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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)



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).

Mid level (500 hPa) - CAPE increase via dynamic lift

What to look for:


- Jet streaks

- Upper level divergence

- Tropopause minima (rising motion on forward flank)



- Most favorable for severe TS: left-exit region

- Also right-entrance region

- Right-exit region when curved jet streak.

Upper Level (300-250 hPa) - Ageostrophic forcing
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