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Response to Partner Issues Eli Jacks, Chief Fire and Public Weather Services Branch

Response to Partner Issues Eli Jacks, Chief Fire and Public Weather Services Branch. 1) Intended Use of “Tornado Emergency” 2) Too many counties in Storm Based Warnings 3) Watches and Warnings on Feb. 11, 2009. Use of “Tornado Emergency”.

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Response to Partner Issues Eli Jacks, Chief Fire and Public Weather Services Branch

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  1. Response to Partner IssuesEli Jacks, ChiefFire and Public Weather Services Branch 1) Intended Use of “Tornado Emergency” 2) Too many counties in Storm Based Warnings 3) Watches and Warnings on Feb. 11, 2009

  2. Use of “Tornado Emergency” • Identified as “Best Practice” in 3 NOAA Service Assessments • Since 1999 – 6 per year (30% without confirmation) • New directive will require confirmation (visual report or radar observation of debris) • Reduces to an average of 4 events per year In exceedingly rare situations, when a severe threat to human life and catastrophic damage from a tornado is imminent or ongoing, the forecaster may insert the headline "...TORNADO EMERGENCY FOR [GEOGRAPHIC AREA]...". Additionally, in such a situation, this headline should only be used when reliable sources confirm a tornado, or there is clear radar evidence of the existence of a damaging tornado such as the observation of debris. --NWSI 10-511 (final draft)

  3. Too Many Counties In Severe Thunderstorm Warnings • Approximately 1% of Severe Thunderstorm Warnings include more than 12 counties • Change to NWSI 10-511: “Warnings should contain no more than 12 counties” • Next Generation Warning Tool Sub-team looking at improved warning formats (text and graphics) - To include both our full text messages and options for parsing to cell phone text messages - Will involve partners

  4. Watches, Warnings, and WindFebruary 11, 2009 500 MB • Fast moving vigorous upper trough • Narrow line of intense convection • Weak Instability • Damaging Winds &Isolated Tornadoes 12Z 500 MB 00Z

  5. Across the Eastern Half of the U. S. in 21 hours

  6. Feb 11, 2009 High Shear – Low InstabilityEnvironments • Difficult from both watch and warning standpoint F4 Franklin TN 12/24/88

  7. Watches – Feb 11, 2009 • Six Watches During Event: - First three – TOR - Second three – SVR Tornado Watch #16 – Issued 11:40AM DESPITE VERY WEAK INSTABILITY...THE THREAT OF LOCALLY DAMAGING WINDS WILL INCREASE WITH TIME DUE TO DRYING ALOFT AND ENHANCED POTENTIAL FOR DOWNWARD TRANSFER OF MOMENTUM. LOW AND MID LEVEL VERTICAL SHEAR PROFILES WILL ALSO BE FAVORABLE FOR BOW/LEWP STRUCTURES ALONG THE LINE AND AN ATTENDANT RISK OF ISOLATED TORNADOES. _ -- From Tornado Watch 16

  8. Wind Gust 92 MPHat Pittsburgh Airport Overlay Reports on Warnings Approximate Projections - • 16 TOR • 2 Tornadoes This Warning is Too Big Tornado Reports..(2) Wind Reports/HI…(353/3) Hail Reports/LG…(4/0) Total Reports……(359) ….Winds >65 kts

  9. Summary • High Shear / Low Instability Events are challenging from a watch and warning standpoint • NWS increasing effort on addressing very large severe thunderstorm warnings • Too many tornado warnings - - Ideas?

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