Two Cases of QLCS Tornadic Wind Estimation and Implications for Impact Based Warnings

T.J. Turnage and Jared Maples National Weather Service

Grand Rapids, Michigan

Outline

QLCS tornado climatology

Impact Assessment

Warning decisions

QLCS Tornado Climatology

% tornado days due to lines1998 - 2000

Trapp et al. 2005

● larger proportion of F1 tornadoes from QLCSs than cells● smaller proportion of F0 tornadoes - likely underreported● more F3–F4 tornadoes from cells

Trapp et al. 2005

QLCS Tornado Climatology

Significant Severe Climatology

Thompson et al. 2013

Courtesy of SPC

Outline

QLCS tornado climatology

Impact Assessment

Warning decisions

Goals● Provide valuable information● Help improve public response● Better addressing of societal

needs

Impact Assessment

What is the IBW experiment?● Began in 2012● Distinguish low and high

impact events● Indicate levels of risk

Impact Based Warnings

http://www.crh.noaa.gov/crh/?n=2013_ibw_info

Phenomena

Impacts

Impact Assessment

*FLYING DEBRIS DANGEROUS TOTHOSE WITHOUT SHELTER

*MOBILE HOMES DAMAGED OR DESTROYED

*DAMAGE TO ROOFS ...WINDOWS… VEHICLES

*TREE DAMAGE LIKELY

*FLYING DEBRIS DANGEROUS TO THOSEWITHOUT SHELTER

*MOBILE HOMES HEAVILY DAMAGED

*CONSIDERABLE DAMAGE TO ROOFS…WINDOWS...VEHICLES

*EXTENSIVE TREE DAMAGE ANDPOWER OUTAGES

Significant SVR

Default TOR

Impact Assessment

REMAIN ALERT FOR A POSSIBLE TORNADO! TORNADOES CAN DEVELOP QUICKLY FROM SEVERE THUNDERSTORMS. IF YOU SPOT A TORNADO GO AT ONCE INTO THE BASEMENT OR SMALL CENTRAL ROOM IN A STURDY STRUCTURE.

INTENSE SQUALL LINES CAN SOMETIMES PRODUCE BRIEF TORNADOES AND WIDESPREAD SIGNIFICANT WIND DAMAGE. ALTHOUGH A TORNADO IS NOT IMMEDIATELY LIKELY...IT IS BEST TO MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A BUILDING. THIS STORM MAY CAUSE SERIOUS INJURY AND SIGNIFICANT PROPERTY DAMAGE

TORNADO...POSSIBLE

Impact Assessment

Outline

QLCS tornado climatology

Impact Assessment

Warning decisions

Decision Factors

Near StormEnvironment(NSE)

StormInterrogation

Ground Truth

Warning Decisions

Near Storm Environment (NSE)SPC Tornado Environment Browser

Case 1

06/22/2010 ~04Z

Near Storm Environment (NSE)

MLCAPE MLCIN

Nontor EF0 EF2+

Thompson et al. 2013

Nontor EF0 EF2+

06/22/2010 04Z

0-6 km BWDEffective BWD

Nontor EF0 EF2+

0-1 km BWD

Nontor EF0 EF2+

Near Storm Environment (NSE)06/22/2010 04Z

Thompson et al. 2013

STPEffective STP

Nontor EF0 EF2+

0-1 km SRHEffective SRH

Nontor EF0 EF2+

Near Storm Environment (NSE)06/22/2010 04Z

Thompson et al. 2013

Atkins and St. Laurent MWR 2009

Storm Interrogation Principles

Descending TVS

Non-Descending TVS

Trapp and Weisman 2003

Trapp et al. 1999

Storm Interrogation Principles

Where did the “tornado” occur?

06/22/2010 04ZReflectivity NROTStorm Interrogation

N

06/22/2010 04ZStorm Interrogation

Gravity wave interaction?

TroughCrest

06/22/2010 04ZStorm Interrogation

Case 2

11/17/2013 ~19Z

Near Storm Environment (NSE)

MLCAPE MLCIN

Nontor EF0 EF2+

Thompson et al. 2013

Nontor EF0 EF2+

11/17/2013 19Z

0-6 km BWDEffective BWD

Nontor EF0 EF2+

0-1 km BWD

Nontor EF0 EF2+

Near Storm Environment (NSE)

Thompson et al. 2013

11/17/2013 19Z

STPEffective STP

Nontor EF0 EF2+

0-1 km SRHEffective SRH

Nontor EF0 EF2+

Near Storm Environment (NSE)

Thompson et al. 2013

11/17/2013 19Z

Reflectivity NROT11/17/2013 19ZStorm Interrogation

N

11/17/2013 19ZStorm Interrogation

11/17/2013 19ZStorm Interrogation

SummaryQLCS Tornadoes

• Climatologically common

• Climatology strongly favors ≤ EF1 wind

• Damage often looks like “straight line” wind

• Similar impacts to SVR t-storms

Summary (cont)

• Shear / SRH best discriminate significant

tornado environments

• MLCAPE / MLCIN / STP less helpful

Warning Decision - NSE

Summary (cont)

• QLCS mesovortices:

• Usually north of bow apex

• Strongest wind south of circulation

• May or may not descend

• Intensity often regulated by gravity waves

• Radar presentation can be deceptive

Warning Decision – Storm Interrogation

Thank you!

Atkins, Nolan T., Michael St. Laurent, 2009: Bow Echo Mesovortices. Part I: Processes That Influence Their Damaging Potential. Mon.

Wea. Rev.,137, 1497–1513.

Thompson, R.; Smith, B.; Dean, A.; Marsh, P.. Spatial Distributions of Tornadic Near-Storm Environments by Convective Mode. E-Journal

of Severe Storms Meteorology, North America, 8 1 09 2013.

Trapp, R. J., E. D. Mitchell, G. A. Tipton, D. W. Effertz, A. I. Watson, D. L. Andra, M. A. Magsig, 1999: Descending and Nondescending

Tornadic Vortex Signatures Detected by WSR-88Ds. Wea. Forecasting, 14, 625–639.

Trapp, Robert J., Sarah A. Tessendorf, Elaine Savageau Godfrey, Harold E. Brooks, 2005: Tornadoes from Squall Lines and Bow Echoes. Part

I: Climatological Distribution. Wea. Forecasting, 20, 23–34.

Trapp, Robert J., Morris L. Weisman, 2003: Low-Level Mesovortices within Squall Lines and Bow Echoes. Part II: Their Genesis and

Implications.Mon. Wea. Rev., 131, 2804–2823.

Impact Based Warnings:

References

http://www.crh.noaa.gov/crh/?n=2013_ibw_info