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Reconsidering Use of “Low” in TCIG Level Descriptors. Rob Molleda National Weather Service Miami/South Florida Forecast Office. Impact Levels are Relative, But. Users may not be thinking in same relative sense. Impact severity is subjective.
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Reconsidering Use of “Low” in TCIG Level Descriptors Rob Molleda National Weather Service Miami/South Florida Forecast Office
Impact Levels are Relative, But... • Users may not be thinking in same relative sense. • Impact severity is subjective. • Local user feedback suggests that the term “Low” in the potential impacts can unintentionally send the wrong message.
Also... • Fairly wide range of impacts within the Low category. • Example: Low wind hazard describes impacts ranging from borderline TS to borderline Cat 1.
Examples of Current “Low” Definitions • Inland Flooding: Flood waters may prompt a few evacuations and brief road closures. • Wind: Unsecured light-weight objects easily blown about and become dangerous projectiles. Dangerous driving conditions on bridges and other elevated roadways, especially for high profile vehicles. • These definitions fit better and can be better described under a separate “Elevated” category between Low and Moderate, with “Low” reserved for very minor impacts.
SPC Has Similar Issue • SPC will experiment with an additional “Enhanced” risk level in 2013. • Enhanced risk will be between SLGT and MDT
Proposed Changes • 1. Replace “Low” with “Elevated (or similar wording). • 2. Add a separate “Elevated” category between Low and Moderate. • Color scheme would be: Low (light blue), Elevated (yellow). • Personal preference is for #2 due to greater consistency with experimental SPC categories.
Pros/Cons • Pro: Separate borderline moderate conditions from very minor ones (think SPS/SVR or Urban Flood Advisory/FFW. Less potential for underestimation of threat by public. • Con: Adding an extra category could slightly add to forecaster workload.
Recap • Current use of “Low” descriptor in TCIG may be correct in a relative sense, but can mislead the public into thinking that a low threat is unimportant. • “Elevated” or a similar-worded term to cover borderline moderate conditions can more effectively convey a significant threat to life and/or property.
Questions? Thank you for your time! National Weather Service Miami/South Florida Forecast Office