Anyone have anything to say about last night's storms in NSW?

satpic:

JMcB

Harald Richter

JMcB's question#234 was:

> Anyone have anything to say about last night's storms in NSW?

Gippsland had ESE surface flow advecting dewpoints > 10 C towards
the ranges.  Convection first intiated on the VIC side
of the ranges,  then spread into SE NSW.  I noticed a cooling
14/23Z MML sounding (e.g. -19C at 500) with a decent cap in Melbourne,
which the ranges managed to break.  The current MesoLAPS 500 hPa
forecast (+6h valid at 16/05 LT) show an exiting thermal trough tilting
NNW-SSE extending from S of Sydney out to sea.  The 15/11Z MML sounding
shows slight deep layer warming corroborating that the mid- and upper
levels over C VIC were warming again during the evening.

The upper-level cold pool seemed to have a surface reflection / surface
through associated with it (e.g. S flow in C VIC, but WNW flow in
the SWG area, along with a surface pressure trough and thermal ridge.

Has anyone done a real analysis of the event (VIC/NSW folks ???)

Harald

Later message from Harald

John,

Most of my analysis was from memory - here's one chart that I still
have. 500 Temp.gif

Harald

Harald Richter

Date: Wed, 16 Jan 2002 13:33:08 +1100 (EDT)
From: Harald Richter <h.richter@BoM.GOV.AU>
To: BOM Synoptic Discussion Group <synoptic_discussion@bom.gov.au>
Cc: Aussie Weather <aussie-weather@world.std.com>
Subject: [synoptic_discussion] Coffs Harbour/Grafton Storms
 

More on storms ...

Without having examined the details of the 15/11Z-Now data,  the
cold pool that crossed the E VIC ranges yesterday might also have
something to do with the current convection in the Coffs Harbour /
Grafton area.  Potent storms with reflectivities beyond 55 dBZ
and good lightning rates are in progress.  The 23Z MOR sounding
to the WNW sports -14C at 500 hPa;  from memory that's about 8 C
colder than a day ago.  Some decent deeper (~100 mb+) moisture
of 10-12 g/kg has also returned to the area over the recent days.

The 16/01 UTC surface obs show a broad cyclonic surface circulation
in the Coffs Harbour area - convectively forced or pre-existing?
Does anyone here do surface streamline analyses?

Planting a vaguely easterly surface flow below the 23Z MOR sounding
yields 40+ knots of deep layer shear,  enough to support supercells.
The latest Coffs radar (02 UTC) shows some suspicious-looking
large cells on top and west of Grafton.  NSW, have you got more?

I shall subside again,
Harald

John Colquhoun
Wed, 16 Jan 2002 15:03:07 +1100

Concerning the NE NSW storms, a supercell has been tracking from near
Grafton to Lismore over the past hour or so. There is a mesoscale low
pressure centre in the area. The Grafton radar gives the best pictures.

Grafton radar images: 0300, 0310, 0320, 0330, 0340, 0350, 0400 UTC
Sat pics:  0000, 0300 UTC

soundings:  Sydney, Moree, Brisbane

John Colquhoun
NSWRO