July 4th 2012 Severe Weather Case Review and DSS

July 4th 2012 Severe Weather Case Review and DSS

Andrew Loconto

NWS Burlington, VT

Andrew Loconto

NWS Burlington, VT

Presentation OutlinePresentation Outline

• Brief Background

• Synoptic-scale & Radar Overview

• NWS Decision Support Activities

• Brief Background

• Synoptic-scale & Radar Overview

• NWS Decision Support Activities

IntroIntro

• 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

• 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

Storm Reports from July 4thStorm 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

Storms #1: Northeast Kingdom Mini-bow echo

Storm #2: “The Pig” Supercell in St. Lawrence County

Storm #3: Champlain Valley Bow Echo

500mb jet of ~ 85 kts

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

700 mb Analyses

Northwest Unidirectional Deep-layer shear profile

0-6km shear magnitudes support organized multicells/some supercells …

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.

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!

Storm #1: Northeast Kingdom Bow EchoStorm #1: Northeast Kingdom Bow Echo

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 SupercellStorm #2: “The Pig” – SLV Supercell

Storm #2: “The Pig” – SLV SupercellStorm #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)

Storm #3: Champlain Valley Bow Echo @ 2215ZStorm #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…

Storm #3: Champlain Valley Bow Echo @ 2310ZStorm #3: Champlain Valley Bow Echo @ 2310Z

Office Decision Support Actions

Office Decision Support Actions

DSS Activities: Work Log Entries

DSS Activities: Work Log Entries

Use of Social Media:Storm ExpectationsUse 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!

NWSChat Logs

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?

SummarySummary

• 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!