QUANTITATIVE APPLICATIONS OF BROADCAST MEDIA WEATHER RADAR DATA Neil I. Fox Department of Atmospheric Science University of Missouri-Columbia Columbia, MO

With thanks to Mike Roberts (KRCG – TV) Mike Roberts (KRCG – TV) –Also Matt Chambers and Kelly Green Stacy Allen (Premier Marketing Group) Stacy Allen (Premier Marketing Group)

Content What’s the problem? What’s the problem? Why use media radars? Why use media radars? Why not use them? Why not use them? Let’s see an example! Let’s see an example!

US Nexrad network

Factors limiting the utility of the WSR-88D to detect or measure weather phenomena (Adapted from Wilson) Factors limiting the utility of the WSR-88D to detect or measure weather phenomena (Adapted from Wilson) Weather Typical max Range limiting Weather Typical max Range limiting Phenomena Range (km) Factors Supercell mesocyclone resolution, overshoot mesocyclone resolution, overshoot hookecho resolution, overshoot hookecho resolution, overshootMini-supercell miso (<4km) or miso (<4km) or mesocyclone resolution, overshoot mesocyclone resolution, overshoot hookecho resolution, overshoot hookecho resolution, overshoot Misocyclone resolution, overshoot Tornado Vortex resolution, overshoot Signature Microburst/Macroburst overshoot reflectivity signature overshoot velocity signature overshoot resolution velocity signature overshoot resolution

Precipitation Estimation convective rain overshoot, resolution stratiform Rain overshoot, brightband resolution lake effect snow overshoot, clutter. lake effect snow overshoot, clutter. Winds overshoot, Convergence Lines (warm season) overshoot, resolution, (warm season) overshoot, resolution, Melting level resolution (bright band). Winter storms overshoot

Range related errors in Precip estimation

Relative Beam heights St Louis: KLSX Fulton Pleasant Hill, KEAX

Not so simple Media radars usually don’t give a full volume scan, so we cannot say that information is ‘better’ (more useful) even when beam is lower. Media radars usually don’t give a full volume scan, so we cannot say that information is ‘better’ (more useful) even when beam is lower.

Beamwidths (resolution) St LouisFulton Pleasant Hill, KC

Use of broadcast radars Regular low-level PPI Regular low-level PPI Flexibility when desired Flexibility when desired –But must put broadcasters’ needs first

Benefits to be gained Low-level cold season precip Low-level cold season precip Low-level modification of warm season precipitation Low-level modification of warm season precipitation Low-level and small-scale (high-resolution) rotation Low-level and small-scale (high-resolution) rotation Boundaries Boundaries

Low-level rotation Ideally we want to observe this at more than one elevation to confirm: Ideally we want to observe this at more than one elevation to confirm: –That it’s real –That it has some vertical extent

Limitations Quality Control Quality Control Calibration Calibration Staffing considerations Staffing considerations Only PPI Only PPI

Benefit to Broadcasters Publicity Publicity Community service Community service Radar is not really used most of the time Radar is not really used most of the time

 S-band  1  Beamwidth  250kW  25m tower

Example from the tornado outbreak of May 2003 Numerous rotations spotted (and shown on TV) using the radar, but not detected by NWS radars Numerous rotations spotted (and shown on TV) using the radar, but not detected by NWS radars Some (small) hook echo features clearly observable were not so clear with NWS radar imagery Some (small) hook echo features clearly observable were not so clear with NWS radar imagery

Chariton County is roughly 105 km from the radar site in Fulton and the beam height is roughly 1550 m. KEAX is 150 km: 2750 m. KLSX is 210 km away: 4300 m.

The Northern Audrain County Cell: From Fulton : m From KEAX: 4150 m From KLSX: m. The Boone County Cell: From Fulton: m. From KEAX: m. From KLSX: m

Not alone Using the radar as a supplement to NWS can provide valuable additional information Using the radar as a supplement to NWS can provide valuable additional information There’s a long way to go before we can integrate these data There’s a long way to go before we can integrate these data

This winter Routine data collection (inc. Level II CRAFT data) Routine data collection (inc. Level II CRAFT data) Cold season precipitation comparisons Cold season precipitation comparisons Assessment of potential benefits to local interests Assessment of potential benefits to local interests