19 july 2006 derecho a meteorological perspective and lessons learned from this event
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19 July 2006 Derecho: A Meteorological Perspective and Lessons Learned from this Event. Ron W. Przybylinski, James E. Sieveking, Benjamin D. Sipprell NOAA / National Weather Service St. Louis Jared L. Guyer NOAA/NWS/NCEP Storm Prediction Center. 2009 Spring Media Workshop.

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19 july 2006 derecho a meteorological perspective and lessons learned from this event

19 July 2006 Derecho:A Meteorological Perspective and Lessons Learned from this Event

Ron W. Przybylinski, James E. Sieveking, Benjamin D. Sipprell NOAA / National Weather Service St. LouisJared L. GuyerNOAA/NWS/NCEP Storm Prediction Center

2009 Spring Media Workshop


Outline of this presentation
Outline of this Presentation

  • Synoptic scale conditions the morning of 19 July 2006

  • Storm overview (large scale perspective)

  • Mesoscale Environment during the afternoon of 19 July 2006 over southern Iowa, Missouri and Illinois.

  • WSR-88D Doppler radar analysis of the storm complex from WFO Lincoln Illinois and WFO St. Louis perspectives.

  • Some final comments


Upper air analysis 1200 utc 19 july 2006
Upper Air Analysis - 1200 UTC 19 July 2006

250 mb analysis

500 mb analysis


Upper air analysis 1200 utc 19 july 20061
Upper Air Analysis - 1200 UTC 19 July 2006

850 mb analysis

RUC 700-500 mb lapse rate (°C km-1)



Radar imagery composites and 06z spc outlook
Radar Imagery Composites and 06z SPC Outlook

Composite base reflectivity 1210 UTC

SPC radar animation

1200-1315 UTC


Radar imagery composites and 13z spc outlook
Radar Imagery Composites and 13z SPC Outlook

Composite base reflectivity 1610 UTC

SPC radar animation

1454-1615 UTC





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Winchester, IL (WNC) Profiler 1700 - 2200 UTC


SPC Mesoscale analysis for MLCAPE and 0-6 km bulk shear at 2300 UTC

MLCAPE ranged from 2000 – 6000 J kg-1 acrosseastern Missouri throughwest-central Illinois

Deep layer shear weak

with magnitudes of

10 – 22 m s-1



Parker’s Study on Linear MCS archetypes

The 19 July 2006 Damaging Wind Convective system followed theParallel Stratiform (PS) archetype


WSR-88D Radar Imageryfrom Lincoln Illinois (KILX)at 2138 UTC

Parallel Stratiform Parker and Johnson 2000



KLSX radar imagery for 2332 UTC

2332 UTC Radar imagery from St. Louis (KLSX). The strongest winds were associated with convective segment #3 (larger echo mass).Several witnessesover southern Macoupin County experience hail up to nickel size with the stronger downbursts behind the leading gust front.


I Was Here!

7:01 PM CDT Reflectivity (left), Base velocity (right). The strongest winds were detected with the higher reflectivity cores over northwest Madison County Illinois.


Loop of the evolution of a single severe cell over the western part of the storm complex.


Bunker Hill western part

ASOS / AWOS Surface Observation sites around the GreaterSt. Louis metro area.


When was the last time we documented a case similar western part to the July 19, 2006 Derecho?

Aug 10, 1992. The convective complex formed just southwest of KLSXand moved south-southward through west-central Arkansas. Widespread wind damage occurred with this derecho.


The July 19 2006 damage map reveals that much of the downbursts was oriented from north-northeast to south-southwest – an unusual direction.This direction of damaging winds future intensified the degree of damage over the greater St. Louis metro area.


Tower Grove Park downbursts


Summary downbursts

  • On 19 July 2006 formed over northeast Iowa and causedsevere wind damage from parts of northeast Iowa through central Illinois and then south-southwest across the Greater St. Louis metro area and then into southwest Missouri.(A typical movement).

  • -Over 500,000 people were without power from this windstorm. The oppressive HEAT AND HUMIDTYafter this event brought suffering to a large part of the population. - The environment over the Mid-Mississippi Valley regionwas extremely unstable with ML CAPEs of 2600 to 6000 J/Kg while a deep layer shear was weak (< 22 m s-1 )


  • RUC sounding at 2300 UTC from STL showed a very weak downbursts cap.- The upper-level ridge over the central plains built eastwardinto Illinois allowing the MCS to move in a south-southwestdirection during the late afternoon and evening. - The overall storm morphology took on the characteristics of “parallel stratiform” type system where three convective segments showed “pulse – multicellular” characteristics. - Convective segment #3 (eastern most storm) was themost consistent storm complex of the three groups. -


  • Surface winds along the leading edge of the gust downbursts front varied between 20 to 31 m s-1. - The strongest surface winds were associated with the isolated convective towers through the area of mature convection. Wind speed estimates – 40 m s-1

  • - This wind storm was one of the more challenging cases, from both a national and local WFO perspective.


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