Glorious day on the Gold coast today.

BOM forecast tomorrow 50% chance of 2mm

So not a big day


The rain totals from the storm burst yesterday. Not a bad spread. Looks like sunshine coast got the better deal

Yep the cape crusader

GFS CAPE is usually close to the mark when it comes to typical surface-based thunderstorm areas because of the way CAPE is handled by the model. But there are notable exceptions. For example, it'll often show extreme values off the northwest coast of Australia during the build-up season as well as parts of the tropics even though little to no thunderstorm activity ends up occurring. This is because by default, the CAPE fields displayed on Stormcast is surface based CAPE i.e. CAPE calculated from a parcel that's assumed to rise from the surface and therefore possess the GFS surface forecast temp and dewpoint for that point. In these setups, there's only a very shallow layer of good moisture near the surface which means GFS forecasts those parcels to condense at a low height then cool at the saturated adiabatic lapse rate as it rises further (it stays warmer than the surrounding air and therefore gives rise to unrealistically extreme CAPE values). But on typical hot sunny days, parcels rise from a mixed layer thousands of feet deep in the lower levels so they don't have the same high temp or dewpoint as parcels rising from the surface, and therefore their true CAPE or instability is lower.
Conversely, GFS surface based CAPE often tends to show very low or even non-existent values for dry inland storms even though it results in lots of lightning - this is because convection is helped by a layer of moisture aloft rather than the surface where the surface based CAPE values represent.

This is why there's different types of CAPE that are looked at by forecasters such as mixed layer CAPE in the lowest X hpa of the atmosphere, most unstable (MU) CAPE which uses parcels rising from a level that yields the most CAPE, effective layer CAPE which uses parcels rising from a level where parcels are likely to start rising freely on their own from, etc.

Above is the ACCESS-R CAPE for 4pm yesterday based on its 00z run. I'm allowed to post this particular version. And the preceding image is the detected lightning within the 24hrs after 8am Saturday.
As you can see, the general area is reasonably well represented by the storms that ended up occurring although note the low values inland which is typical of inland low-rainfall storms because convection is encouraged by moisture aloft.

Edited by user Sunday, 29 September 2019 7:36:58 PM(UTC)  | Reason: Not specified

Hi Crikey do you have a peep at WATL? http://www.bom.gov.au/jsp/watl/rainfall/pme.jsp



GFS from WZ. https://www.weatherzone....sp?lt=wzstate&lc=qld



Both are pretty close to each other.

Sunny day today with near average temperature. Near average dew point during today while slowly rising before falling slightly tonight. Relative humidity have been near average. E to SE winds became mostly E to NE later and is now is calm.

Last 24 hours:

Ferny Grove Weather
Date: 30 Sep 2019
Time: 7:50 AM

Min Temp since 9am yesterday: 16.7 C
Max Temp since 9am yesterday: 26.8 C
Min Ground Temp: 13.6 C
Rain since 9am yesterday: 0 mm

Temperature: 21.1 C
Relative Humidity: 64 %
Dew Point: 14 C
MSL Pressure: 1020.3 hPa
Wind Speed: 7 kph - light breeze
Wind Direction: WSW

Present Weather: Clouds generally forming or developing during the preceding hour
Visibility: 20km to 39km - Very Good Visibility
Cloud Cover: 6/8
Ground State: Ground dry

Notes of yesterday weather - 29/9/19: Partly cloudy with cu and sc clouds in the early morning, becoming sunny during the morning with some cu clouds persisting into the late morning before clearing. The temperature rose briefly between 12 am and 1 am before falling. Near average dew point and generally stable early before rising during the morning and stabilising from the late afternoon and fell slightly in the evening. Light WSW to SSW winds from 12am and 1 am with light W winds occasionally early before a SE to E wind change during the early morning becoming ESE to NE from mid morning with some N to NE winds in the morning. Later in the afternoon winds were ENE to NNE and became calm in the evening.

Today: Temperature early today before sunrise was stable or slowly rose instead of falling. Dew point have been near average and slowly rising. Relative humidity have been near average. Light W to SW winds at times early and S to SW in the last hour.

Yeah, I had a detailed look at ACCESS-R, etc soundings for various points around the region. Below is a summary of what I said elsewhere:

" There's definitely more than enough directional and speed shear (caused by the freshening ESE onshore low level flow after the small weak near-coastal low drifts away and weakens, undercutting the strong westerlies above) to support severe storms.
But instability is very modest in most of SE QLD so I think it'll be a case of "only a slight chance but if anything got tall enough, it'd tap into the shear and potentially become severe". "If" being the operative word.

Both EC lightning and ACCESS-R soundings look somewhat more favourable in northern areas such as the Wide Bay and Burnett, and some western parts of SE QLD but it could conceivably go either way.
ACCESS-C tries to develop some convection around the Scenic Rim ranges which then drifts in a rough NNW direction later as it grows somewhat. Will be a wait and see situation with today.
Overall though, today looks far from epic to me. "

Edited by user Monday, 30 September 2019 12:18:54 PM(UTC)  | Reason: Not specified

Thanks Ken
Oh well something to watch

This is a copy of this morning (00z) from YBBN. - I use a program called Digital Atmosphere to generate it, because I can then play with some other settings.