So basically what does all these images mean for Tomorrow.
Model spread is large — GFS is calmer, ECMWF/ICON much stronger — so treat this as a conditional but potentially serious setup. If the higher-CAPE solutions verify, tomorrow could produce locally severe to very severe storms; if GFS verifies, it will be more modest but still capable of strong, damaging cells.
Technical read (from the GFS soundings for Thu 27 Nov)
Brisbane (GFS ~CAPE 1,569 J/kg)
Moderate–strong instability, PW ≈ 46 mm (very moist column), LI ≈ −4, weak-ish cap in GFS here but CIN may be model-sensitive. Low-level helicity on the GFS run was modest (~4–10 1km, 3 km ~30), EHI ~0.3. That’s an environment that supports strong multicells and — if a boundary and low-level shear align — isolated rotating storms (supercell potential).
Warwick (GFS ~CAPE 1,074 J/kg)
Decent instability and moisture, LI ~ −2.6, PW ~34 mm. Helicity moderate (3 km ~35–61 on some runs). Supports organised multicells and locally intense convection; supercells less likely than Brisbane run but possible near boundaries/terrain.
Toowoomba (GFS ~CAPE ~600–1,000 J/kg range depending on parcel choice)
Modest–moderate CAPE, PW ~32–37 mm, weak to moderate shear. Pulse/multicell mode expected unless shear tightens locally.
Model spread (critical):
ECMWF / ICON show much higher CAPE (ECMWF ~3,800 J/kg; ICON ~3,150 J/kg on the runs). That pushes the high-end threat substantially (very large hail, extreme updrafts, violent winds, higher tornado potential) — but those are higher-end solutions and depend on cap erosion timing and boundary placement.
GFS is the more conservative solution (less extreme CAPE). When the ensemble and deterministic runs diverge this much, plan for the range: low-end (GFS) to high-end (ECMWF/ICON) outcomes.
What this means in practice
If ECMWF/ICON verify (strong low-level moisture + very high CAPE + sufficient shear): higher chance of very large hail, destructive straight-line winds, frequent lightning, and increased rotational cell potential in parcels of the warm sector or along the front/boundary. ( chance of tornado, but this is something that can happen in many supercells if they form, but it is not a given or a certainty, just a potential. This goes for all the times when tornadoes are brought into a setup in the post.)
If GFS verifies: still a dangerous day locally — expect damaging gusts, large hail pockets, heavy rain/flash flooding — but the event is likely less widespread and less extreme than the high-CAPE runs indicate.
Key triggers: timing/position of any trough/front, sea-breeze/outflow intersections, and how quickly the cap erodes tomorrow morning–afternoon. Those small-scale factors will control whether cells go supercellular or remain multicell/pulse.
Plain-English summary
Heads-up for Thursday (27 Nov): model spread is large this morning. GFS is the quieter solution, but ECMWF/ICON are showing a far stronger profile.
Either outcome still allows for severe storms in spots — large hail, damaging gusts and heavy rain are possible, and the higher-end model runs show an increased tornado risk ( as per the previous explanation concerning tornadoes, it is extreme case as per storm structures) ,if the boundary and low-level moisture line up. Stay weather-aware: monitor BOM warnings and local radar tomorrow, and be ready to shelter if a severe cell approaches.
Practical checklist to share / follow personally
Charge devices, have local emergency contacts ready.
Secure loose outdoor items (sheds, trampolines, boats).
Move vehicles under cover if possible.
Plan for power outages (fridge, med devices, lights).
Avoid low-lying / flood-prone areas during heavy rain runs.
Keep BOM warnings and your local radar app open during the day.
If driving and a storm is approaching, pull over off the road away from trees until the worst passes.
