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Radar Assistance Web Site

Hail Forecasting

Element Useage

SPC -10C to -30C CAPE

Hail Lapse Rate in AWIPS (0C to -20C) of -6.5C or stronger
Radar Storm Top Divergence: Earliest Signal - Best Correlation
50dbz > -20C Height: Hail Probable
50dbz > Donavon 1" Hail Height: Severe Hail Likely
Three Body Scatter Spike (TBSS): Severe Hail
50 dbz > 30kft: Significant Severe Hail Probable
60dbz > -20C Height: Significant Severe Hail Probable
Melting Keep in mind that if the storm lacks tilt, the hail will fall through the updraft, causing significant melting to occur. So, mid-level shear (pre-storm)/user identified meso/tilted updraft (storm) = favorable significant hail



Meso Nomograms



Radar VCP and Scan Strategies

  • VCP 121: Use for large scale convective systems where flash flooding is the main threat.
  • VCP 11: Use for hail only situations, superior upper level scans for STD evaluation.
  • VCP 12: Use for tornado/wind threats, superior lower level scans for Vel/SRM evaluation.
  • VCP 31: Use for snow situations or pre-storm shear/boundary analysis.
  • If range folding is a problem, chance the PRF!
  • Consider using a VCP Nesting Approach.