1. July 4 th 2012 Severe Weather Case Review and DSS Andrew Loconto NWS Burlington, VT Andrew Loconto NWS Burlington, VT

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

3. Intro High-end severe weather event coinciding with 4 th of July holiday (many outdoors) –Potentially bad things could have happened… NWS and Media Partners did an outstanding job given these circumstances High-end severe weather event coinciding with 4 th 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 #2: “The Pig” Supercell in St. Lawrence County Storm #3: Champlain Valley Bow Echo

6. 500mb jet of ~ 85 kts

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

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

11. 22z LAPS Sfc-based CAPE/CIN & Sfc Obs 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.

12. 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!

13. Storm #1: Northeast Kingdom Bow Echo

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

15. 0.5° SRM: Broad Low-/mid-level rotational couplet (~10,000ft AGL) 6.4° SRM: Storm Top Divergence (~46,000 ft AGL)

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

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

20. Office Decision Support Actions

21. DSS Activities: Work Log Entries

22. 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!

23. Use of Social Media: Fetching Reports Getting information about the St. Lawrence County supercell… General asking for storm reports…

24. NWSChat Logs

25. 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?

26. 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! 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!