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).

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)

 

Tips:

- 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