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Weekly/Special Severe Weather 4/14/2011

Weekly/Special Severe Weather 4/14/2011. Slides Available at www.srh.noaa.gov/shv/briefing. Keith Stellman Warning Coordination Meteorologist. National Weather Service Shreveport, Louisiana. Summary. Moderate Risk for severe storms late today/tonight very large hail

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Weekly/Special Severe Weather 4/14/2011

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  1. Weekly/Special Severe Weather4/14/2011 Slides Available at www.srh.noaa.gov/shv/briefing Keith Stellman Warning Coordination Meteorologist National Weather Service Shreveport, Louisiana

  2. Summary Moderate Risk for severe storms late today/tonight very large hail Strong to violent tornadoes possible Damaging winds SE OK, NE TX, SW AR afternoon/evening NW/N LA, S AR Late tonight Upper level pattern very similar to April 9, 2009 Possible Red Flag conditions on Friday 20-25 mph winds Relative humidity 20-25% National Weather Service Shreveport, Louisiana

  3. Overview Current L Midnight L 140 knot Jetstreak Deep Moisture Gulf Moisture National Weather Service Shreveport, Louisiana

  4. Severe Weather Thursday Moderate Risk Area Highest Probability of Severe Weather Slight Risk Area Threats Large Hail Tornadoes (Some could be strong/violent) Damaging Winds

  5. Timing – 3 PM Today NAM Model • Dryline west of the region moving in • Storms soon developing along the line

  6. Timing – 6 PM Today NAM Model • Dryline still west of the region moving in • Storms developing ahead of the line in NE TX/SE OK

  7. Timing – 9 PM Today NAM Model • Dryline still west of the region • Prefrontal line providing enough lift to break cap • Storms moving into NW LA/SW AR

  8. Very high wind shear values to support supercells /rotating updrafts Instability forecast to be very high 2000-3000 j/kg From 6PM-3AM values are sufficient Wind Shear at 9 PM Orange = <150 (not sufficient) Red = 200-400(Very high) Pink/Purple = 400-600 For Severe Weather we look for 150 or higher 0-3 KM Helicity

  9. Timing – 6 AM Friday • Moving through • Storms should fill in southward along the line • Becoming a damaging wind threat

  10. Heaviest rain in OK/AR Not enough to touch the drought Forecast Rainfall Totals 0.75”- 1.25” 0.50”- 0.75” 0.25”-0.50” <0.25”

  11. Threats/ImpactsDamaging Winds • Highest threat in the moderate risk area • Transitioning across N LA in the early AM

  12. Threats/ImpactsLarge Hail Red outlined area includes Significant hail threat >2” Probability of Severe hail within 25 miles of a point

  13. Threats/ImpactsTornado Pink area denotes Increased probability For strong/violent tornadoes (EF2+) Probability of a tornado within 25 miles of a point

  14. Friday • Slight Risk for storms Eastern LA • Early AM..ending by mid morning • Damaging Winds primary threat

  15. Friday • Winds 20-25 mph • Gusting over 30 • Very dry air filtering in • Very strong and gusty west winds • Possible Red Flag conditions for the first time in many years Sustained Winds Relative Humidity values Friday PM

  16. Weekend Sunday Highs • Pleasant • Dry Saturday Highs

  17. Next Weather Maker Tuesday/Wednesday • Pattern changes next week • Front moves into I-40 corridor and stalls • Possible relief from drought • Severe weather

  18. DROUGHT SITUATION • Drought is worsening in some areas! A D4 rating (Exceptional) area is being included for southern sections of Deep East Texas…while the remainder of much of the area is in the D3 rating (Extreme) area. • Multiple county/parish burn bans in effect.

  19. Summary Moderate Risk for Severe Weather over the north late today/tonight Impacts Tornadoes (some Strong) Very Large Hail Damaging Winds Threat shifts east by early AM Friday – High Fire Danger Moderate Risk Area Highest Probability of Severe Weather Slight Risk Area National Weather Service Shreveport, Louisiana

  20. NEXT CONFERENCE CALL: Thursday 04/21/2011 @ 10 AM www.srh.noaa.gov/shv/briefing National Weather Service Shreveport, Louisiana

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