Case Review: 12 August 2000 SUMMARY

1. Case Review: 12 August 2000SUMMARY Localized heavy rainfall in several locations (CT,NY,NJ) on 11-12 August was the result of regenerative warm-topped convection (very little lightning). A terrain-locked area near Sparta, New Jersey between 1115 and 1900 UTC, 12 August resulted in at least 9.96 inches of rain (backyard reports of 14.11 and 18.65 inches). Rainfall rates of as high as 4.8 in/hr. Roads were closed by water and/or mudslides. Timely Warnings were issued, but no Watch preceded these. (Matt Kelsch COMET Sept 2000)

2. Case Review: 12 August 2000SUMMARY • Anomalous mid/upper level low • 1000-500mb thickness only ~560 dm. • Not very impressive low-level moisture parameters (PW ~1.5” and surface dewpoints mid-60s). • Adjust thinking for the “cool” anomaly by expecting efficient precip production with lower PWs, dewpoints, and e • Saturation thickness reached • Post-frontal relatively moist flow into abrupt terrain rise. • Very low-level precipitation growth. • Steering flow allows for cell growth along ridges to balance movement and dissipation downstream of the ridge.

3. From Funk et al, 1991 Weather & Forecasting, vol 6, 548-564

4. Categories For Midwest ’93, # events, avg rainfall, and area (km2) of accumulation amount. (Junker et al, 1999)

5. Saturation Thickness (Funk et al 1991 WAF)  New Jersey event

6. Storm Total from KDIX 12aug00 2004 UTC

7. Corresponding 0.5o reflectivity and 4-km IR 12aug00 1315 UTC

9. 1200 UTC 12aug00 Upton, NY