Victoria - August 2001 Forecast Outlook, Discussion & Report Page



August 2001 Forecast Outlook, Discussion & Report Page Victoria
Date	Name	Information
		September Forecast Outlook, Discussion & Report page
31	Harald Richter	One of the more potent extratropical cyclones is slowly tracking E. It is currently centred just S of C SA. Its surface pressure signature is one of the best I've seen over the last few months, with a core pressure of less than 996 hPa (N of 35 S), and widespread pressure falls throughout all of E AUS. This morning's MML sounding showed that only a minimal amount of incoming solar radiation would create a well-mixed layer from the ground up to about 700 hPa (~ 3 km AGL). The convective temperature has been reached by now, and a moist 800-700 hPa layer is providing most of the juice for the high-based convection that has started over parts of S VIC. With the synoptic lift ahead of the low I would expect the sounding to cool further aloft, which would open the gates for deeper convection. Enough for thunder? Maybe, the primary limiting factor is poor low-level moisture in Melbourne. If a stout NEly continues to blow into NSW/QLD we might see better convection there as the low moves further E. Back from hibernation, and watching...
30	Andrew McDonald	I had a look at AVN and other models with Anthony today over lunch and we came to the conclusion that the best activity (going by current model runs - hopefully it will change) will be in the NW of the state around Swan Hill but given the complete lack of shear things aren't going to be that interesting anyway. Sunday on the other hand is a lot more interesting if you live in Sydney or north of there. Personally I like the look of the Hunter. Shear is very nice with a tasty 130knt jet over them and 45knts at 500 and nice N to NE'ly inflow at the surface.
29	Michael Thompson (NSW)	The coming weekend is one that all the models cannot seem to agree on. They all agree on a cold pool of air over VIC/NSW, but differ widely on position or whether a cut off low will form. Several models have a cut off low, but one has it passing over inland SA/NSW, another has it forming off the north coast. Other models do not even have it at all. It could be an interesting weekend or a dull one depending on where you live. One thing I notice is the massive body of cold air the south of Australia, not dissimilar to situation Clyve mentioned some time ago. Now if we could get the weather equivalent of a conveyor belt in action we would be looking at widespread snowfalls. Winter may be a long way from over yet.
27	Nick Sykes	I almost thought I was looking at the models from last week when I looked at GASP and EC this afternoon. GASP has a very similar system to the one that has just occurred, recurring this coming weekend. It doesn't have the deep low off the east coast, but sets it up with a strong upper level low. EC has a deep low in eastern Bass Strait on the weekend, bring it on. Will be following this systems development on my web page: www.vicstorms.com (model talk)
26	Laurier Williams (NSW)	I've just noticed that both LAPS and meso-LAPS 00z run move the cold pool to just west of the Blue Mountains by 10pm tonight, before regressing it back to around Wagga by 10am tomorrow, then have it over the southern Northern Tablelands tomorrow evening, maintaining a central thickness around 5350 the whole time. The coldest part of the state at 5pm, on potential temperature (i.e. reduced to 1000hPa) was an oval shaped area between about Cowra and Albury. The overall stagnation of the trough and low are a significant feature of this system -- also the surface wind circulation at 5pm was centred on Melbourne even though there's a clear low pressure system in east Gippsland -- I think this is what you commented upon, Jane, in an earlier posting.
26	Jane ONeill	Radar (in particular the 128km loop) is showing a very interesting circulation over central Victoria - ie: it looks like a low is planted just to the NW of Port Phillip Bay & associated low level instability has increased over the past few hours. They now have isolated Cb's forecast with tops to 28,000 E of 148E....... Keep an eye on the cloudband associated with the storms off the coast of NSW too, things could get interesting later on with all of the tilting going on & the blocking effect of the high in the Tasman Sea - this low is moving as slowly as a dry week......... http://www.cita.utoronto.ca/~rjh/melbourne/satellite_big.html Pressure's down to 1002 & the wrap around is affecting W Victoria - Hamilton has had 16.2mm since 9am this morning. Stay tuned...
25	Nick Sykes	Looking at the latest models it looks like a substantial rain event will developing through the SE of Australia Sunday/Monday. The models have a low forming somewhere from Bass Strait to the NSW Coast. The positioning of the low and resulting wrap around bands will determine where the heaviest rain will occur. A worry is the west Gippsland region which has had some flooding over the last week because of the series of cold fronts. If they get heavy rain some good falls may occur. Atm it looks like the region between Cape Otway and Gippsland is favoured for heavy rain, including Melbourne.
21	Clyve Herbert	An interesting line up of cold CBs west of Tasmania this morning moving rapidly northeast, they seem to be lined up along a vigorous trough and cold front with their leading anvils pointing to south Gippsland!, there is also a respectable amount of mid level cold air with this system and all of this should intensify as the whole kit and caboodle trundles across the relatively warmer waters of Bass Strait later today and tonight , looks to be favourable for another batch of cold air thunderstorms near to coastal Victoria. So batten down the hatches all those in lucky Wonthaggi and the coastal fringes of Victoria. Looking good for some prefrontal orographic snow dumps too over the Vic Alps.
16	Laurier Williams (NSW)	Lots of wind, dramatic barometer falls and temperature changes as the front moves through Vic and NSW, but not much else. Highest gusts today to 8pm: Mt Hotham Vic: 133km/h at 7pm at the airport (suspiciously high), 128 at 6pm on the summit. Cape Grim Tas: 126 at 7pm Thredbo Crackenback NSW: 121 at 9am Mt Wellington Tas: 117 at 9.30am Neptune Is SA: 115 at 12.03pm and 4.29pm Maatsuyker Is Tas: 113 at 11.36pm Mt Buller Vic: 113 at 5pm Cape Nelson Vic: 111 at 5.22pm Deniliquin NSW: 109 at 5.22pm with the change Gellibrand Vic: 109 at 5.27pm Portland Vic: 108 at 8.04pm Cape Otway Vic: 102 at 7.04pm Strahan Tas: 100 at 5.07pm Warrnambool AP Vic: 100 at 5.27pm Eildon Vic: 98 at 4.20pm Hamilton Vic: 98 at 6.28pm Avalon AP Vic: 98 at 5.24pm Port Fairy Vic: 96 at 4.12pm Swan Hill Vic: 96 at 6.20pm Edithburgh SA: 93 at 4.40pm Here at Blackheath the wind has picked up noticeably in the past hour -- Mt Boyce now reporting average 54km/h gusts to 95km/h Most places from central NSW south have been reporting 3-hourly pressure falls between 5 and 7hPa at the past few observations, and 6pm Griffith was reporting a temp of 25.9 while Deniliquin, 170km SW, was reporting 12.6. A very dynamic thermal front, so no wonder there's wind and pressure falls. Latest GASP continues to be interesting into next week, with sub-530 thicknesses over southern Victoria Tues to Thurs, and the 540 line well up into NSW, and lots of precipitation in the south. Last night's EC and this morning's MRF and NOGAPS are a little warmer, but all three go for the low to move south of Tasmania and stop, then spawn a succession of secondaries which dumbbell around the main low through the week, shooting colder air north over Tasmania and into Victoria and the southeast. The devil will be in the detail, but the broadscale pattern looks pretty promising. The NSW BoM has sleet in the forecast for the Central Tablelands, and snow to 1000m on the Southern Tablelands for tomorrow and early Saturday. I'd say there's a good chance of snow flurries in the Blue Mountains when the front comes through tomorrow morning, and possibly with the second front tomorrow night, while the Oberon area should at least get some snow cover.
16	Greg Stewart	Mildura was warm today it's currently around 14 'out the back'. The front arrived at about 3:20 or so, the temp had dropped to about 17 by 4:30. ON my trip home there were two 40 - 50 cm diam. trees snapped at the bottom, lots of debris and lo and behold the old tree had blocked my drive. No rain to speak of.
		Melbourne Real Time Temperature Observations Graph Melbourne Real Time Rainfall Graph Port Phillip Bay Wind & Temperatures
16	Blair Trewin	The 1500 bulletin makes interesting reading in the Mallee - the front was obviously somewhere between Walpeup and Ouyen at 1500 (Walpeup is 30km west of Ouyen), because Ouyen was reporting 21 and dust, and Walpeup 14 (with DP 14) and rain. Lots of warm temperatures ahead of the front - in Victoria Mildura got to 28, and further east, 25 at Lakes Entrance and 24 at Orbost. Numerous records for early-season warmth have been approached, but none broken that I've seen (yet). Canberra's rounded max was 20 - if it made it to 20 this would be their earliest-ever 20 (previously 18/8/ 1995), but based on the hourly obs I suspect they may have fallen just short.
16	Laurier Williams (NSW)	There have been a few strong gusts recorded this morning: Mt Hotham 126km/h at 7am Thredbo Crackenback 121 at 9am Mt Wellington 117 at 9.30am Maatsuyker Island 113 at 11.36am Mt Buller 109 at 8.30am Falls Creek 96 at 11.30am Mt Lofty 93 at midnight Also of note is that Crackenback reported 10 minute average speeds of 102km/h at both its 8 and 9am reports. All the snow is melted in Thredbo Village, with a 9am temp of 9C.
16	David Jones	For those Melbournian like myself who woke up warm last night.. the graph below shows exactly why http://www.earthsci.unimelb.edu.au/~awatkins/melbtemp.html Interestingly, the 850hPa temperature over Melbourne was around 13C, which would translate to a mid to high 20s day temperature with full sun (concurs with the 33C at Eucla yesterday). Quite amazingly, there was a significant scrub fire last night in Traralgon (Gippsland), a place which should be sodden this time of year. BTW the latest batch of progs, while backing off a bit for tonight's front (thickness values over Victoria bottoming near 530 - read snow to about 600m), are ramping up the follow-up sequence of fronts. It might be 10 weeks late, but it looks like winter might be about to arrive in the SE.
16	Clyve Herbert	Impressive thermal trough (cold) at 500hpa extending from near Albany to almost the Antarctic, and edging eastward. This large cold air field is one of the best I have seen in the Australian region this year, lets hope it will keep together, also a remarkable thermal contrast across the complex troughs over the eastern Bight region should see the potential for strong pressure falls west of Tasmania and south of Adelaide over the next 6 to 12 hours.
15	Clyve Herbert	Apart from the impressive and huge cloud band across southern Aus, a rather interesting paddock of cold air has moved from the 'black abyss' into the southwest Aus Bight, this area of cold air has some possibilities, although at the moment seems to be a little too far south but worth keeping a close look at. Judging by the large scale CB development in that area I wouldn't be surprised if sea surface temps over that region are close to freezing.
13	David Jones	The latest 00Z GASP run has dug up a near classical cold outbreak for SE Australia on Friday. The 00Z run shows an 850hPa temperature over Melbourne of around -5 with a thickness of ~522gpdm Friday 10am. This is promptly followed by a significant warm-front on Saturday (well the closest we Victorian get to see) with a warming of nearly 7C at 850hPa, then a second cold-outbreak on the Sunday with 850hPa around -5C by Monday morning (thickness values ~525gpdm). The Friday cold-outbreak is nearly optimal for heavy snow to low levels in Victoria with the coldest air coming through in the early morning hours, and a substantial southerly component to the winds (often we see westerlies or northwestlies) leading to rain-shadowing of much of the state. For those unfamiliar with thickness values, a value of around 524-6gpdm is the typical rule of thumb cut off for snow to ~ sea level. Probably as remarkable as the low temperature following the fronts is the warmth ahead. On Thursday, the 850hPa temperature is progged to reach 11C over Melbourne, WHICH could feasibly give a maximum of about 26C.... but with the expected cloud, rain, and bad timing of warmest air (early morning) will probably see something closer to around 18C. The alpine AWSs could be interesting to watch as these should see a change of around 15C with the front... with rain changing to snow.
8	Clyve Herbert	A very decent pressure gradient over Victoria this morning, with Wangaratta reporting 1013hpa and almost due south Wilson Prom displaying 998hpa and 55knott winds . With yet another small tight little low unsettling the dust over northern Tasmania, also rather cold at 500hpa close to -27c, and it looks as though the sequence of events is not over with yet another cold front due later Thursday. For the snow lovers this is great stuff orographic loading over the North-eastern high country and the Snowys should see plenty of depth accumulation today and later Thursday.
6	Clyve Herbert	There was an interesting but small cold pool just west of the front near Esperance this afternoon, there is a marked thermal contrast across the front which seems to be holding, with some warm advection at 850 to 700hpa tomorrow and a little cold advection between 500hpa and 300hpa - this front has similarities to active frontal bands that produced isolated cold season tornadoes last year.
6	Nick Sykes	Nice front in the bight atm. Looks like SA and Vic could be quite interesting the next couple of days. GASP has thickneeses down to 533 over Vic on Weds. Tracker is currently showing lighting in the bight. Some nice gusts up to 100km have been recorded with this front's passage so far.
4	Robert Goler	Analysis of the Odd Baroclinic Leaf over SA
4	Laurier Williams (NSW)	It has some intriguing leaf-like features and very sharp discontinuities that are hard to explain, especially the "map of NSW" shaped feature over the Nullarbor Plain and the long but very narrow clear slot to its south.
4	Jane ONeill	Images of the baroclinic leaf
3	Clyve Herbert	At last things are looking better for Victoria and Tasmania over the next few weeks with what seems to be a pending procession of fronts troughs and cold air outbreaks!. An interesting and unusual prognostic chart from the Mel BoM showing a developing high over the southern Bight area with lows 'piggy backing' across the top. A rather odd looking' half 'of a baroclinic leaf moving across the Eyre Peninsula SA at the moment. A rather striking eastern edge to it .
2	Blair Trewin	It will come as no surprise to snow-watchers that June and July have been abnormally mild in parts of SE Australia; whilst June 2001 was generally somewhat cooler than June 1957 and 1991, and July 2001 cooler than July 1975, the combined two-month means were notably high in both Melbourne and Sydney. For the two-month period: Melbourne max 15.2 (equal 4th; record 15.5 in 1957) min 8.8 (highest on record; previously 8.7, 1991) mean 12.0 (highest on record; previously 11.9, 1991) Sydney max 18.7 (2nd; highest 18.8, 1921) min 9.9 (nothing too exceptional) mean 14.3 (2nd; highest 14.5, 1988) In addition, Hobart did not have any sub-10 degree days in July (although it did get one yesterday!). This is only the second such July (after 1930).