Many of the severe weather index value are enhanced by the following ingredients: warm at surface, humid in lower troposphere, unstable, strong surface winds, wind speed changing speed and direction with height. It is the morning time when the troposphere tends to be most stable, when wind speeds are less, and when surface temperatures are coolest. This is why a morning sounding is not always a good indicator of severe weather. However, if it is already warm, humid, unstable with strong winds at the surface then you can expect the sounding to become even more favorable for severe weather later in the day provided the unstable air mass remains over the area. A morning sounding may not be a good indicator for severe weather later in the day because the atmosphere can change through several processes even if the morning sounding looks great for severe weather. A few are given below: Cold Air Advection (cold front) passage makes troposphere more stable Drier air may advect in at the surface reducing the storm chance Cap aloft could strengthen during the day There may not be a lifting mechanism to initiate storms Wind shear could weaken It is a good idea to look at forecast soundings using model data to get an idea of how the morning sounding will change during the day. |