One definition of a bust is a complete failure.  Add to that definition the snow accumulation forecast of March 1, 2009.  Now that forecast was a bust.  It may have been less painful if it had occurred a month later.  Most people would have laughed it off as a cruel joke.

    However, the forecast for much of that day was for the focus of heavy snow to occur in the Piedmont from Greenwood, SC to Charlotte, NC.  In that area I was forecasting 4-6" of snow.  The forecast for Columbia was about 2 inches maximum with lesser amounts south of the city.

    It turns out that the focus of the heavy snow was about 50 miles farther north along the I-85 corridor.  The result was no accumulation for much of the Midlands.  Accumulations were confined to parts of Newberry and northwestern Fairfield counties.  Snow was observed in the Columbia area, but it was mixed with rain so as to preclude any accumulation.

    This is not the first time that such forecasts have failed to materialize.  I can remember other forecasts of 1-2 inches for Columbia that have met with the same result; no accumulation.  To be sure this was going to be a difficult forecast.   First, there was heavy snow from east of Atlanta to Greenville to Charlotte.  Everything seemed on track that afternoon.

    Second, I knew that the snow accumulation gradient was going to be tight on the south side of the snow band.  However, there was no way to forecast this due to the margin of errors in the computer models.  It remains extremely difficult to forecast no snow for one point then 4 inches just 20 miles away.

    Finally, there was the issue of warm soil temperatures.  The soil temperatures for the Midlands measured at the 4 inch depth that morning were in the mid 50s.  Thus, if the snow was heavy enough to accumulate, then there would be some melting by the warm ground.  It was assumed that the first 1-2 inches might melt.

    Those concerns were factored into my forecast as I tried to forecast the snowfall estimates.  However, there were other issues in the atmosphere that were not resolved by the computer models.  I have heard some say that dry air became entrained in the system much like what happens in hurricanes to weaken the storm.  That may have happen, but I have been unable to find any evidence of that.  In fact, precipitation continued to be intermittent until midnight.

    A thorough analysis of the atmospheric conditions needs to be made to uncover the true picture.  My suspicion is that the dynamics did not evolve as the models projected.  Let me point out that the surface and mid-level (4500 feet) low pressure systems became tilted and stretched making it difficult to intensify.  The systems did intensify, but not until farther up the coast.  An examination of the moisture field shows that there was ample low-level moisture.  This is evident by the heavy snow band just to the north.

There seems little chance that a different forecast would have been made based on what we know at present.  Thus, there will continue to be the chance that future snowfall forecast will bust.

    Some have accused me of hyping the situation which has no foundation in fact.  In 25 years of forecasting weather in Columbia I have never hyped a bad weather situation.  I have done the opposite when it comes to snow.  Once the four-letter word is uttered, people don't hear anything else.  So I tend to be cautious when it comes to winter weather.  In fact, bad weather does not need to be hyped; I already have your attention.

    What I have done, presently do, and will continue to do is give you my best estimate of what will happen.  This is true of snow, tornadoes, hurricanes, drought, and sunny days.  Bust are a fact of life in weather forecasting, however I can not remember one of this magnitude in the recent past.  Fortunately, they do not happen often.