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Premium member Presentation Transcript An Examination of the 22 May 2004 Hallam, Nebraska Tornado: An Examination of the 22 May 2004 Hallam, Nebraska Tornado Rebecca Adams Creighton University and WFO Omaha/Valley, NebraskaEvent Description: Event Description supercell formed in southwest Thayer county shortly after 23Z first severe report 2345Z 2.00” hail (as large as 3.00”) tornadic by 2352Z report near 3 NW Hebron Hallam Supercell Radar Imagery: Radar Imagery NWS Omaha/Valley WSR-88D radarRadar Imagery: Radar Imagery Daykin Hallam PalmyraRadar Imagery: Radar Imagery 78.2 kts away 105.9 kts towardEvent Description: Event Description Touchdown: 0030Z Daykin, NE Lifted: 0210Z Palmyra, NE Length: 52 mi. 1 hr. 40 min. Max width: 2.5 mi. Hallam Tornado Map and information taken from storm survey conducted by NWS Omaha/Valley and Emergency ManagementSlide8: Damage from Hallam tornado Near Firth South of HallamEvent Description: Event Description Two Supercells Supercell A Supercell BEvent Description: Event Description Two Supercells: why the difference? Synoptic Environment: Synoptic Environment 200 mb left exit quadrant of jet max 500 mb Southwesterly flow: sharp trough over western U.S. shortwave evident in both 12Z, 00Z RUC 50 kt wind max positive vorticity advection apparent by 18Z cold air advection Upper LevelsSynoptic Environment: 18Z RUC80 22 May 200 mb heights winds isotachs Synoptic EnvironmentSynoptic Environment: Synoptic Environment 500 mb heights vorticity 00Z RUC80 23 MaySynoptic Environment: Synoptic Environment 700 mb moisture advection: 3.43 g/kg over 3 hrs warm air advection (isentropic lift) maximum over south central Nebraska 18Z onward 850 mb strong low level jet (40 kt max at 01Z) warm air, moisture advection maximums Lower Levels Slide15: 23 May 310 K Surface pressure winds (streamlines) Synoptic Environment 00Z RUCSlide16: 00Z RUC80 23 May 700 mb heights winds temperature temperature advection Synoptic EnvironmentSynoptic Environment: Synoptic Environment 850 mb temperature winds isotachs 01Z RUC40 23 MaySynoptic Environment: Synoptic Environment 925 mb winds theta-e 00Z RUC40 23 MaySynoptic Environment: Synoptic Environment strong low pressure over NW Kansas warm front across Nebraska into southern Minnesota dryline west-central KS outflow boundary warm temperature axis west of moisture pool 70° dewpoints Surface Synoptic Environment: Synoptic Environment METARs SLP temperature dewpoint Surface 00Z RUC40 23 MaySynoptic Environment: Synoptic Environment Four lifting mechanisms: Upper-level divergence from jet streak DPVA from strong shortwave Convergence along warm front, outflow boundary Isentropic lift Mesoscale Conditions: Mesoscale Conditions Tornado A1 SBCAPE 3231 J/kg SBCIN: -110 J/kg LCL: 1176 m LFC: 2213 m 22Z 22 May modified RUC40Mesoscale Conditions: SBCAPE: 4088 J/kg SBCIN: -29 J/kg LCL: 1001 m LFC: 1350 m Mesoscale Conditions Tornado B3 00Z 23 May modified RUC40Mesoscale Conditions: Mesoscale Conditions Comparison + SPC Mesoanalysis page * Surface-modified RUC40 sounding at hour closest to tornado touchdownThermodynamics: Thermodynamics Comparison of Hallam Tornado to the ‘A’ Set Jon Davies’s parameters for “good” or “strong” support of supercell tornadoes LFC: 2000 m CIN: -100 J/kg A1 A2 A3 A4 A5 A6 Start Mid End http://members.cox.net/jondavies1/tornado_fcsting/sprcll_tors.htmThermodynamics: Thermodynamics Comparison of Hallam Tornado to the ‘A’ Set red lines: 50th percentile of that parameter in the significant tornado class (F2-F5) as per Davies blue lines: 75th percentile Davies, J., 2004: Estimations of CIN and LFC Associated with Tornadic and Nontornadic Supercells. Wea. Forecasting, 19, 714-726.Low-Level Shear: Low-Level Shear Supercell B 0-1 km SRHConclusions: Conclusions Very favorable synoptic situation abundant lift cold air advection upper levels/warm, moist air advection lower levels cap weakened enough low-level shear outstanding Hallam TornadoConclusions: Conclusions Mesoscale environment can vary widely over small distances and times Height of LFC and amount of CIN key Low-level shear profile important Be on the lookout for very small-scale changes Supercell ComparisonAcknowledgements: Acknowledgements NWS Omaha/Valley for providing AWIPS data Dan Nietfeld and Cathy Zapotocny for helpful insights Matthew Bunkers for the Excel Hodograph Program You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
2 4 Adams Hallam Me_I Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 103 Category: News & Reports.. License: All Rights Reserved Like it (0) Dislike it (0) Added: October 07, 2007 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript An Examination of the 22 May 2004 Hallam, Nebraska Tornado: An Examination of the 22 May 2004 Hallam, Nebraska Tornado Rebecca Adams Creighton University and WFO Omaha/Valley, NebraskaEvent Description: Event Description supercell formed in southwest Thayer county shortly after 23Z first severe report 2345Z 2.00” hail (as large as 3.00”) tornadic by 2352Z report near 3 NW Hebron Hallam Supercell Radar Imagery: Radar Imagery NWS Omaha/Valley WSR-88D radarRadar Imagery: Radar Imagery Daykin Hallam PalmyraRadar Imagery: Radar Imagery 78.2 kts away 105.9 kts towardEvent Description: Event Description Touchdown: 0030Z Daykin, NE Lifted: 0210Z Palmyra, NE Length: 52 mi. 1 hr. 40 min. Max width: 2.5 mi. Hallam Tornado Map and information taken from storm survey conducted by NWS Omaha/Valley and Emergency ManagementSlide8: Damage from Hallam tornado Near Firth South of HallamEvent Description: Event Description Two Supercells Supercell A Supercell BEvent Description: Event Description Two Supercells: why the difference? Synoptic Environment: Synoptic Environment 200 mb left exit quadrant of jet max 500 mb Southwesterly flow: sharp trough over western U.S. shortwave evident in both 12Z, 00Z RUC 50 kt wind max positive vorticity advection apparent by 18Z cold air advection Upper LevelsSynoptic Environment: 18Z RUC80 22 May 200 mb heights winds isotachs Synoptic EnvironmentSynoptic Environment: Synoptic Environment 500 mb heights vorticity 00Z RUC80 23 MaySynoptic Environment: Synoptic Environment 700 mb moisture advection: 3.43 g/kg over 3 hrs warm air advection (isentropic lift) maximum over south central Nebraska 18Z onward 850 mb strong low level jet (40 kt max at 01Z) warm air, moisture advection maximums Lower Levels Slide15: 23 May 310 K Surface pressure winds (streamlines) Synoptic Environment 00Z RUCSlide16: 00Z RUC80 23 May 700 mb heights winds temperature temperature advection Synoptic EnvironmentSynoptic Environment: Synoptic Environment 850 mb temperature winds isotachs 01Z RUC40 23 MaySynoptic Environment: Synoptic Environment 925 mb winds theta-e 00Z RUC40 23 MaySynoptic Environment: Synoptic Environment strong low pressure over NW Kansas warm front across Nebraska into southern Minnesota dryline west-central KS outflow boundary warm temperature axis west of moisture pool 70° dewpoints Surface Synoptic Environment: Synoptic Environment METARs SLP temperature dewpoint Surface 00Z RUC40 23 MaySynoptic Environment: Synoptic Environment Four lifting mechanisms: Upper-level divergence from jet streak DPVA from strong shortwave Convergence along warm front, outflow boundary Isentropic lift Mesoscale Conditions: Mesoscale Conditions Tornado A1 SBCAPE 3231 J/kg SBCIN: -110 J/kg LCL: 1176 m LFC: 2213 m 22Z 22 May modified RUC40Mesoscale Conditions: SBCAPE: 4088 J/kg SBCIN: -29 J/kg LCL: 1001 m LFC: 1350 m Mesoscale Conditions Tornado B3 00Z 23 May modified RUC40Mesoscale Conditions: Mesoscale Conditions Comparison + SPC Mesoanalysis page * Surface-modified RUC40 sounding at hour closest to tornado touchdownThermodynamics: Thermodynamics Comparison of Hallam Tornado to the ‘A’ Set Jon Davies’s parameters for “good” or “strong” support of supercell tornadoes LFC: 2000 m CIN: -100 J/kg A1 A2 A3 A4 A5 A6 Start Mid End http://members.cox.net/jondavies1/tornado_fcsting/sprcll_tors.htmThermodynamics: Thermodynamics Comparison of Hallam Tornado to the ‘A’ Set red lines: 50th percentile of that parameter in the significant tornado class (F2-F5) as per Davies blue lines: 75th percentile Davies, J., 2004: Estimations of CIN and LFC Associated with Tornadic and Nontornadic Supercells. Wea. Forecasting, 19, 714-726.Low-Level Shear: Low-Level Shear Supercell B 0-1 km SRHConclusions: Conclusions Very favorable synoptic situation abundant lift cold air advection upper levels/warm, moist air advection lower levels cap weakened enough low-level shear outstanding Hallam TornadoConclusions: Conclusions Mesoscale environment can vary widely over small distances and times Height of LFC and amount of CIN key Low-level shear profile important Be on the lookout for very small-scale changes Supercell ComparisonAcknowledgements: Acknowledgements NWS Omaha/Valley for providing AWIPS data Dan Nietfeld and Cathy Zapotocny for helpful insights Matthew Bunkers for the Excel Hodograph Program