On March 7, 2008, a deep upper-level trough strengthened over the central U.S.  The image below shows the trough at 500-hPa, or about 20,000 feet above the ground.  At 7 pm, the trough was positively-tilted, meaning its axis was oriented southwest to northeast. By 7 am on March 8, the trough had strengthened and became negatively tilted, or oriented from northwest to southeast.  Negatively-tilted troughs imply that a storm system is strengthening and reaching maturity, as was the case here.  This orientation favors advection of cold air at upper levels, and strong advection of warm air at low levels, which creates instability and allows low pressure at the surface to deepen.

500 hPa:



Further down in the atmosphere at 850 hPa (about 5,000 feet), the area of low pressure deepened from 7 pm on the 7th to 7 am on the 8th.  This caused a surge of warm air to advect toward the center of the low from the southeast, while cold air funneled in from the northwest.  As a result, the temperature gradient over Ohio increased, a process known as frontogenesis.  This process is evident in the maps below by the way the temperature lines (dashed red and blue) become packed closer together across Ohio and West Virginia.  Frontogeneis is an important factor in many heavy snow events.  This process enhances vertical motion, often creating bands of heavy snow.

850 hPa:



Finally, we analyze the surface maps at 7 pm on March 8th, and 7 am on March 9th.  As the upper trough became negatively tilted, it resulted in a rapidly deepening surface low, apparent in the maps below.  When surface lows deepen rapidly, they often bring a surge of warm air from the southeast, which causes the low to deepen further.  When the surge of warm air reaches the surface low, it may slant upward with height, resulting in a surge of warm air aloft and increasing frontogenesis.  This, in turn, increases the heavy precipitation threat.  Finally, as the low deepened, the tight pressure gradient to the northwest of the surface low resulted in very strong winds and near-blizzard conditions across much of Ohio. 

Surface: