Grampian Weather Services
"The weather ... as forecast"
Synoptic scale: Priming
Features that will prime the atmosphere for DMC (eliminate CIN and / or increase CAPE)
What to look for:
- Mid-level troughs (vorticity maxima, 500-hPa height falls, cyclonic swirls on loops of water-vapor images)
- Wind maxima (associated with relative large height gradient near the bases of 500-hPa shortwave troughs)
Tips:
- Discount severe TS in areas where shortwave troughs and their associated dynamic lifting aren't predicted to arrive during the forecast time.
- Severe storms can still occur in the absence of a 500-mb shortwave (merging storms associated with the collision of sea-breeze fronts).
What to look for:
- Jet streaks
- Upper level divergence
- Tropopause minima (rising motion on forward flank)
Tips:
- Most favorable for severe TS: left-exit region
- Also right-entrance region
- Right-exit region when curved jet streak.