Storm Prediction as A Source
Sometimes the worst storms seem to pop up out of no where, but believe it or not, forecasters in one organization spend every second of every day dissecting those threats for your safety. There primary goal is simple, giving citizens enough time in advance to react to a potential hazard.
The Storm Prediction Center, or SPC, is a government agency that operates under the National Weather Service and the National Oceanic and Atmospheric Administration. Everyday forecasters pinpoint areas of severe thunderstorm or tornado risk across the continental United States. Predictions are created as far as 8 days in advance, with their main thunderstorm outlooks or Convective outlooks focused on the first 3 days.
Bill Bunting, Chief of Forecast Operations, at the SPC says "The convective outlook is our forecasters assessment of where the risk areas exist across the lower 48 states and in general how widespread we expect those sever storms to be. it is a very useful tool for planning for citizens, emergency officials, and of course broadcast meteorologists."
The outlooks can be viewed by anyone, from those just interested in meteorology to those seriously concerned about a possible threat. Storm risk is narrowed down in an easy to read, color based system, that breaks the storm up into 5 possible categories. Each category has to do with the expected coverage of the storms across a given area and possible danger the storm possesses.
The levels begin with Marginal, the lowest level, then move to Slight or Enhanced, the mid range levels. Next is Moderate, with the final category set at high.
Bunting says "if the risk is marginal, we expect very isolated-just a few storms. and as the risk increases we get up into enhanced, moderate and high we expect more severe storms, so the risk to any given area is higher.”
Now this does not mean that if your in an area of low risk, that you won't receive dangerous storms. The Convective Outlook is focused on depicting the "likelihood" of a damaging storm, not the guarantee. The are can still have really bad, or even severe storms at a marginal risk level but the idea is that as the risk increases, the likelihood of something severe grows for any given location.
Another resource offered by the Storm Prediction Center are Mesoscale Discussions. These discussions focus on potential tornado formation and provide a more detailed that may not be known in advance. Mesoscale discussions pinpoint areas that have potential of large damaging hail, and damaging wind gusts of 65 mph or higher, as well as risk of tornadoes.
During Spring and Summer it is not uncommon that forecasters will map out large areas of thunderstorm or tornado risk.
How do they decide where to draw the lines? Well it comes down to several years of forecast skill.
Bunting says “a lot of information goes into the forecast process but in the end its a human judgment.” The forecasters locate severe storms everyday and they very quickly get the type of skill and expertise needed to alert residents within a given area. He also says that they aren't always perfect, but they are very useful especially when preparing for the worst case scenario.
To access the convective outlooks for Days 1, 2 and 3, Click http://www.spc.noaa.gov/products/outlook/
For the general website Click http://www.spc.noaa.gov/
For updated Mesoscale Discussions Click http://www.spc.noaa.gov/products/md/