SPC day 2 outlooks will soon have probabilistic hazard outlooks!

SPC day 1 outlook probability of hail, soon to be available for day 2 outlooks

Starting on January 28, 2020, SPC tornado, hail and wind probability maps and products will become available for the SPC Day 2 Convective Outlook. SPC has been testing these products internally, and the quality of the accuracy has been deemed acceptable or official and public/private use. (Image courtesy of the Storm Prediction Center)

Starting on January 28, 2020, individual severe convective threats will be added to the Storm Prediction Center (SPC)’s day 2 convective outlook. Currently, the day 2 includes a total risk percentage. But advances in data, models, and forecaster experience has allowed SPC to advance the risk forecast product further, to be broken up into their individual hazards. SPC has been testing these products internally for some time, and the accuracy/quality of these products has been acceptable for release to the public. The National Weather Service explains:

“Research to operations and improvements in numerical forecast guidance, particularly with certain convection-allowing weather forecast models, are providing necessary confidence in the forecasting of these individual hazards into the Day 2 time frame. These improvements have allowed SPC to issue forecasts of individual hazard probabilities for tornadoes, damaging wind, and hail potential along with a separate probability for significant severe, if forecast, for each hazard type. These individual hazard probabilistic forecasts will replace the current “total severe” probabilistic forecast, fully mirroring the types of output from the Day 1 Convective Outlook, in terms of the Categorical risk forecast and the three individual probabilistic hazard forecasts.”

The high-resolution NAM model has shown some eye-opening skill over the past few years. In fact, this year, it has done remarkably well out to 36 hours, and advances in the HRRR model will continue to improve confidence as well.

These new products will mirror their day 1 counterparts exactly in terms of percentage probabilities, and associated graphics. This means that weather enthusiasts, emergency managers and those responsible for the safety of venues will see another excellent tool in the toolbox for determining the status and safety of events in the day 2 (tomorrow) timeframe.

Of course, AllisonHouse will carry these products after they become available, and we are excited to see this tremendous advance in science and technology!

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