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July 4 th 2012 Severe Weather Case Review and DSS

July 4 th 2012 Severe Weather Case Review and DSS. Andrew Loconto NWS Burlington, VT. Presentation Outline. Brief Background Synoptic-scale & Radar Overview NWS Decision Support Activities . Intro. High-end severe weather event coinciding with 4 th of July holiday (many outdoors)

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July 4 th 2012 Severe Weather Case Review and DSS

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  1. July 4th2012 Severe Weather Case Review and DSS Andrew Loconto NWS Burlington, VT

  2. Presentation Outline • Brief Background • Synoptic-scale & Radar Overview • NWS Decision Support Activities

  3. Intro • High-end severe weather event coinciding with 4th of July holiday (many outdoors) • Potentially bad things could have happened… • NWS and Media Partners did an outstanding job given these circumstances

  4. Storm Reports from July 4th • Notable Reports: • 63 mph gust at BTV • 75 mph gust at Diamond Island • Tennis Ball Hail in Peasleeville, NY (Clinton County) • Ping-pong ball Hail in Canton NY

  5. Storms #1: Northeast Kingdom Mini-bow echo Storm #3: Champlain Valley Bow Echo Storm #2: “The Pig” Supercell in St. Lawrence County

  6. 500mb jet of ~ 85 kts

  7. 700 mb Analyses By 00z, 700mb winds increased to ~35-40kts due to passage of Quebec mid-level shortwave trough

  8. Northwest Unidirectional Deep-layer shear profile 0-6km shear magnitudes support organized multicells/some supercells …

  9. 22z LAPS Sfc-based CAPE/CIN & SfcObs Much more stable in eastern VT due to first bow echo passing through ~1 hr earlier CAPEs exceeded 3000 J/kg in Champlain Valley; similar CAPEs in southern St. Lawrence Cty.

  10. RAP 40km Deep-layer Shear at 21z • North Country deep-layer shear of 40-60kts higher than 00z ALB sounding (closer to strongest mid-level winds) • CAPEs in excess of 2000 J/kg for most of the North Country • Northwest Flow: Bad!

  11. Storm #1: Northeast Kingdom Bow Echo

  12. TBSS signature indicative of hail Storm #2: “The Pig” – SLV Supercell 68 dbZ to 25 kftupradial of TBSS… probably big hail Evidence of a hook-echo at 0.5° (~10,000 ft elev.) 6.4° Z (up to ~46 kft) … 52 dbzat this level! 5.1° Z (up to ~38 kft) … still had ~60 dbZ up to this height

  13. Storm #2: “The Pig” – SLV Supercell 0.5° SRM: Broad Low-/mid-level rotational couplet (~10,000ft AGL) 6.4° SRM: Storm Top Divergence (~46,000 ft AGL)

  14. Much of the impacted area very unstable (recall the > 3000 J/kg LAPS CAPE). No reason to believe storms wouldn’t continue to weaken… Storm #3: Champlain Valley Bow Echo @ 2215Z

  15. Storm #3: Champlain Valley Bow Echo @ 2310Z

  16. Office Decision Support Actions

  17. DSS Activities: Work Log Entries

  18. Use of Social Media:Storm Expectations Morning Pre-Storm “Heads-Up” Severe T-Storm Watch issuance – great job of informing the public of the impending destructive wind threat!

  19. NWSChat Logs

  20. Will be updating this form soon • Will be placed on the Severe Intranet page for easy access • Good place to document what worked and what didn’t work out so well: • Helps us improve as an office • Identify Changes/Best Practices • SWOP staffing model changes?

  21. Summary • High-end severe outbreak that took place during a busy holiday. • Office decision support activities should serve as a model for future outbreaks. • MANY THANKS to our media partners for getting the message out!

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