|
October 2001 Forecast Outlook,
Discussion & Report Page
Victoria |
| Date |
Name |
Information |
| . |
. |
Victorian Weather Glass |
| 31 |
David Jones |
With
the terrible conditions being suffered by those to our north
(HEAT/bushfires),
it is noteworthy that the cool drizzly weather today in Melbourne
caps a quite remarkable month of "miserable" weather in southern
Victoria
(particular the eastern half). In particular, for many stations in
Melbourne's
east, October will come in as one of the wettest Octobers on
record (at least
in 50 years). Among these, Scoresby with 51 years of records
breaks it previous October record by ~15mm, as does Dunns Hill by a
remarkable 110mm
(though record is just 7 years long). Many stations in Melbourne's
east easily exceeded 150mm for the month, with most stations
near the ranges
east of the city cracking the 200mm mark - Dunns Hill 246mm (an
estimate, as one days obs were missed), Mt Dandenong (township) 241mm.
My obs for Ferny Creek show 228mm. My back
of the envelope estimate is that monthly
rainfall totals of this magnitude are about a one in 2-5 year event
for any month,
and about 1 in 20-50 years for October. Still... these high values
pale against October 1937 (can't say I remember it... maybe Blair
does?), when
rainfall in these same areas exceeded 350mm (and likely 400mm),
only to be
followed by the driest November in approximately 100 years.
The progs hold out for a very pleasant
weekend in Melbourne (mid 20s Saturday,
higher 20s Sunday), then a return to cooler wetter weather next
week. Some
models (NOGAPS, ECMWF) are suggesting the possibility of further
significant rain
in the SE next week as the cloud over southern WA interacts with
a substantial mid/upper level trough next week, but this is a long long
way into the
future. |
| 25 |
Clyve
Herbert |
Victoria
is looking better today with increased instability, surface moisture
is higher and it's colder than yesterday above 700hpa to 400hpa, also
the low pressure system seems to be drifting east rather than south.
With a bit of heating things may become a little
interesting later today as a trough
associated with the low moves across the state. |
| 24 |
David Jones |
.....
yesterdays event was very well forecasted. The predictions of
heavy falls in the NE of Vic in particular came off very well with up to
77mm reported at Mt Hotham, and widespread 25 to
50mm falls covering most of Northern Victoria
and southern NSW east of Bendigo (http://www.bom.gov.au/hydro/flood/vic/).
Many rivers in this region are now near or at
flood levels (eg http://www.bom.gov.au/cgi-bin/wrap_fwo.pl?IDV36050.txt).
With further showers and thunderstorms in
coming days, and another rain event looking likely
for late on the weekend, things could get a bit interesting.
This is the
second October in a row which has seen good rains for Victoria, once
again going towards relieving rainfall deficiencies/"drought
conditions associated with poor winter rains.
Closer to
home, a further 27mm to report from Melbourne's eastern suburbs last
night (Ferny Creek) bring us to just short of 170mm for the month. Also
a stand-out for the month is how the Melbourne CBD
rain repellent is working as good as ever..
the city gauge recorded just 3mm, and sits on ~53mm for the
month (well below normal), while sites in the suburbs east and west are
above/well above average. |
| 24 |
Clyve
Herbert |
Nice
looking complex low south west of Mt Gambier at 0400,after the rain
band crossed Vic last night left us in a 'returning'
airmass of southern origin which is
conditionally unstable although lacking 'proper' moisture, nevertheless
as the trough over eastern SA moves in today there is some marginal
possibility of the odd storm popping up. |
| 23 |
Jane ONeill |
Video stills of the
formative stages & the latter stages of the Leopold tornado added to http://www.stormchasers.au.com/3_10_01.htm A discussion page for this event can be
found at http://www.stormchasers.au.com/0310discussion.htm |
| 23 |
Clyve Herbert |
Typhoon/hurricane
Podul has been a little odd since its early stages showing very
little serious movement except a slow northward drift, at midday today (Aus time) it has finally developed an eye and looks very intense,
still seems to be drifting slowly to the north. Podul's early
twin in the southern hemisphere can still be found at the top
of an upper mid level trough in the same Longitude. Podul has
developed good divergence aloft, in the early stages there
also seemed to be some interaction with an equatorward cold
pool low to the northeast. The sub tropical jet is well to the
north so Podul's is also well away from the shearing affect. It will be interesting to keep an eye on its progress, also, I noticed your area
missed out on that tropical disturbance that moved into North
Vietnam and Laos over the past two days. |
| 22 |
Clyve Herbert |
The trough running north
south through central Aus to SA has certainly stepped up in activity over the past 12
hours with some nice inflow of mid level moisture mixing in, should be ok for the eastern
states over the next 2 to 3 days, also noticed what seems to be a dry line running
north-south through inland QLD from near the Gulf area and southward into the interior. |
| 17 |
Jane ONeill |
Video stills of the
Leopold tornado added to http://www.stormchasers.au.com/3_10_01.htm |
| 13 |
Clyve Herbert |
Looks to be another area of vorticity
developing over se Aus this weekend with the large baroclinic cloud band over NSW which
seems to be taking shape. Still some cold air to mix in yet, although the 500hpa thermal
trough does not seem all that strong just to the west. |
| 12 |
TORNADO |
Here is the 1st large image of the
Leopold tornado (& there should be lots more to follow). All images that appear
of this tornado anywhere, are & will remain copyright Clyve Herbert (ASWA Archive). Please note this is a video capture: http://www.stormchasers.au.com/Oct01/Leopoldtornado0030.jpg |
| 12 |
Harald Richter |
The 23Z MML
sounding is peculiar - with nice lapse rates from the surface up
to about 550 hPa, and some moisture, partially from the evaporation of yesterday's rain. An unusually strong inversion sits unusually low,
between 550 and 500 hPa. But, the most amazing feature is the wind
field. MML had strong flow and good turning all the way up to
this inversion/tropopause hybrid at mid-levels. We had 85
knots at 500 hPa!! The Li of +8.7 in the MML sounding is
fairly meaningless (another classic example). The 18Z AVN has
MML in the rear left quadrant of a departing 500 hPa jet, suggesting
support for lift in case you subscribe to the quadropole model. VIC needs some bigger holes in that cloud cover that keeps hanging around. The "play:" look for eddies (i.e. backed flow) in the
surface obs, combined with radiative heating. What to expect:
showers with cloud tops at 510.85 hPa, little or no
lightning, and a downburst if you hit the jackpot. After recent events (Ballarat,
Wonthaggi, Clyvetown) this kind of setup might be good for
one of those unforecastable downbursts/spin-ups. We just need
an aus-wx: observer every 100 km^2, thanks. |
| 12 |
Andrew McDonald |
Potential for an interesting day in
central and southern Victoria today with a nice low level upper system crossing the
region. Again the cold air is only reaching about 450mb but with temperatures
forecast to hit 19C it could make things a little interesting. We should see some
fast moving showers and possibly a thunderstorm or two later this morning and throughout
the afternoon with the chance of hail with thunderstorms. Radar shows an area of
showers developing around Melbourne and moving at about 80-90km/h in a generally easterly
direction (with one cell pulsing into the pink briefly). Low - mid level
speed shear is quite nice with 30knts near the surface increasing to 50knts at about
18,000ft (hence the fast movement of the cells). I'd love to see a little more
moisture but in the NW'ly airstream we are currently sitting in I doubt it will
increase much beyond what it is now. |
| 11 |
Clyve Herbert |
A very nice looking
depression south west of Mt Gambier this morning complete
with a dry inflow band, also the strengthening of the 300hpa trough running through eastern Aust has allowed the incursion of tropical
activity to get close to the north of QLD, also a thermal
trough just west of Adelaide may be worth keeping a look at
over the next 6 to 12 hours. The cold front moving across Western Vic has just come into view west of
Geelong (1045hrs) apart from an overcast mid level cloud deck and
some light rain it is also marked by a band of low cu that is
just starting to form a sort of shelf type line, the surface
front is also moving from the west northwest showing that the
frontal boundary is starting to pivot around the low
southwest of Vic. |
| 8 |
Clyve Herbert |
The tropical moisture plume that has
sporadically been dropping out of the very persistent area of moisture west and south west
of Indonesia over the past few months is on the move again, this time dragged southward
along a strengthening sub tropical jet and deepening long wave trough west of WA, seems to
be heading for the southwest of that state, also another wave of cold air pushing towards
the Aus Bight region looks very interesting for the Australian region over the next few
days. |
| 6 |
Clyve Herbert |
It seems at the moment the area of
vorticity associated with the developing low has come ashore at Portland Vic, the cold air
pool is very cold and not a bad field of cold air following behind. |
| 6 |
Andrew McDonald |
Interesting afternoon in central Victoria
today. Forecast is for showers with the chance of a thunderstorm with hail this
afternoon. Currently a few moderate showers pulsing into the yellow on green on
radar are working their way across Melbourne with some nice dark bases and some moderate
TCu going up. The front is out to the west and a few low topped CB's can be seen
through the gaps in the cloud out to the west. Going by this morning's sounding
convection will not get above about 400mb (at best) but quite cold air is moving into
the middle layers so some moderate low topped CB's with some strongish updrafts are
possible this afternoon. Temperatures are creeping in to the mid-teens across
central Victoria and dewpoints are around 8-10C. |
| 6 |
Clyve Herbert TORNADO |
Most of the area affected
by the tornado is grassland with a few trees and also private property with guard
dogs!?.When this funnel first toughed down it was rather weak, however I did find minor
track damage near to the Sands Caravan Park with branches broken and on the ground also
leaf litter etc, this appeared over a narrow track, also grass in the nearby paddock was
showing a chaotic appearance. The locals I talked to indicated that they heard some noise
about 1800 but could not be sure. A little further east about 500m I found some tea trees
snapped off but nothing significant. From this point it seems the tornado skirted the
coast and then moved onto Corio Bay. I will continue further investigation today. In
respect to the description as a 'land spout' type this tornado did not exhibit this
appearance, at its maximum (ex Video) it had an appearance of a large tornado almost wedge
like complete with large rotating wall cloud. |
| 5 |
Clyve Herbert |
Interesting
developments showing up for south east Australia and Tasmania later
tonight and especially tomorrow. A nice field of cold air looks as if it will be catapulted towards south east Aus as the high southwest of WA
strengthens and works a strong ridge to the south. The baroclinic
cloud band over WA seems to be on the move towards a Low that
should develop west of Vic tonight as the thermal gradient
becomes greater as the cold air approaches overnight, the
cold air has come from below 60 south (the black abyss
reference to no satellite region) and with a bit of luck may send sufficiently cold air across SE Aus for snow to low levels during the
weekend. |
| 5 |
Jane ONeill |
This area of cloud
over WA associated with the approaching rapidly deepening trough
is expanding very rapidly. There's a strengthening infeed of moisture
from the area around Indonesia again, and a lot of cold air at 850hPa lurking in the SW Bight area. Is
this starting to sound a bit like last weekend & this
week? |
| 4 |
Jane ONeill |
Imagery & analysis
collected so far regarding the Leopold tornado can be found at: http://www.stormchasers.au.com/3_10_01.htm |
| 5 |
Clyve Herbert TORNADO |
Harald.
I am extremely interested in your reply, and I will endeavour to answer (from a visual
perspective) your request for further information. At the moment I am still suffering from
only what I can describe as retina retention of what I saw(I cant get it out of my mind),I
am also continually analysing and trying to remember everything I observed. In respect to
the local scale low you mentioned I observed this just south of Cape Otway on the Vic
visual satpic for 1230hrs Mel time, it seems this local/meso scale low had moved northeast
towards the Geelong area by 1530hrs local time. I feel the presence of this meso feature
is a significant aspect of the study I will carry out on the occurrence of this tornado.
In regards to the lightning you are correct I detected only two discharges prior to the
storm moving over the Leopold area and this was when the system was just southwest of my
location (I photographed what I would describe as a small multicell of rather low tops).
Another area worthy of investigation is the possible presence of convergence points to the
lee of the Otway range in a southwest flow this may have also aided in updraft potential.
The tornado became very large between 1815 and 1820 and at times almost seemed wedge like,
at this time the tornado had passed onto Corio Bay and effectively became a water spout. I
would be keen to receive any ideas and suggestions |
| 4 |
Harald Richter TORNADO |
(1) It is hard to
judge from the "Geelong Info" picture what the funnel is actually attached to. There seems to be a low rainfree base in the
background, but there's also a lighter-coloured lowering in
the foreground. Clyve, was that lowering rotating
with the tornado, i.e. could that be indicative of a
low-level mesocyclone? (2) The Laverton radar volume scans reveal a rather nondescript storm:
1800 LT: 43 dBZ core extends from ground to ~1 km AGL
1810 LT: 61 dBZ core developed centred around 2 km AGL;
50+ dBZ reflectivity extending from 1 to 3 km AGL
Formation of an echo overhang on
the N side of the storm
1820 LT: 62.5 dBZ core (c.f. "red" starts at 55 dBZ) centred at 1 km AGL
50+ dBZ extend from ground -> 2.5 km AGL
40+ dBZs remain below 4 km AGL at all times !!
1830 LT: max dBZ ~ 51 dBZ at 1.5 km AGL
1840 LT: a new 60 dBZ core appears near the ground from the northernmost of 3 reflectivity
cores ( the S core was associated with Clyve's TOR)
The amazing upshot of the
reflectivity pattern is:
(a) the storm does not look like a supercell in the reflectivity pattern IF this was the
final word on the storm type, the TOR would be a "landspout" or
"non-supercell tornado"
(b) the 40 dBZ echo top never exceeded 4 km AGL - that's extremely low-topped for a
tornadic storm (I am not sure whether any lower-topped tornadic storm has ever been
documented)
(3) Surface mesoscale data (which I
haven't seen yet) showed a surface trough/wind shift line in the region. Behind (W of)
that line dewpoints were higher, and the wind direction changed from SW to W across the
boundary. The storm probably crossed / rode along that boundary around its tornadic phase.
(4) The MML 23/2 UTC (0900 LT)
sounding showed about 5 g/kg LL moisture quickly dropping off with height, a dry adiabatic
lapse rate from the ground up to ~750 hPa (!) and a lacklustre wind field with near calm
at ground level, and 20 knot westerlies around 500 hPa. The MML 11/3 UTC (2100 LT)
sounding had 6-6.5 g/kg of moisture up to ~920 hPa, and had a dry adiabat running into the
surface parcel LCL at ~920 hPa! The wind field has tightened up considerably with 10-20
knot W/SW near the surface turning to 40 knot SW around 500 hPa.
(5) The 23 UTC MesoLAPS run showed
a cold pool (initialised form the 23 UTC MML sounding) that slowly drifted E. Leopold
would have been along the back edge of the coldest mid-level air. MesoLAPS also showed a
25kt mid-level flow at 2200 LT, which is a little weaker than the mid-level winds in the
11 UTC MML sounding.
(6) The lightning network showed
only a couple of strikes W and SW of Leopold between 1800-1810 LT. Maybe the tornadic cell
was simply too shallow to produce all the microphysiscs needed for a lightning show. This
also shows that lightning and tornadogenesis can happen apart from each other.
(7) The 0532 UTC VIS GMS-5 image
shows that the cell was embedded in a disconnected line of cells arching counter-clockwise
from King Island to Geelong to Ballarat to Horsham. A mesolow between King Island and
Colac seems to have advected "useful" air across Cape Otway into VIC behind the
surface boundary mentioned above.
My current hypothesis is that we
had deep, dry adiabatic lapse rates from the ground up, combined with an increase in LL
moisture on the NW periphery of a parent surface low somewhere E of TAS. This combination
led to a short fat CAPE profile in the LL, and hence could be accomodated in a short fat
storm. The surface boundary supplied extra lift and vorticity to the updraft, which took
the vorticty, tilted and stretched it.
Forecasting an event like this with
an acceptable FAR (False Alarm Ratio) is beyond anyone's capability ATM. I wish nothing
more than being proven wrong on this statement! I suppose that the "discriminating
" factors that made this overgrown Cumulus :) (remember: 40 dBZ cloud top at 4 km
AGL) tornadic are tucked away into small time and spatial scales such as LL lapse rates at
1800 LT E of Geelong (not 11 UTC, not 23 UTC, not Melbourne Airport).
I would like to know more about
what boundaries were in the area around 1810 LT, and what their vertical structure was. |
| 4 |
Robert Goler |
Report in the Geelong Advertiser this
morning http://www.stormchasers.au.com/geeadv1003.htm |
| 3 |
Clyve Herbert TORNADO (Leopold) |
At approx 1800hrs 3/10/01 a heavy
shower commenced here at Leopold, the shower and occasional thunder was of a cold
air type that had drifted from southwest of Geelong over the previous 20 minutes. As this
CB moved north east of Leopold a flanking line came into view which extended westward from
the main rain area. This flanking line showed massive and rapidly growing updrafts
and ragged lowerings...all back lit by the low sun. At approx 1810 the very rear of
the flanking line and immediately under a very strong updraft showed what I would describe
as weak rotation, this area of rotation rapidly intensified and formed a small funnel. The
funnel then moved just north of Leopold and increased in length and actually touched down
at approx 1814hrs in a grass paddock. (no debris seen) Then lifted and continued to move
northeast as a funnel initially weakening and then intensifying. By 1820 the funnel now 3
or 4 klm northeast of Leopold became large and touched down again, the tornado was
occurring immediately under a massive and persistent updraft and was maintained for at
least another 10 minutes, and finally dissipated over Port Phillip Bay at about 1832,
however the wall cloud continued to show rotation and was rather large, at about 1840
another smaller funnel developed along the infeed flanking line but only lasted about 3
minutes.
The video sequence lasts about 5 minutes and shows the tornado near to its most intense
phase with another view lasting about 39 seconds showing an almost wedge shaped tornado.
The early stages of this tornado were unable to be videoed due to water in the camera!!!
and the auto dew cut out was activated I need not tell any ASWA member what that made me
feel like........ The passage of this storm across the Geelong area seems to have
coincided with the passage of a thermal trough although I have not checked the soundings I
believe the 500hpa temp was close to -24c surface temps were not high being around 13c
however the low to mid layers were very moist.
|
| 3 |
Lindsay Smail (Grovedale) |
I've just been watching beautifully
videoed footage of a fair dinkum tornado by Clyve Herbert. Forming around 6.10 pm
after massive downbursts just north of Leopold in farm paddocks (about 12 km due east of
Geelong CBD) the creature rotated its way northeastwards and seemed to dissipate over
Corio Bay just east of the Sands Caravan Park (old Melways 232 H4) around 6.30 pm. No
reports of damage yet. |
| 3 |
Bureau of Meteorology SEVERE THUNDERSTORM WARNING |
NEWS FLASH - FOR IMMEDIATE
BROADCAST
Top Priority
Severe Thunderstorm Warning
for Melbourne Metropolitan area, Geelong, Ballarine and Mornington Peninsulas and Port
Phillip.
Issued at 6:46pm on Wednesday the 3rd of October 2001
A severe thunderstorm with a tornado has been reported over the Ballarine Peninsula east
of Geelong and is expected to move northeast at 45 km/h towards the city area in the next
half hour. Damaging winds and locally heavy rainfall are possible.
[radio media to play Severe Weather News Tag Alert 4 here]
The current thunderstorm warning, issued by the Bureau of Meteorology, indicates the
strong probability of intense storm activity in this area.
In the interest of community safety the SES suggests some simple precautions:
- secure any loose objects in the vicinity of your home
- stay indoors if possible
- if you are outdoors, avoid sheltering under trees
- listen to the radio station for storm updates
- switch off computers and electrical appliances |
| 3 |
Clyve Herbert |
Victoria is still
under a good cold pool even with low surface temps, some of the
updrafts near to the ranges are already looking good, so lets
keep a look out today. A line of cool air CB's approaching Geelong from the west
(1500hrs) have returned sporadic lightning, tops are up to 24 to 27,000 approx and are
showing some shear to the north.
No rest today, I 'regret' to advise we here in
Geelong (Leopold) have received yet another thunderstorm,this one was a little beauty
(cold air) passing through at 1630hrs. Some nice cg,s, hail (<1cm) and torrential rain
9.2mm in 7.3min. |
| 2 |
Andrew McDonald |
After looking at a
few things this morning I thought there maybe a chance of
thunderstorms anywhere east of Melbourne. There are now
showers pulsing into the yellow to the W of Melbourne so I may even have to revise my forecast further west. A significant upper trough
is approaching from the W and upper temps are already low
with 500mb temps of -22C. Surface temps around 20-22C should
see storms pop here today. There is already some nice cells over the E ranges and along the SE coast
near Sale. Should be an interesting day
for much of the E coast of Australia withsevere storms likely in NSW. |
| 2 |
Clyve Herbert |
Interesting flow
patterns over central Vic this morning, surface flow from south
west however above 1200m all cloud moving from almost due north, the north east of Vic looks ok for activity this afternoon. 12pm: Looks as if much of eastern Vic
and even the possibility of central Vic may see some decent
thunderstorm activity today, already some good lightning returns
on the lightning detector all within 100 to 200 klm of Melbourne (am radio) its interesting to note all this has fired up over the last 1 hour
or so, keep a lookout. |
| 1 |
Clyve Herbert |
Some interesting things going on over Aus
at the moment check the sudden strengthening of the sub tropical jet over central Aus and
an associated baroclinic cloud band (moisture ex west of Indonesia) just commencing to
join with the cloud band stalling over south-eastern Australia. Also there appears
to be a wave over north-eastern Vic along the clearing edge of the cloud band, enhanced
uplift going on here too with a few storms , also there is some unusual movement of the
large cloud band north of New Zealand which has been edging towards the southwest over the
past 12 hours! and a lingering cold pool west of Tasmania - all worth keeping a
close look at with the possibility of vorticity near to southeastern Australia. |
| 1 |
Clyve Herbert |
Interesting feature on the clearing edge
of the cloud band over southeast Aus this morning with a distinctive bulge pushing
south-westward just north of Melbourne and has propagated along the line from southern NSW
over the past 6 hours worth watching, also the weakening low west of Tasmania is
continuing to edge eastward rather than south-eastward, the position of the low and the
'Bulge' may be connected. |
|
|
Go back to September Forecast Outlook, Discussion
& Report page for information regarding the September 30 storms in Victoria |
| 1 |
Kevin Parkyn |
Re: September 30 storms With respect to Sunday evening did anyone, apart from Clyve
(who seems live in Victoria's severe weather belt!), come across any damage to property or
vegetation or perhaps experienced severe wind gusts in excess of 90 km/hr? |
| . |
. |
Melbourne Real Time Temperature Observations Graph
Melbourne Real
Time Rainfall Graph
Port Phillip Bay Wind &
Temperatures |
