1 / 23

Large, Sparsely Verified Severe Thunderstorm Warnings: Can we do better…and do we want to?

Large, Sparsely Verified Severe Thunderstorm Warnings: Can we do better…and do we want to?. Eric Lenning and Ben Deubelbeiss NWS Chicago 2014 GLOMW. Motivation. Goal: An increased understanding of the types of severe weather systems (lines/clusters) that prompt large warnings.

callum
Télécharger la présentation

Large, Sparsely Verified Severe Thunderstorm Warnings: Can we do better…and do we want to?

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Large, Sparsely VerifiedSevere Thunderstorm Warnings:Can we do better…and do we want to? Eric Lenningand Ben DeubelbeissNWS Chicago 2014 GLOMW

  2. Motivation • Goal:An increased understanding of the types of severe weather systems (lines/clusters) that prompt large warnings. • Concern is large polygons with few if any reports: • Training? • Verification? • Population? • Radar sampling? • Workload? • Fear? • Conclusion:Environment + Radar Signatures  Better Decisions

  3. Narrow the Focus Consider “LARGE” SVR polygons (> 7000 sqkm). • Consider “SPARSELY VERIFIED” polygons (< 20% coverage). • Over 72% of large polygons from GL offices (139 of 191) were sparsely verified from 2008-2013.

  4. LSR 15km Buffer Polygon Area: 12538 sqkm 5 LSRs and 21% Areal Verification • Polygon Area: 2088 sqkm • 1 LSR and 43% Areal Verification

  5. Questions • Can we better distinguish between high-end and low-end lines or clusters of storms? • ** Use both environment and radar signatures ** • For lower-end lines/clusters, can we focus the warning area? • Are we willing to take a few hits to avoid over-warning? • Is there an SPS or IBW approach? • Is over-warning even a problem??? • Are we missing something else?

  6. Large (>7000 sq km) Polygons: 08-13

  7. 2008-2013

  8. 2008-2013

  9. What do we know about damaging lines/clusters? • Wind is main concern with large polygons? • Favorable Environments • Marginal to large (sfc-based?) instability. • Marginal to large shear (0-6km or 0-3km?). • Cold pool potential, LFC height, wind/shear orientation… • Radar Characteristics • Fast motion, tight reflectivity gradients, rear-inflow jets, rotational couplets, MARC signatures, cell intersections, leading/trailing/parallel stratiform, bookend vortices, reflectivity tags….

  10. FamiliarResearch Corfidi, 2003

  11. MORE Recent Research Schaumann and Przybylinski, 2012

  12. 2008 Aug 4vs2012 Jun 29

  13. 3km VGP and 0-3km Shear Vector 20080804 23 UTC 20120629 14 UTC

  14. Result • 4-5 August 2008: • Warning 163 from 0018z-0130z • 68% areal verification • Widespread damage • 29 June 2012: • Warning 54 from 1544z-1645z • 8% areal verification (Still a HIT!) • ~60 mph gust, power lines down

  15. VGP and 0-3km Shear Vector06/12/2013 23Z

  16. VGP and 0-3km Shear Vector07/03/2012 01Z

  17. Conclusions • Use large polygons based on morphology, not geography. • Large polygons best suited for derecho / bowecho types. • A large but ordinary line or cluster may warrant warnings, but only for smaller portions. • Environmental factors: • Orientation of 3km Shear Vector to lines of cells • Strength of 3km shear relative to cold pool

More Related