national weather service wilmington, oh seth binau dan hawblitzel noaa/nws wilmington oh june 23...

National Weather ServiceWilmington, OH

Seth Binau Dan Hawblitzel NOAA/NWS Wilmington OH

June 23 2010

TDWR Detection of Small-Scale Thunderstorm Events


Outline• Overview of ILN TDWR network

• Severe cases caught by TDWR, but not 88D– Height above ground level– Viewing angle– Temporal resolution

• Hints of severe weather occurring on 88D data


TDWR Overview – Locations

WDTB TDWR Training – Part One


TDWR Locations – WFO ILN• A nearly ideal setup• 3 TDWRs

– TCVG (Cincinnati)– TDAY (Dayton)– TCMH (Columbus)

• Cover nearly all of the ILN forecast area with VCP80 data– One volume scan/minute– Redundancy if 88-D fails


TDWR Locations – WFO ILN

• 90% of CWA covered by at least one TDWR• 49 of 52 counties

• 20% of CWA covered by two TDWRs

• 65% of CWA closer to TDWR than 88D


Examples To Follow

Falmouth KY Downburst

Ripley IN TornadoDarke County Straight-Line Winds

Mason KY Downburst


Ripley (IN) Tornado – Mar 8 2009

Courtesy: Charles Woodrum (PBZ)




TCVG 0.1 Reflectivity Loop TCVG 0.1 SRM Loop

KILN 0.5 Reflectivity Loop KILN 0.5 SRM Loop


• Evident on TDWR: Tight spin-up as convergence acts on kink in storm-scale boundary

• Evident on 88D: Boundary, convergence



Darke County (OH) – May 7 2010



TDAY 0.3 Reflectivity – 0045Z KILN 0.5 Reflectivity – 0047Z

TDAY 0.3 Velocity – 0045Z KILN 0.5 Velocity – 0047Z

~350ft AGL ~3000ft AGL


Darke County (OH) Straight-Line Winds May 7 2010

• Evident on TDWR: Intensifying RIJ; near-ground divergence; ground-relative velocity >70 kt

• Evident on 88D: deepening/strengthening MARC (weak!)


May 28 2010 – Falmouth KY Downburst

Classic Pulse Severe/Downburst Sounding



TCVG 0.1 Reflectivity – 2308Z

TCVG 0.1 Velocity – 2308Z

KILN 0.5 Reflectivity – 2308Z

KILN 0.5 Velocity – 2308Z




TCVG 0.1 Reflectivity – 2309Z KILN 0.5 Reflectivity – 2308Z

TCVG 0.1 Velocity – 2309Z KILN 0.5 Velocity – 2308Z




• Evident on TDWR: Near-ground divergence associated with downburst; 1-min of 40-kt V



• Evident on 88D: Descending core aloft


Mason County KY Downburst – June 15, 2010





• Evident on TDWR: 60+ kt winds 800 ft AGL 24-kt winds 2400 ft AGL

at time of damage 12 min AFTER damage



• Evident on 88D: 25-kt MARC at 9300 ft AGL Almost no MARC at

12 min BEFORE damage time of damage



Conclusions• Low level scans of TDWR reveal much goes on

below lowest 0.5 scan of 88D• Tornado “spin ups”

– May have to rely on conceptual model – Upward tilting/stretching acting on storm-scale

boundary (landspout mechanism)• eg storm merger + “kink” in boundary

– Warn on conceptual model even if no rotation?


Conclusions• Highest winds at base of downburst may be

significantly below radar beam

• Must rely on indicators before core hits the ground

• MARC– Poor viewing angle?– Consider trends


Bottom Line: Many small-scale tornado and wind events will go undetected on 88D data

Even IF event is detected (eg TDWR), lead time will be very little if not negative

What do we do to anticipate severe winds or non-descending tornadoes?


Thanks!

[email protected]@noaa.gov

national weather service wilmington, oh seth binau dan hawblitzel noaa/nws wilmington oh june 23...

Documents

oh evident

oh ripley

z tday

ft agl slide

oh examples

d slide

z kiln

oh tdwr locations wfo