# Presentation: 816228

## A Brief Overview of Two Tornadic Quasi-Linear Convective Systems (QLCS) across the Mid-Mississippi Valley Region 

- Ron W. Przybylinski  Science and Operations Officer
- Gary K Schmocker
- Forecaster
- NOAA/NWS St. Louis

## Some Critical Issues

- Can we anticipate when and where a bowingstructure may occur?- Where will they go? How will they evolve?- Where will the most intense swaths of damagingstraight-line wind occur?- Do we expect any tornadoes with the convective   line or bow echoes embedded within the line?- Where will the tornadoes form?

## Shear / Convective Morphology Relationships

- - What type of shear environments are related to what  kinds of convective organizations?

- - Hodograph interpretation

- - Understanding the difference of the various shear and  thermodynamic parameters: Bulk vs Total Shear   SBCAPE, MLCAPE, etc

## Effects of mesoscale environment on convective lines

- - inhomogeneous moisture

- - Pre-existing frontal boundaries, outflows

**-** ‘traveling’ along an axis of instability

## Our Focus in BAMEX: 

**Early – Mature Evolution of Bows (A-B-C-D)**

## Conceptual Models of Bow Echoes

- - Squall Line - Bow Echo   Evolution (merger with  low-level boundary)   **Groups 1 and 2****     *****Most Common***

- - Squall Line Bow Echo

- - Supercell – BE complex    **Group 4**

## Brief Overview of Two QLCS Cases 

- - May 12, 2002 (southeast Missouri  Event – Desloge MO) (Group 2)

- - May 27, 2000  Northern half of Missouri-  West-central Illinois (Group 2)

## May 7, 2002 Tornadic Quasi-Linear Convective System (QLCS) Event 

- 1:30 am CDT 7 May 2002

## Analyzed Surface chart for 0600 UTC (1:00 am cdt)

## 1:51 AM CDT.  Note the identification of a fine line (arrow)in the reflectivity field. This features marks the location ofan low-level outflow boundary.   

- 1:51 AM CDT.  Note the identification of a fine line (arrow)in the reflectivity field. This features marks the location ofan low-level outflow boundary.

## 2:06 AM CDT.  Fine Line still present.  Circulation (#2) formsalong the leading edge of the bow.  

- 2:06 AM CDT.  Fine Line still present.  Circulation (#2) formsalong the leading edge of the bow.

## 2:12 am CDT (1.4 slice).  Circulation 2 rapidly intensifies and spawns a weak tornado just west of the Mississippi River (southeast Lincoln county). Green shades – inbound velocities.  Red shades – outbound velocities 

- 2:12 am CDT (1.4 slice).  Circulation 2 rapidly intensifies and spawns a weak tornado just west of the Mississippi River (southeast Lincoln county). Green shades – inbound velocities.  Red shades – outbound velocities

## 212 am CDT.  Mesocyclone algorithm overlay on storm-relative velocity field.  

- 212 am CDT.  Mesocyclone algorithm overlay on storm-relative velocity field.

## Reflectivity / storm-relativevelocity Cross-section ofCirculation 2.

- Reflectivity / storm-relativevelocity Cross-section ofCirculation 2.

## 2:17 am CDT. Circulation 2 remains very strong and spawnsa second weak tornado over southern Calhoun county. 

- 2:17 am CDT. Circulation 2 remains very strong and spawnsa second weak tornado over southern Calhoun county.

## 2:27 am CDT.  Circulation 2 weakens as it cross the point

- of merger between the Mississippi and Illinois rivers.

## Time-Height Cross-section of Rotational Velocities (Strengthof Rotation) of Circulation 2.  Non-descending characteristic(up-scale growth and low-level rotation increasing with time). Solid black line represents time of tornado occurrence. 

## Damage map – 7 May 2002 across Calhoun county ILand northern St. Charles county. 

- Damage map – 7 May 2002 across Calhoun county ILand northern St. Charles county.

## May 12, 2002 Tornadic QLCS Event

- 5:31 pm cdt.

## 1:00 pm CDT Surface Analysis.  Stationary frontdraped across east-central Missouri and southwestIllinois. 

- 1:00 pm CDT Surface Analysis.  Stationary frontdraped across east-central Missouri and southwestIllinois.

## 3:00 PM CDT Surface Analysis. Dewpoints of 68 degreesand higher covered much of east-central Missouri andexpanded northeastward into south-central Illinois.   

- 3:00 PM CDT Surface Analysis. Dewpoints of 68 degreesand higher covered much of east-central Missouri andexpanded northeastward into south-central Illinois.

## 5:46 pm CDT. Circulation 1 formed along the leading edgeof a bowing segment embedded within the line. 

- 5:46 pm CDT. Circulation 1 formed along the leading edgeof a bowing segment embedded within the line.

## 6:02 pm CDT.  Small isolated cells outline the location of alow-level boundary. 

## 612 pm CDT:  Movement clues – bow begins to accelerateIsolated cells anchored to the boundary (convergence zone) begins to move northward. 

## 612 pm CDT:   Magnified view.  

## 6:17 pm CDT. Isolated cells (boundary/convergence zone) continue to move northward.  Circulation #1 further intensifies. 

## 6:22 pm CDT. Circ 1 – strongest rotation. 

## Time-Height cross-section of Rotational Velocities ofCirculation 1. 

- Time-Height cross-section of Rotational Velocities ofCirculation 1.

## Damage in the Desloge Missouri

- Area.

## Damage Track of the Desloge MO Tornado

## May 27, 2000 QLCS

## Surface Analysis 0200 UTC May 27, 2002

## Skew-t Log-P 0000 UTC 27 May 2000 from KSGFMLCAPE 2512 J/KgBulk Shear 0-3 km  16 m s-1;  0-5 km  21 m s-1. 

- Skew-t Log-P 0000 UTC 27 May 2000 from KSGFMLCAPE 2512 J/KgBulk Shear 0-3 km  16 m s-1;  0-5 km  21 m s-1.

## VWP from KLSX for the period 0207 – 0253 UTC

## 0213 UTC 27 May 2000 hodograph from KLSX0-1 km SRH 210 m2 s-2;  0-3 km SRH  424 m2 s-2

- 0213 UTC 27 May 2000 hodograph from KLSX0-1 km SRH 210 m2 s-2;  0-3 km SRH  424 m2 s-2

## Plan-view reflectivity from KLSX  0207 UTC 27 May 2000Asymmetric reflectivity structure. 

- Plan-view reflectivity from KLSX  0207 UTC 27 May 2000Asymmetric reflectivity structure.

## Plan-views reflectivity / storm-relative velocity (0.5 slice)0227 UTC  27 May 2000.  

- Plan-views reflectivity / storm-relative velocity (0.5 slice)0227 UTC  27 May 2000.

## Plan-views reflectivity / storm-relative velocity  (0.5 slice)0242 UTC  27 May 2000. 

- Plan-views reflectivity / storm-relative velocity  (0.5 slice)0242 UTC  27 May 2000.

## Plan-views reflectivity / storm-relative velocity  (0.5 slice)0253 UTC  27 May 2000 (KLSX). 

- Plan-views reflectivity / storm-relative velocity  (0.5 slice)0253 UTC  27 May 2000 (KLSX).

## Plan-views reflectivity / base velocity (0.5 slice)0253 UTC 27 May 2000 (KLSX). 

- Plan-views reflectivity / base velocity (0.5 slice)0253 UTC 27 May 2000 (KLSX).

## Plan-views reflectivity / storm-relative velocity (0.5 slice)0303 UTC  27 May 2000.  

- Plan-views reflectivity / storm-relative velocity (0.5 slice)0303 UTC  27 May 2000.

- Arrow represents location of Rear Inflow Notch

## Plan-views reflectivity / storm-relative velocity (0.5 slice)0303 UTC 27 May 2000 (KLSX)

- Plan-views reflectivity / storm-relative velocity (0.5 slice)0303 UTC 27 May 2000 (KLSX)

## Plan views reflectivity / storm-relative velocity (1.5 slice)0303 UTC 27 May 2000  (KLSX)

- Plan views reflectivity / storm-relative velocity (1.5 slice)0303 UTC 27 May 2000  (KLSX)

- Arrow represents location of the MARC velocity signatureStrong outbounds (+58 kts) adjacent to inbounds velocities(-29 kts).

## Plan-views reflectivity / storm-relative velocity (0.5 slice)0328 UTC 27 May 2000 (KLSX)

- Plan-views reflectivity / storm-relative velocity (0.5 slice)0328 UTC 27 May 2000 (KLSX)

## Plan-views reflectivity / storm-relative velocity (0.5 slice)

- 0338 UTC  27 May 2002.

## Plan views reflectivity / storm-relative velocity (1.5 slice)0354 UTC  27 May 2000.  

- Plan views reflectivity / storm-relative velocity (1.5 slice)0354 UTC  27 May 2000.

## Plan-views reflectivity / storm-relative velocity (0.5 slice)0359 UTC 27 May 2000 (KLSX)

## Plan-views reflectivity / storm-relative velocity (1.5 slice)0410 UTC  27 May 2000.  (KLSX)

- Plan-views reflectivity / storm-relative velocity (1.5 slice)0410 UTC  27 May 2000.  (KLSX)

## Rotational Velocity trace – Circ 2 (tornado-cyclone).Delta-V values in m s-1. 

- Rotational Velocity trace – Circ 2 (tornado-cyclone).Delta-V values in m s-1.

## Damage Map 27 May 2000

## May 9, 2002 Tornadic QLCS Event

## 10:00 pm cdt surface analysis

## Awips surface plot with LAPS moisture convergence /computed Lifted Index fields for 1:00 am cdt.

- Awips surface plot with LAPS moisture convergence /computed Lifted Index fields for 1:00 am cdt.

## 0145 am cdt. Strong low-level reflectivity gradients along the leading edge.Small - weak circulations identified along the leading edge(sampling issues). 

- 0145 am cdt. Strong low-level reflectivity gradients along the leading edge.Small - weak circulations identified along the leading edge(sampling issues).

## 0201 am cdt.- Individual line segments embedded within the larger    Squall line. - Small-scale circulations

- 0201 am cdt.- Individual line segments embedded within the larger    Squall line. - Small-scale circulations

## 0206 am cdt. Weak small vortex C3 identified westof Centralia. 

- 0206 am cdt. Weak small vortex C3 identified westof Centralia.

## 0211 am cdt.  C3 – very small vortex. 

- 0211 am cdt.  C3 – very small vortex.

## NSSL Experimental product – Integrated vorticity plot. 

- NSSL Experimental product – Integrated vorticity plot.

## Comparison of mesocyclone characteristics for 8 MCS cases (Group 1)Squall Line – Bow Echo evolution (merger with a low-level boundary)D = Descending vortex; ND = Non-Descending vortex; T = TornadoOccurrence. 

| Case# | 1 | 2 | 3 | 4 | 5 | 6 | 7/BE1 | 7/BE2 | 8 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Shear | MDT | WK | MDT | WK | MDT | MDT | WK |  | MDT |
| Circ #1 | D | ND | D | D | D | D | D | D | D |
| Circ #2 | ND/T | D | ND | ND | ND | ND/T | ND | ND | ND/T |
| Circ #3 | ND/T |  | ND | D | ND/T | ND/T |  | ND |  |
| Circ #4 | D |  |  |  | D | ND/T |  |  |  |

**Comparison of mesocyclone characteristics for 8 MCS cases (Group 1)****Squall Line – Bow Echo evolution (merger with a low-level boundary)****D = ****Descending vortex****; ND = ****Non-Descending vortex****; ****T ****= ****Tornado****Occurrence. **

**Table #1 (Group 1 cases)**

## Table #1 (Group 1 cases)

| Case# | 1D | 2D | 3D | 4D | 5 | 6D | 7/BE1 | 7/BE2 | 8 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| Shear0-5km | 19m/s | 11 | 17 | 13 | 19 | 15 | 11 |  | 19 |
| MLCAPE | 4500 J/Kg | 3600 | 3500 | 3750 | 4500 | 3400 | 4300 |  | 3300 |
| CIRC #1 | D | ND | D | D | D | D | D | D | D |
| CIRC #2 | ND/T | D | ND | ND | ND | ND/T | ND | ND | ND/T |
| CIRC #3 | ND/T |  | ND | D | ND/T | ND/T |  | ND |  |
| CIRC #4 | D |  |  |  | D | ND/T |  |  |  |

**Table #1 (Group 1 cases)**

**Comparison of mesocyclone characteristics for 8 MCS cases (Group 1)****Squall Line – Bow Echo evolution (merger with low-level boundary)****D = ****Descending vortex****; ND = ****Non-Descending vortex****; ****T ****= ****Tornado **

## Summary 

- We first introduced storm types (conceptual models) that a bow may evolve from          - Squall Line to Bow Echo evolution with merger          of low-level boundary (Groups 1 and 2 – most           common;  Klimowski (WFO RAP) – has shown this             type to be most common)**          ****- **Squall Line Bow Echo
-           **- **Supercell – Bow Echo complex

## Summary cont’

-  We briefly reviewed two tornadic QLCS cases–      -  May 12, 2002      -  May  27, 2000
-   May 12th and 27th cases were associated with    with low-level boundaries. - Tornadic circulations (May 12 and 27th) revealed   *‘non-descending’  *characteristics:        - upscale growth       - increase in low-level rotation with time - *Trend Information is very useful.*

## Summary cont’ 

-  For more info check out:  www.crh.noaa.gov/lsx/science/newcomet.htm* **e-mail:  ron.przybylinski@noaa.gov*