Victoria: Trough - showers/rain/storms - 6th-10th November

[Meso]

For a weather watch l am particularly interested in thunderstorm development in the early morning( 4.00am) in the west when RH is possibly around 95% and the front when it reaches the east when the RH is lower.in the afternoon.?

RH is always higher at night, crikey. It goes up as the temp drops. Won't be any storms developing at 4am, need the sun to come out and get the ground heated up first. I can't explain all the techy stuff behind how RH is calculated either, but if you do some Googling you'll see it drops during the day and rises again overnight. Dew point is more what you're interested in when it comes to storms and a better measurement of how "humid" it feels.

Check this - http://www.usatoday.com/weather/resourc ... lhum_x.htm" onclick="window.open(this.href);return false;

[Meso]

Hopefully also there'll be some clearance on Wednesday afternoon; the forecast calls for rain periods and the idea of imbedded storms doesn't sound all that flash

Yeah, that's the biggest concern. Despite how mouth watering stormcast looks, Wednesday could turn out to be just a massive mess of embedded storms and heavy rain. Tuesday afternoon could be the one to watch for the purists.

[stratospear]

There's certainly the potential for big rainfalls next week. I'm thinking 30-50mm here. One area to watch is Lake Eildon. It's at 99.8% and most forecast models suggest areas upstream (and downstream) could really cop it. Interestingly they are ramping up releases into the Goulburn River from 2000 to 7000 ML per day on Monday.

My final essay is due on Tuesday... good timing

[Rhino]

Would'nt be concerned with the positioning of the heavier rainfall that GFS is forecasting at the moment, has had the heavier falls anywhere from NE vic to the western district but heavy falls are on the cards anywhere across 2/3 rds of vic at the moment. Looks huge for storm potential on wed but will wait a few more model runs before I start blowing out my fly . Should get at least 20mm for most bar the far NW IMO.

Rhino.

[Twister]

Tues Through Thursday going to be very wet will see some 40-80mm falls in the NE over this 36 hour period the NE N NW flow is going to be quite humid.

Sunday ONCE AGAIN another tricky one NW flow DPs drop then raise behind Trough Will be almost exact to what happened on Friday i think So annoying when are we going to get a good day

Wed looks repeat of Sept 28th but weaker and Lots more rain and very embedded and will go early

Nice to have some action though a Very interesting 5 days ahead.

Enjoy heat and sun next 36 hours

BRING ON STORMS

[droughtbreaker]

Most important thing is to not religiously follow the GFS CAPE and LI progs every run and take that to mean we will all get smashed with HP supercell storms. GFS is usually very good the day before or a couple of days before, but I would use extreme caution in forecasting storms from that model any further out, i.e. 3 days or more. GFS had massive storm potential for midweek (bordering on stupid) in the 00z run with 50-125mm widespread across the state but now in the very next 6 hourly run has moderated things massively. At the same time, EC is only looking at about 20mm for here and OCF has 10-30mm for many locations.

IMHO, the best storm potential is Sunday. My reasoning for this is based on the fact we have a trough/front moving in late in the afternoon carrying high moisture levels following a relatively dry (but still reasonable moisture) morning and early afternoon and a rather hot air mass. We will get clear skies right up to the arrival of the front allowing for maximum heating of the surface air mass and then the front comes through near the time of peak solar radiation. The setup is excellent for an organised line of storms to come through or at least an 'outbreak' of storms.

Tuesday and Wednesday are a different story. The moisture levels are very high all day. There will be thick cloud on those days and rain is likely to develop before there is any chance of surface heating. Tuesday should see some localised severe storms and widespread showers/storms but it looks to me like the high energy content of the atmosphere will be wasted thanks to cloud capping surface heating. Wednesday should see widespread rain with locally heavy falls and potential to cause flash flooding in some parts. Sure some major weather ahead but storms won't necessarily be the main feature. I still reckon Sunday is the best day for it though.

[Meso]

Great post, db! And I hope you're right from a chase perspective, would love for Sunday to be the day for real isolated storms (only because I can't get out during the week! ). The one thing with GFS this week is it really hasn't budged an inch re: Sunday. It's been on to it since early in the week and the progs really haven't changed at all, run after run (which im told is a good sign with GFS), the "target area" has barely shifted.

So, hoping for some decent activity Sunday, my main concern is whether i sit it out here or head further NE and hope to be in good position for when things really kick off. The east looks like it will cop the brunt of the "severe" activity at this stage, but to be honest, I'm not entirely convinced, despite what GFS and the BoM say... more inclined to think a line pushing through from the west will be the go...Will wait til tomorrow night, before really deciding where to head tho.

Re next week, I can see it being a more of a "La nina" type day like we witnessed a few times last year...stormy, but more of a focus on heavy rain. It is going to be moisture overload by the looks of things, so the focus will be on big mass of HP cells, which certainly isn't very photogenic. It's still a good five days away anyway and there is noticeable shift in where it will "bomb" already, so we'll just wait n see...

[Rhino]

Not getting overly excited to be honest at this stage, bar the NE rainfall looks to be in the normal range 20-40mm for most, which is terrific but unless things change might get some isolated storms in other areas and solid rain but no widespread SC outbreak. Then again if you live in the NE time to charge the camera batteries and possibly keep an eye out for flood watches as it will probably develop into heavy rain areas. But will wait until tommorow mornings runs to get a general concensus. Will be nice either way, storms and rain or just rain.

Rhino.

[adon]

Sort of hoping this one misses the NW. Harvest getting going now and this will put a stop to that. But sounds like there will be something going on everywhere

[Jake Smethurst]

Yes Dean says it well. It is interesting though tomorrow with the shallow trough likely to go through, being a key trigger for thunderstorms over the east, and then the cold front in the west during the afternoon, with the air destabilizing following the trough moving through. It's a fairly hard one to say where most action will develop. But I have updated the thunderstorm chart for now.

[crikey]

A westerly wind change has arrived at the Adelaide longitude ( assuming this is the leading edge of the cold front)this evening and barom pressure in Adelaide is 1005 and rising.The deepest part of trough is around 1005 and has climbed 2hpascals this evening and has weakened slightly
The first virga/shower band is nearly at the VIC border. The highest rainfall totals in SA have been on the west side of trough as the cold front does its work. Only about 5mm recorded in rainbands there so far. Some thunderstorms on or behind the cold front line atm. Look forward to see how this progresses tomorrow.
Dew points very low inland atm as expected
Thanks MESO for your link. There was a nifty RH /pressure /dewpoint/temp converter on the site. great stuff
http://www.srh.noaa.gov/epz/?n=wxcalc_rh" onclick="window.open(this.href);return false;

I just plugged in a scenario for tomorrow morning here out my way . as a' guesstimate '..expecting a barom pressure of about 1007 hPascals and RH of say 55% RH and temp at 9.00am at 18 deg C..the converter says the dew point will be 8.8 deg C . Not an exciting figure for storms or rain in the morning here as you suggested

Here is another scenario for Melbourne afternoon scenario
If temp is 32 deg c and RH is 50% and barom drops to 1005 as Access synoptic suggested it might on sunday arvo,.. then dew point is 20 deg c
http://www.srh.noaa.gov/epz/?n=wxcalc" onclick="window.open(this.href);return false;
( l am assuming l have used the converter correctly? )

[tonycynic]

Radar is showing activity in a N_S line thru Ballarat and Airies inlet. Might reach us a bit too early for any fun stuff. Temp at Ballarat and Cape Otway dropped with the wind change, waiting to see the 9am temps but not holding my breath.

[typhoon29]

overcast and warm here this morning. Some virga. very high based cloud. Seems to be drying out too much for a storm here today, I hope I'm wrong.

[Anthony Violi]

Still a decent chance one would think, DPs are slowly rising through the West and North of the state despite the early wind change. And the temps are climbing again, so in my opinion this could be a blessing coming through so early, and now the temps can climb a bit again.

Will be an interesting arvo and night thats for sure, if we get back up to the high 20s will have plenty of heat to work with.

[James]

well i have my "storm headache" which i always seem to get when storms are coming...

plus when i opened the window, the smell of tropical moisture..storm brewing weather was so strong...

well i know they arent really scientific signs, but we'll see what happens - if the cloud blows over later it will heat up lots, already 26+ here and the sun is shining

[I_Love_Storms]

Weathezone thinks 10-20mm for here over next 4 days. Awesome if that eventuates... Isolated storms most likely this afternoon or early evening IMO

[Twister]

Very Tricky day

SRH you are bang on GFS progged DPs way to high hence the High LI Cape and the like in NE Vic Dps will only get 12-14c up there is That

Wind change is already in central Vic With W SW winds across much of the west behind the trough

If Dps were a bit higher it be a good day but boy W or E what to do

[Meso]

Yeah, hard day to get your head around. If anything gets going it won't be til late by the looks of it.

[mick]

Wind changed about an hour ago and the temp dropped ahead of this weak virga line crossing the bay, should warm up again this arvo.

[Jake Smethurst]

Yeah quite a tricky one, and the shallow pre-frontal trough which is currently moving across the state is going to become quite difficult to pin-point in regards to estimating positioning from here on out. Generally it should be in Melbourne by about lunchtime and to the eastern districts in the afternoon and evening. Its all ahead of a cold front which will brush southern Victoria later in the day. So following the trough, winds are only expected to have turned west to northwest or thereabouts, with the full swing to the southwest not expected until after the main frontal system. So what is currently on radar is associated with the pre-frontal trough, and this will be one of the areas in focus for thunderstorm development this afternoon across the eastern districts. The atmosphere appears to destabilize following the trough as well, ahead of the cold front, so the other area of interest for showers and thunderstorms will be in the west, gradually extending east. I will be updating the thunderstorm chart at about 11.30am this morning. I would suspect in clearer air in the west temperatures will rise again since the initial wind shift associated with the trough came through so early. DP's I would suspect will remain similar following the trough.

Here is the BoM Fire Weather Briefing for today:

Australian Government Bureau of Meteorology
Victoria

Fire Weather Briefing for Victoria
Issued at 10:45 am EDT on Sunday 6 November 2011.

Fire Weather Forecasts Today:
The Fire Weather Forecast today will depend on the timing of the pre-frontal
trough and then the cold front entering the west of the state later in the day.
Pre-frontal trough looks 2 or 3 hours faster then forecast this morning and is
expected to move through the Melbourne region this morning and extend into
eastern parts of the state this evening. Maximum temperatures likely to be 2-4
deg to high, particularly through central areas and Rel Humidity will also be a
little higher with dew points not falling as much in the afternoon. Fire danger
generally lower then forecast.

Observational Network Status:

Temperature and dewpoint data continue to be unavailable at Mt Buller AWS.
Techs will be visiting the site within the next few weeks. There are no issues
with the remainder of the Bureau's AWS network.