Weather for the weekend of 24 -25 September 2011

Updated 24/9/2011

A high is moving through the Bight and should be off the Vic/NSW border on Sunday night. A further high is moving slowly off the SE Queensland coast. A trough will form between the highs on Friday in far western Queensland. The southern end of this trough will curl east and north on Friday night and into Saturday, bringing unstable weather and showers (possibly with thunder) on Saturday and Sunday. Some of these showers could be locally heavy, but with a CAPE of only 330J/kg and a Standard Lifted Index of only -2C, these are more likely to be towering Cu than fully developed Cb.

There has been no rain on the Downs in the last seven days, but the showers over the weekend could bring falls totaling about 5mm in places.

Saturday 24 September 2011
Dalby              28C
Stability          C
Convection     Dry convection to 10,500ft with cloud base at 8,000ft
Wind               SW @ 5kts

Following the saturated adiabatic lapse rate lines (SALR - the curved dashed lines), cloud tops will be about 25,000ft - but there could be some high cloud about as well.

Sunday 25 September 2011
Dalby              28C
Stability          B
Convection    Dry convection to 12,000ft with cloud base 8,000ft
Wind              NW @ 5kts

The predicted cloud tops are about 30,000ft, which suggests Sunday's showers will be more intense than Saturday's.

A look ahead at the week of
Monday 26 September - Saturday 1 October 2011

Monday will see the trough clearing the coast and some coastal showers are possible. Winds will gradually shift to north and north westerly over Tuesday to Thursday bringing increasing temperatures for the week. A further trough will be approaching SE Queensland over Fri-Saturday - but it's arrival time and effect are as yest a bit hard to forecast. At present, it looks as if the trough will be quite weak and have little impact - but that could of course change!

In general, Sunday (depending on the showers) will be good, but convection height will fall on Monday, gradually increasing during the week to potentially a really good day on Friday.