surface heating over interior NSW and this will continue to be the case. The large high southwest of Albany appears to be now building a ridge towards the Southern Ocean and is also showing a favoured eastward movement at relatively high latitude and should move to the south of WA on Tuesday at about 40 south. Meantime a deepening heat trough will become more prominent over WA extending from the tropics to the far southwest coast; this trough should move slowly eastward over the next five days. The movement of the high to the south of WA will reinforce a push of cold air towards south-eastern Australia later Tuesday with a cold front passing across Tasmania southern Victoria and into the southern Tasman Sea by Wednesday.  A stalling trough over northern NSW and southeast QLD will extend southward ahead of the cold front later Tuesday and Wednesday.  A tropical disturbance over the Top End of the Northern Territory still has some potential and should continue to be watched over the next 36 to 72 hours.

TEMPERATURES......The whole of WA should become hot to very hot over the next three to five days, some very high to extreme temperatures are possible west of a line from Port Headland to Kalgoorlie on Tuesday and almost everywhere on Wednesday and Thursday, this heat should slowly extend into northern and western SA during the week. The tropical north should see seasonal very warm to hot conditions although theTop End of the NT will be a little below average due to high moisture and rain.  Southern Victoria and southern SA will experience below average temperatures over the next several days and Tasmania will see very cool to cold temperatures with near freezing conditions over the central and southern high ground over the next two days although milder air should gradually become established later in the week.

RAINFALL.....Areas favoured for significant rainfall are the Top End of the Northern Territory - some very heavy falls are possible here with some heavy totals moving westward to affect the northern Kimberley regions later in the week. The west coast and mountain regions of Tasmania may receive moderate to locally heavy totals over the next several days.  Isolated heavy totals are also possible over south-eastern QLD and northern NSW due to thunderstorm activity, a few storms may extend southward into central NSW later Tuesday and Wednesday.  A few showers will affect the far southeast of SA and mainly southern and mountain regions of Victoria Tuesday and Wednesday. Local afternoon showers and high based storms will develop in the vicinity of the trough over WA over the next several days.

SYDNEY TO HOBART YACHT RACE.....A trough should develop southward through inland eastern NSW on Tuesday - this may see the development of light to locally moderate northeasterlies during Tuesday morning, however a cold front and following pressure surge should reach Tasmania and western Bass Strait later Tuesday preceded by strengthening northwesterlies. This cold front should then move towards eastern Bass Strait overnight Tuesday and into Wednesday morning followed by fresh to strong southwesterlies and increasing cold, especially over open waters of eastern Bass Strait.  Showers should accompany this cold front. Leeward of the Tasmanian mainland, winds should be lighter but watch for possible afternoon seabreeze effects inshore. The movement of the high pressure system now moving to be near 40S, south of Albany,  may result in the development of a more southerly flow pattern especially on Thursday - also watch for the risk development of a low in the cold air field east of Tasmania later Wednesday or Thursday which may increase the potential strength of a south/southwest flow.

RISKS ......A watch should be maintained on the tropical and persistent disturbance over the top end of the Northern Territory.

Clyve Herbert and the Geelong Weather Services Victoria Australia (n.m.p.)

Hi all weather enthusiasts.

The persistent baric ridge across the southern coastline of Australia over the past few weeks has temporarily broken down today (Friday 22.12.) with a deep trough and a strong moisture plume extending from the far northern tropical areas of Australia.This system has brought significant rainfall to parts of southeastern Australia, however a strong and slow moving high in the south-eastern Indian Ocean is now pushing a moderately strong ridge to the head of the Australian Bight and this process will continue over the next several days,a new high should develop over the northern Bight area on Saturday,the baric ridge should then build along the Victorian coastline. The trough moving through south-eastern Australia Friday and Saturday will weaken and slow down over inland northern NSW and then possibly stall over south eastern QLD on Sunday.  Weak fronts will pass across the southern coastal fringe of SA Victoria and all of Tasmania.

TEMPERATURES....A cooler trend is anticipated for south-eastern Australia and highland areas of Tasmania will become cold over the next several days.The remainder of Australia will experience seasonal warm to hot conditions with increasing more extreme heat over WA towards Sunday and Monday.

RAINFALL.....Areas favoured for moderate to good falls are the west coast and mountains of Tasmania and the top end of the Northern Territory, some very heavy falls are possible over parts of the Northern Territory especially north of Daly Waters and near to the northwest coast.  Some patchy heavy falls may also accompany the trough moving through NSW and QLD over the next two days(Sat/Sun)

RISKS.....There is a persistent area of convergence from the western Gulf of Carpentaria to near Darwin, this area should be watched over the next 36 to 48 hours for potential development.

A very happy Christmas and New Year to everybody ....many regards Clyve Herbert and Lindsay Smail and the Geelong Weather Services Victoria Australia (n.m.p.)

The models all suggest this moisture will become sourced by the approaching front and upper trough, though personally, I'm a bit pessimistic about our chance of getting a major fall of rain (say 25mm+) as the amplitude of the trough looks to be peaking west of Victoria, and also west of where the best moisture interaction might be expected. That said, the models are all forecasting widespread falls in the 5-15mm range across Victoria for Friday, with locally heavier amounts near the ranges. Looking longer range, the models are suggesting the possibility of a quite substantial summer-cold outbreak for Tasmania around Christmas Day, possibly extending into southern Victoria.....

Hello all weather lovers.

Weak high pressure will continue to affect the southern coastal areas of Australia, the baric ridge will favour a line running from south of Albany, WA towards western Bass Strait then to the central Tasman Sea.  A weak trough moving through the south east of Australia today (Monday 18,12,00) will see the southern portion move to the south Tasman Sea while the northern portion will advance up the east coast of NSW and probably peter out before reaching the north coastal areas of NSW.  Meanwhile a remnant trough from this system will linger over inland NSW and then develop a heat trough southward to northern Victoria later Tuesday.  A developing heat trough over WA today should slowly deepen and advance towards south eastern Australia by later Wednesday and combine with a mid latitude cold front, then crossing south east Australia Thursday.

TEMPERATURES.....A brief cooler spell will affect the southeast of SA and Victoria today with warmer conditions spreading to most of eastern Australia by later Tuesday and Wednesday.  Inland parts of NSW and Victoria will become very hot later Wednesday with some heat spreading to Victorian coastal areas also especially on Thursday - the east coast of NSW will remain cooler but with humid north-easterly winds. Most of the remainder of Australia will experience seasonal warm to hot conditions throughout the period although SA will see very hot conditions from Tuesday with cooler air only affecting the far southern coastal areas from later Wednesday.  Parts of the Gulf country will be slightly cooler than normal due to high humidity and rainfall.  A cooler trend appears probable for south-eastern Australia from Friday.

RAINFALL.  Areas favoured for good falls are the region bounding the Gulf of Carpentaria and the north tropical coastal regions of QLD especially north of Ingham. Some very heavy falls are possible in these regions with the risk of further flooding.  The remainder of Australia will see seasonal storms over the Top End and through most of QLD and through the Kimberley region .  A developing heat trough over WA should advance towards eastern Australia during the week reaching the southeast of the country by Thursday - scattered showers and a few storms can be expected along the trough line during its progress.   A stalled trough over inland NSW from Tuesday should see a few showers and the odd storm affect inland NSW and possibly getting into north or northeast Victoria later Tuesday or Wednesday.

A Merry Christmas to all from the Geelong Weather Services Victoria Australia (n.m.p.).... regards Clyve Herbert and Lindsay Smail.