Impact Guidance - Aviation Products

A new set of aviation products have been added to the Impact Guidance that are based on surface observations...they include:

Probability of >3 h MVFR or worse

Probability of >3 h IFR or worse

Probability of >3 h LIFR

Probability of >3 h VIS <5 SM

Probability of >3 h VIS <3 SM

Probability of >3 h VIS <1 SM

Probability of >3 h CEILING <3000 ft

Probability of >3 h CEILING <1000 ft

Probability of >3 h CEILING <500 ft

These are probabilities of the above occurring +/- 12 h from the analog valid time based on the top 15 historical events.

NWS Forecast Offices have asked if products like these can be added to the impact guidance to provide situational awareness beyond traditional TAF forecasts for visibility and ceiling issues. An example of the products are shown below in the Probability of >3 h IFR (or worse) Product. Using the Southeast U.S. domain and based on a 48-h GFS forecast valid at 20121119/1200...the fields that are used to rank the similarity between the forecast and historical events show a significant signal (i.e., organized probabilities > 50%) for IFR conditions across northern Florida.

Below are the surface flight rule observations across the southeastern U.S. valid at 20121119/1200 that show IFR conditions (observations in red) in this area associated with low ceilings.

Please remember that these are new products and their usefulness (or uselessness) is still to be determined. In addition, it may be helpful to focus on the organized probabilities in and close to the domain of interest. These products will most likely be useful when organized aviation threats are possible. If you find that these products are useful as a situational awareness tool, please let us know.